A simplified method for calculating wall stress in infants and children.
Measurement of the end-systolic wall stress-mean velocity of circumferential fiber-shortening relation, a load-independent measure of contractility, has enabled cardiologists to assess ventricular function under various loading conditions and at different heart rates. Unfortunately, it is time-consuming and difficult to perform in routine pediatric practice. Because a close relationship was noted between end-systolic pressure and mean blood pressure, we estimated wall stress by mean blood pressure in 115 patients. There was an excellent correlation between end-systolic blood pressure and mean arterial pressure (r = 0.84) and end-systolic wall stress and mean systolic wall stress (r = 0.98). The difference in mean blood pressure was 5.1 mm Hg (95% confidence interval-10.5 to 20.6 mm Hg), and the difference in mean wall stress was 2.7 gm/cm2 (95% confidence interval-2.0 to 3.8 gm/cm2). More important, substitution of mean blood pressure for end-systolic pressure allowed accurate identification of patients with normal contractility (55/56) and abnormal contractility (57/59).
Karr
S S
SS
Department of Cardiology, Children's National Medical Center, Washington, DC 20010-2970.
Martin
G R
GR
D001794:Blood Pressure / Q000502:physiology; D001795:Blood Pressure Determination; D002648:Child; D004452:Echocardiography; D006801:Humans; D007223:Infant; D009200:Myocardial Contraction / Q000502:physiology*; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology; D016276:Ventricular Function / Q000502:physiology*