Mechanism of shock associated with right ventricular infarction

Various mechanisms have been proposed to explain the shock sometimes associated with right ventricular infarction, but only small numbers of patients with clinical shock have been studied. The haemodynamic profiles of seven patients with clinical cardiogenic shock after right ventricular myocardial infarction were studied prospectively. They were selected because all had a stable cardiac rhythm and none had absolute hypovolaemia during the study period. In all of them the mean right atrial pressure exceeded the pulmonary artery occlusion pressure. After treatment with varying combinations of dopamine, dobutamine, and glyceryl trinitrate (titrated to achieve the optimum haemodynamic response) the mean systemic arterial pressure increased, as did the cardiac index. There was an associated increase in the left ventricular stroke work index but the right ventricular stroke work index was unchanged. There was no significant change in heart rate, mean right atrial pressure, or pulmonary artery occlusion pressure. This suggests that the probable mechanism of the shock associated with right ventricular infarction is concomitant severe left ventricular dysfunction.