Hemodynamic Evaluation of Left Ventricular Function in Shock Complicating Myocardial Infarction

Abstract

Twenty-two patients with shock complicating myocardial infarction were studied hemodynamically and, despite pharmacologic therapy and regulation of intravascular volume, 16 (73%) subsequently expired. Pulmonary artery end-diastolic pressure (PAEDP) or left ventricular end-diastolic pressure (LVEDP) was > 15 mm Hg in 18 of the 22 patients, and cardiac index (CI) was ≤2.3 liters/min/m² in 17 of 22 patients. Fourteen of the 18 patients with PAEDP or LVEDP > 15 mm Hg expired, while two of the four patients with a PAEDP or LVEDP < 15 mm Hg survived. Thirteen of 15 individuals with a CI < 2.3 liters/min/m² died, and four of seven with a CI ≤ 2.3 liters/min/m² survived. A ventricular gallop (S₃) was audible in 15 patients with PAEDP or LVEDP varying from 13 to 60 mm Hg. In 11 patients with an S₃ who expired, the PAEDP or LVEDP ranged from 22 to 60 mm Hg. Mean peripheral vascular resistance was 41.3 units in survivors and 67.8 units in nonsurvivors. Six of eight patients who did not survive the period of hospitalization had a depressed response to dextran infusion manifested by a greater increase in PAEDP or LVEDP than in CI. Hemodynamic evaluation permitted early identification of measurements associated with 100% mortality despite intensive medical treatment. These findings included: (1) PAEDP or LVEDP > 28 mm Hg and (2) PAEDP or LVEDP > 15 mm Hg in association with a CI < 2.3 liters/min/m². Patients in cardiogenic shock with these hemodynamic alterations are presumably candidates for cardiocirculatory mechanical assisting devices and possibly for further surgical intervention.