Masasuke Fujita

Ventricular fibrillation during partial reperfusion following severe myocardial ischemia in the canine model

The authors examined whether partial reperfusion protects against reperfusion ventricular fibrillation (VF) following severe acute myocardial ischemia. Fifty-seven dogs were divided into two groups. In group A (n = 21), the left anterior descending coronary artery was occluded for 10 minutes, followed by full reperfusion. In the remaining 36 dogs (group B), myocardial ischemia was induced by retrograde blood flow (RBF) for 10 minutes. Thereafter, these dogs were divided into three subgroups: in group B1 (n = 10), full reperfusion was made by a carotid-left anterior descending coronary artery bypass; in group B2 (n = 13), partial reperfusion was achieved by collateral flow into the ischemic zone due to stopping RBF; in group B3 (n = 13), RBF was continued for an additional 5 minutes. During 10 minute ischemia, the myocardial blood flow at the ischemic zone measured by the H2 gas-clearance method was 12.3 +/- 2.0 ml/min/100 g in A, 3.4 +/- 0.9 ml/min/100 g in B1, 4.7 +/- 0.6 ml/min/100 g in B2, and 4.7 +/- 0.6 ml/min/100 g in B3 (A vs B1, p less than 0.02; A vs B2 and B3, p less than 0.01). Maximal ST-segment elevation was 11.4 +/- 1.8 mV in A, 28.2 +/- 2.7 mV in B1, 25.1 +/- 3.0 mV in B2, and 27.0 +/- 1.9 mV in B3 (A vs B1, B2, and B3, p less than 0.001). Maximal conduction delay was 48.6 +/- 9.4 ms in A, 106.4 +/- 5.2 ms in B1, 101.6 +/- 9.9 ms in B2, and 91.2 +/- 5.1 ms in B3 (A vs B1, B2, and B3, p less than 0.001). The incidence of reperfusion VF was 14% (3/21) in A, 80% (8/10) in B1, and 69% (9/13) in B2 (A vs B1, p less than 0.001; A vs B2, p less than 0.005). In group B3, VF occurred in only 1 of 13 dogs for the additional 5 minutes. It is concluded that reperfusion VF occurred frequently when ischemia was severe even though the duration of ischemia was short (B1), and that reperfusion VF was not prevented by partial reperfusion when the ischemia was severe (B2).

Effects of Captopril on the Hypertrophied Heart of Essential Hypertensive Patients

Changes in blood pressure and heart rate after exercise, left ventricular wall thickness, ejection fraction and left ventricular mass were examined by echocardiography before and at the 8th week administration of captopril (37.5-75.0 mg/day) in 11 patients with essential hypertension. The blood pressure showed a gradual and significant decrease from the second week of captopril administration, but the heart rate remained unchanged. No changes were observed in the blood pressure or heart rate after exercise, nor before, during and after the administration of captopril. In the echocardiographic examinations, the wall thickness decreased significantly from 12.1 +/- 2.1 mm before administration to 10.6 +/- 1.5 mm at the 8th week of administration in the interventricular septum, from 11.2 +/- 1.8 mm to 10.1 +/- 1.5 mm in the left ventricular posterior wall, and the left ventricular mass in parallel decreased from 266 g to 218 g. In 7 patients, whose wall thickness was 12 mm or more, the thickness of the septum decreased significantly from 13.9 +/- 1.2 mm to 11.7 +/- 2.1 mm and that of the left ventricular posterior wall from 12.6 +/- 1.5 mm to 10.6 +/- 1.8 mm. Captopril administration produced regression of cardiac hypertrophy in patients with essential hypertension within a period of only 8 weeks.