Automatic implantable cardioverter defibrillator. Current status.

The automatic implantable cardioverter defibrillator was conceived by Mirowski as an implantable device for detection and termination of ventricular fibrillation. Since the initial human implant of the defibrillator in 1980, there has been a dramatic expansion of the clinical experience with more than 5000 implants. The technology of the device, which is now capable of sensing and terminating both ventricular tachycardia and fibrillation, has evolved rapidly. Although still not an ideal antiarrhythmic device, it has already had a major impact on arrhythmic mortality with a marked reduction in the sudden death rates in a high-risk patient population.

Survival rates after pacemaker implantation: a study of patients paced for sick sinus syndrome and atrioventricular block.

It is still a matter of controversy as to whether the patients paced for atrioventricular block (AVB) have different prognosis and survival rates than those paced for Sick Sinus Syndrome (SSS). We have compared the survival rates of 962 AVB patients (group A) with that of 283 SSS patients (group B) who underwent pacemaker implantation during the period January 1968 to December 1986. The survival rate graphs of the examined groups were calculated using the actuarial method and the differences in the survival rates between the groups were evaluated using the Logrank test. Our results show that SSS patients have a higher survival rate than AV block with a difference on the rate of survival between the two groups reaching the borderline of statistical significance. Multivariate discriminant analysis was then used to assess that of the parameters (i.e., age at the time of implantation, sex, electrophysiological indication to pacing, etiology or pacing mode) could have had the main influence upon mortality and the different pattern of the survival rate graph within the two groups of patients. Our data show that survival is mostly related to age, pacing mode and, although more slightly, to underlying heart disease; the electrophysiological indication to pacing, instead, does not significantly influence it.

Cardiac pacing and valvular surgery.

Over a 17-year period (1970-1987) 75 patients, 3% of overall valvular surgery (VS) patients have been permanently paced at the time of VS (group 1), nine have been paced long after (group 2), 12 were already paced at the time of valve replacement (group 3), and 81 had a permanent pacing lead inserted during VS without further need for permanent pacing (group 4). Based on pre-, per- and post-operative clinical and electrocardiographic data we studied these four groups (GR). Aortic disease and especially calcified aortic stenosis (CAS) are the main valvular pathologies in all GR. The survival rate in GR 1 is lower than the survival rate of our overall VS PT5 due to older average ages and more severe cardiac conditions. In five patients GR 2 a myocardial pacing lead placed during VS was used long after for permanent stimulation. Patients in GR 3 were older than in other GR at the time of VS. The mortality was high in the patients operated on between 1973 and 1978 (average survived 3.5 years after pacing/2 years after VS) thus demonstrating the benefit of myocardial protection. For GR 4 the ratio of permanent lead implantation during VS was high in the late seventies (10%), it is now around 0.5%. In cases where the evolution of peroperative conduction disturbances is doubtful, it seems to us simpler to place a myocardial lead avoiding subsequent endocardial pacing if necessary, later, especially in patients with tricuspid disease.

Lead fracture in pacemaker patients.

We studied the incidence of lead fractures in 2,226 patients with a total follow-up period of 8,558 patient years. Lead fractures occurred in 100 out of 2,563 implanted leads (3.9%). This corresponds to an average rate of 1.2% per patient year. We found 62 out of 881 singlefilar coil leads fractured (7.0%), 20 out of 809 Siemens Elema 588 leads (2.5%) and only 6 out of 630 multifilar soil leads (1.0%). Lead fractures occurred at a significantly (p less than 0.05) higher rate in singlefilar coil leads than in Simens Elema 588 leads or in multifilar coil leads. Independent of the type of lead, a significantly (p less than 0.05) higher fracture rate was found with leads implanted through the internal jugular vein. Most fractures occurred either inside the pacemaker pocket or on the way from the connector to the venous entry. Only 7% of all fractures occurred within the vascular system. Patients with a second or third degree AV-block and a multifilar coil lead implanted showed a significantly (p less than 0.05) better survival rate compared to those with a singlefilar coil or a Siemens Elema 588 lead. In pacemaker-dependent patients a replacement of singlefilar coil leads might be considered.

Mortality in pacemaker-treated patients. A follow-up study of the impact of HLA B27 and associated rheumatic disorders.

The mortality in pacemaker-treated patients is due to underlying disorders, and is increased in patients with ischemic heart disease, congestive heart failure, diabetes and renal dysfunction. We have recently shown that the HLA B27-associated inflammatory disease process is the probable underlying cause in 15-20% of permanently paced men. Consequently, we undertook this study to evaluate any impact on mortality of HLA B27 and associated rheumatic disorders. The mortality among pacemaker patients was compared with that of the general population. Comparisons were also made between pacemaker patients with and without HLA B27 and associated disorders. We did not find any influence on mortality associated with the immunogenetic marker HLA B27 or with HLA B27-associated rheumatic disorders.

