Pacemaker malfunctions

Austin JL, et al. Analysis of pacemaker malfunction and complications of temporary pacing in the coronary care unit. Am J Cardiol 1982 49 301. 

Das G, Eaton J. Pacemaker malfunction following transthoracic countershock. Pacing Clin Electrophysiol 1981 4 487 90. 

As with all manmade devices there is the possibility that the device can be faulty, either due to a fault in the manufacturing process or in the programming of the device. Pacemaker malfunctions can often be seen on the 12-lead ECG. The most commonly encountered problems associated with pacemaker systems include failure to sense, failure to capture, failure to pace and over sensing. 

CRT is now recommended for patients with LVEF less than or equal to 35%, sinus rhythm, and NYHA functional class III or ambulatory class IV symptoms despite recommended, optimal medical therapy and who have cardiac dyssynchrony, which is currently defined as a QRS duration greater than 0.12 ms, unless contraindicated. To date, over 4,000 patients have been studied in randomized clinical trials of CRT. A recent evaluation of complications from those studies suggest a risk of implant mortality of 0.4%, failure to implant a functioning LV lead in 10%, lead malfunction or dislodgement in 8.5%, and pacemaker infection in 1.4% [123]. 

The most welcome technical achievements in life science are the ones that enhance well-being or restore impaired or lost biological functions. Rehabilitation engineering is a research field that has devoted its full spectrum of efforts to compensate for malfunctions and disorders in human biological systems. This includes the development of devices for the rehabilitation of neural disorders which are termed neural prostheses. Neural prostheses directly interface with the central and peripheral nervous system. The most commonly known neural prosthesis is the cardiac pacemaker, which has existed for more than 30 years. A variety of other lesser known devices have been developed to partially restore neural functions in disabled people. 

To correct problems of rhythm disturbance or SA node malfunction, cardiologists often use a pacemaker, an electrical device implanted in the shoulder or abdomen of the patierrt with a wire leadir to the heart. This mecharrical pacemaker generates the electrical signal which regulates the heart s functions. The rate of heartbeat, which is set when the pacemaker is implanted, can be changed if necessary without surgery. Modem... 

Pacemakers are among the most reliable electronic devices ever built device survival probabilities of 99.9% (excluding normal battery depletion) at 10 years are not unheard of. But despite intensive quality assurance efforts by manufacturers, the devices do remain subject to occasional failures the annual pacemaker replacement rate due to generator malfunction has been estimated at roughly one per 1000 devices implanted, a marked improvement in reliability since the early 1980s (Maisel et al. 2006 Maisel 2006). There have been multiple major advisories and recalls issued by the FDA regarding pacing leads, with more of these because of problems with the lead insulation than with the lead conductor. 

Maisel, W.H., Moynahan M., Zuckerman B.D. et al. 2006. Pacemaker and ICD generator malfunctions Analysis of Food and Drug Administration annual reports. JAMA 295 1901-06. 

When considering indications for lead extraction, whatever they be, it is important to first evaluate the strength of the indication and the risks of the intervention on an individualized patient basis. Thereafter, the risk/benefit ratio of each patient should be balanced with the level of experience of the operator. Age, sex, body mass index, lead implant duration, number of leads, even small calcifications of fibrosis along the lead, venous thrombosis, systemic infection, presence of large vegetations, pacemaker dependency, and physical characteristics of the lead (intrinsic fragility and tensile robustness) are all factors associated with increased procedural risk [2]. Infections, lead malfunction, actual or potential lead failure, interference between multiple leads, lead-induced life-threatening... 

Mond H The Cardiac Pacemaker. Function and Malfunction. New York Grune and Stratton, 1973, pp. 60-66. 

The activity level of the patient in the immediate postoperative period is limited merely by the amount of sedation. Prolonged periods of bed rest are to be avoided. The modem lead systems with active and passive fixation mechanisms offer a new dimension of security. It is important to have the patient active immediately or shortly after arrival in the monitored area. The intention is to detect early those patients with potential pacemaker or ICD system malfunctions. Prolonged periods of inactivity merely result in a false sense of security. The reliability of the pacing or ICD system is demonstrated by early activity. The patient s approach from the ambulatory point of view is made active as soon as sedation has worn off. Postoperative pacemaker and ICD system evaluation with noninvasive studies, monitoring, and reprogranuning... 

Maisel analyzed the weekly FDA Enforcement Reports issued between January 1990 and December 2000. They reported their assessment of 52 advisories involving 408,500 pacemakers and 114,645 ICDs. Hardware malfunctions and computer errors accounted for 95% of device recalls. This included about 1.3 milhon device checks and analyses and involved 36,187 device replacements at an approximate cost of 870 million (186). 

Carefully monitor the patient with ECG and pulse oximetry for pacemaker function during radiation therapy. It may be necessary to have temporary pacing capability available in case the pacing system malfunctions during the treatment. 

Fig. 18.3 Abdominal scout CT image in a patient with a malfunctioning implantable cardioverter-defibrillator. Inspection demonstrated a tight twisting of the lead, which resulted in device malfunction. The most likely diagnosis was twiddler syndrome. (From Hayes DL. Complications and Lloyd MA, Hayes DL. Pacemaker and ICD radiography. In Hayes DL, Lloyd MA, Friedman PA, editors. Cardiac pacing and defibrillation a clinical approach. Armonk [NY] Futura Publishing, 2000 453-84, 485-517. Used with permission of Mayo Foundation for Medical Education and Research.)...

Should a device malfunction be identified or when a device is explanted in response to a Safety Alert, it is extremely important that the explanted unit be returned to the manufacturer along with copies of any noninvasive or invasive documentation that may be available. This is the only way that the manufacturer has for determining whether or not there really is a problem. In addition, if the clinician is unsure as to the meaning of some of the data that was retrieved from the pacemaker, the technical support engineers that are available 24 h a day, 7 days a week from each of the manufacturers should be contacted. The observed behavior may represent totally normal function of a unique algorithm or functional eccentricity of the specific device which does not warrant an operative intervention. 

Levine PA, Love CJ, Pacemaker diagnostics and evaluation of pacing system malfunction. In EUenbogen KA, Kay GN, WiUcoff BL, (eds) Clinical Cardiac Pacing (second edition). Philadelphia, W. B. Saunders Publishers, 1999 Chap. 30. 

Implantable biosensors are continuously becoming more popular and economically viable. In the past, the main contribution in this field was to restore malfunctioning or missing biological structures by artificial prosthetic devices such as an artificial heart and pacemaker for cardiac patients, a neurostimulator for patients with epilepsy and Alzheimer s, stents for damaged arteries, and knee implants for rheumatoid arthritis, osteoarthritis, or traumatic injuries. These biosensors offer improved quality of life... 

Cardiovascular IFN-induced cardiotoxicity which occurs rarely was recently reported in the form of so-called sick sinus syndrome, a malfunction of the sinus node producing arrhythmias. A 45-year-old woman suffered sinus node dysfunction after receiving pegylated IFNa-ribavirin for chronic hepatitis C. Withdrawal of the therapy did not reverse the dysfunction and the patient required the implantation of a permanent pacemaker [31 ]. 

A malfunctioning pacemaker can lead to arrhythmias, syncope, hypotension, and decreased cardiac output. 

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