allergic reaction to the dye or anesthesia used during the procedure; swelling, bruising or bleeding at the generator site, or around the heart, especially if the patient is taking blood thinners, elderly, of thin frame or otherwise on chronic steroid use. a possible complication of dual-chamber artificial pacemakers is 'pacemaker-mediated tachycardia' (pmt), a form of reentrant tachycardia. in pmt, the artificial pacemaker forms the anterograde (atrium to ventricle) limb of the circuit and the atrioventricular (av) node forms the retrograde limb (ventricle to atrium) of the circuit. treatment of pmt typically involves reprogramming the pacemaker. another possible complication is "pacemaker-tracked tachycardia," where a supraventricular tachycardia such as atrial fibrillation or atrial flutter is tracked by the pacemaker and produces beats from a ventricular lead. this is becoming exceedingly rare as newer devices are often programmed to recognize supraventricular tachycardias and switch to non-tracking modes. sometimes the leads, which are small diameter wires from the pacemaker to the implantation site in the heart muscle, will need to be removed. the most common reason for lead removal is infection; however, over time, leads can degrade due to a number of reasons such as lead flexing. changes to the programming of the pacemaker may overcome lead degradation to some extent. however, a patient who has several pacemaker replacements over a decade or two in which the leads were reused may require lead replacement surgery. lead replacement may be done in one of two ways. insert a new set of leads without removing the current leads (not recommended as it provides additional obstruction to blood flow and heart valve function) or remove the current leads and then insert replacements. the lead removal technique will vary depending on the surgeon's estimation of the probability that simple traction will suffice to more complex procedures. leads can normally be disconnected from the pacemaker easily, which is why device replacement usually entails simple surgery to access the device and replace it by simply unhooking the leads from the device to replace and hooking the leads to the new device. the possible complications, such as perforation of the heart wall, come from removing the lead from the patient's body. the free end of a pacemaker lead is actually implanted into the heart muscle with a miniature screw or anchored with small plastic hooks called tines. the longer the leads have been implanted (starting from a year or two), the more likely that they will have additional attachments to the patient's body at various places in the pathway from device to heart muscle, since the body tends to incorporate foreign devices into tissue. in some cases, for a lead that has been inserted for a short amount of time, removal may involve simple traction to pull the lead from the body. removal in other cases is typically done with a laser or cutting device which threads like a cannula with a cutting edge over the lead and is moved down the lead to remove any organic attachments with tiny cutting lasers or similar device. pacemaker lead malposition in various locations has been described in the literature. treatment varies, depending on the location of the pacer lead and symptoms. another possible complication called twiddler's syndrome occurs when a patient manipulates the pacemaker and causes the leads to be removed from their intended location and causes possible stimulation of other nerves. overall life expectancy with pacemakers is excellent, and mostly depends upon underlying diseases, presence of atrial fibrillation, age and sex at the time of first implantation. other devices sometimes devices resembling pacemakers, called implantable cardioverter-defibrillators (icds) are implanted. these devices are often used in the treatment of patients at risk from sudden cardiac death. an icd has the ability to treat many types of heart rhythm disturbances by means of pacing, cardioversion, or defibrillation. some icd devices can distinguish between ventricular fibrillation and ventricular tachycardia (vt), and may try to pace the heart faster than its intrinsic rate in the case of vt, to try to break the tachycardia before it progresses to ventricular fibrillation. this is known as fast-pacing, overdrive pacing, or anti-tachycardia pacing (atp). atp is only effective if the underlying rhythm is ventricular tachycardia, and is never effective if the rhythm is ventricular fibrillation. naspe / bpeg defibrillator (nbd) code – 1993 iiiiiiiv shock chamberantitachycardia pacing chambertachycardia detectionantibradycardia pacing chamber o = noneo = nonee = electrogramo = none a = atriuma = atriumh = hemodynamica = atrium v = ventriclev = ventriclev = ventricle d = dual (a+v)d = dual (a+v)d = dual (a+v) short form of the naspe/bpeg defibrillator (nbd) code icd-sicd with shock capability only icd-bicd with bradycardia pacing as well as shock icd-ticd with tachycardia (and bradycardia) pacing as well as shock history in 1958, arne larsson (1915–2001) became the first to receive an implantable pacemaker. he had 26 devices during his life and campaigned for other patients needing pacemakers. origin in 1889, john alexander macwilliam reported in the british medical journal (bmj) of his experiments in which application of an electrical impulse to the human heart in asystole caused a ventricular contraction and that a heart rhythm of 60–70 beats per minute could be evoked by impulses applied at spacings equal to 60–70/minute. in 1926, mark c lidwill of the royal prince alfred hospital of sydney, supported by physicist edgar h. booth of the university of sydney, devised a portable apparatus which "plugged into a lighting point" and in which "one pole was applied to a skin pad soaked in strong salt solution" while the other pole "consisted of a needle insulated except at its point, and was plunged into the appropriate cardiac chamber". "the pacemaker rate was variable from about 80 to 120 pulses per minute, and likewise the voltage variable from 1.5 to 120 volts". in 1928, the apparatus was used to revive a stillborn infant at crown street women's hospital in sydney, whose heart continued "to beat on its own accord", "at the end of 10 minutes" of stimulation. in 1932, american physiologist albert hyman, with the help of his brother, described an electro-mechanical instrument of his own, powered by a spring-wound hand-cranked motor. hyman himself referred to his invention as an "artificial pacemaker", the term continuing