[The characteristics proper of the cardiac cycle phases of the right ventricle].
OBJECTIVE
The purpose of our study was to define at physiological conditions, the existence or not of an isovolumic relaxation phase in the right ventricle and its ejective phase properties.


METHODS
Right and left ventricular pressures, pulmonary and aortic pressures, pulmonary flow and ventricular diameters by sonomicrometry were measured in nine anesthetized sheep. The first ventricular pressure derivative, ventricular volumes, and the right and left pressure-volume loops, were calculated "off line". An abrupt preload reduction was generated by a posterior vena caval occlusion.


RESULTS
Right ventricle showed an ejection phase which can be subdivided in two phases (early and late). The end of the ejection phase was established by the temporal coincidence of the zero pulmonary flow, the minimum systolic value of the right ventricular volume and a right ventricular pressure of 0-4 mmHg. The time between the beginning of the ejection phase and: a) the end of systole; b) the negative peak of the first derivative of ventricular pressure and c) the end of ejection, were different for the right ventricle (67 +/- 15 ms, 274 +/- 30 ms, 412 +/- 33 ms, respectively), meanwhile the left ventricle showed the following values: 204 +/- 33 ms, 262 +/- 23 ms, 266 +/- 24 ms, respectively.


CONCLUSIONS
Right ventricle exhibits a long lasting ejection phase which can be subdivided in two phases, spreading at the beginning of the next filling phase. This fact allows us to affirm that right ventricle does not show an isovolumic relaxation phase in comparison to left ventricle.
Grignola
J C
JC
Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay. jgrig@fmed.edu.uy
Pontet
J
J
Vallarino
M
M
Ginés
F
F
D000818:Animals; D003971:Diastole; D006334:Heart Function Tests / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data; D012756:Sheep; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors; D016278:Ventricular Function, Right / Q000502:physiology*