Does normalizing mean velocity of circumferential fiber shortening to heart rate (RVC) improve diagnostic reliability in separating normal subjects from patients with cardiac abnormalities compared to uncorrected VCF?
Normalizing the mean velocity of circumferential fiber shortening to heart rate (RVC) improves its diagnostic accuracy for identifying myocardial dysfunction compared to the uncorrected measurement.
Previous studies relating mean velocity of circumferential fiber shortening (VCF) to heart rate suggested a linear correlation. Since there is considerable variability in the heart rate of normal subjects and in patients with myocardial disease, a normalization of VCF to heart rate could possibly increase the reliability of this echocardiographic parameter of myocardial function. In 106 normal subjects, a linear correlation between VCF and heart rate was confirmed (r=0.87). Values normalized to an arbitrary heart rate of 60/min by the calculated regression were called "relative velocity of contraction" (RVC). Because of the independence of RVC from heart rate, the RVC shows an obviously smaller physiological variation than VCF. Two hundred seventy-six patients were grouped and classified according to hemodynamic and angiographic parameters. These parameters correlated closer to RVC than to VCF. In addition, RVC gave definitely superior diagnostic information in separating patients with cardiac abnormality from normal individuals than did VCF.
Wolfram H. Knapp (Wed,) studied this question.
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