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Background: Contemporary implantable cardiac defibrillators (ICD) enable storage of multiple, preepisode R-R recordings in patients who suffered from ventricular tachyarrhythmia (VTA). Timely prediction of VTA, using heart rate variability (HRV) analysis techniques, may facilitate the implementation of preventive and therapeutic strategies. Aim: To evaluate the novel multipole method of the HRV analysis in prediction of imminent VTAs in ICD patients. Methods: We screened patients from the Biotronik HAWAI Registry (Heart Rate Analysis with Automated ICDs). A total of 28 patients from the HAWAI registries (phase I and II), having medical records, who had experienced documented, verified VTA during the 2-year follow-up, were included in our analysis. HRV during preepisode recordings of 4,500 R-R intervals were analyzed using the Dyx parameter and compared to HRV of similar length recordings from the same patients that were not followed by arrhythmia. Results: Our study population consisted mainly of men 25 of 28 (89%), average age of 64.8 ± 9.4 years, 92% with coronary artery disease. HRV during 64 preevent recordings (2.3 events per patient on average) was analyzed and compared with 60 control recordings. The multipole method of HRV analysis showed 50% sensitivity and 91.6% specificity for prediction of ventricular tachycardia/ventricular fibrillation in the study population, with 84.5% positive predictive value. No statistically significant correlation was found between various clinical parameters and the sensitivity of imminent VTA predetection in our patients. Conclusion: The multipole method of HRV analysis emerges as a highly specific, possible predictor of imminent VTA, providing an early warning allowing to prepare for an arrhythmic episode. (PACE 2013; 36:1342‐1347)

The aim of the study was to evaluate our experience with Physiocor 400T, a dual chamber unipolar pacemaker manufactured by Sorin Biomedica. Between March 1993 and December 1994, 63 units of that model were implanted at our center. Patients were followed for 46 +/- 16 months. By the end of follow-up, 15 patients had died, 1 patient was lost to follow-up, and two units had been replaced for unrelated reasons. During follow-up the following phenomena had been observed: (1) Spontaneous backup reversion (VOO, 80 ppm) in 6 (9.5%) of 63 patients. In three patients this phenomenon was accompanied by concomitant ineffective pacing artifacts at 130 beats/min with very low pulse widths. (2) Unexpected battery depletion (EOL) occurred in 3 (5%) of 63 patients; two of the three occurred within weeks of routine evaluation that confirmed normal battery status. (3) Early elective replacement time (ERT) unpreceded by a gradual drop in magnet rate in 2 (3.2%) of 63 patients. (4) Total loss of telemetry without change in pacing mode in 1 (1.6%) of 63 patients. The estimated event-free 5-year survival of this model was 46%. In conclusion, 12 (19%) of 63 patients had adverse events with Physiocor 400T pacemakers. The potential risk of asynchronous pacing for prolonged periods and the risk of unexpected EOL warrants consideration of elective replacement of all remaining units.

Contemporary implantable cardiac defibrillators (ICD) enable storage of multiple, preepisode R-R recordings in patients who suffered from ventricular tachyarrhythmia (VTA). Timely prediction of VTA, using heart rate variability (HRV) analysis techniques, may facilitate the implementation of preventive and therapeutic strategies.To evaluate the novel multipole method of the HRV analysis in prediction of imminent VTAs in ICD patients.We screened patients from the Biotronik HAWAI Registry (Heart Rate Analysis with Automated ICDs). A total of 28 patients from the HAWAI registries (phase I and II), having medical records, who had experienced documented, verified VTA during the 2-year follow-up, were included in our analysis. HRV during preepisode recordings of 4,500 R-R intervals were analyzed using the Dyx parameter and compared to HRV of similar length recordings from the same patients that were not followed by arrhythmia.Our study population consisted mainly of men 25 of 28 (89%), average age of 64.8 ± 9.4 years, 92% with coronary artery disease. HRV during 64 preevent recordings (2.3 events per patient on average) was analyzed and compared with 60 control recordings. The multipole method of HRV analysis showed 50% sensitivity and 91.6% specificity for prediction of ventricular tachycardia/ventricular fibrillation in the study population, with 84.5% positive predictive value. No statistically significant correlation was found between various clinical parameters and the sensitivity of imminent VTA predetection in our patients.The multipole method of HRV analysis emerges as a highly specific, possible predictor of imminent VTA, providing an early warning allowing to prepare for an arrhythmic episode.

To study the importance of a J shape in atrial pacing leads.We compared in a randomized controlled study acute and chronic results with 2 steroid-eluting, polyurethane, screw-in atrial lead models that differ only in shape. A total of 208 patients were randomized to have implantation of either a straight atrial lead (n = 105) or a J-shaped atrial lead (n = 103). Patients were followed up for 1 year.On implantation, there were no significant differences between leads in rates of failure to implant, implant measurements, number of attempts to achieve an acceptable position, and fluoroscopy times. Before discharge and at 3-month and 1-year follow-up, electrical measurements showed no statistical differences between leads. During the first year after implantation, there were 2.9% early dislodgments (1 week after implantation) and 2.9% late dislodgments in the straight lead group (5.9% rate of all dislodgments) vs no dislodgments in the J-shaped lead group (P = .01). There was a trend toward higher rates of exit block and lead malfunction in the J-shaped lead group. Rates of pericardial complications, subclavian/axillary thrombosis, and chronic atrial fibrillation were the same in both groups.Both leads appear to have an equally favorable performance profile for 1 year of follow-up. The J-shaped lead seems to be more stable and have fewer dislodgments, although it may have a somewhat higher malfunction rate.

