[Function of the heart chambers in acute myocardial infarct]

A study of 87 patients, admitted to hospital within the first day of acute myocardial infarction (AMI) identified 3 groups of patients on the basis of their pulmonary capillary occlusion pressure (OP) values. Sixteen normal subjects made up the control group. Myocardial contractility and volume characteristics obtained by sectoral scanning were reviewed. It was demonstrated that the contractility of the left and right heart chambers had different patterns of change in relation to the magnitude of pressure: left-atrial and right-ventricular ejection fraction (EF) gradually declined, and normal pressure values were associated with right-ventricular hyperfunction. Right-ventricular EF also decreased as the OP grew, yet it did not reach the critical values as observed with the left-ventricular EF. The predominance of the right-ventricular function over the left-ventricular one might be one of the mechanisms underlying the development of insufficiency in the lesser circulation. Contractility unbalance was also shown to exist between the right and left atria. A rise in the end systolic volume in the presence of unchanged end diastolic volume is the earliest manifestation of reduced left-ventricular contractility in acute myocardial infarction.