Right ventricular contraction synchronization due to acute afterload increase. Left ventricle-like mechanical properties of the right ventricle

Aim. The aim of this study was to demonstrate right ventricular contraction synchronization during acute and moderate afterload increase. Material and method. Right and left ventricular pressures, pulmonar and aor tic pressures, pulmonary flow, and ventricular volumes by sonomicrometry we re measured in seven anesthetized sheep. Pulmonary arterial hypertension wa s induced by Escherichia coli endotoxemia. Results. Acute increase of the right ventricular afterload, measured as the mean arterial pulmonary pressure (11.9 +/- 1.3 to 24 +/- 3.6 mmHg) produce d the following changes in the right ventricle without preload and contract ility changes: a) maximal elastance shifted towards the end of the ejection (127.5 +/- 18.5 ms) and the ejection time shortened (57.5 +/- 20.3 ms), so that the negative peak of the first ventricular pressure derivative occurr ed at the end of the ejection; b) the pressure-volume loop became rectangul ar, i.e.; the systolic and diastolic phases were isovolumic, and c) the eje ction showed a single phase. Conclusions. Asynchronous and sequencial right ventricular contraction with normal afterload changed to a synchronic contraction pattern -as in the le ft ventricle-during an acute and moderate afterload increase. This left ven tricle-like mechanical property establishes a novel mechanical reserve mech anism of the right heart, since it allows the right ventricle to maintain i ts systolic function during an afterload increase, independently of the pre load and contractility.