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ECHONOMY |
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Purpose |
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| To calculate mitral valve area using the pressure half-time (PHT) principle which was originally a cardiac catheterization method that was later adapted for echocardiography. PHT is the time interval needed for the initial pressure to drop by half. | ||
Technical Hints |
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| Avoid using the very initial (rapid) portion of the mitral flow deceleration slope; use the flat portion of the slope. The method underestimated the severity of MS when there is atrial septal defect with left-to-right shunt (LA pressure is low), or when LV diastolic pressure is high (significant aortic regurgitation; LV diastolic dysfunction). | ||
Calculator |
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Mitral pressure half-time (PHT) |
sec |
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Answer |
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Mitral Valve Area (MVA): |
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cm2 |
FormulasMVA = 220 / PHT If you do not know PHT, you can use deceleration time
(time interval for pressure to drop to 0) instead: PHT = 0.29 * DT MVA = 220 / 0.29 * DT MVA = 759 / DT |
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Reference |
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| Libanoff AJ, Rodbard S,
Atrioventricular presure half-time: measure of mitral valve orifice area.
Circulation 1968;38:144-50. Hatle L, Angelson B, Tromsdal A: Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound. Circulation 1979;60:1096-104.
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