Biomedical subjects
A D Bernstein
Publications and source records attributed to A D Bernstein.
Pacemaker-implantation complication rates: an analysis of some contributing factors.
An examination of 632 consecutive pacemaker implantations performed at a single institution by 29 implanting physicians over a 5 year period was made to determine which factors affected the 37 perioperative complications experienced. The introducer method of vein access contributed significantly to the complication rate, which was also related to the number of physician implanters on the staff and the makeup of the implantation teams. Of greatest interest was the substantially large incidence of complications experienced by implanters who performed fewer than 12 implantations per year, and particularly the incidence of lead-related complications.
Transvenous pacing: a seminal transition from the research laboratory.
In the late 1950s, nonsurgical catheter therapies for the treatment of various disorders did not exist, although surgery was at its highest level of development in the classic sense: extirpation of organs, incision and drainage, diagnostic biopsy. Today we live in an era of diagnostic and therapeutic methods based on catheters: observation, aspiration, drainage, stretching, and manipulation by means of relatively atraumatic tubes. The development of catheter techniques has spawned undreamed-of specialties, industries, and professional societies. Although catheters had been used before then in research laboratories, Furman's clinical application of electrode-tipped venous catheters in treating patients with complete heart block and Stokes-Adams seizures represents a turning point. This advance may be regarded as the catalytic and seminal event for the growth of catheter technologies, which are so prominent in the world of medicine today, and their application to many fields of medicine and surgery.
A method of uniform stratification of risk for evaluating the results of surgery in acquired adult heart disease.
The purpose of the study was to devise a method of stratifying open-heart operations into levels of predicted operative mortality, using objective data that are readily available in any hospital. Following univariate regression analysis of 3,500 consecutive operations, 14 risk factors were chosen that met these conditions. A few factors were excluded because they were insufficiently objective or not always available. An additive model was constructed, using the factors chosen, to calculate the probability of mortality within 30 days. The method was then tested prospectively in 1,332 open-heart procedures at the Newark Beth Israel Medical Center. Patients were categorized in five groups of increasing risk: good (0-4%), fair (5-9%), poor (10-14%), high (15-19%), and extremely high (greater than or equal to 20%). The correlation coefficient of anticipated and observed operative mortality, using the additive model, was 0.99. The operative mortality also correlated closely with complication rates and length of hospital stay. The additive model was compared with a second model based on logistic multiple regression; the resulting correlation coefficient was 0.85. The method was also tested at two other hospitals; although their sample sizes were smaller, the outcomes in each risk group were comparable with those at this institution. The collection of data proved to be acceptably simple for all three centers. This study demonstrates that it is possible to design a simple method of risk stratification of open-heart surgery patients that makes it feasible to analyze operative results by risk groups and to compare results in similar groups between institutions. Wider application of the system is recommended.
Cardiac pacing practices in the United States in 1985.
Physicians active in pacemaker implantation and follow-up were surveyed to obtain a profile of permanent cardiac pacing practices in the United States during 1985. Questionnaires were sent to 628 physicians, mainly in New Jersey; 145 responses were received and analyzed. A separate questionnaire was sent to 9 pacemaker manufacturers to solicit information concerning the volume of pacemaker sales and their opinions on a variety of subjects. The rate of permanent pacemaker implantation declined for the first time: it dropped from 518 devices per million population in 1981 to 374 in 1985. Sinus node dysfunction was the chief indication for permanent pacing in 52% of primary implantations; conduction disorders of the atrioventricular node and His-Purkinje system accounted for 41% and ventricular tachyarrhythmias for 2%. Dual-chamber pacing modes were used less frequently than was predicted in 1981, accounting for 30% of primary and 19% of replacement pacemakers. More than 43% of programmable pulse generators were never reprogrammed after implantation. Surveys such as this continue to provide useful information despite obstacles encountered in the use of questionnaires. Important differences in practice patterns and outcomes were identified between surgeons and nonsurgeons, and between frequent and infrequent implanters. These differences reinforce the suggestion that implanters should work at a volume sufficient to maintain their expertise, and that cooperation between surgeons and nonsurgeons would lead to improvements in patient selection, surgical results and optimal pacemaker programming and follow-up care. Better results could be achieved by adopting the continent-wide system of a pacemaker registry now used in Eastern Europe and Great Britain.
