**Crystal Structures of CH3NH3PbI3 and Related Perovskite Compounds Used for Solar Cells**

Takeo Oku

[17] Chen C. J. Semiconductor Solar Cells. Physics of Solar Energy. Hoboken, New Jersey:

[18] American Society for Testing and Materials (ASTM) (http://www.astm.org/) (ac‐

[19] Smestad G, Ries H. Luminescence and current-voltage characteristics of solar cells and optoelectronic devices. Solar Energy Materials and Solar Cells 1992;25:51-71. [20] Yablonovitch E, Gmitter T. Auger recombination in silicon at low carrier densities.

[21] Araujo L G, Marti A. Limiting Efficiencies of GaAs Solar Cells. IEEE Trans. Electron

[22] Tiedje T, Yablonovitch E, Cody G D, Brooks B G. Limiting Efficiency of Silicon Solar

[23] Andrea Antonini (2010). Photovoltaic Concentrators-Fundamentals, Applications, Market & Prospective, Solar Collectors and Panels, Theory and Applications, Dr. Re‐ ccab Manyala (Ed.), ISBN: 978-953-307-142-8, InTech, Available from :http:// www.intechopen.com/books/solar-collectors-and-panels--theory-and applications/

photovoltaic-concentrators-fundamentals-applications-market-prospective.

[24] Markvart T. Solar cell as a heat engine: energy–entropy analysis of photovoltaic con‐

[25] Kosten E D, Atwater J H, Parsons J, Polman A, Atwater H A. Highly efficient GaAs solar cells by limiting light emission angle. Light: Science & Applications 2013;2e45.

[26] Kostena ED, Atwater H A. Limiting acceptance angle to maximize efficiency in solar cells.: In: Winston R., Gordon J. M. (eds.) Nonimaging Optics: Efficient Design for Il‐ lumination and Solar Concentration VIII: Proceedings of SPIE Vol. 8124 (2011)

[27] Green M.A. Third Generation Photovoltaics: Advanced Solar Energy Conversion. In: Springer Series in Photonics 12, Kamiya T., Monemar B., Venghaus H., Yamamoto Y.

[28] Brown A. S., Green M. A. Detailed balance limit for the series constrained two termi‐ nal tandem solar cell. Physica E: Low-dimensional Systems and Nanostructures 2002;

[29] Bremner S. P., Levy M. Y., Honsberg C. B. Rapid detailed balance calculations for multiple energy gap solar cells 2007. In: Proceedings of 22nd European Photovoltaic

Solar Energy Conference; 2007 Sep 3-7; Milano, Italy; 2007.P.75-8.

John Wiley & Sons Inc.;2011.

App. Phys. Lett. 1986;49:587-9.

Cells. IEEE Trans. Electron Devices 1984;31(5):711-6.

version. physica status solidi (a) 2008;205(12):2752-6.

(Ed.), Springer-Verlag Berlin Heidelberg 2003.

Devices1990; 37(5):1402-5.

81240F1-6.

14(1–2):96–100.

cessed 10 July 2014).

76 Solar Cells - New Approaches and Reviews

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59284


*Article* **Evaluation of Energy-Environment E**ffi**ciency of European Transport Sectors: Non-Radial DEA and TOPSIS Approach**

### **Boban Djordjevi´c and Evelin Krmac \***

Faculty of Maritime Studies and Transport, University of Ljubljana, 6320 Portorož, Slovenia **\*** Correspondence<EMAIL_ADDRESS>
Received: 20 June 2019; Accepted: 26 July 2019; Published: 28 July 2019

**Abstract:** Transport is recognized as a major energy consumer and environment pollutant. Recently scholars have paid considerable attention to the evaluation of transport *energy and environmental e*ffi*ciency* (*EEE*). In this paper, the non-radial Data Envelopment Analysis (DEA) model was employed to evaluate *EEE* on a macro level—i.e., of European road, rail and air sectors. The evaluation was conducted under the joint production framework, which considers energy and non-energy inputs, and desirable and undesirable outputs for the last ten years period. To rank decision-making units and check the aptness of this non-radial DEA model in transport *EEE* evaluation, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method has been proposed. An empirical study has been conducted for as many European countries as possible, depending on availability of data. Based on the non-radial DEA model, it could be said that the level of *EEE* is improving for the road sector, while many evaluated countries have low *EEE* for the rail transport sector. Additionally, results have indicated that the TOPSIS method is more suitable than the non-radial DEA model in transport *EEE* evaluation and for identification of best practices.

**Keywords:** evaluation; energy; environment; efficiency; transport; DEA; TOPSIS


**4. Conclusions**

A compact AlCoCrFeNiTi/Ni60 coating with Ni60 splats uniformly distributed in AlCoCrFeNiTi matrix was deposited by plasma spraying. After spraying, matrix BCC, FCC, and ordered BCC phases were detected in the coating.

The added large Ni60 particles played an important role in strengthening the coating. A strong mechanical bonding between Ni60 and AlCoCrFeNiTi splats caused a higher cohesion strength. Tensile test results showed that bonding strength of this coating was above 60.1 MPa, which is far higher than that of the AlCoCrFeNiTi coating in the previous study.

An average microhardness of 676 HV was obtained for the main body of the coating, which is far higher than that of the HEA coating in the previous work. The main reason can be attributed to the addition of the reinforcement, Ni60. Solution hardening in γ-Ni and dispersion strengthening of the hard interstitial compounds, such as Cr7C3, CrB, Cr2B, and Cr23C6 increased the hardness of Ni60, and then the HEA/Ni60 coating.

During wear testing at 25 ◦C, adhesive wear and abrasive wear occurred, while at 500 ◦C, abrasive wear took place. Volume wear rates of the coating at 25 ◦C and 500 ◦C were 0.55 ± 0.06 × 10−4 mm3·N−1·m−1 and 0.66 ± 0.02 × 10−4 mm3·N−1·m−1, respectively. Wear resistance of this coating was better than that of the HEA coating, which can result from the addition of the hard Ni60. Therefore, Ni60 is an appropriate reinforcement to further enhance the wear resistance of HEA coating.

**Acknowledgments:** This work was supported by the National Natural Science Foundation of China (grant number 51401091); a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); and a Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP).

**Author Contributions:** Lihui Tian and Wei Xiong conceived and designed the experiments; Lihui Tian, Zongkang Feng, and Wei Xiong performed the experiments and analyzed the data; and Lihui Tian wrote the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.


**2. Brief literature review of landmark trials on benefits of rhythm control**

Initial RCTs [5, 6] failed to show superiority of rhythm control on mortality [4], however maintenance of sinus rhythm did show improvement in quality of life and exercise capacity [7, 8]. These particular studies did not include patients with catheter ablation and most patients underwent rhythm control with repeated cardioversions and Antiarrhythmic drugs. Bunch et al. [9] published AF ablation patients have a significantly lower risk of death, stroke, and dementia in comparison to AF patients without ablation. Various experimental studies [10] and scientific position papers [11, 12] have indicated that early intervention with a rhythm-control strategy to prevent progression of AF may be beneficial [4] which eluded to the fact that "AF begets AF" due to electrical and structural myocardial left atrial remodeling. Subsequently, several RCTs have tested the strategy of catheter ablation vs. medical management as discussed below.

MANTRA PAF [13] was one of the initial trials that enrolled 294 patients (June 2005 through 2009) with symptomatic Paroxysmal Atrial Fibrillation (PAF) with no history of antiarrhythmic drug use. These patients were treated with either radiofrequency catheter ablation (146 patients) or therapy with Class IC or Class III antiarrhythmic agents (148 patients) [13]. This trial found no significant difference in cumulative AF burden between both treatment groups over a follow up of 24 months but the burden of symptomatic atrial fibrillation and any atrial fibrillation was significantly lower in the ablation group than in the drug-therapy group. These findings suggested that the efficacy of catheter ablation may be more durable than

#### *Recent Advances in Catheter Ablation for Atrial Fibrillation and Non-pharmacological Stroke… DOI: http://dx.doi.org/10.5772/intechopen.106319*

that of currently available antiarrhythmic drugs. There was no difference in quality of life between both treatment arms, but a perception of more improvement in physical well-being was seen in the ablation group which authors admitted that this may be attributable in part to a placebo effect. There were 36% of patients who were initially assigned to AAD arm who subsequently required ablation for recurrent atrial fibrillation, a finding signaling that though an initial rhythm control strategy with AAD may be initiated, a minority of such patients may subsequently require catheter ablation for adequate rhythm control. A major limitation of this trial was definition of goal of ablation for atrial fibrillation. At the time of the study, this was defined as elimination of complex high frequency electrograms inside encircled areas around the Pulmonary Veins (PV), but with rapid development of ablation techniques, this end point was no longer valid. A general agreement on end point of ablation is considered complete electrical isolation of pulmonary veins. A change in ablation strategy based on this end point may have potentially changed the outcome of the study.

RAAFT 2 [14]. was another contemporary RCT to MANTRA PAF enrolling 127 patients with symptomatic PAF from Europe and North America between July 2006 to January 2010 and then patients were followed up for 2 years till 2012. Patients were randomized to ablation vs. anti arrhythmic treatment arms. Ablation was performed with circumferential pulmonary vein isolation with demonstration of entrance block into pulmonary vein, with additional ablation such as linear lines in Left Atrium (LA), ganglionic plexi, targeting complex fractionated electrogram, superior vena cava (SVC) isolation, cavotricuspid isthmus (CTI) ablation all at the investigator's discretion [14]. With change in ablation goal when compared to MANTRA PAF, RAAFT 2 trial demonstrated catheter ablation resulted in significantly lower rate of recurrent atrial tachyarrhythmia at 2 years, and reduced the frequency of repeated episodes of AF and thus improvement in quality of life however, recurrence was documented in approximately 50% of patients. Ablation extends the time free of both symptomatic and asymptomatic AF and significantly reduced the recurrence of repeated episodes, potentially having an effect on AF progression [14]. This study was limited by small sample size, and findings restricted to mostly young people with PAF. So authors suggested that when offering ablation as a therapeutic option to patients with paroxysmal AF naive to antiarrhythmic drugs, the risks and benefits need to be discussed and treatment strategy individually recommended.

