Ratio of cardiopulmonary blood volume to stroke volume as an index of cardiac function in animals and in man

A scintillation probe was used to record a radiocardiogram as 99mTc flowed through the heart with the first pass after an intravenous injection. The ratio of cardiopulmonary blood volume to stroke volume, which could be determined indirectly from the simultaneous recording of a radiocardiogram and an electrocardiogram, was found to be a very sensitive and reliable index to describe the efficiency of the pump function of the heart with the different models of heart disease induced in experimental animals. It was found that left ventricular, right ventricular and biventricular failures were reflected by a large increase and pulmonary emboli by a decrease in the value of this index, which was named the cardiopulmonary flow index (CPFI). The technique has also been tested on a number of control and heart patients. The general principles found for animals could also be applied to man. As this is a noninvasive bedside technique it may have an important implication for the diagnosis of heart disease.