Report of the policy conference on computer communications in pacing sponsored by the North American Society of Pacing and Electrophysiology. October 13, 1987.
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Communication based upon the use of agreed upon symbols.
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The NASPE/BPEG generic pacemaker code for antibradyarrhythmia and adaptive-rate pacing and antitachyarrhythmia devices.
A new generic pacemaker code, derived from and compatible with the Revised ICHD Code, was proposed jointly by the North American Society of Pacing and Electrophysiology (NASPE) Mode Code Committee and the British Pacing and Electrophysiology Group (BPEG), and has been adopted by the NASPE Board of Trustees. It is abbreviated as the NBG (for "NASPE/BPEG Generic") Code, and was developed to permit extension of the generic-code concept to pacemakers whose escape rate is continuously controlled by monitoring some physiologic variable, rather than determined by fixed escape intervals measured from stimuli or sensed depolarizations, and to antitachyarrhythmia devices including cardioverters and defibrillators. The NASPE/BPEG Code incorporates an "R" in the fourth position to signify rate modulation (adaptive-rate pacing), and one of four letters in the fifth position to indicate the presence of antitachyarrhythmia-pacing capability or of cardioversion or defibrillation functions.
Techniques for implantation of antitachyarrhythmia devices.
Implantation of ATDs is similar surgically to transpericardial implantation of conventional antibradycardia pacemakers, but considerable special expertise is involved in choosing the appropriate device and deciding how it should be programmed. Experience has reinforced our view that ATD implantation should be performed in what is essentially an operating-room setting, by a qualified team possessing the necessary surgical, electrophysiologic, and technical skills. ATD follow-up is different from that of conventional pacemakers and, particularly in the case of AIDS and AICDs, requires additional specialized instrumentation and more flexibility in scheduling.
An annotation system for displaying operating parameter values in dual-chamber pacing.
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Computer-assisted measurements in pacemaker follow-up.
The application of increasingly sophisticated engineering techniques to cardiac pacemaker design has resulted in substantially greater complexity of follow-up which requires that more complicated measurements be made and interpreted. A feasibility study was conducted in which microcomputer software was designed to permit direct electronic communication between the computer and a commercial follow-up measurement device. This technique eliminates human error in reading or copying measurement data, and facilitates the application of computerized error-trapping, predictive interpretation of measurements, and database-management methods to pacemaker follow-up.
Recommendations of the NASPE computer committee.
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Pacing in perspective: concepts and controversies.
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The 1981 United States survey of cardiac pacing practices.
A survey of physicians implanting pacemakers was conducted to obtain a profile of permanent cardiac pacing practices in the United States during 1981. Questionnaires were mailed to 5,832 implanters with 765 responses (13%) received and 680 analyzed. It was estimated that there were approximately 5,600 physicians, 66% surgeons and 34% nonsurgeons, implanting pacemakers at 3,670 centers. About 118,000 new primary implants were performed, or 518 per million population. Only 17% of implantation procedures in 1981 were replacements compared with 31% in 1978. Roughly half the respondents worked in teams, most implanting from 46 to 55 pacemakers annually. The chief indications for permanent pacing were sick sinus syndrome (48%) and impairment of conduction in the atrioventricular node and His-Purkinje system (42%). Ninety-five percent of pacing leads were implanted transvenously. Seventy percent of the respondents had had experience with atrial and dual-chamber pacemakers, used largely to increase cardiac output. The use of ventricular demand (VVI) pacing decreased accordingly from 91% in 1975 to 84% in 1981. Although approximately 90% of primary pacemakers were programmable to some degree, almost half were not reprogrammed within the first 3 months after implantation and 30% were never reprogrammed. Most patients (85%) were followed up by transtelephonic electrocardiographic monitoring, 68% in conjunction with private office visits. The respondents estimated that dual-chamber pacing, accounting for 10% of implants in 1981, would increase to 37% by 1985. Early electrode malfunctions were less frequent when implantation was performed by high volume and solo implanters, and in public and community hospitals. It is concluded that periodic surveys of this type disclose important trends in the practice of cardiac pacing.
Report of the NASPE Mode Code Committee.
