Comparison of left ventricular volumes by dye dilution and angiographic methods in the dog

In each of 12 mongrel dogs, data for end-diastolic volume, end-systolic volume, and stroke volume of the left ventricle were obtained by two independent methods: the indicator dilution method and a radiographic method. While the values for stroke volume showed good agreement between the two methods, a significant and directionally constant difference was found between values for end-diastolic volume and end-systolic volume calculated by the two different methods. This was observed in dogs with fast heart rates (exceeding 150 beats/min), as well as in dogs with heart rates of about 100 beats/min. The findings strongly suggest that a fundamental error is present in estimations of volume based on the washout of an indicator dye.