**1. Introduction**

The classic case of aortic stenosis is a healthy middle-aged patient with/without symptoms, but in practical life, patients with severe calcific aortic valve come with several and severe comorbidities such as advanced age, coronary artery disease, atherosclerotic aorta, significant left ventricular dysfunction. Aortic valve replacement (AVR) is the only options in these patients, and it requires patient-by-patient analysis of clinical, echocardiograhic, and hemo‐ dynamic data with associated pathologies. The curative treatment of calcific aortic valve stenosis is the replacement of the aortic valve with a prosthetic valve, and selection of a perfect prosthetic valve is the main goal to get a successful treatment. But, there is no any perfect heart valve prosthesis which may mimic the characteristics of the normal native aortic valve: excellent hemodynamics, life-long durability, thromboresistance, and excellent implantability. That means that native valve disease will be traded for prosthetic valve disease and the outcome of AVR is affected by the type of prosthetic valve. Mechanical valves are non-limited durable, but have a substantial risk of hematologic complications (thromboemboli, thrombotic obstruction, hemorrhage related life-long anticoagulation therapy) with/without hemolysis potential. In contract, bioprosthetic valves have a low risk of thromboembolism without anticoagulation, but their durability is limited by calcific or noncalcific tissue deterioration. Biological prostheses, especially homografts, are often believed to be the substitute of choice in AVR, but the limited availability of homografts prevents their more broadly usage. To overcome this problem and all possible complications of mechanical valves, xenogenic biological prostheses have been developed. The design of bioprosthetic valves purports to mimic the anatomy of the native aortic valve and their flow characteristics are better than mechanical valves, whereas stentless bioprostheses have hemodynamic performance similar to the healthy native aortic valve. Although stented bioprostheses can be implanted easier,

© 2013 Kirali; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

they decrease the effective orifice area due to the rigid stent and result turbulent flow through the valve. Stented valves also increase stress at the attachment of the stent which cause earlier primary tissue failure. Stentless biologic valves have been introduced into clinical practice to solve all these problems and to reproduce the anatomy and function of the native aortic valve, but their clinical use has still not exceeded the number of stented aortic bioprostheses because of more demanding technique of implantation. To gain more widespread clinical use and general recommendation of stentless bioprostheses, their advantages and simple implantation techniques must be popularized.

especially in younger patients, which are less durable than commercially available stentless bioprostheses and cannot be recommended as the ideal device [9]. The use of the patients own pericardium for constructing a heart valve prosthesis is biologically more appealing than the use of animal tissue or heterologous material. The feasibility of autologous pericardial stentless aortic valve was shown in an animal study [10]. The feasibility and durability of truly stentless autologous pericardial AVR sutured directly onto the aortic wall has been also performed in human recently [11]. Stentless porcine or pericardial xenogenic bioprostheses have been introduced to get better long-term durability and become a routine device when a stentless

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There are a lot of stentless bioprostheses with/without the aortic root in the market, but some of them are not used widespread and implantation of a few xenografts is stopped (Table 1). The first modern (first generation) stentless valves were glutaraldehyde-fixed porcine prostheses with a fully scalloped shape or a complete aortic root (Figure 1). The most preferred approach was root replacement technique because subcoronary approach needed more suture line. The second generation of stentless valves improved the technical difficulties related to free-hand implantation with two rows of sutures for subcoronary implantation of porcine bioprostheses (Figure 2). The third generation of stentless prostheses are made by xenogenic pericardium, because the pericardial valve is free from the compromises of the porcine aortic root, it is flexible, and easy to implant either with an interrupted or running suture technique (Figure 3). There are different xenogenic pericardial valves (bovine or equine), and horse pericardium is thinner, however, stronger than the bovine pericardium and also much more pliable. The fourth generation of stentless valves are produced by a proprietary process and the unique conditioning technology paves the way for autologous repopularization of the valve in patients. The durability of current bioprosthetic heart valves is diminished by glutaraldehyde-associated leaflet calcification or by the host immune reaction. As a novel tissue engineering approach to improving replacement heart valve durability, a new acellular (nonglutaraldehyde-fixed) tissue heart valve for autologous recellularization is developed to limit xenograft antigenicity. As no glutaraldehyde is used in the whole process lack of calcification and also lack of toxicity, and the method delivers a very pliable valve with very low gradients. To use of autologous pericardium fixed with glutaraldehyde avoids any immune reaction between the host and the implanted heart valve and so minimizes tissue calcification and pannus formation. The last generation of stentless valves provides avoidance of suture lines during AVR: closed [transcatheter (transfemoral or transapical)] or open

Every effort should be made to avoid moderate prosthesis-patient mismatch during AVR. Stentless valves enable to select the largest bioprosthesis to the patient's annulus and provide better aortic root and valve behavior, larger effective orifice area (EOA), reduced transpros‐

biologic valve is implanted.

(transaortic = sutureless) techniques (Figure 4).

thetic gradient and greater left ventricular mass regression.

**2. Hemodynamic recovery**

It is believed that the aortic root is probably the best stent for the native or prosthetic aortic valve. The anatomy and function of the aortic root may dampen the mechanical stress to which the leaflets are subjected during diastole. The ideal stentless prosthesis should have no synthetic materials, preserve the aortic root dynamics, restore flexibility and distensibility of the native valve annulus after decalcification, and have minimal xenograft aortic wall, short implantation time, and excellent hemodynamic performance to facilitate the recovery of left ventricular function.

#### **1.1. Historical background**

Homografts were the first biological prostheses used in clinical practice to treat aortic valve stenosis in early 1960s, and they were the first stentless valves, too [1,2]. The authors used the aortic root of the patient to secure the homograft aortic valve in the subcoronary position. The most complicated implantation technique and the restricted availability of homografts prevented their widespread usage. First stentless pig and calf xenografts were used in limited patients, but the valves were abandoned because of poor tissue fixation [3]. Stented biopros‐ theses were considered as the gold standard for several years, but abnormal stress on the leaflets was believed to decrease durability. To overcome this problem with a rigid stent on the aortic position, stentless bioprostheses were re-introduced in the middle of 80's [4], whereas new designed stentless xenografts were proposed and popularized in daily use at the begin‐ ning of 1990s [5]. The main problem (early failure of bioprostheses) was solved with new bioengineering improvement (antimineralization, zero-pressure fixation) [6]. The other problem was partial dehiscence when the heterograft contained muscular bar resulting paravalvular leakage in the area corresponding to the muscular bar, and this problem was abolished with a fine Dacron cloth covered the outside wall of the stentless porcine aortic valve along its inflow [7]. Recognizing the range of aortic root variability and disease of the root itself, the concept of stentless valve replacement was expanded to replacement of the entire aortic root. Full root replacement with a bioprosthesis brought the challenges of homeostasis and coronary reimplantation. In spite of hemodynamic advantages proven for the root replacement technique, acceptance was slowed by risk/benefit ratio concerns. The whole aortic root could be prepared and implanted with modified root inclusion or subcoronary implant techniques.

Biological stentless valve can be prepared by pulmonary autograft, homograft, xenograft, autologous or xenogenic pericardium. Pulmonary autograft has limited durability beyond the first decade [8]. The same problem has been observed with homografts in the aortic position,

especially in younger patients, which are less durable than commercially available stentless bioprostheses and cannot be recommended as the ideal device [9]. The use of the patients own pericardium for constructing a heart valve prosthesis is biologically more appealing than the use of animal tissue or heterologous material. The feasibility of autologous pericardial stentless aortic valve was shown in an animal study [10]. The feasibility and durability of truly stentless autologous pericardial AVR sutured directly onto the aortic wall has been also performed in human recently [11]. Stentless porcine or pericardial xenogenic bioprostheses have been introduced to get better long-term durability and become a routine device when a stentless biologic valve is implanted.

There are a lot of stentless bioprostheses with/without the aortic root in the market, but some of them are not used widespread and implantation of a few xenografts is stopped (Table 1). The first modern (first generation) stentless valves were glutaraldehyde-fixed porcine prostheses with a fully scalloped shape or a complete aortic root (Figure 1). The most preferred approach was root replacement technique because subcoronary approach needed more suture line. The second generation of stentless valves improved the technical difficulties related to free-hand implantation with two rows of sutures for subcoronary implantation of porcine bioprostheses (Figure 2). The third generation of stentless prostheses are made by xenogenic pericardium, because the pericardial valve is free from the compromises of the porcine aortic root, it is flexible, and easy to implant either with an interrupted or running suture technique (Figure 3). There are different xenogenic pericardial valves (bovine or equine), and horse pericardium is thinner, however, stronger than the bovine pericardium and also much more pliable. The fourth generation of stentless valves are produced by a proprietary process and the unique conditioning technology paves the way for autologous repopularization of the valve in patients. The durability of current bioprosthetic heart valves is diminished by glutaraldehyde-associated leaflet calcification or by the host immune reaction. As a novel tissue engineering approach to improving replacement heart valve durability, a new acellular (nonglutaraldehyde-fixed) tissue heart valve for autologous recellularization is developed to limit xenograft antigenicity. As no glutaraldehyde is used in the whole process lack of calcification and also lack of toxicity, and the method delivers a very pliable valve with very low gradients. To use of autologous pericardium fixed with glutaraldehyde avoids any immune reaction between the host and the implanted heart valve and so minimizes tissue calcification and pannus formation. The last generation of stentless valves provides avoidance of suture lines during AVR: closed [transcatheter (transfemoral or transapical)] or open (transaortic = sutureless) techniques (Figure 4).

