Abstract
A single pass ventricular lead with a dual chamber electrode system (atrial bipolar sensing electrodes displaced along the lead axis 11 and 12 cm from distal tip) was implanted in 28 patients (11 men, 17 women; aged 48 to 90 years, mean 76.8; height 130 to 172cm, mean 152.5; weight 27 to 75Kg, mean 47.2) for symptomatic high degree AV block and normal sinus node function from December 1989 to August 1992. Lead insertion and pacemaker implantation was almost the same as the VVI system. P wave amplitude was 1.9±1.1mV at implant. Post-operative complications included a pneumothorax and a pocket hematoma. Two late deaths occurred as a result of myocardial infarction and renal failure. One patient also failed to function in the VDD mode six months post-operatively because the atrial sensing electrodes were relocated itself from the right atrium to the right ventricle due to the decrease in the heart size. Another patient had frequent atrial arrthymias several months post-operatively. The remaining 24 patients had no significant troubles while in the VDD mode. Activity levels improved (from NYHA functional class 3.0±0.7 to 1.3±0.3) significantly (p<0.01) and their preopeative CTR (59.1±7.3%) significantly (p<0.01) decreased to 52.8±7.4%. Under the conventional VVI technique, the single-lead VDD system can achieve physiological pacing; therefore this system must be acknowledged as the advantageous therapeutic choice for selected patients.