The NASPE Mode Code Committee was formed in response to the growing need for efficient means of describing the function of increasingly complex single- and dual-chamber cardiac pacemakers. After considering numeric, alphabetic, and pictorial codes, the Committee recommended the adoption of two codes: a generic code which is similar to the Revised ICHD Code and is suitable for conversational use, and a specific code, based on one developed by Brownlee and others, that permits more detailed specification of both antibradycardia and antitachycardia functions. The specific code described in this report was adopted by the NASPE Executive Advisory Committee as the NASPE Specific Code in March, 1983. The generic code was not adopted but is described herein for future reference in the light of experience to be gained in the use of the recently published Revised ICHD Code.
Iopamidol and metrizamide for myelography: prospective double-blind clinical trial.
In a comparative randomized double-blind study, 73 patients underwent myelography using iopamidol (36 patients) or metrizamide (37 patients) as contrast medium. The overall diagnostic adequacy of iopamidol myelography was found to be comparable to that of metrizamide myelography. The incidence of examinations graded as superior (64%) or adequate (36%) with iopamidol was equivalent to that with metrizamide (57% superior, 43% adequate). Adverse reactions after iopamidol myelography were fewer, less severe, and generally of shorter duration than those associated with metrizamide. In the iopamidol group, adverse reactions occurred in nine (25%) patients, all of whom experienced mild or moderate headache, one with nausea, vomiting, and fatigue. In the metrizamide group, adverse reactions occurred in 17 (46%) patients, all of whom experienced mild or moderate headache, six with nausea and vomiting and four with back and leg pain. Of nine individuals who underwent myelography using 300 mg 1/ml metrizamide injected via lateral C1-C2 puncture, three experienced a toxic encephalopathy with confusion, dysphasia, headache, nausea, and vomiting, and a fourth individual suffered severe nausea, vomiting, fever, and irregular pulse. Encephalopathy was not observed in any of the 11 patients in whom myelography was performed via lateral C1-C2 puncture with a similar concentration of iopamidol. No seizures were encountered, and no clinically significant changes in laboratory studies were observed with either contrast medium.
Dual-chamber pacing for cardiac arrhythmias: controversies in cloning the conduction system.
From the outset, the art and science of cardiac pacing has been beset with a variety of problems. With the passage of time and concentrated effort in the interrelated sciences, many have been solved. We no longer are concerned with premature battery failure or leaking pulse-generator capsules, but now focus on an entirely new set of issues that beg for resolution. Foremost among these is the true role of dual-chamber pacing in the treatment of slow and fast cardiac arrhythmias of a multitude of etiologies. Secondary to that issue is the cascade of problems brought about by a burgeoning of technical capabilities, such as micro-miniaturized computing devices, complex pacemaker programmability with telemetry functions, the impact of these technologies on therapeutic indications and techniques, the proliferation of pacemaker utilization, and the summative socioeconomic implications.
Cardiac pacing in the 1980s: treatment and techniques in transition.
The pacemaker of the 1980s is designed to maintain atrioventricular synchrony through dual-chamber pacing. This pacemaker is multiprogrammable and capable of telemetric transmission of biologic, electronic and electrophysiologic data. Several developments have made this therapeutic modality possible: 1) the cumulative survival rate of many lithium-battery pacemakers exceeds 95% at 5 years; 2) lead and connector problems are rare; 3) atrial and ventricular electrode malfunctions occur in less than 2% of implants; and 4) new introducer techniques have simplified implantation (mortality and major morbidity rates are 0.5 and 0.4%, respectively). With multiprogrammability, pacemaker function can be optimized for the patient's needs, and about 20% of reoperations can be avoided. Ninety-six dual-chamber (DDD) pacemakers, 55 of which have been followed up for more than 3 months, have provided trouble-free performance and have yielded salutary clinical results, particularly when implanted to replace previous ventricular inhibited units. Problems with these pacemakers have included unusual pacing electrocardiograms, pacemaker eccentricities, programmer maintenance, pacing and follow-up complexities and costs. In the 1980s, effort will be required to find a balance between rapidly evolving technology and the clinical need for complex pacing systems. From 1978 to 1981, the rate of pacemaker implantation grew from 309 to 513 implants per million population per year, and there are now approximately 500,000 patients with implanted pacemakers living in the United States. Indications for pacing are ill-defined, because in many cases the assessment of clinical response to pacing is largely subjective, lacking satisfactory quantitative indexes. This decade will be a time of reappraisal of the extent of clinical applicability of new techniques, particularly the multiprogrammable dual-chamber system which, after 3 years of clinical trial, shows promise of being the predominant pacemaker of the immediate future.