#### **2. Hemodynamic recovery**

they decrease the effective orifice area due to the rigid stent and result turbulent flow through the valve. Stented valves also increase stress at the attachment of the stent which cause earlier primary tissue failure. Stentless biologic valves have been introduced into clinical practice to solve all these problems and to reproduce the anatomy and function of the native aortic valve, but their clinical use has still not exceeded the number of stented aortic bioprostheses because of more demanding technique of implantation. To gain more widespread clinical use and general recommendation of stentless bioprostheses, their advantages and simple implantation

It is believed that the aortic root is probably the best stent for the native or prosthetic aortic valve. The anatomy and function of the aortic root may dampen the mechanical stress to which the leaflets are subjected during diastole. The ideal stentless prosthesis should have no synthetic materials, preserve the aortic root dynamics, restore flexibility and distensibility of the native valve annulus after decalcification, and have minimal xenograft aortic wall, short implantation time, and excellent hemodynamic performance to facilitate the recovery of left

Homografts were the first biological prostheses used in clinical practice to treat aortic valve stenosis in early 1960s, and they were the first stentless valves, too [1,2]. The authors used the aortic root of the patient to secure the homograft aortic valve in the subcoronary position. The most complicated implantation technique and the restricted availability of homografts prevented their widespread usage. First stentless pig and calf xenografts were used in limited patients, but the valves were abandoned because of poor tissue fixation [3]. Stented biopros‐ theses were considered as the gold standard for several years, but abnormal stress on the leaflets was believed to decrease durability. To overcome this problem with a rigid stent on the aortic position, stentless bioprostheses were re-introduced in the middle of 80's [4], whereas new designed stentless xenografts were proposed and popularized in daily use at the begin‐ ning of 1990s [5]. The main problem (early failure of bioprostheses) was solved with new bioengineering improvement (antimineralization, zero-pressure fixation) [6]. The other problem was partial dehiscence when the heterograft contained muscular bar resulting paravalvular leakage in the area corresponding to the muscular bar, and this problem was abolished with a fine Dacron cloth covered the outside wall of the stentless porcine aortic valve along its inflow [7]. Recognizing the range of aortic root variability and disease of the root itself, the concept of stentless valve replacement was expanded to replacement of the entire aortic root. Full root replacement with a bioprosthesis brought the challenges of homeostasis and coronary reimplantation. In spite of hemodynamic advantages proven for the root replacement technique, acceptance was slowed by risk/benefit ratio concerns. The whole aortic root could be prepared and implanted with modified root inclusion or subcoronary implant

Biological stentless valve can be prepared by pulmonary autograft, homograft, xenograft, autologous or xenogenic pericardium. Pulmonary autograft has limited durability beyond the first decade [8]. The same problem has been observed with homografts in the aortic position,

techniques must be popularized.

ventricular function.

412 Calcific Aortic Valve Disease

techniques.

**1.1. Historical background**

Every effort should be made to avoid moderate prosthesis-patient mismatch during AVR. Stentless valves enable to select the largest bioprosthesis to the patient's annulus and provide better aortic root and valve behavior, larger effective orifice area (EOA), reduced transpros‐ thetic gradient and greater left ventricular mass regression.

**Figure 1.** First generation bioprostheses (Porcine Stentless Xenografts) A) Scalloped stentless porcine bioprostheses B) Root stentless porcine bioprostheses.

Stented valves fixe the native commissures and do not allow cyclic change of the commissural dimension as it normally occurs. This cyclic expansion of the commissural area serves reduction of stress on the leaflets, which is preserved by stentless bioprostheses. Second, the intrinsically obstructive nature of the stented bioprostheses increases pressure gradient and creates turbulent flow patterns, however, normal laminar flow patterns can be restored after AVR with stentless tissue valves. The opening and closing of the stentless biologic valve constitute a passive mechanism responding to pressure difference between the left ventricle and the aorta. Like the native aortic valve, a stress created by this difference heads toward the central coaptation area of the bioprosthesis during diastole. The negative pressure difference during diastole helps prosthetic valve to be closed. The valve opens rapidly at the beginning of ejection because of rising of pressure difference and persists to remain open as a tunnel

**Shelhigh Suprestentless**

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**Sorin Pericarbon Freedom Sorin Pericarbon Freedom SOLO 3F Therapeutics**

**3F Enable model 6000 Perceval S**

**Figure 3.** Third generation bioprostheses (Pericardial Stentless Xenografts)

**Figure 4.** Sutureless Pericardial Stentless Xenografts

**Figure 2.** Second generation bioprostheses.

To prevent early or late prosthetic failure, maintenance of the aortic root with physiological anatomy must be the primary goal during AVR with a stentless prosthesis. Any kind of bioprosthetic valve will deviate from native aortic valve in terms of leaflet dynamics. Stiffening of the aortic root either by glutaraldehyde or by stent degenerates the opening (wrinkles and blurry edges of leaflets) and closing (asynchronism) behavior of native aortic valve leaflets. Stentless Bioprostheses for Aortic Valve Replacement in Calcific Aortic Stenosis http://dx.doi.org/10.5772/55373 415

#### **Shelhigh Suprestentless**

**Figure 2.** Second generation bioprostheses.

**Figure 3.** Third generation bioprostheses (Pericardial Stentless Xenografts)

**Figure 4.** Sutureless Pericardial Stentless Xenografts

To prevent early or late prosthetic failure, maintenance of the aortic root with physiological anatomy must be the primary goal during AVR with a stentless prosthesis. Any kind of bioprosthetic valve will deviate from native aortic valve in terms of leaflet dynamics. Stiffening of the aortic root either by glutaraldehyde or by stent degenerates the opening (wrinkles and blurry edges of leaflets) and closing (asynchronism) behavior of native aortic valve leaflets.

**Figure 1.** First generation bioprostheses (Porcine Stentless Xenografts) A) Scalloped stentless porcine bioprostheses B)

(A)

414 Calcific Aortic Valve Disease

**St Jude Toronto SPV St Jude Medical-Biocor**

**St Jude SVP Root Edwards Prima Plus**

**Medtronic Freestyle Koehler Elan Root**

**Koehler Elan Labcor CryoLife-O'Brien**

(B)

Root stentless porcine bioprostheses.

Stented valves fixe the native commissures and do not allow cyclic change of the commissural dimension as it normally occurs. This cyclic expansion of the commissural area serves reduction of stress on the leaflets, which is preserved by stentless bioprostheses. Second, the intrinsically obstructive nature of the stented bioprostheses increases pressure gradient and creates turbulent flow patterns, however, normal laminar flow patterns can be restored after AVR with stentless tissue valves. The opening and closing of the stentless biologic valve constitute a passive mechanism responding to pressure difference between the left ventricle and the aorta. Like the native aortic valve, a stress created by this difference heads toward the central coaptation area of the bioprosthesis during diastole. The negative pressure difference during diastole helps prosthetic valve to be closed. The valve opens rapidly at the beginning of ejection because of rising of pressure difference and persists to remain open as a tunnel

during systole, and the aortic root may also expanse at the late diastole to help opening of the leaflets (in native aortic valve, expansion of the aortic root is about 12% and that starts opening the leaflets to about 20%). At the end of systole, the backward blood flow into the sinuses of Valsalva (behind prosthetic leaflets) and initialization of pressure difference help prosthetic leaflets to revert to their original closed position. An in-vivo-study has showed that there is no difference in opening velocities among native, stented and subcoronary stentless valves in a porcine model [12]. However, the closing velocities are significantly higher in the pericardial valves. The bending deformation increases when implanting a glutaraldehyde-treated valve subcoronary. Porcine stentless valves display a distinct folding pattern during opening resulting in an altered stress distribution and also tend to fold during opening causing

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One of the key parameters for stentless xenograft performance is the EOA. In spite of the EOA is significantly higher in stentless bioprostheses it is also dependent on the design and the implantation technique of the prostheses. The EOA will increase especially during the first year and the transvalvular gradient drops dramatically in the first 3 to 6 months after surgery, but some further drop may be seen more later [14]. The reason may be remodeling of the left ventricular outflow tract, diminished aortic root edema, and slight dilatation of the aortic root. Transvalvular gradient is closely related to the EOA: the larger orifice area the lower is the transvalvular gradient. The second reason to increase transvalvular gradient is usage of a rigid stent. Avoidance of a stent enlarges inner diameter of prosthetic valve and eliminates intralu‐ minal obstruction which increases the EOA. Several studies have shown transvalvular gradient across stentless valves is always lower than for their stented valves, especially mean and/or peek gradients [15-1617]. The third possible reason can be excessive tissue of a bio‐ prosthesis: the lesser tissue implanted within the recipient aortic root the lesser obstruction. The full root prostheses reduce the intraluminar obstruction because nothing is implanted inside, and they have larger EOA than subcoronary prostheses. The main differences of stentless biologic tissue valves are the specific gravity of the leaflets which is not equal to that of blood like native human aortic leaflets and the specific thickness of the leaflets which is thinner in pericardial tissue valves. Both parameters cause transvalvular gradient during ejection which is lesser in fully pericardial stentless valves than porcine. The other reasons may be small aortic annulus and physically active patients. The change in gradients during exercise is interesting: when cardiac output increases it also increases the transvalvular flow and raises transprosthetic gradient, but these gradients under exercise are lower with stentless valves

than stented bioprostheses, which provide better opening-closing behavior [18].

Left ventricular output is maintained by the development of the left ventricular hypertrophy which results in a large pressure gradient across the stenotic valve. The left ventricle mass increases and becomes less compliant. Left ventricular hypertrophy and increased mass can be correlated with sudden death, congestive heart failure, and other cardiovascular events. Left ventricular hypertrophy will regress after AVR regardless of the type of prostheses, and an improved hemodynamic performance of prostheses should result in a faster regression, especially in patients with severe calcific aortic stenosis and left ventricular hypertrophy, because incomplete regression after AVR is related to poor long-term outcome [19]. This

increased leaflet bending stress [13].