Rhythm control vs. rate control for AF in patients with heart failure (HF) were studied in multiple studies. In a multi center RCT [15], 1376 patients who had congestive heart failure with EF ≤ 35% were enrolled. Maintenance of sinus rhythm with Antiarrhythmic drugs did not reduce the rate of death from cardiovascular causes, as compared with a rate-control strategy. Role of catheter ablation was however not studied in this RCT. Significant proportion of patients do not tolerate anti arrhythmic drugs due to various side effects, is not responsive to AAD, or has difficulty in medication adherence or compliance. Catheter ablation is a suitable alternative for rhythm control. There have been several studies that has shown positive effect of ablation in AF and CHF patients [16–20]. CASTLE AF was a landmark large multi center open labeled randomized control trial [21] where 398 patients were enrolled with symptomatic Paroxysmal or Persistent AF who failed, had unacceptable side effects, or had an unwillingness to take antiarrhythmic drugs. These patients also had New York Heart Association (NYHA) Class II, III, or IV heart failure and a left ventricular ejection fraction (LVEF) of 35% or less. As compared to multiple previous trials showing benefit of catheter ablation [16–20], this was the first trial that tested the effectiveness of catheter ablation in improving rates of hard primary end points such as death

or the progression of heart failure. Primary end point which was a composite of death from any cause and lower rates of hospital admission for heart failure was significantly fewer in the ablation group. In addition there were other secondary outcomes seen such as increase in LVEF and reduction in AF burden.

CABANA trial [1] (published in 2019) was a landmark trial that enrolled 2204 symptomatic AF patients (paroxysmal, persistent and long persistent) from 126 centers over 10 countries and tested catheter ablation vs. medical management with antiarrhythmic and/or rate control medications. Catheter ablation did not significantly reduce the primary composite end point of death, disabling stroke, serious bleeding, or cardiac arrest, but secondary end point of mortality or CV hospitalization showed a significant 17% relative lower event rate for the catheter ablation group [1]. Post 90 day blanking period, patients were monitored for time to first AF recurrence defined as AF/AFl/AT for ≥30 s. Catheter ablation was associated with a lower AF recurrence rate than drug therapy (50% vs. 69% at 3 years post blanking follow-up). Another significant observation in this study was low rate of procedure related complication seen in catheter ablation group indicating that ablation is feasible. The trial had several limitations [1] such as higher rate of patient withdrawal in drug therapy group, catheter ablation and drug therapy may have changed over the long course of the trial, small percentage of patients may have received only rate control drugs. Comparisons of the intention to treat (ITT) results with the treatment received and per-protocol analyses suggest that the combined effect of crossovers and withdrawals reduced the estimated treatment effect and the precision of the effect size estimates as assessed by ITT. Additionally, potential introduction of bias due to unblinded site adjudication of cause of hospitalization etc. might have affected the results of the study. Authors concluded that the estimated treatment effect of catheter ablation was affected by lower-than-expected event rates and treatment crossovers, which should be considered in interpreting the results of the trial.

With initial belief that rhythm control strategy is not superior over rate control, based on AFFIRM study published in early first decade of twenty-first century, we have witnessed through several trials discussed above, the evolution of scientific evidence demonstrating efficacy of ablation strategy in improving quality of life, improvement of heart failure symptoms, improvement of exercise tolerance, survival benefits, reduce hospitalization etc. A monumental trial that brought a paradigm shift is EAST AFNET 4 [22]. This study was published in 2020 and sought to compare early rhythm control vs. usual care. This was a multi center randomized trial that enrolled over 2700 patients from 135 sites in 11 countries. Early rhythm control required antiarrhythmic drugs or atrial fibrillation ablation, as well as cardioversion of persistent atrial fibrillation, to be initiated early after randomization. Usual care arm patients were initially treated with only rate control therapy and rhythm-control therapy was used only to mitigate uncontrolled atrial fibrillation–related symptoms during adequate rate-control therapy. The trial was stopped for efficacy at the third interim analysis after a median of 5.1 years of follow-up per patient. The first primary outcome was a composite of death from cardiovascular causes, stroke (either ischemic or hemorrhagic), or hospitalization with worsening of heart failure or acute coronary syndrome [22]. First primary outcome event was found to have occurred less often in patients assigned to early rhythm control than in patients assigned to usual care achieving a conclusion that early rhythm control was beneficial that was associated with lower risk of adverse cardiovascular outcomes [22]. The results of this study

*Recent Advances in Catheter Ablation for Atrial Fibrillation and Non-pharmacological Stroke… DOI: http://dx.doi.org/10.5772/intechopen.106319*

was different from previously published studies comparing rhythm vs. rate control because of incorporation of catheter ablation which is a powerful tool for restoring sinus rhythm.

Another recent study, STOP-AF First [23] was published in 2021 which compared the efficacy of cryoboalloon ablation over AAD in patients with symptomatic paroxysmal AF. Cryoballoon ablation as initial therapy was superior to drug therapy for the prevention of atrial arrhythmia recurrence in patients with paroxysmal atrial fibrillation with low procedure related adverse events.

There are three modes for rhythm control: Electrical (direct current cardioversion), Pharmacological (Antiarrhythmic mediation) and catheter ablation. With the scope of this chapter we will focus more on evolution and rapid advent of catheter ablation strategy over past few years (**Figure 1**).

Current AHA/ACC/HRS Atrial Fibrillation guidelines [4] and 2017 HRS/EHRA/ ECAS/APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation recommend catheter ablation in patients with symptomatic PAF (COR Class I) who are intolerant or refractory to Class I or Class III AAD, or ablation as initial strategy before trial of AAD (COR Class IIa). In recent 2019 focused update new recommendation have been added as AF catheter ablation may be reasonable in selected patients with symptomatic AF and HF with reduced left ventricular (LV) ejection fraction (HFrEF) to potentially lower mortality rate and reduce hospitalization for HF based on evidence from CASTLE AF data (COR Class IIb, LOE B-R) (**Table 1**) [24].

#### **Figure 1.**

*Strategies for rhythm control in patients with paroxysmal\* and persistent AF† . \*Catheter ablation is only recommended as first-line therapy for patients with paroxysmal AF (Class IIa recommendation). † Drugs are listed alphabetically. ‡ Depending on patient preference when performed in experienced centers. § Not recommended with severe LVH (wall thickness > 1.5 cm).* ‖ *Should be used with caution in patients at risk for torsades de pointes ventricular tachycardia. ¶ Should be combined with AV nodal blocking agents. AF indicates atrial fibrillation; AV, atrioventricular; CAD, coronary artery disease; HF, heart failure; and LVH, left ventricular hypertrophy. Adopted from [4].*

**Table 1.**

*Professional society guideline recommendations for atrial fibrillation catheter ablation.*

### **3. Catheter ablation of atrial fibrillation**

Pathogenesis of AF is incompletely understood. Broadly generalized, there is a trigger that initiate AF and there is a perpetuating factor that sustain the arrhythmia. Usually a PAC or a focal atrial tachycardia triggers atrial fibrillation that further creates a rapid irregular multiple wavelets of depolarization.

Dr. Cox in 1987 first described surgical ablation of atrial fibrillation [25] by creating multiple scars by "cut and sew" technique to create lines of conduction block to prevent atrial reentry and allow sinus impulses to activate the entire atrial myocardium, thereby preserving atrial transport function postoperatively. However, application of the maze III operation has been limited by the morbidity and risk associated with sternotomy-thoracotomy and cardiopulmonary bypass, as well as by limited adoption by cardiothoracic surgeons [26]. Seminal publication by Dr. Michel Haïssaguerre [27] in 1998 that pulmonary vein ectopics are frequent triggers for AF and ablation of these foci can treat AF laid the initial foundation for catheter ablation of AF. With the success of surgical lines, catheter ablation was tried with different curve sheaths but procedure was fraught with high complication rates and exceedingly high fluoroscopic times. Initial catheter ablations tried to target Right Atrium (RA) by creating Intercaval lines along the interatrial septum and Cavotricuspid isthmus line and target Left Atrium (LA) by creating three or four lines. Pappone and Co workers published Circumferential Radiofrequency Ablation of Pulmonary Vein Ostia with electroanatomic guidance is safe and effective in either paroxysmal or permanent AF [28].

Since then, different approachs for catheter ablation for atrial fibrillation have evolved such as segmental ostial PV Isolation, circumferential antral Pulmonary vein isolation (PVI), wide area circumferential LA ablation, catheter Maze (lines to connect the ipsilateral pairs of the PVs and a line to link the left PV encircling lesion to the mitral annulus), complex fractionated electrogram ablation (CFAE), Box lesion sets with linear lines ("floor line" and "roof line") to isolate posterior wall, Left atrial Appendage (LAA) isolation, Superior Vena Cava (SVC) isolation, autonomic ganglionated plexi ablation or Cardioneural ablation, alcohol ablation of vein of Marshal etc. There is no clear consensus about efficacy of one approach over another,

*Recent Advances in Catheter Ablation for Atrial Fibrillation and Non-pharmacological Stroke… DOI: http://dx.doi.org/10.5772/intechopen.106319*

**Figure 2.**

*Schematic diagram of various approaches of catheter ablation shown. Red circles are ablation lesions. Picture adopted from [26].*

but approaches often vary between paroxysmal Atrial Fibrillation and persistent Atrial Fibrillation. In PAF targeting the trigger for Atrial Fibrillation with wide antral circumferential ablation of bilateral PVs may prove sufficient in freedom from recurrent AF/AFl/AT. In contrast, patients with persistent Atrial Fibrillation, both trigger and substrate needs to be ablated and ablation may be necessary beyond routine PVI which may include posterior wall isolation or additional linear lines in left atrium depending on operator's discretion (**Figure 2**).

