The effect of diltiazem on myocardial recovery after regional ischemia in dogs.

The effect of diltiazem on post-ischemic metabolic and functional recovery was investigated in regionally ischemic dog hearts. The duration of ischemia was 60 min, followed by 60 min of reperfusion. Diltiazem (bolus injection of 0.1 mg X kg-1 body weight prior to ischemia, followed by a continuous infusion of 0.1 mg X kg-1 X h-1) had no effect on residual coronary flow in the centre of the ischemic area, but blunted the reactive hyperemia response after restoration of flow. The drug partially prevented the depletion of ATP and glycogen in the severely underperfused subendocardial layers, i.e. when residual flow was below 0.1 ml X min-1 X g-1. Reduction of the content of these substances in the subepicardial layers was moderate and not influenced by diltiazem. Segment shortening in the subepicardial layers disappeared whereas segment lengthening was observed in the subendocardial layers during the ischemic period. Diltiazem did not prevent the loss of contractile function. Despite an initial restoration of contractile function within 10 min after reperfusion, no significant beneficial effect of diltiazem treatment on mechanical function of the reperfused area was present thereafter.