[Synchronization of the contraction of the right ventricle against an acute afterload increase. Left ventricle-like mechanical function of the right ventricle].
OBJECTIVE
The aim of this study was to demonstrate right ventricular contraction synchronization during acute and moderate afterload increase.


METHODS
Right and left ventricular pressures, pulmonary and aortic pressures, pulmonary flow, and ventricular volumes by sonomicrometry were measured in seven anesthetized sheep. Pulmonary arterial hypertension was 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) produced the following changes in the right ventricle without preload and contractility 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 occurred at the end of the ejection; b) the pressure-volume loop became rectangular, i.e.; the systolic and diastolic phases were isovolumic, and c) the ejection showed a single phase.


CONCLUSIONS
Asynchronous and sequential right ventricular contraction with normal afterload changed to a synchronic contraction pattern as in the left ventricle during an acute and moderate afterload increase. This left ventricle-like mechanical property establishes a novel mechanical reserve mechanism of the right heart, since it allows the right ventricle to maintain its systolic function during an afterload increase, independently of the preload and contractility.
Ginés
F
F
Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
Grignola
J C
JC
D000222:Adaptation, Physiological; D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D006976:Hypertension, Pulmonary / Q000503:physiopathology; D009200:Myocardial Contraction / Q000502:physiology*; D011651:Pulmonary Artery / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology; D012756:Sheep; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*