**Table 1.** Stentless Bioprostheses.

during systole, and the aortic root may also expanse at the late diastole to help opening of the leaflets (in native aortic valve, expansion of the aortic root is about 12% and that starts opening the leaflets to about 20%). At the end of systole, the backward blood flow into the sinuses of Valsalva (behind prosthetic leaflets) and initialization of pressure difference help prosthetic leaflets to revert to their original closed position. An in-vivo-study has showed that there is no difference in opening velocities among native, stented and subcoronary stentless valves in a porcine model [12]. However, the closing velocities are significantly higher in the pericardial valves. The bending deformation increases when implanting a glutaraldehyde-treated valve subcoronary. Porcine stentless valves display a distinct folding pattern during opening resulting in an altered stress distribution and also tend to fold during opening causing increased leaflet bending stress [13].

**A. Autograft B. Homograft C. Xenografts**

416 Calcific Aortic Valve Disease

*Dacron reinforced inflow tract*

*pericardial reinforced inflow tract*

*tri-composite design (three noncoronary leaflets)*

**II. Second generation (porcine with single suture line,**

**III. Third generation (Stentless Pericardial Bioprosthesis)**

**IV. Fourth generation (non-gluteraldayhde fixed +**

**V. Sutureless generation (Sutureless + Stentless**

Koehler Elan Root

**No-react treatment)**

*porcine pericardium*

**decellularized)**

**Pericardial Bioprosthesis)**

**D. Autologous pericardium**

**Table 1.** Stentless Bioprostheses.

Matrix A

Sorin Pericarbon Freedom SOLO *horse (equine) pericardium*

**I. First generation (Stentless Porcine Bioprosthesis)**

Toronto SPV (stentless porcine valve) St Jude Medical, Inc., St Paul, MN, USA St Jude Medical-Biocor St Jude, Belo Horizonte, MG, Brazil

Koehler Elan Koehler, Bellshill, Scotland

Labcor Labcor, Inc., Belo Horizonte, MG, Brazil

Sorin Pericarbon Freedom Sorin Biomedica Cardio SpA, Saluggia, Italy

3F Therapeutics 3F Therapeutics, Inc., Lake Forest, CA, USA

3F Enable model 6000 3F Therapeutics, Inc., Lake Forest, CA, USA Perceval S Sorin Biomedica Cardio SpA, Saluggia, Italy

Shelhigh Suprestentless Shelhigh, Inc, Millburn, NJ, USA

CryoLife-O'Brien Model 3000 CryoLife International Inc, Atlanta, GA, USA Toronto SPV Root St Jude Medical, Inc., St Paul, MN, USA Edwards Prima Plus Edwards Lifesciences, Inc., Irvine, CA,USA Medtronic Freestyle Medtronic, Inc., Minneapolis, MN, USA

One of the key parameters for stentless xenograft performance is the EOA. In spite of the EOA is significantly higher in stentless bioprostheses it is also dependent on the design and the implantation technique of the prostheses. The EOA will increase especially during the first year and the transvalvular gradient drops dramatically in the first 3 to 6 months after surgery, but some further drop may be seen more later [14]. The reason may be remodeling of the left ventricular outflow tract, diminished aortic root edema, and slight dilatation of the aortic root. Transvalvular gradient is closely related to the EOA: the larger orifice area the lower is the transvalvular gradient. The second reason to increase transvalvular gradient is usage of a rigid stent. Avoidance of a stent enlarges inner diameter of prosthetic valve and eliminates intralu‐ minal obstruction which increases the EOA. Several studies have shown transvalvular gradient across stentless valves is always lower than for their stented valves, especially mean and/or peek gradients [15-1617]. The third possible reason can be excessive tissue of a bio‐ prosthesis: the lesser tissue implanted within the recipient aortic root the lesser obstruction. The full root prostheses reduce the intraluminar obstruction because nothing is implanted inside, and they have larger EOA than subcoronary prostheses. The main differences of stentless biologic tissue valves are the specific gravity of the leaflets which is not equal to that of blood like native human aortic leaflets and the specific thickness of the leaflets which is thinner in pericardial tissue valves. Both parameters cause transvalvular gradient during ejection which is lesser in fully pericardial stentless valves than porcine. The other reasons may be small aortic annulus and physically active patients. The change in gradients during exercise is interesting: when cardiac output increases it also increases the transvalvular flow and raises transprosthetic gradient, but these gradients under exercise are lower with stentless valves than stented bioprostheses, which provide better opening-closing behavior [18].

Left ventricular output is maintained by the development of the left ventricular hypertrophy which results in a large pressure gradient across the stenotic valve. The left ventricle mass increases and becomes less compliant. Left ventricular hypertrophy and increased mass can be correlated with sudden death, congestive heart failure, and other cardiovascular events. Left ventricular hypertrophy will regress after AVR regardless of the type of prostheses, and an improved hemodynamic performance of prostheses should result in a faster regression, especially in patients with severe calcific aortic stenosis and left ventricular hypertrophy, because incomplete regression after AVR is related to poor long-term outcome [19]. This regression is related to EOA and transvalvular gradient constituted by the prosthetic valve. A significant improvement will occur in all type of valves in the first year, but this improvement is greater and faster with the stentless bioprostheses [20]. A lasting benefit beyond the first year is possible, especially in severely enlarged ventricles [21]. These improvements include mass regression, wall thickening, fractional shortening, and diastolic relaxation. Patients with small aortic annuli or with compromised left ventricular function (EF < 50%) might benefit more from stentless prostheses [22,23].


*3.1. Gouy–Chapmann–Stern Model*

The GCS model is the simplest extension of the PB theory in accounting for the effect of the finite size of ions. As illustrated Figure 5, it conceptualizes the structure of EDLs near the electrode surface as being composed of two layers: (i) a compact Stern layer where the ions are immobile and strongly adsorbed to the electrode surface, with a thickness corresponding to the closest approach of hydrated ions to the electrode surface; (ii) a diffuse layer where thermal motion causes the ions to be spread out in space.

It follows that no free charges exist in the Stern layer, while the distribution of ions in the diffuse layer can still be described by the Boltzmann equation, i.e.,

$$n\_i = n\_{i, \infty} \exp\left(-\frac{z\_i e \psi}{k\_B T}\right) \tag{3}$$

where *ψ* is the electric potential (V), *ni*,∞ is number density (1/m3) of the *i*th species at the bulk solution, e is the elementary charge (C), *zi* is the valence of the *i*th species and *kB* is the Boltzmann constant (J/K), respectively.

The distribution of electric potential can, therefore, be described by the Poisson equation as

$$\nabla \times (\varepsilon\_0 \varepsilon\_r \nabla \psi) = -e \sum\_i z\_i n\_i \tag{4}$$

where *ε*0 and *εr* are the free space permittivity and the relative permittivity of the electrolyte solutions, ∇ is the divergence operator.

As a result, the GCS model can be expressed as:

$$\nabla^2 \psi = \begin{cases} 0 & \text{in Stern layer} \\ -\frac{c}{\varepsilon\_0 \varepsilon\_r} \sum z\_l n\_{i,\infty} \exp\left(-\frac{z\_l r \psi}{k\_B T}\right) & \text{in Diffuse layer} \end{cases} \tag{5}$$

subject to the following boundary conditions:

$$\left.\psi\right|\_{x=0} = \psi\_s \tag{6}$$

$$\left.\psi\right|\_{x=\delta^-} = \left.\psi\right|\_{x=\delta^+} \tag{7}$$

$$\left. \frac{d\psi}{d\mathfrak{x}} \right|\_{\mathfrak{x}=\delta^{-}} = \left. \frac{d\psi}{d\mathfrak{x}} \right|\_{\mathfrak{x}=\delta^{+}} \tag{8}$$

$$\left.\psi\right|\_{x\to\infty} = 0\tag{9}$$

where *x* is the normal distance from the electrode surface, *δ* is the thickness of the Stern layer and *ψs* is the surface potential, ∇2 is the Laplace operator.

The GCS model, as given above, is quite general in that it can be applied to electrode particles with any geometry immersed in any electrolyte solution and can readily be solved numerically to obtain the relation between the surface potential *ψs* and the surface charge *σs*. When used in practice, however, it is commonly assumed that the particle is of planar geometry and that the electrolyte is symmetric. For this special case, the analytical solution to the GCS model can be obtained to give the profile of electric potential *ψ* as a function of *x*,

$$\psi = \begin{cases} \begin{array}{c} \psi\_{\sf s} - \Delta \psi\_{\sf St} \times \text{x} / \delta \\ \frac{4k\_B T}{\varepsilon} \tanh^{-1} \left( \frac{\varepsilon \Delta \psi\_{\sf d}}{k\_B T} \right) \exp\left( \frac{\mathbf{x} - \delta}{\lambda\_D} \right) & \text{in Diffuse layer} \end{array} \tag{10}$$

with the Debye length *λD* given by:

$$
\lambda\_D = \sqrt{\frac{\varepsilon\_0 \varepsilon\_r k\_B T}{2c^2 n\_{i,\infty}}} \tag{11}
$$

where Δ*ψSt* is the electric potential drop across the Stern layer, Δ*ψSt* = *ψs* − *ψd*, Δ*ψd* is the electric potential difference across the diffuse layer, Δ*ψd* = *ψd* − *ψ*∞ and *ψd* and *ψ*∞ are the electric potential at the outer Stern plane and in the bulk solution, respectively.

