Related Experiment Videos
A simplified method for calculating wall stress in infants and children
1Department of Cardiology, Children's National Medical Center, Washington, DC 20010-2970.
Insights
Measuring ventricular contractility using mean blood pressure is a simpler alternative to end-systolic wall stress. This method accurately identifies normal and abnormal cardiac function in pediatric patients.
Area of Science:
- Cardiology
- Pediatric Cardiology
- Biomedical Engineering
Background:
- End-systolic wall stress-mean velocity of circumferential fiber-shortening is a load-independent measure of contractility.
- Assessing ventricular function is crucial but challenging in routine pediatric practice.
- Current methods for measuring contractility are time-consuming and difficult to perform.
Purpose of the Study:
- To evaluate the feasibility of using mean blood pressure (MBP) as a surrogate for end-systolic pressure (ESP) in estimating contractility.
- To determine if MBP can accurately assess ventricular function in pediatric patients.
- To simplify the measurement of cardiac contractility in clinical settings.
Main Methods:
- Correlational analysis between end-systolic pressure (ESP) and mean arterial pressure (MAP) in 115 pediatric patients.
- Estimation of wall stress using MBP instead of ESP.
- Comparison of contractility assessment using both methods.
Main Results:
- Excellent correlation found between ESP and MAP (r = 0.84).
- High correlation observed between end-systolic wall stress and mean systolic wall stress (r = 0.98).
- MBP substitution accurately identified patients with normal (55/56) and abnormal (57/59) contractility.
Conclusions:
- Mean blood pressure can reliably estimate end-systolic pressure for assessing cardiac contractility.
- This simplified approach allows for accurate identification of ventricular function in pediatric patients.
- Using MBP offers a practical alternative for routine pediatric cardiology practice.
Abstract:
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).