Comparison between left and right heart function in the isolated biventricular working rat heart

To provide a basic characterization of the crystalline perfused isolated rat heart preparation in its biventricular working mode.

In 110 isolated biventricular heart preparations, flows and intraventricular pressures were examined by applying 24 and 28 different loading conditions to the left (LV) and right ventricle (RV), respectively.

LV and RV flows responded analogously to changes in loading conditions and were in accordance with the Frank-Starling principle. Linearization of parameters derived from the LV and RV function curves showed that the operation of both ventricles was quantitatively similar when unloaded and increasingly dissimilar when loaded. With increasing RV preload, the characteristics of the RV pump function curves changed; however, those of the LV hardly changed. Power, contractility and relaxation data of the ventricles were compared by applying the concept of corresponding afterloads, which showed that these parameters, except for power, had an inconsistent preload and afterload dependence in the LV and RV. Even though LV and RV performances displayed coexisting analogies, quantitative similarities and qualitative dissimilarities, in the case of relaxation, a concept unifying the heterogeneous data set for both ventricles has been developed. The hypothesis may be put forward that the macroscopic relaxation process of the heart muscle runs in parallel with cellular calcium handling.

At the level of the isolated denervated rat heart model, the common LV and RV functional parameters were only partially similar between the ventricles. However, a particular functional interdependence of relaxation data has been proposed to provide a unifying description of both LV and RV function.