Influence of coronary artery pressure upon myocardial elasticity.

PHYSIOLOGIC mechanisms which influence cardiac function through alterations of the physical state of heart muscle have not been demonstrated, despite much experimental effort. This type of cardiac regulation can be identified only by sudden changes of myocardia! stiffness or distensibility. Experimental evidence for alterations of myocardial elasticity which occurred after variation of physiologic parameters has usually been considered negative or unconvincing." During an investigation of experimental heart failure,' we observed phenomena which suggested an influence of coronary artery pressure upon the elasticity of heart muscle and which led to the experiments described here. The data show a reversible, significant influence of the pressure in the coronary tree upon the distensibility of the dog's left ventricle.