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Doppler evidence that true left ventricular-to-aortic pressure gradients exist in hypertrophic cardiomyopathy
P C Come1, M F Riley, L V Carl
1Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA 02215.
Insights
Systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy can cause left ventricular outflow tract obstruction. Doppler echocardiography confirmed significant pressure gradients, suggesting obstruction rather than cavity obliteration.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- The cause of systolic pressure gradients in hypertrophic cardiomyopathy (HCM) is debated.
- Cavity obliteration and left ventricular outflow tract (LVOT) obstruction are proposed mechanisms.
Purpose of the Study:
- To investigate whether left ventricular pressure exceeds aortic pressure, indicating obstruction in HCM patients.
- To differentiate between cavity obliteration and LVOT obstruction as the cause of pressure gradients.
Main Methods:
- Utilized imaging and Doppler echocardiography in five HCM patients with asymmetric septal hypertrophy.
- Measured outflow tract pressure gradients and mitral regurgitant jet velocities.
- Correlated Doppler-derived pressures with simultaneous sphygmomanometry and carotid pulse tracings.
Main Results:
- All patients exhibited significant outflow tract pressure gradients (peak 85 +/- 10 mm Hg).
- Peak flow velocities in the outflow tract and mitral regurgitant jets were recorded.
- Calculated peak left ventricular systolic pressure based on mitral regurgitant velocity.
Conclusions:
- Doppler echocardiography provides a method to assess LVOT obstruction in HCM.
- Findings support LVOT obstruction as a primary mechanism for systolic pressure gradients in HCM.
- Further investigation is needed to fully elucidate the etiology of these pressure gradients.
Abstract:
The etiology of systolic left ventricular-to-aortic pressure gradients in hypertrophic cardiomyopathy is still controversial. While cavity obliteration has been proposed by some investigators as the cause for recording of a high left ventricular systolic pressure, the concept of left ventricular outflow tract obstruction has received more experimental support. To investigate further whether left ventricular pressure truly exceeds aortic pressure and implies obstruction, we studied, with imaging and Doppler echocardiographic techniques, five patients with asymmetric septal hypertrophy and systolic anterior movement of the mitral valve occasionally causing it to abut upon the septum. All had outflow tract pressure gradients (peak 85 +/- 10 mm Hg) and trace to mild mitral regurgitation. Continuous wave Doppler study recorded peak flow velocities in the outflow tract (4.6 +/- 0.3 m/sec), and mitral regurgitant (mean 6.6 +/- 0.3 m/sec) jets. Aortic systolic and diastolic blood pressures were measured by cuff sphygmomanometry, and simultaneous carotid pulse tracings were recorded. The magnitude of systolic aortic pressure was determined at the time of peak velocity in the mitral regurgitant jet. Since the peak systolic pressure gradient across the mitral valve (left ventricular minus left atrial pressure) should equal 4 times the square of the peak velocity (V) in the mitral regurgitant jet, peak left ventricular systolic pressure should equal 4 x V2 plus the height of left atrial pressure at the time of peak mitral regurgitant velocity. In each case, calculations were made assuming an upper normal left atrial pressure of 10 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)