Left ventricular ejection fraction determined with the nuclear stethoscope, gamma camera and contrast ventriculography

Left ventricular ejection fractions (EF) were measured with a nuclear stethoscope (NSt, beat-to-beat and ECG gated summation method) and contrast ventriculography (VG) immediately following one another (IFOA) (r x 0.96 and 0.95, respectively, n = 13). NSt and ECG gated gamma camera (MUGA) recordings IFOA were compared (r = 0.97 and 0.96, respectively, n = 23) as were non-IFOA recordings (r = 0.90 and 0.91, respectively, n = 13). Correlation between repeated NSt EF measurements gaver = 0.91 (n = 22) for both methods.Paired NSt recordings in an invasive test situation (during invasive angiocardiography) and in a noninvasive situation (supine, 30 min of rest) gave for patients with EF < 50 (mean ± S.D.)EFinvasive = 36±12, EFnoninvasive = 41±13 (n = 4, p < 0.05), and for patients with EF ≥ 50EFinvasive = 59±7, EFnoninvasive = 57±7 (n = 9, N.S.). The mean paired differences (EFnoninvasive –EFinvasive) in the low (< 50) and high ( ≥ 50) EF range differed significantly+5.3 versus –1.3, respectively (p < 0.001). The recordings with the ECG-gated summation method gave similar results. The heart rate (beats min) in the noninvasive and invasive situation were (mean±S.D.)68±11 and 78±16, respectively (p < 0.01). We conclude that the patients were in a higher level of stress in the invasive situation. Accordingly ventricles with normal contractility (EF ≥ 50) reacted with a slight increase in EF, and ventricles with compromised function (EF < 50) reacted with a decrease in EF, compared to the values in the noninvasive situation. Incorporated in a correlation between MUGA and VG are, besides methodologically based differences, test-situation based systematical differences. Consequently the results of MUGA method should be given uncorrected.The results documents the accuracy and reliability of the NSt.