Optimal Level of Filling Pressure in the Left Side of the Heart in Acute Myocardial Infarction

Abstract

Balloon-flotation catheterization of the pulmonary artery at the bedside, a practical and safe diagnostic procedure in acutely ill patients, was used to measure pulmonary-artery occluded pressure (left ventricular filling pressure in 23 patients with acute myocardial infarction). The optimal level of this pressure was between 14 and 18 mm Hg. Manipulations that increased filling pressure above this range did not improve cardiac performance, which, in fact, usually deteriorated. On the contrary, an increase in cardiac performance could be related directly to changes in the occluded pressure when the initial value was less than 14 mm Hg. A parallel similar relation between filling pressure and performance existed in the right side of the heart. When right atrial pressure was increased up to 6 to 8 mm Hg, performance generally improved, but above that value, no consistent further improvement in right ventricular function was observed. Patients with depressed left ventricular performance also tended to demonstrate depressed right ventricular performance, but correlation of actual pressure levels was poor. (N Engl J Med 289:1263–1266, 1973)