in use to this day. an apparent hiatus in the publication of research conducted between the early 1930s and world war ii may be attributed to the public perception of interfering with nature by "reviving the dead". for example, "hyman did not publish data on the use of his pacemaker in humans because of adverse publicity, both among his fellow physicians, and due to newspaper reporting at the time. lidwell may have been aware of this and did not proceed with his experiments in humans". transcutaneous in 1950, canadian electrical engineer john hopps designed and built the first external pacemaker based upon observations by cardio-thoracic surgeons wilfred gordon bigelow and john callaghan at toronto general hospital. the device was first tested on a dog at the university of toronto's banting institute. a substantial external device using vacuum tube technology to provide transcutaneous pacing, it was somewhat crude and painful to the patient in use and, being powered from an ac wall socket, carried a potential hazard of electrocution of the patient and inducing ventricular fibrillation. a number of innovators, including paul zoll, made smaller but still bulky transcutaneous pacing devices from 1952 using a large rechargeable battery as the power supply. in 1957, william l. weirich published the results of research performed at the university of minnesota. these studies demonstrated the restoration of heart rate, cardiac output and mean aortic pressures in animal subjects with complete heart block through the use of a myocardial electrode. in 1958 colombian doctor alberto vejarano laverde and colombian electrical engineer jorge reynolds pombo constructed an external pacemaker, similar to those of hopps and zoll, weighing 45 kg and powered by a 12 volt car lead–acid battery, but connected to electrodes attached to the heart. this apparatus was successfully used to sustain a 70-year-old priest, gerardo florez. the development of the silicon transistor and its first commercial availability in 1956 was the pivotal event that led to the rapid development of practical cardiac pacemaking. wearable in 1958, engineer earl bakken of minneapolis, minnesota, produced the first wearable external pacemaker for a patient of c. walton lillehei. this transistorized pacemaker, housed in a small plastic box, had controls to permit adjustment of pacing heart rate and output voltage and was connected to electrode leads which passed through the skin of the patient to terminate in electrodes attached to the surface of the myocardium of the heart. in the uk in the 1960s, lucas engineering in birmingham was asked by mr abrams of the queen elizabeth hospital to produce a prototype for a transistorised replacement for the electro-mechanical product. the team was headed by roger nolan, an engineer with the lucas group research centre. nolan designed and created the first blocking oscillator and transistor-powered pacemaker. this pacemaker was worn on a belt and powered by a rechargeable sealed battery, enabling users to live a more-normal life. one of the earliest patients to receive this lucas pacemaker device was a woman in her early 30s. the operation was carried out in 1964 by south african cardiac surgeon alf gunning, a student of christiaan barnard. this pioneering operation took place under the guidance of cardiac consultant peter sleight at the radcliffe infirmary in oxford and his cardiac research team at st george's hospital in london. implantable illustration of implanted cardiac pacemaker showing locations of cardiac pacemaker leads the first clinical implantation into a human of a fully implantable pacemaker was on october 8, 1958, at the karolinska institute in solna, sweden, using a pacemaker designed by inventor rune elmqvist and surgeon åke senning (in collaboration with elema-schönander ab, later siemens-elema ab), connected to electrodes attached to the myocardium of the heart by thoracotomy. the device failed after three hours. a second device was then implanted which lasted for two days. the world's first implantable pacemaker patient, arne larsson, went on to receive 26 different pacemakers during his lifetime. he died in 2001, at the age of 86, outliving the inventor and the surgeon. in 1959, temporary transvenous pacing was first demonstrated by seymour furman and john schwedel, whereby the catheter electrode was inserted via the patient's basilic vein. in february 1960, an improved version of the swedish elmqvist design was implanted by doctors orestes fiandra and roberto rubio in the casmu 1 hospital of montevideo, uruguay. this pacemaker, the first implanted in the americas, lasted until the patient died of other ailments, nine months later. the early swedish-designed devices used batteries recharged by an induction coil from the outside. implantable pacemakers constructed by engineer wilson greatbatch entered use in humans from april 1960 following extensive animal testing. the greatbatch innovation varied from the earlier swedish devices in using primary cells (a mercury battery) as the energy source. the first patient lived for a further 18 months. the first use of transvenous pacing in conjunction with an implanted pacemaker was by parsonnet in the united states, lagergren in sweden and jean-jacques welti in france in 1962–63. the transvenous, or pervenous, procedure involved incision of a vein into which was inserted the catheter electrode lead under fluoroscopic guidance, until it was lodged within the trabeculae of the right ventricle. this became the method of choice by the mid-1960s. cardiothoracic surgeon leon abrams and medical engineer ray lightwood developed and implanted the first patient-controlled variable-rate heart pacemaker in 1960 at birmingham university. the first implant took place in march 1960, with two further implants the following month. these three patients made good recoveries and returned to a high quality of life. by 1966, 56 patients had undergone implantation with one surviving for over 5+1⁄2 years. lithium battery the first lithium-iodide cell-powered pacemaker. invented by anthony adducci and art schwalm. cardiac pacemakers inc. 1972 the preceding implantable devices all suffered from the unreliability and short lifetime of the available primary cell technology, mainly the mercury battery. in the late 1960s, several companies, including arco in the us, developed isotope-powered pacemakers, but this development was overtaken by the development in 1971 of the lithium iodide cell by wilson greatbatch. lithium-iodide or lithium anode cells became