Low output syndrome in right ventricular infarction.

In this paper we describe clinical and hemodynamic data in ten patients with right ventricular infarction and low output syndrome. Atrioventricular block and supraventricular arrhythmias were a common finding. All of them had a right atrial pressure disproportionately increased (average 16.3 +/- 5.2 mm. Hg) in relation to left ventricular filling pressure (average 15 +/- 4.5 mm. Hg), and a very low cardiac index (average 1.42 +/- 0.45 liters/min./m.2). The right atrial pulse tracings were similar to those of constrictive pericarditis, showing a deep "y" descent in every patient. We made the differential diagnosis between similar hemodynamic entities and constructed function curves of right and left ventricles. Right ventricular diastolic work index was always increased (average 6.26 +/- 3.63 gm./beat/M.2), being higher than net work index (average 3.28 +/- 1.87 gm./beat/M.2). While all function curves of the right ventricle were flat or depressed, those of the left ventricle were very different. Treatment consisted mainly of fluid overload and, in some cases, of vasodilators or dopamine. Mortality rate was 40%. We think that coexisting left ventricular damage may account in part for the bad prognosis of these patients.