Key result
Invasive testing situations induced a stress response that decreased ejection fraction in patients with compromised ventricular function and slightly increased it in those with normal contractility.
Why the study?
Does the nuclear stethoscope accurately measure left ventricular ejection fraction compared to contrast ventriculography and gamma camera?
Cross-Sectional (n=23)
Does the nuclear stethoscope accurately measure left ventricular ejection fraction compared to contrast ventriculography and gamma camera?
Answers are grounded in this paper and cite their sources.
The nuclear stethoscope provides accurate and reliable measurements of left ventricular ejection fraction comparable to contrast ventriculography and MUGA, while highlighting that invasive testing situations can alter EF based on baseline ventricular function.
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.
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Lund et al. (1986) conducted a cross-sectional in Patients undergoing left ventricular ejection fraction measurement (n=23). Nuclear stethoscope (NSt) vs. Contrast ventriculography (VG) and MUGA was evaluated on Left ventricular ejection fraction (EF) correlation and differences between invasive and noninvasive situations (p=<0.001). Invasive testing situations induced a stress response that decreased ejection fraction in patients with compromised ventricular function and slightly increased it in those with normal contractility.
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