[Programming VTIM physiologic pacemakers (evoked QT)]

Seventeen VTIM pacers were implanted in seventeen patients. Average follow up were 16.7 months. This paper concerns TX track and TX on modes only. Sensing window period and slope, which determine the rate response, must be programmed carefully. Potential competitive rhythms, severe ventricular arrhythmias or inadequate rate response to physical stress may potentially develop under inadequate programming. Consequently, it is advisable to program the sensing window 20-25 ms longer than the QTE max (at LRL) and the slope at 100% of the whole value. No complications were detected. Figures 1, 2 and 3 show examples of competitive rhythms without heart stimulation and unsensed beats by abnormally long programmed SW values. When properly shortened, this interval allows proper measurement of the Stim.-T and no competitive rhythm, during almost the same spontaneous rhythm. This system fulfills the major conditions for pacing the heart: rate adaptation to neurohormonal release, to physical stress and operative mode as a close-loop system during the recovery period.