Complications with permanent endocardial electrode systems. A comparison between two types of electrodes.

The study comprises 375 patients who had received an endocardial pacemaker electrode primarily. A stylet electrode of the Medtronic type was used in 165 patients and of the Elema type in 79 patients. Elema's flexible electrode model 588 EMT was used in 131 patients. The total number of electrode complications was surprisingly high. In 92 out of the 375 patients, 141 serious episodes of pacing failure occurred during the observation period of from 6 to 42 months. The complication rate increased with pacemaker function time. The stylet electrodes gave the highest complication rate. The choice of vein for introducing the electrode into the heart seems not to affect the complication rate significantly. Nor did the initial threshold value of stimulation influence the complication rate to any marked degree. The pacemaker manufacturers have devoted much effort to producing long-life impulse generators but there is also a great need for well-functioning long-life electrodes.