A multi-chamber stimulation device and associated method reliably and automatically
distinguish fusion from loss of capture during ventricular stimulation. The stimulation
device provides immediate and accurate fusion detection when a loss of capture
is suspected in the ventricles without delivering back-up stimulation pulses. To
achieve this objective, the far-field signal present in the atrial channel is examined
for evidence of a far-field R-wave whenever the ventricular channel detects a loss
of capture. If a far-field R-wave is present, fusion is confirmed, and a far-field
R-wave is absent, loss of capture is confirmed. Additionally, the stimulation device
inhibits unnecessary back-up stimulation and threshold tests when fusion occurs,
and provides appropriate adjustment of stimulation parameters based on confirmed
fusion detection such that fusion re-occurrence is minimized.
