Susumu Kamihara

Age-related changes in left and right ventricular filling velocity profiles and their relationship in normal subjects

To confirm age-related changes in left and right ventricular filling velocity profiles and to compare left and right ventricular filling parameters in normal subjects, we performed pulsed Doppler echocardiographic studies in 108 normal subjects (72 men and 36 women) aged 15 to 78 years. An age-related decrease in peak early velocity (E velocity), an increase in peak atrial velocity (A velocity), and augmented ratio of A velocity to E velocity (A/E) were observed in left ventricle (r = -0.71, 0.63, and 0.83, respectively). Similar age-related changes were found in right ventricle (r = -0.71, 0.54, and 0.78). Aging had a greater effect on the filling of the left ventricle than the right one (i.e., a steeper slope). The difference between left and right ventricular filling increased with advancing age. Left ventricular filling indexes exceeded those of the right ventricle. Significant correlations were observed between the right and left ventricular filling parameters (r = 0.58 to 0.90). A strong relation was noted in A/E (r = 0.90). There was no significant relation between age and left ventricular mass. The left ventricular mass appeared to have little effect on left and right ventricular filling in normal individuals. Thus in clinical studies the age-related decrease in early diastolic filling and the increased atrial filling in both left and right ventricles should be considered. The atrial contribution to ventricular filling may be more pronounced in the left ventricle than the right ventricle in older subjects.

Effects of a new vasodilator, nicorandil, on exercise-induced impairment of left ventricular function in patients with old myocardial infarction.

Hemodynamic effects of nicorandil on exercise-induced impairment of left ventricular function were studied in nine patients with old myocardial infarction but without angina pectoris. Hemodynamic data were obtained by symptom-limited supine multistage bicycle ergometer exercise testing before and 1 h after single oral administration of 15 mg of nicorandil. Systolic and diastolic blood pressure at rest decreased significantly after nicorandil administration (p < 0.01). A most remarkable change in the hemodynamic response to supine dynamic exercise after nicorandil was a decrease in pulmonary artery wedge pressure (both at rest and at peak exercise, p < 0.001). An index of cardiac function, obtained from the relation between pulmonary artery wedge pressure and left ventricular stroke work index, improved significantly after nicorandil. The ratio of pressure-rate product to coronary sinus flow, which is an index of the ratio of myocardial oxygen consumption to myocardial oxygen supply, decreased significantly (p < 0.05) after nicorandil administration. Reproducibility of the testings was also studied in six patients with old myocardial infarction. Invasive hemodynamic variables between two successive symptom-limited supine leg exercise testings, except pulmonary artery wedge pressure, were reproducible in patients with old myocardial infarction but without angina pectoris. Only pulmonary artery wedge pressure at rest in the second exercise testing showed a significantly lower value (p < 0.05). It is concluded that nicorandil is a useful drug for improvement of exercise-induced impairment of left ventricular function with an increase in myocardial oxygen supply.

Effects of a new second generation calcium channel blocker, nilvadipine (FR34235), on exercise-induced hemodynamic changes in stable angina pectoris.

The mechanism of the antianginal actions of nilvadipine was investigated in 11 patients with effort angina pectoris. Hemodynamic data were obtained by angina-limited supine multistage bicycle ergometer exercise testing before and after a single 6 mg dose of nilvadipine. Compared with chest pain during control exercise testing, pain at peak exercise disappeared or abated and the ST segment at peak exercise also showed less significant depression after administration of nilvadipine. At rest and at peak exercise, mean blood pressure, pulmonary artery wedge pressure and systemic vascular resistance decreased significantly, whereas heart rate and cardiac index increased significantly after nilvadipine. Rate-pressure product and stroke volume index did not change significantly. Coronary sinus flow at peak exercise increased significantly and total coronary vascular resistance at rest and at peak exercise decreased significantly after nilvadipine. The plasma concentrations of nilvadipine 1.5 hours after administration ranged from 1.15 to 8.23 ng/ml. These data suggest that the principal factors in the antianginal actions of nilvadipine are an increase in myocardial oxygen supply due to increased coronary blood flow and a reduction in myocardial oxygen demand mainly by a decrease in afterload and additionally by a decrease in preload.

Hemodynamic determinant factor of exercise tolerance in patients with prior myocardial infarction

左室駆出分画(LVEF)が50%未満に低下しているにもかかわらず良好な運動耐容能を示すとともに狭心症を認めない陳旧心筋梗塞患者(II群; 13例)における運動耐容能の規定因子を究明するために,障害群と同等の運動耐容能を有しLVEF50%以上の陳旧心筋梗塞患者(I群; 13例)を対照として仰臥位多段階自転車ergometer運動試験を施行した. peak運動時心係数は両群間に有意差を示さなかった.運動時間を従属変数とする重回帰分析にて, I群では運動時心拍数および平均肺動脈楔入圧の増加分が, II群では運動時末梢血管抵抗の減少分および心拍数の増加分が高い寄与度を示した.以上より, I群に比しII群では運動時の後負荷減少が運動耐容能の重要な規定因子であると考えられた.