Electrophysiologic Implanted Device Failure
Electrophysiologic Implanted Device Failure
Abstract & Commentary
By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville. Dr. DiMarco is a consultant for Novartis, and does research for Medtronic and Guidant.
Source: Hauser RG, et al. Clinical Experience With Pacemaker Pulse Generators and Transvenous Leads: An 8-Year Prospective Multicenter Study. Heart Rhythm. 2007;4:154-160.
This paper describes results from a multi-center registry located at the Minneapolis Heart Institute Foundation that collects data on device failure in pacemakers and implantable defibrillators. For each device failure or removal at centers participating in the registry, data is collected concerning the model number, the manufacturer, the dates of implant, failure or removal, how the failure was detected, symptoms associated with failure, how the failure was verified, the actual presumed cause of failure, and resolution of the problem. During the period of the study, 2,652 pacemaker pulse generators from 12 manufacturers were removed from service and were included in this registry. The devices were removed an average of 7.3 + 3.1 years after implant. Battery depletion was the reason for explant in 92% of these models. In 95% of these cases, the generator exhibited normal battery function and just reached its elective replacement indicator after more than 3 years of service. Most battery depletion was routine and managed according to standard protocols. Severe battery depletion was noted in 43 cases and was associated with either loss of telemetry (n = 18), no or inadequate stimulation output (n = 18), or other signs of failure (n = 5). For both single and dual chamber pace-makers, battery longevity was shorter if the device had rate response capability. Major adverse clinical events were experienced by 62 patients when their pulse generators failed or reached end of life. One patient died when an electronic component failure resulted in sustained rapid pacing that led to acute heart failure. Severe battery depletion was associated with syncope in 11 patients, heart failure in one patient, and tachycardia in one patient. After battery depletion, the next most common reason for removing a pulse generator was an advisory or recall. This was noted in 4% of cases. Other reasons for removal included electronic failures (2%), connector failures (1%) and unspecified causes (1%). Electronic and connector failures caused syncope or near syncope in 16 patients and heart failure in 2 patients. Normal battery depletion was not totally benign. Major symptoms at the time of normal battery depletion were reported by 21 patients, including syncope (13), heart failure (5), tachyarrhythmia (2) and angina (1). An additional 133 patients reported minor symptoms. Usually, this was caused by reversion to a VVI or non-rate responsive mode when the battery reached its end-of-service indicator.
Transvenous lead failures were noted in 615 leads during the study. Insulation defects were the most common cause of failure with a median time to failure of 7.2 + 5.2 years with a higher number of polyurethane lead failures noted. Conductor failures, fixation mechanism failures, or unknown causes also contributed. Major adverse clinical events were seen in 16% of the leads failures. The most common symptom was syncope, but there were 11 non-fatal surgical complications and one death associated with lead extraction.
The authors conclude that the vast majority of pace-maker pulse generators are reliable and perform as expected. However, unexpected device failure is frequently associated with major adverse clinical events and even normal battery depletion may cause symptoms. In addition, lead failures were commonly associated with clinical events and surgical extraction was not benign. The authors argue that major opportunities for improving the clinical performance of cardiac pacing systems exist.
Commentary
In 2005, there was major media and public attention focused on the failure risks associated with cardiac pacemakers and defibrillators. The cause for the increased interest was the unfortunate death of a 23-year-old man with hypertrophic cardiomyopathy whose defibrillator malfunctioned and failed to prevent his sudden death. As a result of the controversy, all major manufacturers have enhanced their product performance reports and provide much clearer information on product performance for both physicians and patients. The data in this paper, however, point out that pacemaker generator and lead failures unfortunately remain common clinical problems. The data here cover only devices that were removed. An event that might have led to a death where the device was not recovered would not have been detected by this registry. The registry also only provides the numerators and we don't know what proportion of implanted devices actually fail. The manufacturers' product performance reports now give a better picture of the probability of failure. Fortunately, the reliability of the devices has greatly improved over the last several decades, and efforts to improve the safety of implantable rhythm management devices should obviously continue.
This paper describes results from a multi-center registry located at the Minneapolis Heart Institute Foundation that collects data on device failure in pacemakers and implantable defibrillators.Subscribe Now for Access
You have reached your article limit for the month. We hope you found our articles both enjoyable and insightful. For information on new subscriptions, product trials, alternative billing arrangements or group and site discounts please call 800-688-2421. We look forward to having you as a long-term member of the Relias Media community.