[Pacemaker with mechanical sensors. Accumulated experience in long-term follow-up]

To evaluate the behavior of single chamber stimulation system, rate responsive with vibration sensing, taking into consideration the results of long term clinical follow-up.

From september 1986 to april 1989, 70 patients received pacemakers with vibration sensing. Sixty four patients (91.9%) implanted Activitrax I model and six (8.1%) Activitrax II. Thirty-one (44.3%) were men and the mean age was 51.2 years. Fifty-one patients (72.9%) had complete atrioventricular block, 11 (15.7%) sinus node dysfunction, one (1.4%) sinus node and atrioventricular disease, and one (1.4%) for therapeutic support of arrhythmia. The etiology of these dysfunctions were Chagas' disease in 31.4%, myocardiosclerosis in 35.7%, post-operative in 15.6%, post-av node fulguration in 5.8% and idiopathic in 11.5%. The group was submitted to clinic and electronic evaluation and laboratory examinations: echocardiogram, dynamic ECG, stress test and ergoespirometric test. The mean follow-up as 19.6 months.

Clinic evaluations: decrease in congestive heart failure functional class in 86% of the patients. No recurrence of syncopes and no cardiac deaths. Echocardiogram: increase in ejection fraction in 42% of patients. Dynamic ECG: appropriate rate response in 94.3% of patients (good cronotropic response). Ergoespirometry: increase in oxygen consumption in 75% of studied cases, Electronic evaluation: absence of generator dysfunction; complications in 18% of cases, all corrected by reprogramation.

The single chamber cardiac stimulation system with vibration sensing showed safety, efficacy and low rate of complications.