Nuclear stethoscope monitoring of left ventricular function: A validation study

During cardiac catheterisation, the changes of stroke volume obtained with a single crystal scintillation probe were compared to those obtained at the same time by the thermodilution technique in 5 patients at rest and during rapid incremental pacing. An average of 34 cardiac outputs by the thermodilution technique were taken for each patient. A linear relationship ranging between 0.755 and 0.906 was found between the measurement obtained by the two techniques in the 5 patients. The minimum significant variation in stroke volume, measured by the thermodilution technique and detectable by the nuclear probe, was 10 ± 5 ml. Our results show that continuous precordial counting of the labelled blood pool is a sensitive technique to detect rapidly changing left ventricular volume events that occur on a beat-to-beat basis.