Right Ventricular Function

The crescent-shaped right ventricle is composed of embryologically distinct inflow and outflow tracts^{[148] [149]} that differ in their structure and response to autonomic nervous system activity. ^[150] The sequential contraction of the right ventricular (RV) inflow and outflow tracts establish regional pressure gradients within the right ventricle during systole^{[151] [152] [153]} and account for the peristaltic mechanical action of this pump. True isovolumic relaxation does not occur in the right ventricle. ^[154] Instead, ejection of blood from the outflow tract into the pulmonary artery continues after the inflow tract has begun to relax. ^{[152] [154]}

The effects of volatile anesthetics on the function and contraction sequence of the RV inflow and outflow tracts have been incompletely studied. Halothane was shown to produce similar depression of contractile function in RV inflow and outflow tracts in dogs using a uniform definition of end systole and end diastole for both regions of the right ventricle.^[155] Another investigation conducted in anesthetized pigs^[156] demonstrated that halothane caused dose-related decreases in RV contractility, which was evaluated using regional PRSW derived from RV pressure-segment length diagrams in the RV inflow and outflow tracts in the presence and absence of autonomic nervous system reflexes. Halothane also abolished the normal RV sequential contraction pattern without exerting differential negative inotropic effects in different regions of the right ventricle.^[156] These data suggest that volatile anesthetics may alter RV contraction dynamics by adversely affecting cardiac autonomic nervous system activity.