The use of biosensors in pacemaker technology: experience with a ventricular rate responsive pacemaker.

Ten elderly patientes each had a ventricular rate responsive pulse generator (Activitrax) placed in then to help correct severe conduction abnormalities; none had suspected ischemic heart disease. The pulse generator was programmed to a maximal pacing rate of 125 ppm, a medium activity threshold, and a rate response of 6. Six weeks after implantation of the pulse generator, the patients were evaluated before exercing and again when the pacing rate reached 125ppm. The evaluation protocol included an M-mode echocardiogram from which the following measurements were taken; the left ventricular end-diastolic volume (EDV), the end-systolic volume (ESV), the ejection fraction (EF), and the peak systolic pressure/end-systolic volume (PSP/ESV). The numerical values were recorded, clculated, and compared statically with the following results: the EDV increased from 91 n 10 to 125 n 20 cc (p