#### **3.1 Substrate based ablation for persistent/long persistent atrial fibrillation: targeting pulmonary and non pulmonary vein triggers**

Though PV are most frequent triggers for AF, investigators have shown several non PV triggers, incidence ranging between 3.2% and 47%, especially in Persistent/ Long standing Persistent AF. Triggers have been demonstrated in SVC (common in female patients), LA posterior wall, (common in patients with enlarged LA), Crista terminals, Left atrial appendage, Coronary sinus, Ligament of Marshall, Interatrial septum. Additionally, SVTs such as AVN reentrant tachycardia (AVNRT) and AV reentrant tachycardia (AVRT) can be identified in up to 4% in unselected patients referred for AF ablation and can serve as a triggering mechanism for AF [26]. Previous studies have suggested a benefit to intervention with ablation before drug failure, because a shorter "diagnosis-to-ablation" time is associated with lower rates of arrhythmia recurrence or repeat procedures and fewer hospitalizations [29–31].

STAR AF II [32] was a randomized trial that compared efficacy of three different approaches to catheter ablation of AF in patients with Persistent AF. They randomized patients into three arms: (1) PVI alone (2) PVI with CFAE (3) PVI and Linear ablation lines along the LA roof and Mitral Isthmus. Primary outcome of the study was to see any documented episode of atrial fibrillation lasting longer than 30 s and occurring after the performance of a single ablation procedure, with or without the use of antiarrhythmic medications. Clinical assessments, 12-lead electrocardiograms, and 24-h Holter-monitor recordings were obtained at baseline and at 3, 6, 9, 12, and 18 months after the initial ablation. Study showed no reduction in the rate of recurrent atrial fibrillation when either linear ablation or ablation of complex fractionated electrograms was performed in addition to pulmonary-vein isolation. Recurrence of atrial arrhythmia despite extensive ablation on a substrate based approach with targets beyond PV such as CFAE, linear lines probably created iatrogenic areas of arrhythmogenesis potentially from incomplete ablation of areas with complex electrograms or conduction gaps in linear lines.

A meta-analysis of 113 studies including 18,657 patients examined the impact of ablation approach on outcomes associated with Persistent or Long standing persistent AF [33]. Findings of this meta-analysis supports the findings of the STAR AF II trial, with collated results indicating that a simpler PVI approach (57% success) yields at least equivalent single-procedure results (or potentially better) compared with more complex substrate ablation techniques including PVI + Linear ablation lines (46%), PVI + CFAE (46%), and PVI + Linear ablation lines + CFAE (33%) as currently performed and reported. This study also concluded that the efficacy of a single-AF ablation procedure for Persistent or Long standing persistent AF is 43%; however, can be increased to 69% with the use of multiple procedures and/or anti-arrhythmic drug.

#### **3.2 Left atrial appendage electrical isolation/vein of marshall alcohol ablation**

BELIEF trial [34] is an RCT that included 173 patients with long standing persistent atrial fibrillation that were randomized into two arms: (1) Standard ablation arm that comprised of an extended PV antrum ablation plus non-PV trigger ablation (2) standard ablation plus empirical electrical left atrial appendage isolation. Primary end point of the study was freedom from atrial arrhythmia (AF, A Fl, AT) defined as >30 s after initial 12 weeks blanking period while off anti arrhythmic drugs, secondary end points were 12-month post-procedure incidence of stroke, death, and rehospitalization. Trial results showed that in patients with Long standing Persistent

### *Recent Advances in Catheter Ablation for Atrial Fibrillation and Non-pharmacological Stroke… DOI: http://dx.doi.org/10.5772/intechopen.106319*

AF, empirical isolation of LAA improved long-term freedom from atria arrhythmia without increasing complications. An important finding to consider however is life long need for uninterrupted anticoagulation in patients who underwent LAA isolation as post procedure lack of proper mechanical function in the LAA may contribute to stroke.

Recently, Alcohol ablation of Vein of Marshall (VoM) has gained significant attention. This method of ethanol infusion into VoM in addition to catheter ablation was investigated in VENUS [35] RCT. 343 patients with Persistent AF were randomized into catheter ablation alone vs. catheter ablation with VoM ethanol infusion. Primary end point was freedom from AF/AT > 30 s without AAD at 6 and 12 months, several secondary endpoints including AF burden, freedom from AF after multiple procedures, perimitral block, and others were studied. VoM is the embryological remnant of left superior vena cava is implicated as AF trigger, parasympathetic and sympathetic innervation contributing to AF, located in the mitral isthmus contributing to perimitral atrial tachycardia. Results of this study concluded that addition of VoM ethanol infusion to catheter ablation increased the likelihood of remaining free of AF or atrial tachycardia at 6 and 12 months. Adverse events were not significantly different between both group: intraprocedural pericardial effusion occurred in two patients in VoM ethanol infusion group (one in ablation only group), subacute pericardial effusion requiring drainage occurred in four patients (two in each group), symptomatic inflammatory pericarditis not requiring drainage occurred in 11 patients in the VoM ethanol infusion group and in 6 in the catheter ablation group. The benefits of VoM ethanol infusion in addition to

**Table 2.**

*Professional society recommendations for catheter and surgical ablation strategies and endpoints.*

catheter ablation was attributed to elimination of AF trigger, achieving more reliable perimitral block, enhanced atrial denervation (**Figure 3**).

2017 HRS/EHRA/ECAS/APHRS/SOLAECE Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation recommends following Atrial fibrillation ablation strategies, techniques, and endpoints (**Table 2**).

#### **3.3 High power short duration (HPSD) ablation**

High power short duration (HPSD) ablation strategy is a newer approach in effective lesion formation. Conventionally AF ablation has been performed with low power long duration (LPLD) at 25–35 W power delivery for 30–60 s per lesion. Success of AF ablation is dependent on durability of lesions that in turn is influenced by several variables like catheter stability, orientation of ablation catheter (perpendicular vs. parallel), time duration, effective power and current delivered at catheter tip, transmurality of lesion etc. HPSD (50–80 W power for 5 s) was initially described by Bhaskaran et al. [36] in 2016 as safe and effective as the conventional ablation. Current definition of HPSD varies between power of 50–90 s and time duration of 2–20 s. Based on principles of biophysics of Radiofrequency (RF) ablation, HPSD is believed to cause majority of tissue death via resistive heating and, as a result, theoretical advantages have been proposed, including optimized lesion geometry, reduced collateral tissue damage and increased durability of electrical isolation, in addition to obvious benefits in reduction in procedural duration [37]. Winkle et al. [38] reported very low complication rates with HPSD (45–50 W for 2–10 s) compared to LPLD (35 W for 20 s) in total of 13,974 ablations performed in 10,284 patients, of these, 11,436 ablations performed in the posterior wall. They also found HPSD ablations shorten procedural and total RF times and create more localized and durable lesions. Recently, Very High Power Short

*Recent Advances in Catheter Ablation for Atrial Fibrillation and Non-pharmacological Stroke… DOI: http://dx.doi.org/10.5772/intechopen.106319*

Duration (vHPSD) with 90 W for 4 s with a novel catheter design (THERMOCOOL SMARTTOUCH SF-5D System) was studied in Q DOT FAST trial [39] where 52 patients with PAF underwent ablation with no deaths, stroke, atrioesophageal fistula, pulmonary vein stenosis, or unanticipated adverse device effects. This study showed safety, feasibility and short term efficacy of vHPSD ablation along with substantial reduction in procedural and fluoroscopic time. Currently there is an ongoing prospective clinical trial (HIPAF) comparing two strategies: HPSD-PVI (70 W over 5 s posterior and 7 s anterior) ablation vs. Cryo PVI [40].

#### **3.4 Pulsed Field Ablation (PFA)**

So far, RF or Cryo ablation has been the only two available technologies for endocardial ablation of Atrial Fibrillation. In recent years, clinical research on an emerging modality for cardiac ablation has demonstrated significant advantages over existing thermal ablation modalities. Irreversible Electroporation is a non thermal modality with emerging application in the field of cardiology with more selective and effective ablation with minimal surrounding tissue damage. Dr. Steven Mickelsen at University of Iowa developed Pulsed Field Ablation (PFA) system and adapted catheters to deliver pulsed field electricity to the tissue for treating AF with his start up called "IOWA APPROACH" in 2012 later known as FARAPULSE Inc., which was later acquired by Boston Scientific in 2020.

Pulsed Field Ablation (PFA) is based on the premise of irreversible electroporation, where trains of high voltage, short duration energy are pulsed to create an electric field of substantial strength to injure tissue. The principle of electroporation has been used in a wide variety of practices ranging from gene therapy to tumor ablation but has only recently been applied to cardiac ablation. It is the unique properties of the cell membrane that are manipulated during electroporation. Cell membrane is composed of a phospholipid bilayer that is stabilized by Van der Waals forces that allow for aqueous pores to form in the membrane due to molecular water interactions across the cell membrane. The application of an electric field amplifies the molecular interaction of the water molecules across the cell membrane disrupting the Van der Walls forces of the phospholipid bilayer to create aqueous pores. If an electric field of substantial strength and duration is applied to the cell, these aqueous pores can become stabilized resulting in permanent disruption to the permeability of the cell membrane resulting in an apoptotic like cell death, which is termed irreversible electroporation or PFA (**Figure 4**).