It follows from Gauss' law that the surface charge *σs* can be related to both Δ*ψSt* and Δ*ψd* as

$$
\sigma\_{\rm s} = -\varepsilon\_0 \varepsilon\_r \left(\frac{d\psi}{d\mathbf{x}}\right)\Big|\_{\mathbf{x}=0} = -\varepsilon\_0 \varepsilon\_r \frac{\Delta\psi\_{\rm St}}{\delta} = \sqrt{8n\_{\rm cs}\varepsilon\_0 \varepsilon\_r k\_B T \sin\mathbf{h}\left(\frac{\mathbf{z}\varepsilon\Delta\psi\_d}{2k\_B T}\right)}\tag{12}
$$

The total differential capacitance of the double layer, *C*, can then be given by

$$\frac{1}{C} = \frac{1}{C\_{St}} + \frac{1}{C\_d} \tag{13}$$

where *Cst* and *Cd* are the differential capacitances to the Stern layer and the diffuse layer, respectively, with

$$\mathbf{C}\_{St} = -\frac{d\sigma\_s}{d\Delta\psi\_{St}} = \frac{\varepsilon\_0 \varepsilon\_r}{\delta} \tag{14}$$

and

$$\mathcal{C}\_{d} = -\frac{d\sigma\_{s}}{d\Delta\psi\_{d}} = \frac{\varepsilon\_{0}\varepsilon\_{r}}{\lambda\_{D}}\cos\mathrm{h}\left(\frac{ze\Delta\psi\_{d}}{2k\_{B}T}\right) \tag{15}$$

As a result, the surface charge density *σs* from Equation (12) can also be written as a product of Δ*ψSt* and *CSt*, i.e.,

$$
\sigma\_s = -\Delta \psi\_{St} \times \mathbb{C}\_{St} \tag{16}
$$

#### *3.2. Modified Poisson–Boltzmann–Stern Model*

The GCS model accounts for the effect of the finite size of ions only in the Stern layer but treats the ions in the diffuse layer still as point-charges. In the case of high ion concentration and high surface potential, however, the interfacial region can be largely enriched in counterions to the extent that the point charge hypothesis for the EDL structure leads to unrealistically high counterion concentrations in the vicinity of the solid/solution interface [34]. This fact means a non-negligible role of the size of the ions, even in the diffuse layer, and therefore, as illustrated in Figure 5, a maximum ion concentration must exist corresponding to the closed packing of ions. As a result, the model for the diffuse layer should properly be modified to address the non-ideal behavior of ions therein. This leads Bikerman [34–36] to arrive at, by means of the approximate "free volume" approach:

$$m\_i = \frac{n\_{i,\infty} \exp\left(-\frac{z\_i c \psi}{k\_B T}\right)}{1 + \nu \sum\_k n\_{k,\infty} \left[\exp\left(-\frac{z\_k c \psi}{k\_B T}\right) - 1\right]}\tag{17}$$

where *ν* has the meaning of average excluded volume per ion.

When combined with the Poisson equation and consideration of a Stern layer, the MPBS model can be written for a (*z*:*z*) symmetric electrolyte as,

$$\nabla^2 \psi = \begin{cases} 0 & \text{in Stern layer} \\ -\frac{\varepsilon}{\varepsilon\_0 \varepsilon\_r} \frac{2zu\_\infty \sin \hbar \left(\frac{x\phi}{k\_B T}\right)}{1 + 2\nu \sin \hbar^2 \left(\frac{x\phi}{2k\_B T}\right)} & \text{in Diffuse layer} \end{cases} \tag{18}$$

with

$$\mathbf{v} = 2d^3 n\_{\infty} \tag{19}$$

where *d* is the spacing of counterions near a highly charged surface, and it is unnecessarily the diameter of the counterions. One may think of it as a cutoff [36] for the unphysical divergences of PB theory and could include at least a solvation shell (ion–ion correlations could effectively increase it further).

Equation (18) should also be subject to the same boundary conditions of Equations (6)–(9) as the GCS model, and therefore it is also convenient to be solved numerically. However, for a planer electrode surface, an analytical solution to the surface charge density *σs* is available for a symmetric electrolyte and it can be written as,

$$\sigma\_{\rm s} = -2z e n\_{\rm cs} \lambda\_D \sqrt{\frac{2}{v} \ln \left[ 1 + 2v \sin \text{h}^2 \left( \frac{z e \Delta \psi\_d}{2k\_B T} \right) \right]} \tag{20}$$

The relation between *σs* and Δ*ψSt*, as given in Equation (16), also holds in the MPBS model.


*3.1. Between Groups Comparison (ANOVAs)*

As reported in Table 3, psychiatric patients demonstrated lower scores on DASS-21 Anxiety, BRCS, Risk Perception, and Worry. In more detail, ANOVAs showed a significant difference between groups on DASS-21 Anxiety and Stress, Risk Perception, and Worry. In particular, psychiatric patients scored lower on Stress and higher on Anxiety, Perceived Risk of getting infected with COVID-19 and Worry about the emergency situation, compared to healthy controls.

**Table 3.** Between groups comparison (ANOVAs).

Note. BRCS: Brief Resilient Coping Scale. Emboldened results were found to be significant, with *p* < 0.05.

No significant differences were found between groups on DASS-21 Depression and the BRCS.


**2.5 Extracorporeal life support (ECLS) for life-threatening complications in MPM's surgery: is it worthwhile?**

In thoracic surgery, the use of ECLS in the postoperative period is augmented in the last decades [53]. Up to now, the unique absolute contraindication to extracorporeal membrane oxygenation (ECMO) is a pre-existing state incompatible with healing, such as an end-stage tumor [54]. Literature provides only a few reports on ECLS as a bridge to support oncological patients affected by complications of their illness [55], its therapy [56, 57] or cardiac arrest [58]. MPM is a locally aggressive tumor, with a very poor prognosis. The multimodality therapies including surgery offered to selected cases (early stages with epithelial histology) are often characterized by major and/or minor perioperative morbidities [13]. According to Burt et al., the EPP is burdened by a significantly higher rate of acute distress respiratory syndrome (ARDS) (8.4 vs. 0.8%) and 30-day mortality (10.5 vs. 3.1%), compared to the PD [52, 59]. Anyhow, in the case of perioperative complications after surgery for MPM the employment of ECLS represents an ethical dilemma due to the fatal nature of this malignancy.

Fica and collaborators mentioned the use of a single-site veno-venous ECMO to support ventilation in an early post-pneumonectomy broncho-pleural fistula [57], while Bellini and collaborators successfully used the veno-arterial (V-A) ECMO as cardiac support in two MPM patients (66%), conversely, the only case (33%) of V-A ECMO implanted primarily for respiratory support in pneumonia-associated ARDS of the residual lung had a negative outcome [60]. Similar results were reported in the literature; according to Gow and collaborators, patients with a better pulmonary reserve and cardiac indication for ECLS are the better oncological candidates for ECMO [61].

The disease process itself and/or the employed treatments lead patients with thoracic cancer to have less pulmonary reserve compared to adults generally demanding ECLS. Secondary infections and bleeding are the major problems for the use of ECLS for oncological patients [61], both potentially life-threatening. In this scenario, on one hand, we have potentially reversible complications not responsive to conventional therapies, while on the other hand frail and immunosuppressed patients with poor prognosis and at risk to develop life-threatening ECMO-related drawbacks.

In accordance with the aforementioned recent literature, in case of a potentially reversible condition especially if heart-related, ECLS could be used as a stopgap device until common therapies work, in very selected MPM patients, permitting the recovery and the completion of the multimodal protocol [60, 61].

#### **2.6 Palliative surgery**

The MesoVATS trial is an open-label randomized controlled trial conducted in 12 centres in the United Kingdom, that compared PP by VATS versus talc pleurodesis in *Surgical Management of Malignant Pleural Mesothelioma: From the Past to the Future DOI: http://dx.doi.org/10.5772/intechopen.103686*

patients with MPM [62]. There were no differences between groups in the OS at 1 year nor at 6 months of follow-up. Furthermore, the benefits of VATS-PP (better quality of life, less short-term pleural effusion) do not balance the inconveniences (surgical complications and longer hospital stay leading to more costs). Guidelines strongly recommend talc poudrage via thoracoscopy to control a recurrent MPM effusion as the first choice to achieve pleurodesis in patients with expanded lungs, while weakly suggest, with a low grade of recommendation, palliative VATS-PP to obtain pleural effusion control in symptomatic patients fit enough to undergo surgery who cannot benefit from (or after the failure of) chemical pleurodesis or indwelling catheter [8].

### **2.7 Surgery for MPM relapse**

Recurrence of MPM after multimodality treatment is a common problem. Nevertheless, there has been no established therapy for relapse to date. Major studies about the treatment of recurrent MPM are reported in **Tables 3** and **4**. Over the literature, MPM with distant spread (associated or not with local relapse) is the most frequent pattern of recurrence, mostly in the EPP group, while the PD group showed a higher local-only failure rate [63–71]. A poor prognosis for recurrent MPM after multimodality treatment has been reported in the literature, with a median postrecurrence survival (PRS) after EPP ranging from 3 to 6.5 months [64–66, 72]. Newly,

*MPM: malignant pleural mesothelioma; EPP: extrapleural pneumonectomy; PD: pleurectomy/decortication; NR: not reported; L: local; D: distant; L + D: local+distant.*

#### **Table 3.**

*Major studies about the treatment of recurrent MPM: Multimodality regimen and pattern of failure.*

*MPM: malignant pleural mesothelioma; EPP: extrapleural pneumonectomy; PD: pleurectomy/decortication; NR: not reported; L: local; D: distant; L + D: local+distant; DFS: disease-free survival; PRS: post recurrence survival; OS: overall survival, calculated from the date of surgery, except (a) from the first cycle of neoadjuvant chemotherapy; (b) from the date of pleural biopsy.*

#### **Table 4.**

*Major studies about the treatment of recurrent MPM: Oncological outcomes.*

comfortable PRS were described after PD by Nakamura et al. and Kai and collaborators (14.4 and 20 months, respectively) [65, 67].

