[Effect of left heart bypass on right ventricular function in normal and acute heart failure dogs--an application of the conductance catheter to the right ventricle].

We investigated right ventricular function during left heart bypass (LHB) with 18 mongrel open-chest dogs, in normal and acute heart failure (AHF) dogs which underwent aortic cross clamp. Left ventricular unloading was completely accomplished with a centrifugal pump. For more accurate evaluation of right ventricular volume, conductance catheter was employed to assess right ventricular function. Analysis were performed with right ventricular pressure-volume curve which was changed by transient volume loading on right ventricle. And right ventricular properties with and without LHB were compared by the use of load independent parameters as follows. Right ventricular systolic property was evaluated by maximum elastance (Emax) and stroke work-end-diastolic volume relation (SW/EDVR), and its diastolic function was evaluated by end-diastolic pressure-volume relation (EDP/VR). Overall right ventricular performance was assessed by stroke work-end-diastolic pressure relationship (SW/EDPR). In the normal heart, only a parallel shift to the right in EDP/VR and SW/EDVR was noted without any significant changes in slope with LHB. On the other hand, in AHF dogs, the slope of SW/EDVR and SW/EDPR were increased from 0.14 +/- 0.08 to 0.18 +/- 0.08 (p < 0.05), from 0.22 +/- 0.15 to 0.34 +/- 0.19 (p < 0.01), respectively, and the curve of EDP/VR was shifted right and downward. These result suggested that decompression of the left ventricle and septal shifting by LHB provided good diastolic compliance and afterload unloading of the right ventricle, and these effects had a more significant role in acute heart failure than in the normal heart.