RF ablation is associated with very low rate of complications but include pulmonary vein stenosis, atrio-esophageal fistula. Similarly Cryoablation is associated with low rate of complications as well but include phrenic nerve palsy. In contrast during PFA ultra rapid (microseconds to nanoseconds) electrical energy is delivered to destabilize cell membrane by forming irreversible nanoscale pores resulting in ell death, however threshold field strength for tissue necrosis is different for different tissues such as myocardium, blood vessels, nerve fibers thus rendering a great advantage of tissue selectivity. This differential tissue sensitivity to pulsed electrical fields is believed to decrease collateral damage. This single shot ablation technology in addition to being associated with clinical safety, success and durability has significantly reduced procedural time [41].

So far there have been three Multicenter studies three multicenter studies with PFA system: (IMPULSE [A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation], PEFCAT [A Safety

#### **Figure 4.**

*Figure adopted from Reddy [41].*

and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation], and PEFCAT II [Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation]). Reddy et al. [41] reported 1 year outcome of PFA in patients with PAF from these three trials. In a patient cohort of 121 patients, acute PVI with PFA was achieved in 100% of patients, primary adverse event occurred in 2.5% of patients (2 pericardial effusion, 1 transient ischemic attack, 1 hematoma), Freedom from recurrence of any atrial arrhythmia at 1 year was around 78%. In >100 patients and with 5 operators, the mean procedure times were only 96.2 ± 30.3 min, inclusive of ∼20 min of voltage mapping time after PVI which is faster than procedure times with other technologies. With increased operator experience and elimination of voltage mapping, procedure times should improve further. PVI with a "single-shot" PFA catheter results in excellent PVI durability and acceptable safety with a low 1-year rate of atrial arrhythmia recurrence ushering in a new era in the front of modern day advanced Atrial Fibrillation management.

#### **3.5 Cryoablation for atrial fibrillation**

An alternative mode of PAF ablation is Cryoablation. STOP AF [42] trial compared Cryoablation and AAD and demonstrated the safety and effectiveness of Cryoablation therapy as an alternative to antiarrhythmic medication for the treatment of patients with symptomatic PAF, for whom at least one AAD has failed. RF ablation requires operator skill and training and longer time for catheter navigation to complete point by point ablation around the pulmonary veins. In contrast, cryoballoon is a balloon catheter which is positioned inside pulmonary vein and with good occlusion, with a single Cryo application pulmonary vein isolation can be achieved rather simply with short procedure time. FIRE and ICE trial [43] compared both technologies (RF vs. Cryo ablation) and found Cryoablation was non inferior to radiofrequency ablation with respect to efficacy, no significant difference in overall safety between two methods. The mean total procedure time was shorter in the cryoballoon group than in


**6. English Translation of the** *D. ak¯ arn ¯ . ava* **15**

## **6.1. Introduction**

Now, I shall explain the secret [that is] characterized by right meditation, by which glorious Heruka is carefully established. There is no other [way]. **(1)**

[The universe] is dissolved [into emptiness] at the outset, [and the universe containing the man. d. ala] is generated [from emptiness] at the end;808 [it] indicates [this]: the Emanation [Body] (viz., the man. d. ala) manifests. The Dharma, the Enjoyment, and the other [Bodies are also realized]; therefore, all [of the Bodies] are aggregated together in this [secret].809 **(2)**

## **6.2. From the Selection of Ritual Place to the Absorption into Emptiness**

First, having found a proper place in a lonely spot or [other spots] such as a mountain,810 he should make [that place] a charnel ground. There [he should honor] with a *bali* offering the protector [deities] of that land.811 **(3)**

808 I have interpreted that the terms *sam. varti* (or *sam. vartin*) and *vivarti* (or *vivartin*) are related to the concepts of *sam. varta* and *vivarta*, respectively (and not *sam. vr.ti* and *vivr.ti*, the Conventional Truth and the Ultimate Reality Truth). The words *sam. varta* and *vivarta* are traditionally used in the Buddhist cosmology to describe the cycle of the dissolution and regeneration of the universe, respectively. For the regeneration (*vivarta*) and dissolution (*sam. varta*) of the universe in the *Abhidharmako´sa* (its *karik ¯ a¯* and *bha¯s.ya*), see (Sadakata 2011, pp. 237–45), and for those in the *Manobhumi ¯* part of the *Yogac¯ arabh ¯ umi ¯* , (Kajiyama 2000); there are cases where the same concepts of *vivarta* and *sam. varta* were used conversely, as indicating dissolution and regeneration, respectively. For the case in the *Da´sabhumis ¯ utra ¯* and commentaries on it, see (Kim 2007), and for the case in the *Kalacakra ¯* and *Vimalaprabha¯*, (Newman 1988, p. 131).

809 My interpretation of verse 15.2 relies much on the *Bohita¯*'s comment on it (D 1419, 131r2–r4). The universe, which consists of the worlds of environment and sentient beings, is dissolved into emptiness; subsequently it emerges from emptiness. A practitioner generally meditates on this as part of visualizing a man. d. ala. The word *atra* in 15.2d indicates *rahasya* in 15.1a. The *Bohita¯* does not clarify what the word *adi ¯* of the *dharmasam. bhogadi ¯* indicates. I have interpreted it as indicating the other aspect of the Tantric body, the Innate Body (*sahajakaya ¯* ) or equivalent.

810 According to the *Bohita¯* (D 1419, 131r6–r7), externally, the other spots are a cave, a rock shelter, an ocean shore, a charnel ground originally perfected, and a pleasing place.

811 According to the *Bohita¯* (D 1419, 132r1), externally, the *bali* offering means various kinds of fish, meat, and so on.

A yogin should offer water for a respectful reception (*argha*) and so on812 after a sipping water for purification (*mukha´sauca*) and others.813 Employing an image, the Blessed One taught a visualization by [use of] a cloth [painting] and other [devices]. **(4)**

[This is] a visualization of the very terrifying one [who] resides on a corpse;814 [he] brings benefits to the world. [A practitioner] should take recourse in every kind of meditation instantly.815 **(5)**

(The meaning of the letter *sr´ ¯ı*, i.e., the nondual consciousness816—) The letter *sr´ ¯ı* is the meaning of every originated being (*sarvabhuta ¯* ).817 [Every originated being is] known to be external and internal,818 and both of these [external and internal aspects] are [present as assuming] the form [in terms] of the conventional [truth].

812 According to the *Bohita¯* (D 1419, 132r2), the word *adi ¯* ("so on") indicates water for washing the feet (*zhabs bsil*), a flower (*me tog*), incense (*bdug spos*), a lamp (*mar me*), perfume (*dri*), and foods for deities (*lha bshos*).

813 According to the *Bohita¯* (D 1419, 132r6), the word *adi ¯* ("others") indicates a tooth-cleaning stick (*so shing*).

814 According to the *Bohita¯* (D 1419, 132v4–v6), the very terrifying one is Vajradhara (*rdo rje 'chang*), and the *preta* or a corpse indicates the dead body of Brahman, who has four faces and who is of the nature of the *dharmadhatu ¯* or reality realm (*zhal bzhi pa tshangs pa chos kyi dbyings kyi bdag nyid can ni yi dags so*).

815 According to the *Bohita¯* (132v7–133r1 and 139v3–v4), the words *sarvasarvakam* or "every kind of" indicate the Triple Samadhi (the First Yoga, the Supreme King of Ma ¯ n. d. ala, and the Supreme King of Action, *dang po sbyor ba dang dkyil 'khor rgyal po mchog dang las rgyal po mchog*), the Bindu Yoga (*thig le'i rnal 'byor*), and the Subtle Yoga (*phra mo'i rnal 'byor*). The First Yoga, the first of the Triple Samadhi, consists of the Service ( ¯ *bsnyen pa*), Auxiliay Service (*nye ba'i bsnyen pa*), Perfect Realization (*sgrub pa*), and Great Perfect Realization (*sgrub pa chen po*). Obviously, Jayasena followed the *Bohita¯*'s instruction: the Triple Samadhi, the Bindu Yoga, and the Subtle Yoga constitute the whole structure of ¯ the *Ratnapadmaraganidhi ¯* . See also Chapter 9 in this monograph.

816 Verses 15.6–7b expound the meaning of the letter *sr´ ¯ı* (of *sr´ ¯ıheruka*), based on the traditional doctrine that the letter *sr´ ¯ı* refers to the nondual consciousness or gnosis, which the *Hevajra* is the first to teach (*sr´ ¯ıkaram advayam ¯ . jñanam ¯ .* , Skt ed. (Snellgrove 1959), I.7.27).

817 It is also possible to translate *sr´ ¯ıkara sarvabh ¯ ut¯ artham ¯* (15.6a) as "The letter *sr´ ¯ı* (viz., the nondual consciousness) [expresses the absolute reality of] every originated thing"(*artha* means "thing" and not "meaning"). If the text is edited as *sr´ ¯ıkarasarvabh ¯ ut¯ artham ¯* (compound), it may be translated as "Every originated thing, [which is represented] by the letter *sr´ ¯ı*, . . . ".

