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The Cardiac Pacemaker and The Manufacturer's Responsibility

1972; Elsevier BV; Volume: 61; Issue: 5 Linguagem: Inglês

10.1378/chest.61.5.411

1931-3543

Seymour Furman,

Cardiac pacing and defibrillation studies

We are at a pivotal time in the development of cardiac pacemakers. We are beyond early experimental work when each innovation was a pioneering effort to be applauded, and not yet at a period when prolonged stability of design and utility of cardiac pacemakers ensures a slower rate of change. The field is active in new clinical application and still alive with innovation. New energy sources, new pacemaker rhythms and new electrodes can be anticipated with consequent change in pacemaker indications, longevity and complications. Yet, because of their deep involvement in patient care, the manufacturers have inherited both prosperity, and an obligation to the patient and his intermediate, the physician.This obligation should be as important and honored by each manufacturer as is his balance sheet before the company auditors. Not all live up to that standard. Perhaps the difference is that the auditors have a legal right to examine accounting practices. What is required is a commitment to excellence of manufacture and improvement of design and not only a commitment to change for its sake alone. Obviously that statement can be platitudinous, but a few specific instances may suffice.Because of the position of cardiac pacing in medicine today we are likely to see new manufacturers entering the field. In each instance that manufacturer will introduce the “best” pacemaker manufactured today. In the present state of the art it is likely that patients and physicians will validate the new pacemaker at their own jeopardy. This is so as the determination of late failures and an estimation of longevity is virtually impossible early after pacemaker implant. As statistically significant numbers of longterm animal implants can be prohibitively expensive, it is likely that such validation will be done in humans. Unfortunately the pacemaker will probably not be the best, but will represent an initial attempt by a new company and a new engineering group to enter a lucrative field.What are the problems the new manufacturer will face? The design of a battery powered stimulator which emits regular stimuli at a fixed rate (say 70 BPM) is relatively easy. Even the design of a ventricular inhibited, (demand-standby) pulse generator is not difficult. What is difficult is the design and testing of a pacemaker to function satisfactorily to today's standards. Pacemaker manufacturers have been loathe to allow others to utilize aspects of the technology which they have patented. Other manufacturers have sought small and even inconsequential changes to circumvent existing patent protection. For example, the ventricular inhibited pulse generator is the most common in use. Patent protection is for one in which pacemaker automatic rate and escape interval (that period from the last sensed spontaneous beat to the next pacemaker emission) are the same. Consequently two manufacturers have made ventricular inhibited pulse generators in which the escape interval is longer than the automatic rate (rate hysteresis). No physiologic benefit has been demonstrated from this approach.The pacemaker refractory period has been a matter of great concern to those interested in cardiac and especially pacemaker physiology. Some ventricular inhibited pacemakers have not had a refractory period (or have so stated) and others have. Again, the physiologic argument has raged concerning the need for a refractory period. Yet, many articles have been written about the irregular pacemaker rate and false recycling, because of sensing of P or T waves or the residual intracardiac voltage after a preceding pacemaker emission. It would seem that a refractory period is desirable though not yet fully agreed upon. What has not been pointed out is that the presence of a refractory period is a patented feature of one manufacturer and other manufacturers have not felt free to use it. It is certainly possible that patient care would be enhanced were free licensure, without regard to the financial penalties involved, encouraged between manufacturers.Terminology has been another sore point. The originally introduced noncompetitive pacemaker was called demand, by the authors. The pulse generator was ventricular inhibited in operation. Subsequently, another manufacturer introduced the term standby for his noncompetitive pulse generator, which was, however, ventricular triggered or synchronous. Still a third manufacturer introduced a ventricular inhibited generator and called it standby while manufacturer two now refers to both his ventricular inhibited and triggered units as standby/demand. This further obscures any distinction, and makes it more rather than less difficult for a physician to understand the difference between the two units which operate in different fashions, have different complications and different responses to such ambient influences as electrical interference. One is inhibited, the other driven to more rapid rates in the presence of interfering signals.We need not assume that a manufacturer, once having designed a device, will be aware of all its capabilities. These are limited only by the ingenuity of all of the users. What we can expect and have a right to know is the presence of change and its presumed significance. The lack of information in the pacemaker booklet is an indication that, left to their own devices, some manufacturers will provide the least information and hope for the most widespread use of their product.Nor are manufacturers compelled to inform the medical public