title: Rate-corrected mean velocity of fiber shortening-stress at peak systole as a load-independent measure of contractility.
abstract: The relation of mean velocity of fiber shortening-stress at end-systole is a good load-independent index of left ventricular contractility, but involves simultaneous M-mode echocardiography, carotid tracing and blood pressure determination, which may be impractical in children. As stress at peak systole and end-systole are closely related, this study examined whether the relation of mean velocity of fiber shortening-stress at peak systole could be used as a simpler method of assessing left ventricular contractility in a normal population of children. In addition, the cross-sectional normal range for a pediatric population was obtained. In 25 normal children aged 4 to 17 years (mean age 11), rate-corrected mean velocity of fiber shortening (MVCFc), stress at peak systole (sigma PS), and end-systolic stress (sigma ES) were determined using echocardiography, carotid pulse tracing and blood pressure measurement. Six patients with cardiomyopathy (mean age 8 years) were also studied. The relation of stress at peak systole and end-systolic stress was sigma PS = 1.004 sigma ES + 12.0 (r = 0.91, SEE = 4.98; p less than 0.001) for the normal group, and sigma PS = 1.083 sigma ES + 7.7 (r = 0.99, SEE = 4.07; p less than .001) for the cardiomyopathic group. This slope of the regression line was slightly higher and the difference was statistically significant. The slope of MVCFc = 0.0066 sigma PS + 1.55 (SEE = 0.131, r = -0.52) was nearly identical to that of MVCFc = 0.0065 sigma ES + 1.46, (SEE = 0.135, r = -0.46), with no difference in the regression coefficients.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Paediatrics, University of British Columbia, Vancouver, Canada.
authors.forename: G G
authors.initials: GG
authors.lastname: Sandor
authors.forename: R
authors.initials: R
authors.lastname: Popov
authors.forename: E
authors.initials: E
authors.lastname: De Souza
authors.forename: S
authors.initials: S
authors.lastname: Morris
authors.forename: B
authors.initials: B
authors.lastname: Johnston
mesh_terms: D000293:Adolescent; D001794:Blood Pressure; D002648:Child; D002675:Child, Preschool; D004452:Echocardiography; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology*; D012044:Regression Analysis; D013599:Systole / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*