The effect of intravenous
nifedipine (5 micrograms/kg) on the recovery of myocardial function after occlusion of the left anterior descending coronary artery was studied in 18 closed chest dogs. Using computer-aided analysis of two-dimensional echocardiograms, systolic and diastolic function of ischemic segments in low papillary left ventricular cross sections were characterized, respectively, as holosystolic fractional area change and early diastolic velocity of
luminal area change. The time required for systolic function to return to preocclusion values after a 1 minute untreated control occlusion (n = 12) was 5 to 10 minutes, and after a 2 minute occlusion (n = 6) it was 20 to 30 minutes. When
nifedipine was administered during the occlusion, recovery after a 2 minute occlusion was accelerated slightly to 10 to 15 minutes. Recovery times of early diastolic function were substantially longer, and
nifedipine effects were more pronounced. After a 1 or 2 minute control
coronary occlusion, 60 to 75 minutes or 90 to 105 minutes were needed to return early diastolic function to normal levels.
Nifedipine administered during a 1 or 2 minute
coronary occlusion improved these recovery times to 10 to 15 minutes. When the dogs were treated with intravenous
nifedipine before
coronary occlusion, recovery after 1 or 2 minutes of acute
ischemia was apparent as early
as 2 minutes after reperfusion. Thus, intravenous
nifedipine accelerates the recovery of myocardial function after brief periods of
ischemia, and when administered before
coronary occlusion, it assures very prompt recovery of function.