of difficulties arising from the use of their products. It is here that they most clearly can argue that economic consequences of such disclosure may be too grave, to inform the public. The consequences to the patient are deemed less consequential, those to the corporate exchequer more significant. One manufacturer had several serious problems with design of a ventricular inhibited pulse generator, which caused severe patient morbidity. The generator was eventually removed from sale and replacement of all implanted units was recommended after 15 months of use. This followed presentation by physicians of data concerning the defects of the unit and the substantial hazard of runaway pacemaker. The manufacturer never did publish the data he had accumulated prior to physician presentation of the damaging data, but reorganization of the pacemaker portion of the organization indicated the importance of the problem. This manufacturer has again issued a new series of unique pulse generators and despite their availability for the past one and one-half years, no information concerning the function of the series is available. Several physicians have experienced difficulty, but each series is small and in itself suggestive, not conclusive. Yet, advertising and sales persist and no accumulated data are available to the profession.What is always desirable is some method of enforcing cooperative self-policing from the manufacturers. Clearly changes will be made, for if not, information will not be distributed and terminology will be misused, at the fiscal option of the manufacturer.We must recognize that attention paid to corporate structure is not an evil undertaking. It does not benefit the patient, manufacturer or the profession for a well established and reputable manufacturer to become insolvent because of an error which causes it to be disbanded and leave the field to less talented organizations. Quite the reverse, only a fiscally and organizationally sound manufacturer can assure a continuing supply of satisfactory equipment and orderly progress. Nevertheless, the public and the profession both have an equal right to the fruits of their commitment and should have their interest enforced.What is needed is a force, able to assert itself in an organized fashion and adequately funded to do so and to cooperate with and, if necessary, confront the manufacturing community. The government is probably not that organization, as compulsion often occurs and political manipulation is possible. Rather, a professional body, such as the American Heart Association, American College of Surgeons, American College of Cardiology, Society of Thoracic Surgeons, American College of Chest Physicians, etc, might serve admirably as the vehicle for such an effort.While total objectivity and the satisfaction of all objections is probably beyond the capacity of any human organization, a far better effort than is now available is needed if one is to produce maximum safety and maximum efficacy for the public. We are at a pivotal time in the development of cardiac pacemakers. We are beyond early experimental work when each innovation was a pioneering effort to be applauded, and not yet at a period when prolonged stability of design and utility of cardiac pacemakers ensures a slower rate of change. The field is active in new clinical application and still alive with innovation. New energy sources, new pacemaker rhythms and new electrodes can be anticipated with consequent change in pacemaker indications, longevity and complications. Yet, because of their deep involvement in patient care, the manufacturers have inherited both prosperity, and an obligation to the patient and his intermediate, the physician. This obligation should be as important and honored by each manufacturer as is his balance sheet before the company auditors. Not all live up to that standard. Perhaps the difference is that the auditors have a legal right to examine accounting practices. What is required is a commitment to excellence of manufacture and improvement of design and not only a commitment to change for its sake alone. Obviously that statement can be platitudinous, but a few specific instances may suffice. Because of the position of cardiac pacing in medicine today we are likely to see new manufacturers entering the field. In each instance that manufacturer will introduce the “best” pacemaker manufactured today. In the present state of the art it is likely that patients and physicians will validate the new pacemaker at their own jeopardy. This is so as the determination of late failures and an estimation of longevity is virtually impossible early after pacemaker implant. As statistically significant numbers of longterm animal implants can be prohibitively expensive, it is likely that such validation will be done in humans. Unfortunately the pacemaker will probably not be the best, but will represent an initial attempt by a new company and a new engineering group to enter a lucrative field. What are the problems the new manufacturer will face? The design of a battery powered stimulator which emits regular stimuli at a fixed rate (say 70 BPM) is relatively easy. Even the design of a ventricular inhibited, (demand-standby) pulse generator is not difficult. What is difficult is the design and testing of a pacemaker to function satisfactorily to today's standards. Pacemaker manufacturers have been loathe to allow others to utilize aspects of the technology which they have patented. Other manufacturers have sought small and even inconsequential changes to circumvent existing patent protection. For example, the ventricular inhibited pulse generator is the most common in use. Patent protection is for one in which pacemaker automatic rate and escape interval (that period from the last sensed spontaneous beat to the next pacemaker emission) are the same. Consequently two manufacturers have made ventricular inhibited pulse generators in which the escape interval is longer than the automatic rate (rate hysteresis). No physiologic benefit has been demonstrated from this approach. The pacemaker refractory period has been a matter of great concern to those interested in cardiac and especially pacemaker physiology. Some ventricular inhibited pacemakers have not had a refractory period (or have so stated) and others have. Again, the physiologic argument has raged concerning the need for a refractory period. Yet, many articles have been written about the irregular pacemaker rate and false recycling, because of sensing of P or T waves or the residual intracardiac voltage after a preceding pacemaker emission. It would seem that a refractory period is desirable though not yet fully agreed upon. What has not been pointed out is that the presence of a refractory period is a patented feature of one manufacturer and other manufacturers have not felt free to use it. It is certainly possible that patient care would be enhanced were free licensure, without regard to the financial penalties involved, encouraged between manufacturers. Terminology has been another sore point. The originally introduced noncompetitive pacemaker was called demand, by the authors. The pulse generator was ventricular inhibited in operation. Subsequently, another manufacturer introduced the term standby for his noncompetitive pulse generator, which was, however, ventricular triggered or synchronous. Still a third manufacturer introduced a ventricular inhibited generator and called it standby while manufacturer two now refers to both his ventricular inhibited and triggered units as standby/demand. This further obscures any distinction, and makes it more rather than less difficult for a physician to understand the difference between the two units which operate in different fashions, have different complications and different responses to such ambient influences as electrical interference. One is inhibited, the other driven to more rapid rates in the presence of interfering signals. We need not assume that a manufacturer, once having designed a device, will be aware of all its capabilities. These are limited only by the ingenuity of all of the users. What we can expect and have a right to know is the presence of change and its presumed significance. The lack of information in the pacemaker booklet is an indication that, left to their own devices, some manufacturers will provide the least information and hope for the most widespread use of their product. Nor are manufacturers compelled to inform the medical public of difficulties arising from the use of their products. It is here that they most clearly can argue that economic consequences of such disclosure may be too grave, to inform the public. The consequences to the patient are deemed less consequential, those to the corporate exchequer more significant. One manufacturer had several serious problems with design of a ventricular inhibited pulse generator, which caused severe patient morbidity. The generator was eventually removed from sale and replacement of all implanted units was recommended after 15 months of use. This followed presentation by physicians of data concerning the defects of the unit and the substantial hazard of runaway pacemaker. The manufacturer never did publish the data he had accumulated prior to physician presentation of the damaging data, but reorganization of the pacemaker portion of the organization indicated the importance of the problem. This manufacturer has again issued a new series of unique pulse generators and despite their availability for the past one and one-half years, no information concerning the function of the series is available. Several physicians have experienced difficulty, but each series is small and in itself suggestive, not conclusive. Yet, advertising and sales persist and no accumulated data are available to the profession. What is always desirable is some method of enforcing cooperative self-policing from the manufacturers. Clearly changes will be made, for if not, information will not be distributed and terminology will be misused, at the fiscal option of the manufacturer. We must recognize that attention paid to corporate structure is not an evil undertaking. It does not benefit the patient, manufacturer or the profession for a well established and reputable manufacturer to become insolvent because of an error which causes it to be disbanded and leave the field to less talented organizations. Quite the reverse, only a fiscally and organizationally sound manufacturer can assure a continuing supply of satisfactory equipment and orderly progress. Nevertheless, the public and the profession both have an equal right to the fruits of their commitment and should have their interest enforced. What is needed is a force, able to assert itself in an organized fashion and adequately funded to do so and to cooperate with and, if necessary, confront the manufacturing community. The government is probably not that organization, as compulsion often occurs and political manipulation is possible. Rather, a professional body, such as the American Heart Association, American College of Surgeons, American College of Cardiology, Society of Thoracic Surgeons, American College of Chest Physicians, etc, might serve admirably as the vehicle for such an effort. While total objectivity and the satisfaction of all objections is probably beyond the capacity of any human organization, a far better effort than is now available is needed if one is to produce maximum safety and maximum efficacy for the public.