818 I interpret the text (15.6ab) as saying the nonduality of the external and internal aspects of originated beings. The Sam. vara tradition has the idea in common that the abstract structure of the outer universe (the external) is also present in the body of each individual practitioner (the internal): they are nondual. According to the *Bohita¯* (D 1419, 133r1–r2), the external means the strata of [the Five Elements] such as the Earth [Element] (*sa la sogs pa dkyil 'khor*) and the Three Realms [comprising the Five Elements] (*khams gsum*), and the internal refers to the physical body comprising the [Five] Elements such as the Earth [Element] (*sa la sogs pa'i khams kyi rang bzhin gyi lus*). It appears that in the *Bohita¯*, the word *sarvabhut¯ artha ¯* (15.6a) means "everything [that comprises] the [Five] Elements" (*bhuta ¯* = the [Five] Elements).

The ultimate [truth] is what is at the end of the pleasure.819 The syllable letter *sr´ ¯ı* is also explained by *evam.* 820 and others [that are] nondual.821 **(6–7b)**

(The meaning of the letter *he*, i.e., the emptiness of cause and so on, etc.822—) The letter *he* is [as follows]: From the heart,823 [he should visualize] all [deities], such as Heruka, [who] reside on their own circles. [Vajra-]holders and others824 are originating; [he should know] all [of them] originating through visualization.825 That [letter *he* represents the principle that] the cause (*hetv-*) is empty by nature;826 there is no conceptualization of cause and so on827 as selves. That [letter *he* refers to] the selflessness of phenomenal existences by nature, [or the state of] being empty.828 [Emptiness] brings the meditative union. **(7c–9b)**

819 I interpret the text (verse 15.6cd) as also implying the nonduality of the Conventional Truth (*sam. vr.ti*) and the Ultimate Reality Truth (*vivr.ti*). According to the *Bohita¯* (D 1419, 133r3), what is at the end of the pleasure means the pleasure of the middle beyond verbal expression (*bar ma'i bde ba brjod du med pa*), which he experiences at the end of the Innate Pleasure (*lhan cig skyes pa'i dga' ba'i mthar*) as long as he is keeping [his semen] unfallen (*lhung ba med pa bral ba ji srid pa*, "as long as not, [viz.,] without, falling").

820 In Tantric traditions, the word *evam.* often symbolizes the nonduality: the letter *e* (which is shaped like an inverted triangle) represents the female genital organ, and the letter *vam.* (shaped like a stick), the penis, comes into the triangular space of *e*.

821 As the *Bohita¯* (D 1419, 133r3–r5) suggests, it is possible to emend the text of verse 15.7ab as *evamady ¯ advayenapi ´ ¯ sr¯ıkara\*var ¯ n. a* (*m.c.* for *-varn.ena*) *varn. itam* ("Evam. and others are also explained by the syllable letter ´sr¯ı, [which represents] the nondual").

822 Verses 7c–9b elucidate the meaning of the letter *he* (of *sr´ ¯ıheruka*), based on the traditional doctrine that the letter *he* refers to the emptiness of cause and so on. (For what "and so on" indicates, see footnote 827.) The earliest version of this doctrine can be found in the *Hevajra* (*hekara ¯ m. hetvadi´ ¯ sunyat ¯ a¯*, Skt ed. (Snellgrove 1959), I.7.27b).

823 If the text (15.7c) is edited as *hekarahr ¯ .dayat¯* (compound) and not as *hekara hr ¯ .dayat¯* , it can be translated as "From the heart, [which refers to the meaning of] the letter *he*."

824 For "holders," the *Bohita¯* explains thus (D 1419, 133r7–v1): *sna tshogs pa'i rdo rje 'chang gi gzugs* ("[assuming] the form of a crossed-vajra-holder"). The *Bohita¯* does not explain what "others" mean.

825 In this passage, "the heart" and "visualization," from and through which the deities appear, respectively, are examples of the empty "cause," which is represented by the letter *he*.

826 If the text (8c) is edited as *sa´sunyahetv ¯ atmakañ ¯* (compound) and not as *sa ´sunyahetv ¯ atmakañ ¯* , it can be translated as "[He should know that the letter *he*] represents (*sa*; 'has [the meaning of]') that the cause is empty by nature."

827 The *Bohita¯* does not explain what the word *adi ¯* ("so on") of *hetvady- ¯* indicates. According to the *Yogaratnamal¯ a¯* (Skt ed. (Snellgrove 1959), p. 123, l. 8–l. 10) and the *Muktaval ¯ ¯ı* (Skt ed. (Tripathi and Negi 2001), p. 73, l. 9–l. 10), which are the two commentaries on the *Hevajra*, the word *adi ¯* refers to *svabhava ¯* ("intrinsic nature"), and the words *hetvadi ¯* mean "cause and intrinsic nature." D¯ıpankara´ ˙ sr¯ıjñana's ¯ *Abhisamayavibhanga ˙* (D 1490, 187r6) and Alakakala´sa's *Upade´sanus ¯ ari ¯ n. ¯ı* (Skt ed. (Pandey 1998), 9.7–8 (p. 88, l. 4)) suggest that *adi ¯* indicates origination (i.e., the effect of that cause).

828 It the text (15.9b) is edited as *sa´sunya ¯ m.* (compound) and not as *sa ´sunya ¯ m.* , it can be translated as "having [the meaning of] being empty".

(The meaning of the letter *ru*, i.e., being free from conceptual arrangement, etc. 829—) [Taught in connection with] the conceptual arrangement (*vyuha ¯* ),830 the selflessness of person,831 the great, is [accompanied by] a web of conceptualization.832 The letter *ru* [represents the principle that] myself is conditioned:833 That [letter *ru* refers to the state of] being free from the conceptual arrangement of "mine".834 **(9c–10b)**

(The meaning of the letter *ka*, i.e., not being located anywhere, etc.835—) *Ka* [refers to] all that I repeat narrating in the nonduality of consciousness. [It is] not located anywhere (*kvacit*); hence, [it is] the letter *ka*. Therefore, (*yatah.*), [it is] not [that] direct perception of things is void; [it is] of the nature of the pure reality (*vastumatra ¯* ).836 **(10c–11)**

829 Verses 9c–10b explain the meaning of the letter *ru* (of *sr´ ¯ıheruka*), based on the traditional idea or a doctrine that the letter *ru* refers to the state of being free from conceptual arrangement (*apagatavyuha ¯* ) or equivalent. The *Hevajra* was the first to teach this (*rukar¯ apagatavy ¯ uha ¯ m.* , Skt ed. (Snellgrove 1959), I.7.27c). The term *vyuha ¯* , which I have translated as "conceptual arrangement," or variant terms, refers to "thinking" or "reasoning" (*vitarka*) according to the *Yogaratnamal¯ a¯* (Skt ed. (Snellgrove 1959), p. 123, l. 10); to have the concept of "I" (*aham.* ) according to the *Muktaval ¯ ¯ı* (Skt ed. (Tripathi and Negi 2001), I.7.27 [p. 73, l. 11]); "[the concepts of] continuation and destruction" (*gnas pa dang 'jig pa*), which follow the cause and origination (= *hetvadi ¯* ), according to D¯ıpankara´ ˙ sr¯ıjñana's ¯ *Abhisamayavibhanga ˙* (D 1490, 187r6); "characteristics" (*nimitta*) or "linguistic proliferation" (*prapañca*) according to Alakakala´sa's *Upade´sanus ¯ ari ¯ n. ¯ı* (Skt ed. (Pandey 1998), 9.7–8 (p. 88, l. 11)); "mental defilements such as greed" (*'dod chags la sogs pa'i nyon mongs pa*) according to Tarisena's ¯ *Vajrag¯ıtibha¯s.ya* (D 1208, 308r2–r3); and "conceptualization" (*rnam par rtog pa*) according to Vajrapa¯n. i's *Guruparamparakramopade´sa* (D 3716, 177r7).

830 In the next line (15.10b), the conceptual arrangement (*vyuha ¯* ) is related to the selflessness of person, expressed as "[the state of] being free from the conceptual arrangement of 'mine'" (*vyuh¯ apagatam ¯ mama*). Therefore, I have translated verse 15.9c as "[Taught in connection with] the conceptual arrangement (*vyuha ¯* ), the selflessness of person . . . ."

831 In the *D. ak¯ ar¯ n. ava*, the letters *he* and *ru* are also thus connected with the selflessness of phenomenal existence (*dharmanairatmya ¯* ) and the selflessness of person (*pudgalanairatmya ¯* ), respectively.

832 By "[accompanied by] a web of conceptualization" (*kalpanaj¯ alakam ¯* , 15.9d), I mean the covering of what is to be known (*jñeyavara ¯ n. a*): it is traditionally taught in Buddhism (particularly as a criticism of the H¯ınyana or Lesser Vehicle) that one who has just realized the selflessness of person is not ¯ freed from the covering of what is to be known yet, which is removed by realizing the selflessness of phenomenal existence. For this, I appreciate Dr. Taiken Kyuma and Dr. Kazuo Kano's suggestion. In the present passage in the *D. ak¯ ar¯ n. ava*, the selflessness of phenomenal existence is represented by the letter *he* (15.9a).

833 In the *D. ak¯ ar¯ n. ava*, the letters *he* and *ru* are also thus connected with the cause (*hetu*) and condition (*pratyaya*), respectively.

834 If the text (15.10ab) is edited as *rukarapratyay ¯ atmañ ca savy ¯ uh¯ apagatam mama ¯* (compounds), and not as *rukara pratyay ¯ atmañ ca sa vy ¯ uh¯ apagatam mama ¯* , it can be translated as "The letter*ru*, [which represents the principle that] myself is conditioned, has [the meaning of] being free from the conceptual arrangement of 'mine'".

