Reocclusion after successful coronary reperfusion occurs in 15 to 35% of patients receiving
thrombolytic therapy for acute
myocardial infarction. The present study was designed to simulate the clinical situation of reocclusion and determine whether
verapamil might be effective in reducing myocardial
necrosis and preserving high energy
phosphates in this setting.
Pentobarbital-anesthetized, open chest dogs underwent occlusion of the left anterior descending coronary artery for 2 hours followed by 1 hour of reperfusion and a further 4 hours of coronary artery occlusion. Treatment with
verapamil (intravenous bolus dose of 0.2 mg/kg
body weight followed by infusion of 0.56 +/- 0.14 mg/kg per h) was begun 1 hour after occlusion and infusion was continued for the remainder of the experiment. The dose of
verapamil was adjusted to lower mean arterial pressure to approximately 90 mm Hg. The area at risk was determined by intraatrial injection of
monastral blue dye and the area of
necrosis was assessed by
triphenyltetrazolium chloride staining. In vivo myocardial needle biopsy for determination of
adenosine triphosphate and
creatine phosphate was performed at the end of the experiment. The area of the left ventricle at risk was similar in both groups (control [n = 8], 20.2 +/- 1.6% versus
verapamil-treated [n = 9], 23.1 +/- 2.9%; p = NS). The area of
necrosis expressed as a percent of the area at risk was reduced in the
verapamil-treated group compared with the control group (43.3 +/- 5.0% versus 63.1 +/- 6.8%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)