A retrospective study was carried out on 36 patients (33 males and 3 females) to determine the incidence of VVI pacemaker dependency following coronary artery bypass surgery. Pacemaker dependency was defined as the presence of pacemaker activity when pacing rate was programmed at 50 beats/min and/or when no hemodynamic adequate rhythm was present during pulse generator replacement. The patients were divided into two groups: (group I) 26 patients with complete atrioventricular (AV) block developing in the early postoperative period. In most of them a pacemaker was implanted up to 3 weeks following surgery (range 2 days to 1 year); (group II) ten patients in whom the indication for pacemaker implantation was sick sinus syndrome with sinus arrest and/or tachy-bradycardia. These patients underwent pacemaker implantation at varying periods of time following surgery (range 12 days to 4 years). Unipolar endocardial leads with VVI programmable pacemakers were implanted in all patients included in this study. Mean follow-up time was 3 years. In group I the pacemaker dependency rate was 65%, whereas in group II it was 30% throughout the follow-up period. It is concluded that the low incidence of pacemaker dependency in patients who undergo pacemaker implantation after coronary bypass surgery necessitates frequent evaluation in the nondependent patient, in order to reassess the need for the pacemaker before pulse generator replacement. Such reassessment should probably include prolonged ambulatory monitoring as well as invasive evaluation of the conduction system, if avoidance of pulse generator replacement is considered.

Seventy-nine per cent of a series of 48 patients with implanted pacemakers developed arrhythmias during exercise. There were 23 patients without known previous competition, and in 69.5 per cent of them arrhythmias developed during exercise. No serious arrhythmias developed, but there were three cases of repetitive firing or short bursts of ventricular tachycardia, five instances of pacing on the apex of the T wave, and one instance of R-on-T phenomenon. None of these cases of ventricular tachycardia was preceded by spike-on-T or R-on-T stimulation. Based on these observations, recommendations for selection of the proper pacemaker have been made.

Cardiac pacemaker malfunctions are of continuous concern to the medical profession as well as to the electronics industry. Certain failures in cardiac pacemaker performance are critical and can result in patient deaths. Cardiac pacemakers are vulnerable to certain malfunctions in the electrode, batteries and the electronic circuit. This paper focuses on failures and reliability of the electronic circuit and how they affect its choice and design. The paper discusses the issues of balancing the various failure modes by considering both failure rates and failure outcomes. As the choice of an appropriate pacemaker is a decision problem under conditions of uncertainty, we employ decision analysis as the analytical and conceptual framework. Use of utility theory enables a systematic quantitative evaluation of such seeming intangibles as the various failure outcomes. Probabilities are assessed using specific engineering and reliability literature. The method is demonstrated on a choice problem between two specific electronic circuit designs. The methodology can be useful in designing the electronic circuit to meet certain reliability specifications, deciding whether or not to introduce redundancy, decisions affecting components and technology, and establishing minimal reliability standards, with regard not only to cardiac pacemakers but to other electronics as well.

Cardiac pacemaker malfunctions are of continuous concern to the medical profession as well as to the electronics industry. Several dozen pacemaker models are on the market and cardiologists often find it difficult to choose amongst them. The main concern is for the distribution of the various failure modes due to premature battery exhaustion or malfunctions in the electronic circuit, and the criticality of the failure. This paper employs a decision analytic framework to help cardiologists choose among several pacemaker models. Failure data were obtained from the literature and a utility function over failure outcomes was elicited from a cardiologist. The paper presents a ‘Batch Reliability Comparison’ method for utility assessment which might also be attractive in other reliability settings. Three specific pacemaker models used at the Chaim Sheba Medical Center were evaluated. The expected utility approach yielded a different ranking than the conventional expected life approach. The results have already been implemented even though they implied choosing a different model than was originally preferred.

Findings in 11 families with cardiomyopathy are reviewed. Of 98 persons examined, 47 were affected. Their mean age at the time of detection was 24 years (range 2 to 61 years). The diagnosis was made by exclusion. The presence of other affected members, often in 2 or 3 generations of the same family, enabled us to establish the familial character. The clinical findings included palpitations, arrhythmias, syncope and sudden death. Nine patients had intractable congestive heart failure, and 6 Stokes-Adams attacks; 4 of the 6 had implanted pacemakers. Several patients had proved or suspected hypertrophic subaortic stenosis. The electrocardiogram proved to be the best single tool for the detection of cardiomyopathy. Rhythm disturbances, left ventricular hypertrophy, intraventricular conduction defects and abnormal Q waves were frequent. The Wolff-Parkinson-White pattern was found in 4 patients. Clinically the diagnosis of mitral valve disease and myocardial infarction was often considered. The prognosis is uncertain; when first detected 28 patients were asymptomatic, and only 13 have remained asymptomatic during a follow-up period of 7 years. Ten of the 47 patients died during this period, and in the 9 who came to autopsy, no congenital, rheumatic, infectious or coronary heart disease was found. The hearts were enlarged, and histologie examination revealed diffuse fibrosis with severe hypertrophy of the muscle fibers. Of special interest were the dynamic changes in the electrocardiogram with the disappearance of the abnormal Q waves and infarctionlike patterns with advancing age, as well as appearance of left bundle branch block. Serum enzyme disturbances were detected in some families, and their possible significance is discussed. Genetically, the findings are consistent with transmission by an autosomal dominant gene with high penetrance.

In 183 out of 763 patients (24%) without sinus node dysfunction belonging to the atrioventricular conduction defect group, a spontaneous loss of sinus activity was detected after a 2–3 year follow-up period, following permanent VVI pacemaker implantation. Atrial fibrillation and/or atrial fibrillo-flutter may precede this final stage of loss of sinus activity.