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Left ventricular ejection fraction determined with the nuclear stethoscope, gamma camera and contrast
Abstract:
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 gave: r = 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 less than 50 (mean +/- S.D.): EF invasive = 36 +/- 12, EF noninvasive = 41 +/- 13 (n = 4, p less than 0.05), and for patients with EF greater than or equal to 50: EF invasive = 59 +/- 7, EF noninvasive = 57 +/- 7 (n = 9, N.S.). The mean paired differences (EF noninvasive -EF invasive) in the low (less than 50) and high (greater than or equal to 50) EF range differed significantly: +5.3 versus -1.3, respectively (p less than 0.001). The recordings with the ECG-gated summation method gave similar results. The heart rate (beats min-1) in the noninvasive and invasive situation were (mean +/- S.D.): 68 +/- 11 and 78 +/- 16, respectively (p less than 0.01). We conclude that the patients were in a higher level of stress in the invasive situation. Accordingly ventricles with normal contractility (EF greater than or equal to 50) reacted with a slight increase in EF, and ventricles with compromised function (EF less than 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.