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Noncompressibility of myocardium during systole with freehand three-dimensional echocardiography
Donald L King1, Lyna El-Khoury Coffin, Mathew S Maurer
1College of Physicians and Surgeons, Columbia University, New York, NewYork, USA. dlathamking@yahoo.com
Insights
Myocardial volume remains constant during the cardiac cycle, supporting the assumption of noncompressibility. This finding validates the use of freehand 3D echocardiography for accurate ventricular function measurements.
Area of Science:
- Cardiology
- Biomedical Engineering
- Medical Imaging
Background:
- Ventricular performance measures often assume myocardial noncompressibility, a principle lacking extensive supporting data.
- Freehand 3-dimensional (3D) echocardiography offers high accuracy in myocardial mass and volume assessment.
- This study aimed to validate the noncompressibility assumption using 3D echocardiography.
Purpose of the Study:
- To test the hypothesis that myocardial volume is noncompressible during systole.
- To assess the accuracy of freehand 3D echocardiography in measuring myocardial volume changes.
- To provide data supporting the assumption of myocardial noncompressibility in ventricular function analysis.
Main Methods:
- Freehand 3D echocardiography was used to examine 41 athletes and 17 patients with hypertrophy.
- Endocardial and epicardial surfaces were reconstructed at end diastole and end systole.
- Myocardial, endocardial, and epicardial volumes were calculated and compared using paired t tests.
Main Results:
- Myocardial volume showed no significant change between diastole and systole (174.7 mL vs. 174.6 mL, P=NS).
- Endocardial and epicardial stroke volumes were identical (76.0 mL vs. 76.0 mL, P=NS).
- The average absolute difference in myocardial volume was less than 1.1% of end-diastolic volume.
Conclusions:
- Myocardial volume is constant during systole, supporting its noncompressibility.
- Freehand 3D echocardiography confirms myocardial noncompressibility for ventricular function measurements.
- Comparing diastolic and systolic myocardial volumes can serve as a quality assurance measure for 3D reconstructions.
Background:
Measures of ventricular performance, such as the ejection fraction, assume that myocardium is noncompressible and does not change volume significantly from end diastole to end systole. Although this principle is widely accepted as true, little data exist in the literature to support it. Freehand 3-dimensional (3D) echocardiography has previously been shown to be highly accurate for measurement of myocardial mass and volume. Therefore, we hypothesized that it has sufficient accuracy to test the validity of this assumption. We measured myocardial volume at end diastole and end systole in 2 groups of subjects with hypertrophy.
Methods:
Forty-one healthy young adult athletes and 17 adult patients with hypertension, hypertrophy, normal ejection fraction, and heart failure symptoms underwent examination with freehand 3D echocardiography. Endocardial and epicardial surfaces at end diastole and end systole were reconstructed, and their volumes were computed. From these surface volumes, myocardial volume at end diastole and end systole and epicardial stroke volume and endocardial stroke volume were calculated. These volumes were compared with the 2 sample paired t test.
Results:
Myocardial volume was constant from diastole to systole (174.7 +/- 45.3 mL versus 174.6 +/- 45.8 mL; P = not significant), and endocardial and epicardial stroke volumes were identical (76.0 +/- 17.4 mL versus 76.0 +/- 17.1 mL; P = not significant). The average absolute difference between the end-diastolic and end-systolic myocardial volumes was 1.9 mL, or less than 1.1% of end-diastolic volume.
Conclusion:
Myocardial volume measured with freehand 3D echocardiography does not change significantly during systole. Myocardial volume may be considered noncompressible for purposes of measurement of ventricular function with freehand 3D echocardiography. Comparison of end-diastolic and end-systolic myocardial volumes may be used for quality assurance in performing 3D reconstructions.