Mechanisms of Contraction of the Normal and Failing Heart

Myocardial Mechanics and HemodynamicsSpann et al.227 recently compared the intrinsic contractile state of myocardium removed from normal, hypertrophied and failing hearts. Constriction of the pulmonary artery was carried out in cats, and papillary muscles removed from the right ventricles of animals in which either right ventricular hypertrophy or overt right ventricular failure had developed, and the removed muscles were then studied in vitro. Both right ventricular hypertrophy and heart failure reduced the maximum velocity of shortening (V max ) as well as the development of maximum isometric tension (P 0 ) below the values observed in muscles obtained from . . .