Conversely, Bellini and collaborators recently noted that the type of surgical resection did not affect the PRS (14 and 8 months in the EPP and PD group, respectively) if patients are fit enough to receive post-recurrence treatments [71]. Across the literature, the post-recurrence treatment is the main predictor of better PRS [63, 65, 67], in particular, Bellini and co-authors found tailored medical therapies as the best strategy to face relapse, even in the case of local failure [71], in contrast with satisfactory PRS after redoing surgery, which was reported by Kostron et al. [63]. The Italian group cautiously hypothesized that the early local-only failure may likely reflect a less radical local resection that could benefit from timely systemic therapies, rather than redo surgery that is rarely radical in most of the cases [71]. Moreover, several authors reported a long disease-free survival (DFS) (≥12 months) as significantly associated with good survival [61, 67, 71], probably reflecting a slower tumor growth speed associated with a less aggressive recurrent disease. Furthermore, epithelial histology [65, 71] and local recurrence [71] resulted as a favorable prognostic

factor for PRS, the latter may be due to a less deleterious effect on performance status and, consequently, on survival compared with distant spread [71]. In conclusion, in patients presenting with recurrence of MPM after an MCR procedure, radical surgery to resect the recurrent tumor could have a role in the improvement of survival in selected patients [73].


**4. Abnormalities of placenta**

### **4.1. Placenta succenturiata**

The accessory lobe is developed from the activated villi on the chorionic leave, may be placed at varying distances from the main placental margin. A leash of vessels connecting the main to the small lobe traverses through the membranes (**Figure 5**). In cases of absence of communicating blood vessels, it is called placenta spuria. The incidence of placenta succenturiata is about 3%. If the succenturiate lobe is retained, the following birth of the placenta may lead to:

**c.** preterm labor

It can be:

**4.4. Placenta extrachorialis**

There is increased chance of:

**b.** Hydrorrhea gravidarum **c.** Antepartum hemorrhage

**e.** Preterm delivery

**d.** Growth retardation of the baby

**f.** Retained placenta or membranes

**4.5. Morbidly adherent placenta**

the peritoneum or bladder.

**a.** Abortion

**d.** decreased birth weight of baby and placenta

the fetal vessels appear to terminate.

**1.** Circumvallate placenta: the fetal surface is divided into a central depressed zone surrounded by a thickened white ring which is usually complete. The ring is situated at varying distances from the margin of the placenta and is composed of a double fold of amnion and chorion with degenerated decidua (vera) and fibrin in between. Vessels radiate from

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**2.** Placenta marginata: a thin fibrous ring is present at the margin of the chorionic plate where

Morbidly adherent placenta, which includes placenta accreta, increta, and percreta, implies an abnormal implantation of the placenta into the uterine wall (**Figure 6**). The incidence of placenta accreta has increased significantly over the past several decades, with the main risk factors including prior cesarean section and placental previa. Sonographic markers of placenta accreta can be present as early as the first trimester and include a low uterine implantation of a gestational sac, multiple vascular lacunae within the placenta, loss of the normal hypoechoic retroplacental zone, and abnormality of the uterine serosa-bladder interface, among others.

**a.** Placenta accreta is an extremely rare form in which the placenta is directly anchored to the myometrium partially or completely without any intervening decidua. The probable cause is due to the absence of decidua basalis and poor development of the fibrinoid layer.

**c.** Placenta percreta: The placenta penetrates whole of the myometrium and may reach up to

**b.** Placenta increta: The placenta invades whole thickness of myometrium.

the cord insertion as far as the ring and then disappear from view.

**Figure 5.** Placental abnormalities.

*Treatment*: Whenever the diagnosis of missing lobe is made, exploration of the uterus and removal of the lobe under general anesthesia is to be done.

#### **4.2. Velamentous placenta**

Normally, the umbilical cord inserts into the middle of the placenta as it develops. In velamentous cord insertion, the umbilical cord inserts into the fetal membranes (chorioamniotic membranes) and then travels within the membranes to the placenta (between the amnion and the chorion). The exposed vessels are not protected by Wharton's jelly and hence are vulnerable to rupture (**Figure 5**). Rupture is especially likely if the vessels are near the cervix, in which case they may rupture in early labor, likely resulting in a stillbirth. Once it is diagnosed, baby should be delivered by cesarean section.

#### **4.3. Battledore placenta**

Umbilical cord may be attached in the center, off center, on the edge, or in the membranes of the placenta. Battledore placenta is a placenta in which the umbilical cord is attached at the placental margin. The shortest distance between the cord insertion and the placental edge is within 2 cm. The incidence of the battledore placenta is 7–9% in singleton pregnancies and 24–33% in twin pregnancies [4, 5]. Complications associated with the battledore placenta are:

#### **4.4. Placenta extrachorialis**

It can be:

There is increased chance of:

**a.** Abortion

*Treatment*: Whenever the diagnosis of missing lobe is made, exploration of the uterus and

Normally, the umbilical cord inserts into the middle of the placenta as it develops. In velamentous cord insertion, the umbilical cord inserts into the fetal membranes (chorioamniotic membranes) and then travels within the membranes to the placenta (between the amnion and the chorion). The exposed vessels are not protected by Wharton's jelly and hence are vulnerable to rupture (**Figure 5**). Rupture is especially likely if the vessels are near the cervix, in which case they may rupture in early labor, likely resulting in a stillbirth. Once it is diag-

Umbilical cord may be attached in the center, off center, on the edge, or in the membranes of the placenta. Battledore placenta is a placenta in which the umbilical cord is attached at the placental margin. The shortest distance between the cord insertion and the placental edge is within 2 cm. The incidence of the battledore placenta is 7–9% in singleton pregnancies and 24–33% in twin pregnancies [4, 5]. Complications associated with the battledore

removal of the lobe under general anesthesia is to be done.

nosed, baby should be delivered by cesarean section.

**4.2. Velamentous placenta**

**Figure 5.** Placental abnormalities.

6 Placenta

**4.3. Battledore placenta**

placenta are:

**a.** fetal distress

**b.** intrauterine growth restriction

#### **4.5. Morbidly adherent placenta**

Morbidly adherent placenta, which includes placenta accreta, increta, and percreta, implies an abnormal implantation of the placenta into the uterine wall (**Figure 6**). The incidence of placenta accreta has increased significantly over the past several decades, with the main risk factors including prior cesarean section and placental previa. Sonographic markers of placenta accreta can be present as early as the first trimester and include a low uterine implantation of a gestational sac, multiple vascular lacunae within the placenta, loss of the normal hypoechoic retroplacental zone, and abnormality of the uterine serosa-bladder interface, among others.

pregnancies and in female babies [6]. Chorioangiomas that are clinically evident are less common with an incidence between 1:3500 and 1:9000 births [6]. It is believed to arise by 16th day of fertilization, although there is no documentation of the tumor in the first trimester [7]. In the majority of cases, it is small or microscopic and of no clinical significance. If it increases in size >5 cm, then it may be associated with serious maternal and fetal complications (**Figure 7**) [6]. The pathogenesis of these neoplasms is controversial; however, they can originate from any part of the placenta excluding the trophoblastic tissues [8]. Three histological patterns of cho-

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• The angiomatous is the most common, with numerous small areas of endothelial tissue,

These lesions are sometimes classified as placental hamartomas rather than true neoplasia [10].

Large tumors probably act as arteriovenous shunts and cause complications. Maternal complications are preeclampsia, preterm labor, placental abruption, polyhydramnios, and postpartum hemorrhage [11]. The correlation of chorioangioma with hydramnios and preterm delivery is found to be significant among the various reported clinical complications. Fetal congestive heart failure may develop because of the increased blood flow through the low resistance vascular channels in the chorioangioma acting as an arteriovenous shunt. Other associated fetal complications are nonimmune hydrops, fetal demise, hemolytic anemia, congenital anomalies, fetal thrombocytopenia, cardiomegaly, intrauterine growth restriction, and neonatal death [12].

rioangiomas have been described: angiomatous, cellular, and degenerate [9];

• The cellular pattern has abundant endothelial cells within a loose stroma.

capillaries, and blood vessels surrounded by placental stroma.

• The degenerate pattern has calcification, necrosis, or hyalinization.

There is no malignant potential.

**Figure 7.** Chorioangioma of placenta.

**Figure 6.** Morbidly adherent placenta (A: Accrete, B: Increta, C: Percreta).

#### **4.6. Gestational trophoblastic disease/neoplasm**

Gestational trophoblastic disease is divided into molar and nonmolar tumors. Nonmolar tumors are grouped as gestational trophoblastic neoplasia. It is classified as:

#### **4.7. Chorioangioma of placenta**

Placental chorioangioma is the commonest benign tumor of the placenta. Its incidence is around 1% when examined microscopically and is seen more frequently in multiple pregnancies and in female babies [6]. Chorioangiomas that are clinically evident are less common with an incidence between 1:3500 and 1:9000 births [6]. It is believed to arise by 16th day of fertilization, although there is no documentation of the tumor in the first trimester [7]. In the majority of cases, it is small or microscopic and of no clinical significance. If it increases in size >5 cm, then it may be associated with serious maternal and fetal complications (**Figure 7**) [6].

The pathogenesis of these neoplasms is controversial; however, they can originate from any part of the placenta excluding the trophoblastic tissues [8]. Three histological patterns of chorioangiomas have been described: angiomatous, cellular, and degenerate [9];

These lesions are sometimes classified as placental hamartomas rather than true neoplasia [10]. There is no malignant potential.

Large tumors probably act as arteriovenous shunts and cause complications. Maternal complications are preeclampsia, preterm labor, placental abruption, polyhydramnios, and postpartum hemorrhage [11]. The correlation of chorioangioma with hydramnios and preterm delivery is found to be significant among the various reported clinical complications. Fetal congestive heart failure may develop because of the increased blood flow through the low resistance vascular channels in the chorioangioma acting as an arteriovenous shunt. Other associated fetal complications are nonimmune hydrops, fetal demise, hemolytic anemia, congenital anomalies, fetal thrombocytopenia, cardiomegaly, intrauterine growth restriction, and neonatal death [12].

