Clinical Evaluation of Left Ventricular Pressures in Myocardial Infarction

Left venitricular pressures were obtained in 14 patients with acute myocardial infarction, of whom seven survived. Calculated contractile element velocity (VCE), left ventricular end-diastolic pressure, and maximum dp/dt were compared with other hemodynamic measurements of LV function. VCE at 5 mm Hg (VCE5) was calculated according to the Maxwell three-component model of muscle and used as an index of overall contractile state. There was considerable overlap between survivors and nonsurvivors in the levels of VCE5, LVEDP, cardiac index, heart rate, and systemic vascular resistance. There was a reasonably good separation between survivors and nonsurvivors with measurements of mean arterial pressure, maximum LV dp/dt, mean isovolumic &Dgr;p/&Dgr;t, and stroke work. Changes in VCE5 were no more sensitive after five inotropic interventions than ventricular function curves in monitoring changes in conitractile state. It is concluded that LV pressure measurements in acute myocardial infarction offer little further clinical information of importance beyond that which can be obtained from measurements of pulmonary capillary wedge pressure, arterial pressure, and cardiac output.