835 Verses 15.10c–11b expound the meaning of the letter *ka* (of *sr´ ¯ıheruka*), based on the traditional doctrine that the letter *ka* refers to not being located anywhere. The oldest version of this doctrine can be found in the *Hevajra* (*kakaram ¯ . na kvacit sthitam*, Skt ed. (Snellgrove 1959), I.7.27d).

836 For the concept of the *vastumatra ¯* or "pure reality" in the *Tattvartha ¯* Chapter of the *Bodhisattvabhumi ¯* and the *Vini´scayasam. grahan. ¯ı*, see (Takahashi 2005).

O, goddess! At the outset, [a practitioner] contemplates the word *sr´ ¯ı-he-ru-ka*, [which] permeates all. **(12ab)**

[He should visualize] a seed of knowledge [representing] the self-existent one (viz., *hu¯m.* ) 837 at the center of a lotus on a sun [disk] in [his] heart. Then he should emit rays of various colors,838 [which] fill the sky. Having attracted an assembly (*jala ¯* ) of deities formed by Jñana ¯ d. akin ¯ ¯ı,839 he should make the Lord of the world840 seated at the center of a hollow space in the sky. Having made offerings of the nectar and so on and [articles] originated in himself through the moon[rise] and sunrise,841 and having performed the confession of sin and others,842 he should reflect on compassion and so on.843 Then, [having made] himself being of the nature of emptiness,844 he should contemplate [the mantra of] *yoga´suddha* ("being purified by yoga").845 **(12c–15)**

837 According to the *Bohita¯* (D 1419, 134v7), a seed of knowledge is the letter *hu¯m.* , which is a summary (*bsdus pa*) of the four letters *sr´ ¯ı*, *he*, *ru*, and *ka*.

838 According to the *Bohita¯* (D 1419, 135r2), the "various colors" are the five colors and so on.

839 According to the *Bohita¯* (D 1419, 135r3), the words "formed by Jñana ¯ d. akin ¯ ¯ıs" indicate Vajravar¯ ah¯ ¯ı and other female deities. Male deities are referred to by the words "of deities" (*devatam used ¯* in the sense of *devatan¯ am¯* ).

840 It appears that "the Lord of the world" (*jagatah. pat¯ım* used in the sense of *jagatah. patim*) indicates Heruka according to the *Bohita¯* (D 1419, 135r3) and D. ak¯ ar¯ n. ava (another name for Heruka) according to Jayasena in his *Ratnapadmaraganidhi ¯* (D 1516, 4r7).

841 According to the *Bohita¯* (D 1419, 135r4–r5), the nectar means the *vi mu ´su ra ma*, the fivefold nectar (excrement, urine, semen, menstrual blood, and human flesh). The articles originated in himself refer to fluid essences flowing in the practitioner's body, which represent all constituents of his body. The fluid essences emerge by controlling the "moonrise and sunrise," which refers to the movement of two vital airs, *pran¯. a* (*srog*) and *apana ¯* (*thur sel*).

842 According to the *Bohita¯* (D 1419, 135r5–r6), they refer to the seven best offerings (*bla na med pa'i mchod pa rnam pa bdun rnams*), which are (1) the confession of sin (*sdig pa bshags pa*), (2) the vow of never doing [evil actions] (*mi byed pa'i sdom pa*), (3) rejoicing at [others' acquiring merit] (*bsod nams la rjes su yi rang ba*), (4) the complete dedication [of merit] (*yongs su bsngo ba*), (5) taking refuge in the three [jewels] (*gsum la skyabs su 'gro ba*), (6) generating awakening of the mind (*byang chub kyi sems bskyed pa*), and (7) relying on the path (*lam la brten pa*).

843 According to the *Bohita¯* (D 1419, 135r6), the words "compassion and so on" signify the Four Immeasurables: mercy, compassion, sympathetic joy, and equanimity.

844 According to the *Bohita¯* (D 1419, 135r6–r7), this indicates the contemplation of these mantras: (1) *om. sarvadharma¯h. s´unyat ¯ a-\*svabh ¯ av¯ a¯h. (em.; -svabhava) ´ ¯ sunyo 'ham ¯* ; (2) *om. [svabhava´ ¯ suddha¯h.] sarvadharma¯h. svabhava´ ¯ suddho 'ham*; and (3) *om. s´unyat ¯ ajñ¯ anavajrasvabh ¯ av¯ atmako 'ham ¯* . The second mantra is taught in many scriptures of the Sam. vara tradition. The version found in the *Catus.p¯ıt.ha* is perhaps one of the oldest (Skt ed., 2.3.7 and 2.3.120). The third mantra is quite popular among various traditions in Buddhist Tantrism. The version found in the *Guhyasamajatantra ¯* (abbreviated to *Guhyasamaja ¯* , Skt ed. (Matsunaga 1978), Chapter 3, p. 11, l. 16) is perhaps the oldest. The first mantra is uncommon. The *Abhidhanottara ¯* (3.6–9, 12–22, and 24–50) teaches fifty mantras that are in the form of < *om.* something-*suddh ´ a¯h. sarvadharma¯h.* something-*suddho 'ham ´* >. The first mantra is perhaps a currupted form of one of them.

845 According to the *Bohita¯* (D 1419, 135r7), this mantra is *om. yoga´suddha¯h. sarvadharma yoga´ ¯ suddho 'ham*. This mantra is taught in many scriptures that belong to the Sam. vara tradition. The version found in the *Catus.p¯ıt.ha* is perhaps one of the oldest (Skt ed., 2.3.9 and 2.3.122).

#### **6.3. The Rise of the Universe and Causal Vajra-Holder from Emptiness**

Then, after [those whose] intrinsic natures are the five seeds,846 he should visualize a divine castle [at the top of them], and, afterward, the Causal Vajra-holder [in that castle placed] on a lotus on Mt. Meru clearly. **(16)**

[The Causal Vajra-holder] is white in color, [has] four faces, [has] three eyes [on each], [has] twelve arms, is devoted to the yoga of union with wisdom (his female consort), and is adorned with youthful ornaments. [His four faces are], counterclockwise, white, green, red, and yellow [in color, respectively]. [He has] twisted locks of hair and has a crossed vajra and a crescent moon on the face (head). **(17–18)**

[He] stands in the al¯ ¯ıd. ha posture with the feet placed on both Hara and Gaur¯ı.  On the twelve [circles], provided with sixteen gates, pleasing, and [complete with] thirty-two charnel grounds, [marks of] (1) knife, (2) jewel, (3) vajra, (4) lotus, (5) disk, (6) sword, (7) crossed vajra, (8) skull bowl, (9) hairless head, (10) skeleton, a powerful entity's head, (11) noose, and (12) hook are to be known: circular patterns [of these marks] are on the respective circles. Every [circle is] also [provided with] thirty-six spokes. A vajra on a lotus is [placed on] a sun [disk].847 **(20d–23)**

846 According to the *Bohita¯* (D 1419, 135r7–v1), the five seeds are *yam.* , *ram.* , *vam.* , *lam.* , and *sum.* , from which the wind, fire, water, and earth disks and Mr. Sumeru are developed.

847 This paragraph means this: At the center of the whole man. d. ala, there is an all-colored lotus of forty-eight petals, where the twenty-four d. akin ¯ ¯ıs reside. Outside this lotus there are twelve circles, which are located in a concentric manner; on which there are twelve circular patters; and which are provided with thirty-six spokes. The meaning of the last line, "A vajra on a lotus is [placed on] a sun [disk]," is not clear. I speculate it as mentioning a part of how the deities on the man. d. ala are developed; they are developed from a vajra on a lotus placed on a sun disk. The *Bohita¯* does not explain this line. The *Ratnapadmaraganidhi ¯* (D 1516, 5v6–6r1) teaches a visualization of a five-pronged vajra on a sun disk placed on a moon disk as a practice to be performed immediately before the visualization of the Causal Vajra-holder (Causal Heruka). This is slightly different.

From the causal vajra,848 [a man. d. ala] is developed, [which] consists of the five hundred and four and so on.849 The wheel of man. d. ala completely manifests by ceaselessly singing voices850 **(24)**

"O Lord, though people invite [you] to feast every day, why do you remain in emptiness? Please arise, O Lord, the compassionate one, for me! Please love [me]. O you Great Pleasure, Vajra-holder!851 **(25)**

Please listen, please listen. The welfare of others has disappeared. As (*jima*) animals (people) are dying, so (*tima*) please love my blooming lotus, please make all people happy.852 **(26)**

848 It is possible to interpret that the causal vajra means the Causal Vajra-holder (\**hetuvajradhara*, the *D. ak¯ ar¯ n. ava*, 15.17–18). According to the *Bohita¯* (D 1419, 136v2–v3), the Causal Vajra-holder is transformed into a fluid drop with his female consort. The *Ratnapadmaraganidhi ¯* (D 1516, 6v1–v7) expounds this meditation: after Causal Heruka (Vajra-holder) and his female consort have been melted and become a fluid drop, a five-pronged vajra appears from it; then, it is transformed into the man. d. ala. This suggests that the causal vajra means the five-pronged vajra, from which the man. d. ala is developed.

