Relation Between Mural Force and Pressure in the Left Ventricle of the Dog

An investigation of the relationship in the dog between left ventricular pressure, left ventricular size, and total longitudinal force developed by the wall of the left ventricle is reported. This study required the development of a method for recording the force needed to keep together the two edges of a slit in the ventricle. Such a method is described, and samples of the force curves are shown, the general features of which are consistent with predictions from the physiology of muscle strips. The net force which the muscle fibers develop perpendicular to a given plane through the ventricle is almost identical to the product of the intracavitary pressure and the area of the cavity included in the plane. This relationship holds true regardless of the thickness of the wall or the shape of the ventricle.