Artificial pacemakers: indications and management.

SUMMARY The development of artificial pacemakers for the electrical control of the cardiac rhythm has greatly enhanced the physician's ability to treat cardiac dysrhythmias. Pacemakers have been useful in treating Stokes-Adams syndrome and symptomatic bradyeardias; they have helped control the occurrence of tachyarrhythmias and have played an important role in the management of arrhythmias accompanying myocardial infarctions. With their more frequent use, pacemakers have contributed to our knowledge of underlying conduction and natural pacemaker disorders. As new indications for artificial pacemaking have been elucidated, more complex pulse generators have been developed, and newer technics found for their insertion. II1 spite of recent developments , the pulse generators in general use have a limited useful lifetime. This paper reviews the indications for pacemaker insertion that are commonly employed. In addition, an approach to the problem of pulse generator replacement is presented. Additional Indexing Words: Heart block Bradyeardia Stokes-Adams syndrome Myocardial infarction LOLL DESCRIBED an effective means of supporting patients with failure of cardiac pacemaker activity and/or conducting tissue for the first time in 1952.1 Pacing of the heart was accomplished by subcutaneous electrodes, but could be maintained for only short periods of time. In 1957 complete heart block, resulting as a complication of open-heart surgery, was successfully treated by means of electrodes attached directly to the myocardium.2 These electrodes were directed externally through the chest wall and attached to a lightweight transistorized pacemaker. Although the patient could be completely mobile, he was constantly vulnerable to infection along the electrode tract; furthermore, the electrodes were fragile and easily broken. It was clear from these early but limited experiences that electrical failure of the heart could be controlled. These early observations prompted Chardack, Gage, and Greatbatch3 to develop a self-contained, totally implantable pacemaker. A number of laboratories are engaged in the design and testing of power sources that hopefully will function longer than the 24-30-month period that is currently thought to be safe for most pulse generators. The recent development of atomic power sources seems to be the most promising for long-term function. As the use of pacing of the heart was extended, efforts were directed toward the development of means for implanting the electrodes in the heart without a thoracotomy. This was especially desirable in the elderly patient. Furman in 1959 reported the use of catheters that could be implanted in the right ventricle by the venous route.4 Several reports attest to …