Apex cardiogram and systolic time intervals in acute myocardial infarction.

Abstract

Simultaneous recordings of apex cardiogram, phonocardiogram, indirect carotid pulse, and electrocardiogram were made in 12 patients with acute myocardial infarction and in I2 normal subects of comparable age.The apex cardiogram showed in the patients increased amplitude and duration of the 'a' wave and in 40 per cent a notching. Half of the cases had a flat systolic plateau and over 8o per cent a systolic 'bulge'.The a-E interval and the time to the systolic peak of the apex cardiogram were significantly shortened. The systolic time intervals showed shortening of the pre-ejection period i, isovolumetric contraction time, electromechanical systole, and ejection time along with the E-J interval which represents the phase of maximum ventricular ejection. The changes observed were thought to be due to an increase in circulating catecholamines. Estimation of the urinary excretion of adrenaline and noradrenaline in two cases showed three times normal values.Apex cardiography is a technique for recording low frequency praecordial movements. It was introduced by Marey as early as I863 but was not generally used until about two decades ago. Since then it has been studied in different heart diseases, e.g. mitral valvular disease (Benchimol et al., i960), hypertrophic subaortic stenosis (Wolfe, I966), angina pectoris (Dimond and Benchimol, I963), ischaemic heart disease (Benchimol and Dimond, I962; R6rvik, i963), and left ventricular aneurysm (Ahuja, Gutierrez, and Manning, i967), but its value in acute myocardial infarction has so far not been explored. Apex cardiograms, phonocardiograms, and indirect carotid pulse tracings are now being commonly used to time the various systolic time intervals (Oreshkov, I968; Spodick and Kumar, I968). These are thought to give information about myocardial function from studies on patients with heart failure (Weissler, Harris, and Schoenfeld, i968), hypertension, coronary heart disease, cardiomyopathy, etc. (Tarazi, Frohlich, and Dustan, I969; Weissler, Harris, and Schoenfeld, I969). The purpose of this work is to study the apex cardiogram and systolic time intervals during the early stage of acute myocardial infarction.

Apex-Carotis Diagram as Related to Systolic and Diastolic Time Intervals in Myocardial Infarction

“…The systolic 'bulge' in the ACG [6,16] is related to the decrease of the field of ven tricular ejection in the ACD in myocardial infarction.…”

“…The decrease of the field of ventricular filling in myocardial infarction may be explained by an increase of the 'a' wave ratio in ACG [6,15,16] and an increase of the diastolic amplitude of ACG [4]. The systolic 'bulge' in the ACG [6,16] is related to the decrease of the field of ven tricular ejection in the ACD in myocardial infarction.…”

“…Several investigators have already described systolic [1,6,13] and diastolic [16] time inter vals in patients with myocardial infarction.…”