Isometric Contraction Period of the Left Ventricle in Acute Myocardial Infarction

Abstract

The usefulness of nontraumatic methods for measuring the left ventricular isometric contraction period (ICP) in myocardial infarction (MI) has been evaluated. The ICP was measured in 13 normal men and 38 patients admitted to a coronary care unit with chest pain, including 18 with acute MI, 12 with old MI, and nine with chest pain of miscellaneous origin; one of these nine was also included in the group with acute myocardial infarction. ICP was determined by three different methods: (1) time between the onset of systolic wave (A) of apexcardiogram (ACG) and the beginning of upstroke (C) of carotid pulse tracing (CPT); (2) time between A and ejection crest (E) of the ACG; and (3) time between the initial low frequency, low amplitude vibration of the first heart sound, and the C of CPT. Statistically significant differences of ICP between the normal group and the three groups of patients were demonstrated only by method 1. Likewise, acute coronary ligation in seven dogs produced characteristic changes in ICP by method 1, which were associated with a reduction in the left ventricular (LV) stroke volume, LV dp/dt, and the aortic flow velocity. The ICP obtained by method 1 appears to be of value in the bedside evaluation of acute myocardial infarction. Additional Indexing Words: Abnormal apexcardiogramEarly systolic bulge First heart sound ATTEMPTS to quantitate circulatory function in acute myocardial infarction have been limited because of the transient nature of the hemodynamic changes and the fear of undertaking elaborate diagnostic procedures in patients with major illnesses. However, recent advances in technics for the recording

Ultrasonic Measurement of Left Ventricular Wall Motion in Acute Myocardial Infarction

“…All *Electronics for Medicine, White Plains, N. Y. measurements are tabulated in table 1. Figure 2 shows the interrelationship of the sequence of time events between the posterior wall echogram and the other simultaneous tracings of the apexcardiogram, phonocardiogram.…”

Ventricular Relaxation and Mitral Opening Time in Various Ventricular Conditions of Old Age

“…A more rapid contraction, followed by a more rapid relaxation, caused by hormonal factors (catecholamines, angiotensin), may be postulated. As a correlation, it should be mentioned that the PEP interval of hypertensive subjects is frequently normal, and lower than in ischemic heart disease [13], Whatever mechanism is visualized, the IIA-E interval reflects functional changes that are proportional to changes of systolic contraction. Thus a longer IIA-E interval is found in subjects with altered contractility as a result of myocardial fibrosis (RBBB, MI, and especially LBBB) while a shorter interval is found in hypertensive subjects, in whom hormonal factors are responsible for both a more rapid contraction and a more rapid re laxation.…”

“…This finding results in a useful, noninvasive method of evaluation of the left ventricular function in nonhypertensive subjects. A comparison between the PEP of the 'systolic time intervals' and the IIA-E interval would also be extremely valuable, especially because the former have been found prolonged in coronary heart disease [13][14][15][16].…”

Time relation between apex cardiogram and left ventricular events using simultaneous high-fidelity tracings in man.

“…The end of the upstroke of the apex cardiogram, called E-point, has been advocated by some authors (Benchimol and Dimond, 1963;Tavel et al, 1965;Inoue et al, 1970;Willems et al, 1971), and opposed by others (Oreshkov, 1965;Spodick and Kumur, 1968), as a valid indicator of the onset of the ejection phase of the left ventricle or of the peak dP/dt. In our study the E-point followed in all cases by a considerable interval both the onset of the ejection in the aorta and the peak dP/dt.…”