Shigeki Mochizuki

Analysis of a cardiac cycle of the left side of the heart in cases of left ventricular overloading or damage with the ultrasonic Doppler method.

Abstract The time of occurrence of rapid movements of the heart valves was detected with the ultrasonic Doppler method in cases of hypertension with or without myocardial involvements, congestive heart failure resulting from these conditions, and aortic regugitation, and then changes in each phase in a cardiac cycle under these conditions were studied. 1. 1. The duration of electromechanical latent time is not affected in hypertension without electrocardiographic signs of myocardial involvement, but is slightly prolonged in cases of hypertensive heart disease. Changes are more marked in the isometric contraction time than in the electromechanical latent time. The tension period is generally prolonged. The isometric relaxation time is markedly prolonged in hypertension, especially in cases of left ventricular hypertrophy and strain pattern. This prolongation is manifested prior to the changes on the ST-T segment. 2. 2. Changes in myocardial conditions secondary to the changes in hemodynamic conditions are possibly more responsible for the above-mentioned changes in the time phase than changes in hemodynamic condition, e.g., high arterial pressure, as primary changes. 3. 3. Similar findings are obtained also in cases of arteriosclerotic heart disease. 4. 4. Congestive heart failure causes remodifying of changes in the above-mentioned periods. The electromechanical latent time is prolonged, and the prolongations of isometric contraction time and of tension period are further deteriorated. The prolongation of isometric relaxation time shows a tendency to return to a normal range. When congestive heart failure subsides, the above-remodified changes immediately return to the previous pattern. 5. 5. In aortic regurgitation the isometric contraction time and the tension period are shortened, the isometric relaxation time being little affected. It is assumed that the response of the myocardium to a diastolic overloading, e.g., aortic regurgitation, is different from the response to a systolic overloading, e.g., hypertension.