849 The Sanskrit manuscripts' reading of *pañca´¯saccaturadikam ¯* literally means "fifty, four, and so on," which is obscure. It is "five hundred and four additional" (whose Sanskrit may be *pañca´satacaturadhikam*) according to the Tibetan translation and the *Bohita¯*. The "five hundred and four additional" makes sense. Five hundred and four is the total number of the twenty-four d. akin ¯ ¯ıs on the central lotus, the twelve groups of thirty-six d. akin ¯ ¯ıs (who are d. akin ¯ ¯ıs on the twelve circles), sixteen gates, and thirty-two charnel grounds: they account to five hundred and four in total. The "additional" or "so on" indicates the other deities on this man. d. ala. The *pañca´¯saccaturadikam ¯* ("fifty, four, and so on") is better in meter than the *pañca´satacaturadhikam* ("five hundred and four additional"). Therefore, I have interpreted that that the *pañca´¯saccatur-* is used as a secret language to mean the *pañca´satacatur-*.

850 The Apabhram. sa song in verse 15.25–28 is recited by the goddesses to entreat the melted Lord to ´ arise for the sake of the world. Although the used words and phrases are different, and hence they cannot be deemed as equivalent verses, somewhat similar songs by goddesses to entreat the Lord in Apabhram. sa can be found in many Buddhist Tantric texts. As Isaacson (Isaacson 2007, p. 301) pointed ´ out, the *Guhyasamaja ¯* is the first to teach this sort of song (Skt ed. (Matsunaga 1978), 17.72–75). In the *Guhyasamaja ¯* , the song is composed in Sanskrit. See also (Stephenson 2020), which is perhaps the most

recent study of this topic, although it does not deal with the verses in the *D. ak¯ arn ¯ . ava*. 851 According to the *Ratnapadmaraganidhi ¯* (D 1516, 6v2–v4), verse 15.25 is recited by the first six of the twenty-four d. akin ¯ ¯ıs residing on the central lotus: (1) D. akin ¯ ¯ı, (2) Rupik ¯ a, (3) Cumbik ¯ a, (4) Par ¯ av¯ r.tta, ¯ (5) Sabalik ¯ a, and (6) Anuvart ¯ ¯ı, whose nature is mercy (the first of the Four Immeasurables).

852 The Tibetan translation, in which *jima* (for *yatha¯*) and *tima* (for *tatha¯*) are not connected together, reads verse 15.26 as follows: "Please listen, please listen. The welfare of others has disappeared. Animals (people) [look] as if (*jima*) [they] are dying. Please love my blooming lotus. Please also (*tima*) make all people happy." This also makes sense.

According to the *Ratnapadmaraganidhi ¯* (D 1516, 6v2 and 6v4–v5), verse 15.26 is recited by the second six of the twenty-four d. akin ¯ ¯ıs residing on the central lots: (7) Lam¯ a, (8) Yoge´ ¯ svar¯ı, (9) Bhadra, (10) ¯ Kapalin ¯ ¯ı, (11) Kank˙ alik ¯ a, and (12) R ¯ aj ¯ avart ¯ ¯ı, whose nature is compassion (the second of the Four Immeasurables).

 The nature of the innate is beyond words. The other sentient beings become inanimate.853 As long as you are in emptiness, it is useless.854 **(27)**

You are a cause of all phenomenal existences. Why do you not come to and reside [in] the nature of the innate? Please love me in terms of the ultimate reality, so that you become equal to the world.855 **(28)**"

#### **6.4. The First Sahaja (Innate) Layer**

#### *6.4.1. The Lotus (padma) at the Center*

Then, entreated with the song, Heruka has been aroused spontaneously. "*Om. , a¯h.* , the body, speech, and mind adamantine *hu¯m. phat. hoh.* "—with recitation of this mantra, [the practitioner] performs the instantaneous transformation: the hero of all (Heruka), with [his consort] yogin¯ı (Vajravar¯ ah¯ ¯ı), by nature, instantly emerge by means of the mantra. **(29–30)**

[Standing on] Bhairava and Kalar ¯ atri on fire on the sun [disk] on the pericarp ¯ [of the lotus], [Heruka] is dancing. [He should visualize Heruka] having the body [colored] half black and half green; [complete with] seventy-six arms; [having] seventeen [faces] with three eyes [on each]; wearing a crown of twisted locks of hair; being a hero; [having] a crossed vajra [on top of the head] and a half moon [on the head]; and always having [his] mouth open [and showing] large fangs from the right and left [parts of the mouth]. [Three faces looking to the south, west, and north are colored] yellow, red, and in sequence (viz., green), [respectively,] and the other [fourteen] faces are colored like a black bee.856 [He should meditate on Heruka, who] <is greatly awful and laughs loudly and>857 is grinning and terrifying. **(31–34b)**

853 For "become inanimate," the text is *danda ai¯* (for *dhandham. yati ¯* ). If *danda* indicates *dvandvam.* , the translation should be "perceive in a dualistic way".

854 Acording to the *Ratnapadmaraganidhi ¯* (D 1516, 6v2 and 6v5), verse 15.27 is recited by the third six of the twenty-four d. akin ¯ ¯ıs residing on the central lotus: (13) Khan. d. aroha, (14) ¯ Sma´ ´ san¯ ¯ı, (15) Vidrav¯ı, (16) Kurukullika, (17) Rudant ¯ ¯ı, and (18) Nat.¯ı, whose nature is sympathetic joy (the third of the Four Immeasurables).

855 According to the *Ratnapadmaraganidhi ¯* (D 1516, 6v2 and 6v5–v6), verse 15.28 is recited by the fourth six of the twenty-four d. akin ¯ ¯ıs residing on the central lotus: (19) Rupi ¯ n.¯ı, (20) Bhairav¯ı, (21) Sikh ´ ¯ı, (22) Sikha ´ n. d.¯ı, (23) Jat.il¯ı, and (24) Rudra, whose nature is equanimity (the fourth of the Four ¯ Immeasurables).

856 I consider these as parallel to the colors of Sam. vara's four faces that look to the four cardinal directions: the front (or east) face is black; the north face is green; the west face is red; and the south face is yellow (for example, *Nis.pannayogaval ¯ ¯ı*, Skt ed. (Lee 2004), p. 35, l. 4). Meanwhile, "the other [fourteen] faces are colored like a black bee" (*bhr.ngasannibh ˙ a¯h.* ) appears to be an expression borrowed from the *Hevajra* (Skt ed. (Snellgrove 1959), II.5.12d) or *Sam. put.odbhava* (Skt ed. (DTC 2021), 3.1.17b), *bhr.ngasa ˙ m. nibha¯h.* (for describing Heruka's eight faces).

857 This part may be an interpolation.

A bunch of weapons is to be known in the right and left [hands] in order.  In the *D. ak¯ ar¯ n. ava* (10.44b) and (29.10a), the Tibetan translations for that term are *sgrog* and *skogs*, which means a "chain (or some binding tool)" and a "peel," respectively.

859 The translation is based on Tib (*phub chung yu can or phub chung*). This word, *pit.t.ani ¯* , appears three times in the *D. ak¯ ar¯ n. ava*. This word may come from the verb *pit.t.aya* ("to press into a small mass") or noun *pit.a* ("box").

860 I am not certain of the word *bhoka*. In the *D. ak¯ ar¯ n. ava* (29.3c), the Tibetan translation for this term is *mdung*, meaning "lance".

861 The name of this drum is *d. ukka¯* or *d. uka¯* drum in the other parts of the *D. ak¯ ar¯ n. ava* (10.46c and 29.3c).

They also seem to be derived from *d. hakka¯*. 862 This is a rock (*sil ´ a¯*) in the *D. ak¯ arn ¯ . ava* (10.47b) and a mace (*gad. a¯* = *gada¯*) in the *D. ak¯ arn ¯ . ava* (29.4b).

863 This is a short club (*dan. d. ika¯*) in the *D. ak¯ arn ¯ . ava* (10.47c) and *datrik ¯ a¯* sickle in the *D. ak¯ arn ¯ . ava* (29.4c).

A decoration (headband) made of five hairless heads,864 an ornament of the six seals,865 a garland of a hundred hairless heads [as a necklace],866 sounding armlets and anklets, a garment [made of] some tiger skin, and a *romaval ¯ ¯ı* (or line of bodily hair) are on [his] body. **(44–45b)**

Before him is a great goddess [named] Vajravar¯ ah¯ ¯ı, [who is] as previously.867 **(45cd)**

<[Vajravar¯ ah¯ ¯ı holds] an adamantine knife in the right [hand] and a skull bowl in the left hand; hugs the Blessed One (Heruka) around [his] hips with [her] two shanks and loves [him]; [has] one face; [has her] hair untied; is naked; is red in color; wears a garland of hairless heads [as a necklace]; is adorned with sexually attractive ornaments; is crowned with a string of skulls on [her] head; [has her] body smeared with divine perfumes; is decorated with anklets and armlets; is adorned with a divine garland; is ornamented with the six seals; [has] three eyes; [wears] a garland of hairless heads [as a necklace]; is adorned with jewelry; is flaming like the destructive fire [at the end of a *kalpa*]; and is shining with great fire. **(46–49)**>868

[He should meditate on] moistures of pleasure of wisdom and means in all junctures throughout the body. He should visualize [himself (Heruka)] being splendorous with fires, [which assume the shape of] various [forms of] Heruka.869 The vow-observer should give turbans to the heads of all [Herukas].870 **(50–51b)**

Yogin¯ıs are on the lotus petals [facing to the four cardinal directions] such as the east [and] to every intermediate [direction]. [Yogin¯ıs] starting with D. akin ¯ ¯ı,

864 The *Bohita¯* does not explain what this decoration is. I have interpreted it as a headband after having considered that it is parallel to the string of five skulls on the forehead (*lala¯t.ordhvapañcakapalam ¯ al¯ ¯ı*) of Sam. vara with four faces and twelve arms in the *Nis.pannayogaval ¯ ¯ı* (Skt ed. (Lee 2004), p. 35, l. 9).

