A new technique for estimating myocardial tissue pressure is described. The method is based upon changes in flow through an analog of a small coronary vessel. A gradient of tissue pressure from epicardium to endocardium was observed with peak tissue pressures twice peak ventricular pressure recorded in the inner half of the wall. A theoretical analysis of the concept of intramyocardial pressure is presented, based on the assumption that the tissue is a solid within which both longitudinal and radial compressive forces exist. The similarity between the gradient of longitudinal tissue pressure predicted by the theoretical analysis and the gradient experimentally determined suggests that the latter describes the maximum pressures which exist in the left ventricular wall.