Survival and mortality in 3,701 pacemaker patients: arguments in favor of pacemaker reuse.

This study analyzed the results of 3,701 patients implanted with cardiac pacemakers at the Centre Chirurgical du Val d'Or between 1976 and 1981. Two pacemaker populations were compared: those having a new pacemaker and those implanted with a reused pacemaker. There were no statistically significant differences between the two groups, either in terms of indications for implantation or in terms of actuarial survival of patients. In addition, there was no significant change in survival of the pulse generator. The reutilization of pacemakers appeared to be in no way detrimental to patients.

An argument for pacemaker reuse: pacemaker mortality in 169 patients over ten years.

Retrospective examination of 169 consecutive pacemaker patient deaths was done to test the hypothesis that early mortality would preclude full utilization of current battery longevity. We found a 58% mortality within two years of the last generator implant. Nineteen percent occurred within six months, and 38% occurred within a year. This compares to a current clinic of 246 patients where 43% have utilized these pacemakers for greater than 48 months. The age comparison shows that those who died were older than the living controls. The 58% 24-month mortality demonstrates that many patients underutilize expected battery life. The economic implications of pacemaker reuse can then be understood.

Permanent cardiac pacemaker in infants and children.

Between October 1970 and November 1984, 26 infants and children aged 11 days to 18 years (mean 5.7 years) received 42 permanent cardiac pacemakers (26 primary implants, 16 re-implants) for congenital or surgically acquired heart block, bradycardia and sinus node dysfunction. Twenty-two patients had unipolar pacing and 4 bipolar pacing. Of 26 primary implantations, 2 had fixed rate epicardial pacing, 16 ventricular demand pacing (13 epicardial, 3 endocardial), 3 epicardial VAT (P-synchronous) pacing and 5 DDD (universal) pacing (4 epicardial, one endocardial). Fourteen patients required a further 19 operations for change of generators (16), ventricular lead (1), generator site (1) and generator encasing (1). Thirty-day hospital mortality was 11.5% (3/26), of which one death was possibly related to pacing failure. Four patients died during the follow-up period (3 months to 10 years; mean 3.4 years). Sixteen of the 19 survivors achieved complete symptomatic relief, without any medical therapy. Our results indicate that modern cardiac pacemaker systems are safe and reliable, and are associated with major relief of symptoms in this age group.

Multivariate analysis of pacemaker patient survivorship.

Multiple risk factors of patient mortality need to be evaluated and combined to serve practical purposes. A multivariate statistical model is illustrated here with a large data set and a simulated example. The piecewise parametric model is shown to be simple, efficient, and is suggested to be a good tool for routine usage. The approach should provide a more concise characterization of mortality in terms of multiple risk factors. The results of data analysis also provide a good reference for further explorations.

[Implantation of a cardiac pacemaker in the octogenarian]. / Implantation de stimulateur cardiaque chez l'octogénaire.

Thirteen centres, specialized in pacemakers and studying the implantation, brought together their material. Consequently, 785 patients living with a pacemaker (PM) were grouped. The average age at the time of the first implantation is 83,5 years old. The mortality of 7.5% as well as the morbidity of 16% lie very low. Nevertheless, their causes are discussed and compared to those resulting from other types of surgical pathologies on the octogenarian. It seems that the implantation of a PM, even on a person of 80 or older, is an efficient therapeutic gesture, benign and capable of normalizing the chances and quality of life on a long term basis.

Projecting demand for cardiac pacemakers.

A cardiac pacemaker implantation program involves substantial resources of money, facilities, and manpower. This paper presents a model for forecasting future numbers of implants, thus enabling the more efficient use of such resources. The model embraces both new implants and replacements, both short-term and long-term planning, and can be used with relevant data from any source.

Natural history of high-grade atrioventricular block following permanent pacemaker implantation.

We followed 120 patients 4-14 yr after permanent pacemaker implantation for high-grade atrioventricular block to assess the effect of sex, age at implantation, date of implantation and various chronic co-existent illnesses on survival. The overall survival rates were 91% at 1 yr, 63% at 5 yr and 41% at 10 yr. Patients with congestive heart failure demonstrated the lowest survival rates of all cohorts studied. Survival rates of patients with congestive heart failure were significantly lower than survival rates of patients without congestive heart failure and were also significantly lower than those of patients with conduction system disease only. Similarly, patients with coronary heart disease demonstrated significantly lower survival rates than both patients without coronary heart disease and patients with conduction system disease only. The presence of hypertension, valvular heart disease, diabetes mellitus or cerebral infarction influenced survival less adversely than congestive heart failure or coronary heart disease. Survival decreased progressively with increasing age; however, the differences were not significant. Sex and date of implantation had no apparent effect on survival. Thus, coronary heart disease and the presence of congestive heart failure appear to be the major determinants of survival following permanent pacemaker implantation for high-grade atrioventricular block.