865 The six seals are symbolic ornaments made of bones and ashes, although these are not always identical. They are an ornament for the neck (*kan. t.hika¯*), a bracelet (*rucaka*), an earring (*kun. d. a*), a jewel on the head (*siroma ´ n. i*), a sacred thread (*yajñopav¯ıta*), and ashes (*bhasman*) according to Luy¯ ¯ıpa's *Cakrasam. varabhisamaya ¯* (Skt ed. (Sakurai 1998), 7 (c)).

866 In the *Nis.pannayogaval ¯ ¯ı* (Skt ed. (Lee 2004), p. 35, l. 8), Sam. vara with four faces and twelve arms wears a garland of fifty wet human hairless heads (*pañca´¯satsardranara´ ¯ sirah.sren ´ . ¯ıkah.* ).

867 It is not clear what *purvavat ¯* ("as previously [mentioned]") indicates. I consider that because of this obscurity, verses 15.46–49, which describe Vajravar¯ ah¯ ¯ı's physical features, were interpolated.

868 This passage (15.46–49), which describes Vajravar¯ ah¯ ¯ı's physical features, can be found only in manuscripts D of the *D. ak¯ ar¯ n. ava* and the *Man. d. alarcanavidhi ¯* . The *Ratnapadmaraganidhi ¯* includes a passage that is slightly more extensive than this one (D 1516, 7v3–v6). It seems that this passage was not included in the original text of the *D. ak¯ ar¯ n. ava*. However, its description of Vajravar¯ ah¯ ¯ı's physical features does not contradict instructions in the other passages in this chapter.

869 According to the *Bohita¯* (D 1419, 139v1), this line describes a visualization of Vajravar¯ ah¯ ¯ı. However, I have interpreted it as describing Heruka, or Heruka with his consort Vajravar¯ ah¯ ¯ı, who is resplendent with fires assuming the shape of various forms of Heruka. The "various [forms of] Heruka" perhaps indicate heroes (male consorts of d. akin ¯ ¯ıs) residing on the twelve circles, who are also called "Leader Heruka," "Light Heruka," and so on.

870 According to the *Bohita¯* (D 1419, 139v2), this describes all heroes and their consort d. akin ¯ ¯ıs each wearing a turban on the head. However, I have interpreted it as describing the feature of fires assuming the shape of Heruka, who wears a turban.

twenty-four in total, are [arranged] by sixes. In this manner, D. akin ¯ ¯ı and so on, six [in number], are [arranged on the six petals] from the east to the north. Again, [arranged] from the north, Lam¯ a and so on, six [in number], are [arranged on the next six petals] ¯ to the west. [Arranged] from the west, "lineage" (viz., six) [yogin¯ıs] starting with Khan. d. aroha are [arranged on the next six petals] to the south. And then, [arranged] ¯ from the south, Rupi ¯ n.¯ı and so on, six [in number], are [arranged on the rest six petals] to the east. **(51c–54b)**

(1) D. akin ¯ ¯ı, (2) Rupik ¯ a, (3) Cumbik ¯ a, (4) Par ¯ av¯ r.tta, (5) Sab ¯ alik ¯ a, and (6) Anuvart ¯ ¯ı are half black and half green [in color].871 (7) Lam¯ a, (8) Yoge´ ¯ svar¯ı, (9) Bhadra, (10) ¯ Kapalin ¯ ¯ı, (11) Kank˙ alik ¯ a, and (12) R ¯ aj ¯ avart ¯ ¯ı are half green and half red, in order.872 (13) Khan. d. aroha, (14) ¯ Sma´ ´ san¯ ¯ı, (15) Vidrav¯ı, (16) Kurukullika, (17) Rudant ¯ ¯ı, and (18) Nat.¯ı are stated to be half red and half yellow.873 (19) Rupi ¯ n.¯ı, (20) Bhairav¯ı, (21) Sikh ´ ¯ı, (22) Sikha ´ n. d.¯ı, (23) Jat.il¯ı, and (24) Rudra are goddesses [who are] half yellow and half ¯ black.874 [Their physical features] such as weapons in [their] hands are [the same as those] of Var¯ ah¯ ¯ı. **(54c–58b)**

Skull bowls [filled with] the fivefold nectar of immortality are [placed] on the petals [located] between [the petals where the twenty-four yogin¯ıs reside]. **(58cd)**

Assuming the pratyal¯ ¯ıd. ha posture, [every yogin¯ı] wears a string of skulls and other [good ornaments]. [Every yogin¯ı] is to be discerned on [the lotus petals in] a counterclockwise direction, to have been born on the upper portion (summit) of Mt. Sumeru. **(59)**

< The lotus petals are thus [taught]. **(60)** >875

#### *6.4.2. The Adamantine Circle (vajracakra)*

Outside that is the Adamantine Circle. Inside [this circle, which is colored] dark bluish-black, are: (1) D. akin ¯ ¯ı, also (2) Lam¯ a, (3) Kha ¯ n. d. aroha, (4) R ¯ upi ¯ n.¯ı, (5) Pracan. d. a, (6) Ca ¯ n. d. ak¯ s.¯ı, (7) Prabhavat ¯ ¯ı, (8) Mahan¯ as¯ a, (9) V ¯ ¯ıramat¯ı, (10) Kharvar¯ı, (11) Lanke´ ˙ svar¯ı, and (12) Drumacchay¯ a. Likewise, (13) Air ¯ avat ¯ ¯ı and (14) Mahabhairav ¯ ¯ı

871 They reside on the six petals between the east and the north. According to the *Bohita¯* (D 1419, 140r1–r2), d. akin ¯ ¯ıs (1)–(3) are colored black and d. akin ¯ ¯ıs (4)–(6) are green.

872 They reside on the six petals between the north and the west. According to the *Bohita¯* (D 1419, 140r1–r2), d. akin ¯ ¯ıs (7)–(9) are colored green and d. akin ¯ ¯ıs (10)–(12) are red.

873 They reside on the six petals between the west and the south. According to the *Bohita¯* (D 1419, 140r1–r2), d. akin ¯ ¯ıs (13)–(15) are colored red and d. akin ¯ ¯ıs (16)–(18) are yellow.

874 They reside on the six petals between the south and the east. According to the *Bohita¯* (D 1419, 140r1–r2), d. akin ¯ ¯ıs (19)–(21) are colored yellow and d. akin ¯ ¯ıs (22)–(24) are black.

875 This line (15.60) can be found only in manuscript D. Perhaps it was not present in the original *D. ak¯ ar¯ n. ava*. However, it is unlikely that this lotus circle is a part of the *vajracakra* or Adamantine Circle described below because the text explains that the Adamantine Circle is located outside this lotus circle (15.61a). The *Bohita¯* (D 1419, 140v1) and the *Ratnapadmaraganidhi ¯* (D 1516, 8r4) call this lotus circle *thig le'i 'khor lo* or "Drop Circle".

are taught to be here.  The color [of their bodies] is the ¯ same as [the color] of the circle (dark bluish-black). **(61–65)**

[Every] yogin¯ı on all [twelve] circles—she [has] four arms, [has] one face, holds a skull bowl876 and a skull staff [in the two left hands], also [holds] a small drum and a knife [in the two right hands],877 [has her] hair untied, is naked, [has her] body [ornamented with] the five seals, is adorned with a string of vajras, stands on a corpse, and is very terrifying; [she] wears various [good] ornaments878 and is a wisdom accompanying a means (her male consort).879 **(66–68b)**

The Formless Realm is thus [described]. It (the Adamantine Circle) is also proclaimed to be the *p¯ıt.ha* ("seat"), known to be the Joyful Level. [The *p¯ıt.ha* is inclusive] of, again, the *p¯ıt.ha*, *upap¯ıt.ha* ("near to the seat"), and the other [classes of holy sites]. The [entire body of the] Twelve Levels is also known to be in the middle of each individual Level.880 Similarly, the entire [body of the three realms] is to be known in all individual realms.881 **(68c–70b)**

[On each realm], there are thirty-six [couples of heroes and yogin¯ıs] in total; [it] consists in all merits and is powerful. In this way, [every] realm has the nature of the heroes and yogin¯ıs. In [all circles inside] the ring of mountains, classes of birth (*kula*) of sentient beings are to be generated in order; they are again divided into thirty-six [and arranged] in the respective places [on each circle] in order. **(70c–71)**

The Adamantine Circle, the first, is thus [taught]. **(72)**

876 According to the *Bohita¯* (D 1419, 140v5), this skull bowl is used to hold the nectar (*bdud rtsi*).

877 According to the instruction of Vajravar¯ ah¯ ¯ı's physical features (15.46ab), she holds a knife in the right hand and a skull bowl in the left hand. Therefore, I have interpreted that these d. akin ¯ ¯ıs hold a skull bowl and a skull staff in the two left hands and a small drum and a knife in the two right hands. The *Bohita¯* does not comment on this.

878 The *Bohita¯* does not articulate what these ornaments are, but just explains their inner meaning; replete with all merits (D 1419, 141r1–r2).

879 "Wisdom" (*prajña¯*) and "means" (*upaya ¯* ) signify a woman and a man, respectively, in Buddhist Tantrism.

880 These lines say that each of the twelve classes of holy sites is inclusive of, or has the qualities of, all twelve classes of holy sites, and each of the Twelve Levels is inclusive of all Twelve Levels.

881 This line means the following: The Adamantine Circle, the Heart Circle, and the Merit Circle are equated with the Formless, Form, and Desire Realms, respectively. At the same time, every one of these circles represents all the three realms, namely, the Formless, Form, and Desire Realms.