**Figure 7.** Chorioangioma of placenta.

**4.6. Gestational trophoblastic disease/neoplasm**

**Figure 6.** Morbidly adherent placenta (A: Accrete, B: Increta, C: Percreta).

**a.** Hydatidiform mole

**b.** Gestational trophoblastic neoplasia

**e.** Placental site trophoblastic tumor **f.** Epithelioid trophoblastic tumor

**4.7. Chorioangioma of placenta**

**i.** Complete

**c.** Invasive mole

**d.** Choriocarcinoma

**ii.** Partial

8 Placenta

Gestational trophoblastic disease is divided into molar and nonmolar tumors. Nonmolar

Placental chorioangioma is the commonest benign tumor of the placenta. Its incidence is around 1% when examined microscopically and is seen more frequently in multiple

tumors are grouped as gestational trophoblastic neoplasia. It is classified as:

Antenatal ultrasound examination has made diagnosis and follow up possible before delivery. In the present case, the placental tumor was not diagnosed in the ultrasound documentation rather polyhydramnios was reported. Doppler ultrasound examination is the gold standard in primary diagnosis of hemangioma. But unfortunately, we could not conduct Doppler USG in the present case as delivery was imminent. Magnetic resonance imaging (MRI) is used only in suspicious cases, while the computed tomography (CT) technique has a limited role in the diagnosis of the placental angioma, mainly because of the high radiation risk and poor tissue differentiation.

[6] Guschmann M, Henrich W, Dudenhausen JW. Chorioangiomas-new insights into a well-known problem. II. An immuno-histochemical investigation of 136 cases. Journal

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[7] Bracero LA, Davidian M, Cassidy S. Chorioangioma: Diffuse Angiomatous Form. 1993- 09-18-11. Available from: https://www.hindawi.com/journals/criog/2012/913878

[8] Elsayes KM, Trout AT, Friedkin AM, Liu PS, Bude RO, Platt JF. Imaging of the placenta: A multimodality pictorial review. RadioGraphics. 2009;**29**(5):1371-1391 [PubMed] [9] Marchetti AA.A consideration of certain types of benign tumors of the placenta. Surgery,

[10] Kuhnel P. Placental chorioangioma. Acta Obstetricia et Gynecologica Scandinavica.

[11] Patil M. Placental chorangioma, A rare cause of Pre-Eclampsia. Global Journal for Research Analysis. 2013;**2**(5):197-198. ISSN No: 2277-8160. Available from: https://www.

[12] Kodandapani S, Shrestha A, Ramkumar V, Rao L. Chorioangioma of placenta: A rare placental cause for adverse fetal outcome. Case Reports in Obstetrics and Gynecology.

[13] Wanapirak C, Tongsong T, Sirichotiyakul S, Chanprapaph P. Alcoholization: The choice of intrauterine treatment for chorioangioma. Journal of Obstetrics and Gynaecology

[14] Quintero RA, Reich H, Romero R, Johnson MP, Gonçalves L, Evans MI. In utero endoscopic devascularization of a large chorioangioma. Ultrasound in Obstetrics and

[15] Hosseinzadeh P, Shamshirsaz AA, Javadian P, Espinoza J, Gandhi M, Ruano R, et al. Prenatal therapy of large placental chorioangiomas: Case report and review of the litera-

ture. AJP Reports. Oct 2015;**5**(2):e196-e202. DOI: 10.1055/s-0035-1558829

of Perinatal Medicine. 2003;**31**:170-175 [PubMed]

Gynecology & Obstetrics. 1939;**68**:733-743

researchgate.net/publication/292060070

Research. 2002;**28**(2):71-75

Gynecology. 1996;**8**(1):48-52

2012;**2012**. Article ID 913878. DOI: 10.1155/2012/913878

1933;**13**:143-145

Chorioangioma with complications before fetal viability requires interventions. Alcohol injection, laser coagulation of feeding vessels, and microcoil embolization of the feeding vessels are described for women with fetal complications like hydrops [13, 14]. Large chorioangioma associated with polyhydramnios leads to high perinatal morbidity and mortality. Polyhydramnios is treated with therapeutic amniocentesis and maternal indomethacin therapy [12]. Steroid administration for acceleration of fetal lung maturity before 34 weeks is indicated. If complications appear late in pregnancy, delivery is the choice. A recent literature review concluded that further studies are needed to refine the appropriate selection criteria that will justify the risk of invasive in utero therapy for chorioangiomas [15].


**3. XRD analysis and QXRD (semi-quantitative XRD)**

XRD analysis is useful in the determination of crystalline phases that exists in a powdered sample [30]. Each phase has a specific, identifiable x-ray diffraction pattern, which is used to determine different phases present in the sample. X-rays are generated from the emission of high energy electrons from hot tungsten elements, which are bombarded on a copper metal target. This bombardment causes an electron emission from target atoms, thus generating an electron vacancy which is filled by an electron from higher energy orbitals and this transition generates x-rays. Filtration of these x-rays is performed to get monochromatic radiation which is bombarded on the sample being analysed. Bragg's equation is the main law used in XRD diffraction pattern analysis [31].

$$\mathbf{n}\lambda = \mathbf{2}\text{d}\text{sin}\Theta\tag{1}$$

λ = wavelength of x-rays, *n* = integer, *d* = plane spacing, Ɵ = Bragg's diffraction angle.

To derive Bragg's law, consider two x-rays (A and D) impinging on the atom B and E of a crystal and the angle of incident and angle of reflectance are equal as shown in **Figure 3**. Incident waves A and D are in phase with each other although wave D has to travel an extra distance of GE + EH to remain in the same phase as wave A. This extra

**Figure 3.** *Schematic of X-ray diffraction (left), Bragg–Brentano geometry (right).*

### *Testing and Validating Instruments for Feedstocks of Mineral Carbonation DOI: http://dx.doi.org/10.5772/intechopen.101175*

distance must have been an integral (*n*) multiple of wavelength (λ). The length GE and EH are equal and GE equals to *d sinn*Ɵ. Bragg–Brentano design is the most commonly used instrument geometry for high-resolution powder diffraction. The incident beam through a number of slits diverges towards the sample, the diffracted signal from the sample again converges through a number of slits towards the detector. A Ɵ/2Ɵ rotation is employed to keep incident and diffracted wave paths in symmetry. During sample scanning, the sample rotates by Ɵ while the detector is rotated by 2Ɵ with each step [32].

In practice, finely ground feed materials and carbonated samples (up to 100 μm size particles) were put in the instrument holder for analysis. Samples were finely grounded in order to avoid intensity fluctuations and preferred orientation. XRD analyses were performed using Philips X'Pert Pro multipurpose diffractometer with Cu radiation and 2θ from 5 to 90° or 11 to 31° depending upon the sample being analysed. Collection time used was 1 s with a step size of 0.02°. The patterns from XRD were matched with the International Centre for Diffraction Data ® (ICCD) using X'Pert Highscore® in order to identify crystalline phases. A typical x-ray diffraction pattern for feed dunite is shown in **Figure 4**. Phases identified are lizardite, olivine, brucite and magnetite.

If the reference intensity ratio (RIR) of an analytical phase i (such as silicon) is known, then its concentration can be calculated by doping the original sample with the analytical phase. This can be done by the addition of a known amount of standard (silicon) of which the RIR is known. For semiquantitative method details please see below.

After obtaining the diffraction pattern of the doped sample, the concentration Ci in the original sample is calculated as follows:

$$\mathbf{C}\_{\mathbf{i}} = \mathbf{A}\_{\mathbf{x}} \times \left(\frac{\mathbf{I}\_{\mathbf{i}}}{I\_{\mathbf{x}}}\right) \times \left(\frac{\mathbf{RIR}\_{X}}{\mathbf{RIR}\_{\mathbf{i}}}\right) \tag{2}$$

Ci = concentration of given phase i in the original sample Axe = known amount of standard (silicon) added to the original sample

**Figure 4.** *Typical x-ray diffraction pattern for dunite. L, Lizardite; O, olivine; B, Brucite; M, magnetite.*

### **Table 2.**

*Semiquantitative XRD analysis.*

Ii, Ix = intensities (peak areas) of phases i and x in the doped sample RIRi, RIRx = reference intensity ratio values of i and x respectively The procedure is described below in detail (for calculation detail see **Table 2**)

### **3.1 ICP-OES (inductively coupled plasma: Optical emission spectrometry)**

The elemental composition of solid and liquid samples can be determined using ICP-OES. ICP-OES consists of two major components; the torch and optical spectrometer. The torch comprises quartz tubes [33]. To produce plasma, argon gas is normally used, which passes through the tubes around the induction coil. The argon gas is "ignited" by the Telsa unit and the ionisation process (plasma formation) is initiated. The ionisation of argon gas occurs at this stage. A plasma having approximately 7000 K temperature is generated because of collisions between neutral argon atoms and charged particles [34]. Using a peristaltic pump, an aqueous sample is continuously supplied to the nebuliser where it changes to mist and moves to the plasma envelope. The introduced sample interacts with electrons and ions in the plasma and is converted into charged ions. This causes the decomposition of different molecules into respective atoms that lose electrons to induce the emission of radiation of distinctive wavelengths of elements present inside the sample. The optical spectrometer separates these wavelengths into component wavelengths. Intensities are

*Testing and Validating Instruments for Feedstocks of Mineral Carbonation DOI: http://dx.doi.org/10.5772/intechopen.101175*

**Figure 5.**

*Photo of the ICP-OES set-up and microwave digestion system. A, autosampler with standards and sample tube holders; B, plasma chamber; C, gases exhaust; D, computer for analysis output; E, argon gas cylinders; F, chiller; G, microwave digestion system.*

compared with the intensities of standard solutions of known element compositions and elements concentrations are computed based on the calibration curves. ICP-OES set-up and microwave digestion system is shown in **Figure 5**.

