Kunihiko Hirasawa

Abrupt augmentation of ST segment elevation associated with successful reperfusion: A sign of diminished myocardial salvage

To investigate the significance of abrupt augmentation of ST segment elevation immediately after reperfusion, 36 patients with an initial acute anterior myocardial infarction successfully treated with thrombolysis were studied. Immediately after reperfusion was performed, 17 (47%) patients showed abrupt augmentation of ST segment elevation of anterior area (E group), and 19 (53%) patients did not (N group). The time to reperfusion was not significantly different between the two groups. In the E group the peak level of creatine kinase MB isozyme was higher (p < 0.05) than in the N group. The left ventricular ejection fraction (EF) did not increase in the E group from acute to chronic phase. However, in the N group EF increased significantly. The difference in EF in the chronic phase was significant between the two groups (p < 0.05). The infarcted regional wall motion (RWM) did not increase in the E group, whereas in the N group it increased markedly (p < 0.05). In addition, the infarcted RWM in the chronic phase was worse in the E group than in the N group (p < 0.05). Abrupt augmentation of ST segment elevation associated with successful reperfusion appears to reflect diminished myocardial salvage.

Acute effects of low aortic pressure on cardiac performance

SummaryAortic pressure has dual effects on the heart: One as the afterload pressure for the left heart and the other as a determinant of coronary perfusion pressure. As aortic pressure becomes subphysiological, these two effects may come to an imbalance. In dogs in which aortic pressure, aortic flow and heart rate were controlled at constant levels, a critical level of low aortic pressure (CAP) was studied below which an acute and progressive rise of left atrial pressure was observed. In normal heart, an elevation of CAP was observed from 15 to 36 mm Hg, as aortic flow was increased from 30 to 180 ml/min/kg. The elevation was less marked in response to the increase of heart rate from 100 to 250 beats/min. Coronary ligation or administration of a large amount of propranolol (1 to 2 mg/kg) caused a significant elevation of CAP. The results obtained from the present study is suggestive of the role of low aortic pressure in the development of cardiac deterioration during shock.

Influence of Changes in Heart Rate, Aortic Pressure and Flow Rate upon Experimental Coronary Insufficiency

This study was designed to evaluate the role of heart rate, aortic pressure, and aortic flow in the development of coronary insufficiency following acute coronary stenosis. In dogs, each of these parameters was controlled at a predetermined level while the left anterior descending coronary artery was constricted with a small screw clamp. The critical coronary pressure (CCP), i.e. the pressure below which a rise of left atrial pressure could be detected, was determined at various levels of hemodynamic load. Increases in aortic pressure, elevation of the heart rate and an increase in aortic flow rate were all associated with an elevation of the CCP and an increase in tension-time index (TTI). The changes in CCP were most striking when TTI was increased by aortic flow rate change. These findings suggest that with high aortic pressure, further constriction of coronary artery is required to precipitate coronary insufficiency, that the level of pacing required to induce coronary insufficiency is a useful index in assessing the degree of coronary stenosis, and that an augmentation of aortic flow rate is an important factor in the initiation of coronary insufficiency.

Effect of nisoldipine on variant angina: Assessment by 24-hour holter monitoring

Abstract Nisoldipine, a newly developed coronary vasodilating agent, was administered to 12 patients with variant angina to assess its efficacy in this condition. A placebo was administered during an observation period of ⩾2 days, after which nisoldipine 10 mg/day was administered as a single daily dose during a 3- to 4-day treatment period. The number of angina attacks significantly decreased from 5.4 ± 1.4 times/day/patient during the observation period to 1.1 ± 0.4 times/day/patient during the treatment period ( P P