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A new noninvasive method for the estimation of peak dP/dt
J Rhodes1, J E Udelson, G R Marx
1Division of Pediatric Cardiology, Floating Hospital for Infants and Children, Boston, MA.
Background:
Peak dP/dt is a good index of ventricular performance that is not influenced by afterload, wall motion abnormalities, or the variations in ventricular anatomy and morphology commonly encountered among patients with congenital heart disease. Unfortunately, the clinical utility of peak dP/dt has been limited by the fact that its measurement generally requires an intraventricular catheter. However, peak dP/dt occurs during isovolumetric contraction, and the pressure rise during isovolumetric contraction is almost linear. Therefore, the mean dP/dt during isovolumetric contraction (mean dP/dtic), ie, the ratio of the rise in pressure during isovolumetric contraction (aortic diastolic pressure minus the systemic ventricular end-diastolic pressure [VEDP]) over the isovolumetric contraction time, should provide a good estimate of peak dP/dt that could be generated noninvasively.
Methods And Results:
Echo/phonocardiography was used to measure the isovolumetric contraction time and a blood pressure cuff to estimate aortic diastolic pressure of 27 patients (age, 1 day to 77 years) with congenital or acquired heart disease. VEDP was determined by three methods: (1) intraventricular catheter, (2) assumed VEDP of 10 mm Hg, and (3) assignment of a normal or elevated value on the basis of clinical history. The three estimates of mean dP/dtic thus generated were compared with simultaneous measurements of peak dP/dt obtained during cardiac catheterization. Invasively measured peak dP/dt correlated well with the indirect determinations (r = .95, .89, and .92 for methods 1, 2, and 3, respectively; P < .0001).
Conclusions:
Echo/phonocardiography can be used in conjunction with a blood pressure cuff and indirect estimates of VEDP to generate mean dP/dtic, an index of ventricular function that approximates and closely correlates with peak dP/dt. This noninvasive measurement can be obtained in almost any patient and may be useful in the assessment of ventricular performance in a variety of cardiovascular disorders.