Solid samples used in the present investigation were first digested in acidic solution. Dunite sample (0.1 g) was digested in a microwave oven (**Figure 5**) using a mixture of 4.5 mL HNO3 (65%), 4.5 mL HCl (37%) and 3 mL HBF4 (tetrafluoroboric acid, 50%). Thulium (50 μL) was added as a tracking element. The volume of this mixture was increased to 20 mL by the addition of 2% nitric acid prior to its digestion in the microwave. Digestion was not required for supernatant solution samples and they are diluted using 2% nitric acid to the required level (50%/100% dilution) prior to their analysis by ICP-OES (Varian, Australia). The typical curve for ICP-OES is shown in **Figure 6**. Mg concentration drop with the passage of time due to magnesite precipitation. Si concentration increases during the first hour but then it stays constant, which is due to simultaneous silicon leaching from dunite and its precipitation in the form of silica.

### **Figure 6.**

*Typical curve for ICP-OES. The graph represents Mg and Si concentrations variation with time for supernatant solution of sub 75 μm heat-activated dunite carbonated sample. Carbonation reaction was performed with 15% solids slurry at 185°C, 130 bar pressure and using 0.64 M NaHCO3.*

## *3.1.1 Scanning Electron microscope (SEM)/energy dispersive scattering (EDS)*

Morphology, surface topography and elemental compositions of feed materials and carbonated products were determined using SEM (Zeiss Sigma VP FESEM) and EDS (Bruker). SEM scans a fine electron beam over the material being analysed and uses different detectors to reconstruct the image from signals produced from the sample [35]. SEM consists of different parts, e.g., microscope column which also includes electron gun and electron beam travels in this column; the computer that drives the microscope; ancillary equipment which analyses the composition. SEM can magnify objects from 10 times to 300,000 times. Scanning from an electron microscope can be compared with a person having a torch and looking for objects on the wall. As a person builds an image in his/her memory, SEM works in the same way and uses a fine electron beam instead of the torch to build an image.

EDS is a technique that provides information about the chemical composition of the sample. For EDS, an electron beam is focussed on the sample during SEM analysis and these electrons interact with the atoms. X-rays are produced from these interactions and an energy dispersive detector detects these x-rays and displays a signal in the form of spectrum, histogram or intensity versus x-ray energy. This makes it possible to identify elements present in the sample.

Sample preparation is important for SEM. Samples are gold (imaging) or carbon (EDS) coated prior to their analysis. Gold coating provides a thin layer to the samples and samples were coated four times at a 90° angle and fifth time from the top. A typical SEM micrograph and EDS spectrum of dunite feed sample are shown in **Figure 7**. SEM shows an image of the dunite feed and the EDS spectrum indicates intensities of the elements present in the sample. Polished resin blocks were used to study the silica-rich layers. Polished resin blocks were prepared using feed material, carbonated products and resin. Photo of polished resin blocks and sample holders is shown in **Figure 8**. The polished resin block samples preparation procedure is given in appendix 3D.

### *3.1.2 Transmission Electron microscope (TEM)*

TEM is useful to study the structure, properties and compositions of different mineral powders, especially in the submicron range. Mineral particles should have

**Figure 7.**

*SEM micrograph and EDS spectrum of dunite feed. (a) Dunite feed SEM micrograph, 10 μm is a resolution of the SEM (b) EDS spectrum of dunite feed, intensities of different elements are shown, Mg, magnesium; Si, silicon; O, oxygen; Fe, iron.*

**Figure 8.** *Photo of the sample holders (left) and polished resin blocks (right).*

been in 50–100 nanometres size to be properly analysed by TEM. Electrons transmission through the mineral particles enables detailed analysis of the particle features especially its crystal structure, orientation and chemical composition. In the present study, TEM was used to identify shell (silica-rich layers) and core part of the reacted mineral particles and study the corresponding elemental compositions and structure.

To prepare samples for TEM (JEOL 2100 TEM) analysis, 10 mg of sample powder was added to the pestle and mortar. Ethanol (4 ml) was mixed with the sample powder and contents were ground for 3 min. Ground sample was moved into a 5 ml plastic vile and sonicated for 20 min. Using pipette 1–2 drops were dropped on the TEM grid (200 mesh Cu, ProSciTech) and air-dried overnight prior to TEM analysis.


**CURRENT TOPICS IN CHILDREN'S LEARNING AND COGNITION**

Edited by **Heidi Kloos, Bradley J. Morris**  and **Joseph L. Amaral**

http://dx.doi.org/10.5772/1162 Edited by Heidi Kloos, Bradley J. Morris and Joseph L. Amaral

#### **Contributors**

Mieczyslaw Pokorski, Lukasz Borecki, Urszula Jernajczyk, Ana Flávia Lopes Magela Gerhardt, Kevin Downing, Heidi Kloos, Joseph Amaral, Bradley Morris, Steve Croker, Amy Masnick, Corinne Zimmerman, Steffie Van Der Steen (Ed.M.), Daisy Segovia, Angela Crossman

#### **© The Editor(s) and the Author(s) 2012**

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First published in Croatia, 2012 by INTECH d.o.o. eBook (PDF) Published by IN TECH d.o.o. Place and year of publication of eBook (PDF): Rijeka, 2019. IntechOpen is the global imprint of IN TECH d.o.o. Printed in Croatia

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**3. Results**

*Emerging Contaminants*

cides and encouraging ecological agriculture [2].

related to the use of transgenic cultivars [1, 3, 4].

per hectare and the frequency of harvests [5, 6].

by pesticides, chemicals, and medicines [12].

results in large areas dedicated to monocultures. In turn, it results in increasing pests in plantations, cultivation of transgenics, the imposition of the policy of the green revolution, and the absence of reduction policies and monitoring the use of pesti-

The use of pesticides started to become popular during the Second World War when it emerged as a revolution in pest control. This product is classified as efficient and with an advantageous cost/benefit ratio, which caused new organosynthetic compounds to be produced, thus strengthening the agrochemical industry until today. The use of these chemical products added to the process of developing modern varieties with a high capacity to use these inputs became known as "the Green Revolution". Recently, the increase in the consumption of pesticides is closely

This process, linked to the modernization of agriculture, inserted pesticides and fertilizers into the country's technological package, where the expansion of capital in the countryside forced small producers and farmers to enter the new model of agricultural production. In this perspective, the use of chemical pesticides and fertilizers has become a constant, since the land was forced to produce more in less time, paying attention only to market needs, exponentially increasing productivity

Pesticides interfere with the physiological mechanisms of human beings and, therefore, are harmful to health. According to the World Health Organization (WHO), there are three to five million acute poisonings in the world each year, with approximately 200 thousand deaths annually, mainly in developing countries. The high toxicity of some products, the ease of access, and the increase in the number of products containing these substances are factors related to pesticide poisoning, causing serious public health [7–11]. Exogenous autointoxications are directly involved (about 70%) with pesticides and medications, since hospital admissions, according to the Sistema Único de Saúde (SUS), is related to self-inflicted violence,

In agricultural terms, the state of Bahia stands out nationally and internationally, mainly in irrigated agriculture, showing an increase in exports and favoring population growth. However, with this highlight, it was also possible to observe an increase in the number of notifications for poisoning with pesticides [13]. Therefore, this study aimed to describe and analyze the spatial distribution and epidemiological profile of confirmed cases of pesticide poisoning in the state of Bahia - Brazil, from

This is an ecological and retrospective study of a time series, based on secondary data collected through SINAN (Sistema de Informação de Agravos de Notificação) linked to DATASUS. For this purpose, an analysis of confirmed cases of pesticide poisoning was carried out and data collection of estimates and projections of the population of the state of Bahia in the period from 2007 to 2017. To search for the data, we used the option of Disease and Notifiable grievances from SINAN: Exogenous pesticide infection, with the following variables: sex, age group, education, and area of residence. Data processing was performed using Excel software, in which the calculations of absolute and relative frequencies were performed, in

This research follows the rules of the National Ethics Council of Resolution no. 466/2012, using data available to the public through the DATASUS digital platform.

**120**

2007 to 2017.

**2. Methodology**

addition to the arithmetic mean.

In Bahia, there recorded about 1671 notifications of exogenous poisoning by agricultural pesticides between 2007 and 2017. Where, there confirmed about 1155, of which 96 died. Of the investigated periods, the year 2013 had the highest number of reported cases (240), unlike in the year 2008, where the lowest number was registered (59). The average number of cases during the analyzed period was also verified, which was 151.9 notifications. Regarding the number of confirmed cases (1155) of pesticide poisoning, 2013 had the highest number (195) and 2008 the lowest (42). Also, the investigated period showed an average of 105 confirmed cases (**Table 1**).

In **Table 2**, it is possible to observe the overview of cases of exogenous poisoning by pesticides in cities (health regions) in the state of Bahia, during the years 2007 to 2017. The highest percentage of notifications and confirmed cases were in the city of Salvador, in which there were 268 notifications and about 238 confirmed cases, followed by Juazeiro with 234 notifications and 165 confirmed cases, Feira de Santana with 155 notifications and 140 confirmed cases, and Paulo Afonso with 114 notifications and 93 confirmed cases. The other health regions can also be seen in **Table 2**.

