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CHAPTER 10 PREVENTING SUDDEN CARDIAC DEATH: THE IMPLANTABLE DEFIBRILLATOR In the 1980s, the pacemaker industry transformed itself into the ‘‘cardiac rhythm management industry’’ by introducing an entirely new kind of implantable machine that halted ventricular tachycardia (VT—a ventricular rate of more than 100 beats per minute) and that most sinister of rhythm disturbances, ventricular fibrillation (VF—random electrical activity in the ventricles with no organized ventricular beat). Thomas Lewis had pointed out in 1915 that ‘‘fibrillation of the ventricles is incompatible with existence. . . . If it occurs in man, [it] is responsible for unexpected and sudden death.’’1 The implantable cardioverter-defibrillator (ICD) astonished the international community of heart specialists and attracted the gaze of the media as an important ‘‘breakthrough’’ in treatment. The ICD acts in the most dramatic possible way to save the lives of men and women susceptible to a common cause of heart-disease mortality in industrialized countries: sudden cardiac death (SCD). The ICD represents the quandary that new technologies can pose for the health-care system: it is effective for many kinds of patients, but the cost of treatment is not negligible.2 A word about terminology: Until 1983 the device we call the ICD could not cardiovert and was generally known as the AID, or automatic implantable defibrillator. For a time after 1983 it was called the AICD—automatic implantable cardioverter-defibrillator—but the automatic dropped off as redundant. Cardioversion, a term introduced in the 1960s by Bernard Lown and Barouh Berkovits, referred to timed electrical discharges or shocks that disrupted and terminated tachycardias. Cardioversion was thus somewhat less drastic than defibrillation. ICDs do cardiovert, but the word is little known outside the community of heart-rhythm specialists. (The manufacturers now say that ICD stands for implantable cardiac defibrillator.) The invention and industrialization of the ICD offers interesting parallels to the development of implantable pacemakers more than a decade 236 MACHINES IN OUR HEARTS earlier, along with a few striking contrasts. With both inventions, clinical research groups conceived of the idea and led the effort in the early going by tackling disparate problems that ranged from identifying the population of appropriate patients to designing hardware to raising money. In both cases, too, the larger community of heart specialists expressed some initial skepticism. At first, the indications (medically defined circumstances warranting use of the technology) were quite narrow for both inventions, fixed third-degree heart block for the pacemaker and demonstrated high risk of ventricular fibrillation for the defibrillator. But the very existence of the technology and the early reports of miraculous recoveries by patients then prompted researchers to intensify their investigations into other brady- and tachyarrhythmias that might be treatable with the new devices. From the start, electrophysiologists (cardiologists specializing in rhythm disorders of the heart) and medical-device manufacturers were intensely interested in expanding the population of patients. As with the pacemaker a generation earlier, the ICD held the promise of both professional honor and financial gain. In some respects, the ICD project under Michel Mirowski unfolded differently from the Chardack-Greatbatch invention of a mercury-powered implantable pacemaker two decades earlier. Unlike its cousin the pacemaker , the prototype ICD was the work of a single group of clinicalresearch physicians and engineers instead of several small teams working independently of each other but sharing ideas back and forth. Development of the ICD involved a more formal mapping out of problems and possible solutions than had been true with the pacemaker. From early in the 1970s, the developers engaged in long-range preparation by submitting more than 50 patent applications and carrying out numerous tests that would lead toward high-quality manufacturing and FDA review. The entire effort cost millions of dollars and engaged the efforts and talents of dozens of people. In both cases—the pacemaker and the ICD—device-manufacturing corporations took over the effort after the first clinical successes. The competences of an established company were needed to prepare the device for large-scale production, to manage clinical trials with hundreds of human implantations, and to plan a marketing effort that included training sales reps and physicians. In the case of the ICD, the entire ramping-up period— from prototype in the animal lab, to first clinical use, to the manufacture of thousands of safe and reliable units—took place during the era of FDA oversight of implantable devices. This was a fact of life for the device industry by the late 1970s. [3.142...

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