Own properties of the right ventricle cardiac cycle phases

Aims. The purpose of our study was to define at physiological conditions, t he existence or not of an isovolumic relaxation phase in the right ventricl e and its eyective phase properties. Material and methods. Right and left ventricular pressures, pulmonar and ao rtic pressures, pulmonary flow and ventricular diameters by sonomicrometry were measured in nine anesthetized sheep. The first ventricular pressure de rivative, 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 eyection phase which can be subdivided i n two phases (early and late). The end of the ejection phase was establishe d by the temporal coincidence of the zero pulmonary flow, the minimum systo lic value of the right ventricular volume and a right ventricular pressure of 0-4 mmHg. The time between the beginning of the eyection phase and: a) t he end of systole; b) the negative peak of the first derivative of ventricu lar pressure and c) the end of eyection, were different for the right ventr icle (67 +/- 15 ms, 274 +/- 30 ms, 412 +/- 33 ms, respectively), meanwhile the left ventricle showed the following values: 204 +/- 33 ms, 262 +/- 23 m s, 266 +/- 24 ms, respectively. Conclusions. Right ventricle exhibits a long lasting ejection phase which c an be subdivided in two phases, spreading at the beginning of the next fill ing phase. This fact allows us to affirm that right ventricle does not show an isovolumic relaxation phase in comparison to left ventricle.