Effect of cyclopropane on contractile performance of cardiac muscle with experimental chronic heart failure.

The effect of cyclopropane on contractile performance of papillary muscles obtained from cats with congestive heart failure induced by pulmonary artery constriction was studied and compared with non-operated normal animals. A significant depression of contractile performance in the papillary muscles of cats with congestive heart failure was observed along with elevated right ventricular pressure and reduced cardiac index. In both groups of muscles, cyclopropane caused a shift of the force-velocity curve to the left and downward. At an equipotent anaesdietic concentration (MAC) of cyclopropane, reduction in contractile performance was similar in both muscles. When changes in velocity of shortening and maximal isometric force in muscles with congestive heart failure were compared with the control values of normal muscles at MAC, the depression was 49% and 44% respectively. However, the effect of cyclopropane on the diseased muscle was significantly less than that of either isoflurane or halothane.