The epidemiological profile of intoxication confirmed by pesticides in the state of Bahia (2007 to 2017) was divided according to the following criteria: sex (Male and female), age group (<1 to 9 years, 10 to 19 years, 20 to 39 years, 40 to 59 years, > 60 years and white/ignored), area of residence (Urban, Rural, periurban, and ignored), and education (Illiterate, complete/incomplete elementary school, complete/incomplete high school, complete/incomplete higher education,

#### **Table 1.**

*Distribution in the period from 2007 to 2017 of notified and confirmed cases in the state of Bahia.*

#### **Table 2.**

*Distribution of cases of exogenous poisoning by pesticides in the state of Bahia, during the period from 2007 to 2017.*

white/ignored and does not applied). Of the confirmed cases, the male sex had the highest number of cases, about 756 (65%), when compared to the female sex who presented 399 (35%) (**Figure 1**).

The age range with the highest number of confirmed cases was between aged individuals 20 to 39 years old, which represented 588 cases, following by the age range 40 to 59 years old (279) and the age range 10 to 19 years (148). For those aged >60 years, there identified 78 cases, and the age range < 1 to 9 years (61), lastly, the ignored cases presented only one confirmed case. **Figure 2** shows the percentages by age range of cases confirmed by pesticide poisoning.

**123**

**Figure 3.**

*2007 to 2017.*

*Analysis of Exogenous Poisoning by Pesticide in the State of Bahia-Brazil during the Period…*

According to the area of residence of individuals with confirmed cases of pesticide poisoning in the state of Bahia from 2007 to 2017, the urban area had the highest number, approximately 647 confirmed cases, followed by the rural area (473) and ignored (27), lastly, the peri-urban area (8). **Figure 3** shows the percent-

*Epidemiological profile of pesticide poisoning distributed by sex in the state of Bahia from 2007 to 2017.*

*Epidemiological profile of pesticide poisoning distributed by age group in the state of Bahia from 2007 to 2017.*

*Epidemiological profile of pesticide poisoning distributed by area of residence in the state of Bahia from*

The last epidemiological profile observed was education. For this parameter, the ignored criterion was the one that had the highest number of confirmed cases (622),

*DOI: http://dx.doi.org/10.5772/intechopen.94213*

ages by area of residence.

**Figure 1.**

**Figure 2.**

*Analysis of Exogenous Poisoning by Pesticide in the State of Bahia-Brazil during the Period… DOI: http://dx.doi.org/10.5772/intechopen.94213*

According to the area of residence of individuals with confirmed cases of pesticide poisoning in the state of Bahia from 2007 to 2017, the urban area had the highest number, approximately 647 confirmed cases, followed by the rural area (473) and ignored (27), lastly, the peri-urban area (8). **Figure 3** shows the percentages by area of residence.

The last epidemiological profile observed was education. For this parameter, the ignored criterion was the one that had the highest number of confirmed cases (622),

#### **Figure 1.**

*Emerging Contaminants*

**122**

**Table 2.**

*2007 to 2017.*

presented 399 (35%) (**Figure 1**).

by age range of cases confirmed by pesticide poisoning.

white/ignored and does not applied). Of the confirmed cases, the male sex had the highest number of cases, about 756 (65%), when compared to the female sex who

*Distribution of cases of exogenous poisoning by pesticides in the state of Bahia, during the period from*

**Notification health regions Total of notifications Total of confirmed cases**

Alagoinhas 18 7 Barreiras 101 53 Brumado 81 46 Camaçari 2 1 Cruz das Almas 11 7 Feira de Santana 155 140 Guanambi 92 68 Ibotirama 1 — Ilhéus 13 9 Irecê 57 33 Itaberaba 27 17 Itabuna 29 20 Itapetinga 7 2 Jacobina 29 11 Jequié 80 37 Juazeiro 234 165 Paulo Afonso 114 93 Porto Seguro 51 29 Ribeira do Pombal 23 17 Salvador 268 238 Santa Maria da Vitória 78 55 Santo Antônio de Jesus 35 16 Seabra 8 6 Senhor do Bonfim 24 20 Serrinha 21 11 Teixeira de Freitas 56 21 Valença 38 26 Vitória da Conquista 18 7 **TOTAL 1.671 1.155**

The age range with the highest number of confirmed cases was between aged individuals 20 to 39 years old, which represented 588 cases, following by the age range 40 to 59 years old (279) and the age range 10 to 19 years (148). For those aged >60 years, there identified 78 cases, and the age range < 1 to 9 years (61), lastly, the ignored cases presented only one confirmed case. **Figure 2** shows the percentages

*Epidemiological profile of pesticide poisoning distributed by sex in the state of Bahia from 2007 to 2017.*

#### **Figure 2.**

*Epidemiological profile of pesticide poisoning distributed by age group in the state of Bahia from 2007 to 2017.*

#### **Figure 3.**

*Epidemiological profile of pesticide poisoning distributed by area of residence in the state of Bahia from 2007 to 2017.*

**Figure 4.**

*Percentage by schooling of confirmed cases by pesticides poisoning in the state of Bahia from 2007 to 2017. \* Complete/incomplete.*

followed by complete/incomplete elementary school (334), complete/incomplete high school (103), illiteracy (28), and higher education (8). **Figure 4** addresses the percentage by the education of the aforementioned data.

#### **4. Discussion**

The use of pesticides is a serious problem for human health and the environment. Brazil, in turn, increased the consumption of pesticides in agricultural sectors and insect vector control programs. With these determining factors, the number of records of human poisoning by pesticides is increasing [3, 14]. The release of pesticides in 2019 by the government of Brazil totaled, until July, 290 active ingredients. Despite these alarming decisions, the present study refers to a retrospective study in the state of Bahia (2007 to 2017).  However, this information does not make it any less relevant, as the number of pesticides released and cases of reported poisoning were already alarming.

According to data from the main cities in the state of Bahia, the largest number of cases of pesticide poisoning occurred in Salvador, Juazeiro, Feira de Santana, and Paulo Afonso. The findings of the present study suggest that males are the main victims of pesticide poisoning in the state of Bahia, with about 65% of cases confirmed in the period studied, which corroborates those of Rebelo et al., (2011) and Matos, (2013), who found that males represented a higher percentage of pesticide poisoning.

This data is directly linked to the figure of the man in the handling and use of pesticides in agricultural work, thus being more exposed to these chemicals [8, 10, 11] Regarding the age range, the most affected are concentrated mainly between 20 and 39 years (51%), followed by aged 40 to 59 years (24%). According to these data, the number of pesticide poisonings is increasing mainly in individuals of economically active age groups, as previously described [14, 15].

The results referring to the area of residence (urban, rural, peri-urban, and ignored) in the state of Bahia, demonstrate an important aspect mainly between the rural and urban areas, in which the urban obtained a percentage of 56% of confirmed cases and the rural (41%). It is worth mentioning that the number of confirmed cases in agricultural (rural) regions can be even higher. However, structural problems in health services hamper the efficiency of services, actions, and even the notifications of these individuals. According to LONDON, (2012), these problems have been previously reported, which reappear in the present work demonstrating that they persist, and that is necessary more effective administrative action by the health sectors to change and prevent this situation.

**125**

*Analysis of Exogenous Poisoning by Pesticide in the State of Bahia-Brazil during the Period…*

The data resulting from schooling address mainly that white/ignored had a higher percentage (54%) of confirmed cases, and complete/incomplete elementary education (29%). Complete/incomplete higher education a have a smaller number of individuals affected by pesticide poisoning, since this data is possibly related to the age of education, since, individuals with low education do not have the habit of

It is important to address the limitations of the present study of a large number of ignored, mainly in the epidemiological profile by education, which produces a possible bias regarding the notifications of confirmed cases of pesticide poisoning. Also, notifications must be made insightfully and correctly when diagnosing these individuals, since, the WHO makes the following estimate that for each case record of exogenous poisoning by pesticides, there are about 50 other unregistered cases [14].

The results of the present study of exogenous poisoning by pesticides show that there was an increase in reported and confirmed cases in the state of Bahia from 2007 to 2017, mainly from the year 2011. The health regions most affected were Salvador, Feira de Santana, Juazeiro, and Paulo Afonso that cover other respective municipalities in which the affected individuals reside. According to the epidemiological profile of the risk group with the highest percentages of confirmed cases, the male sex, the age groups of 20 to 39 and 40 to 59 years old, individuals with low schooling, and individuals living in the urban area are the most expressive. However, it is worth mentioning that these data are directly related to deficiencies in the structuring of the health system and the registration of notifications in the

Finally, it is suggested to expand research on the topic in the investigated state, as well as in other states in the region, in order to assess the causes of these pesticide poisonings, besides to encouraging the training of health professionals to carry out the diagnosis, clinical notification, and treatment of the individual affected by pesticide poisoning. Also, it is extremely important to develop and strengthen public policies with surveillance actions to reduce the indiscriminate use of pesticides and, thus, improve the health promotion of the population and

*DOI: http://dx.doi.org/10.5772/intechopen.94213*

**5. Conclusion**

the environment.

using Personal Protective Equipments (PPEs) [16].

rural area when compared to the urban area.

#### *Analysis of Exogenous Poisoning by Pesticide in the State of Bahia-Brazil during the Period… DOI: http://dx.doi.org/10.5772/intechopen.94213*

The data resulting from schooling address mainly that white/ignored had a higher percentage (54%) of confirmed cases, and complete/incomplete elementary education (29%). Complete/incomplete higher education a have a smaller number of individuals affected by pesticide poisoning, since this data is possibly related to the age of education, since, individuals with low education do not have the habit of using Personal Protective Equipments (PPEs) [16].

It is important to address the limitations of the present study of a large number of ignored, mainly in the epidemiological profile by education, which produces a possible bias regarding the notifications of confirmed cases of pesticide poisoning. Also, notifications must be made insightfully and correctly when diagnosing these individuals, since, the WHO makes the following estimate that for each case record of exogenous poisoning by pesticides, there are about 50 other unregistered cases [14].