ECHO 2013 / Mitral Stenosis Quantitation It’s Not All About the Gradient
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Peak and Mean Gradients
•Peak and mean gradients correlate well with cath
•Pressure gradients dependent on absolute pressures in each chamber
LV diastolic pressures
•High LVEDP will lower gradient
•Low LVEDP may increase gradient
Left atrial filling pressures
•Low LAP lowers gradients
•High LAP raises gradients
•Pressure gradient depends on heart rate and
cardiac output
Shorter diastolic filling period, higher LA filling pressures
•Tachycardia (exercise, atrial fibrillation)
Increased stroke volume may increase
gradient
Always report HEART RATE when assessing mitral valve stenosis
Pitfalls of Peak and Mean Gradients
•High gradient with large MVA
•High forward output
–Hyperdynamic LV with high output: anemia, exercise
–Significant mitral regurgitation
•Tachycardia: shortens diastolic filling period
•Subvalvular obstruction (chordal calcification)
•Low gradient with small MVA
•Low forward output (Low stroke volume index < 35 cc/m2)
–Reduced LV function with low cardiac output
–Increased LV diastolic pressures (diastolic dysfunction , AR)
•Low LA pressure (ie: with bradycardia)
Pitfalls of flow-dependent measurements are overcome by the use of the Continuity Equation
Pressure Half-time
•Hatle et al (Br Heart J 1978;40:131) related the PHT to mitral area using an empiric equation:
Mitral Valve Area = 220/PHT
= 750/DT
Note: constant of 220 msec is proportional to net compliance (of LV and LA) and the square root of maximum transmitral gradient and does NOT take into account active relaxation of the LV
Pitfalls of PHT Calculation
•Pressure half-time reflects the rate at which left atrial and ventricular pressures move toward equilibrium in diastole.
PHT will be shortened if:
•Left ventricular diastolic pressure rises faster that expected based on valve area alone
–Aortic regurgitation
–Noncompliant ventricle
•Left atrial pressures fall faster than expected
–ASD (ie: post-valvulotomy)
–Noncompliant left atrium (chronic atrial fibrillation)
PHT will be lengthened if:
•Left ventricular diastolic pressure rises slower that expected based on valve area alone
–Abnormal LV relaxation (note: peak velocities usually low)
PHT Pitfalls: AR and ASD
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LV diastolic pressures rise |
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faster due to filling across |
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both the mitral and aortic |
Pressure halftime shorter |
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valves. |
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PHT Pitfalls: AR and ASD
LA pressures fall faster due to emptying across both the mitral valve and ASD.
Pressure halftime shorter
Pitfalls of PHT Calculation
• PHT (and planimetered MVA) may not be
“flow-independent” |
Mohan J, et al. Is the mitral valve |
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area flow-dependent in mitral |
Continuity equation and PISA are relatively flow independent
stenosis? A dobutamine stress echocardiographic study. J Am Coll Cardiol 2002;40:1809-15.
•PHT is also dependent upon
Initial LA pressure (MV opening pressure)
•Higher with MR
•Higher with prosthetic valves
•Higher with worsening diastolic function
Reported Limitations of PHT in Literature
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-3 |
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Abascal VM et al. Am J Cardiol. 1996 15;78(12):1390 |
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• Patients 60-65 yo |
Messika-Zeitoun et a. J Am Soc Echocardiogr |
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2005;18:1409-1414 |
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Significant reduction in correlation with Gorlin MVA— possibly due to abnormal LV compliance with age
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Thomas JD et al. Circulation 1988;78:980-93. |
• Post-PBMV |
Klarich KW et al. J Am Soc Echocardiogr 1996;9:684-90. |
Messika-Zeitoun et a. J Am Soc Echocardiogr 2005;18:1409-1414 |
Messika-Zeitoun et a. J Am Soc Echocardiogr
• Atrial fibrillation: 2005;18:1409-1414
Kim HK et al. J Am Soc Echocardiogr 2009;22:42–7.
Average multiple beats, avoid short diastoles
• Tachycardia |
Nakatani S et al Circulation 1988;77:78–85. |
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Voelker W. et al. Eur Heart J 1992;13:152–9. |
Reported Limitations of PHT in Literature
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Severe MR Mohan JC et al. Am Heart J 2004;148:703–9 Messika-Zeitoun et a. J Am Soc Echocardiogr 2005;18:1409-1414
Aortic regurgitation
Nakatani S et al. Circulation. 1988 Jan;77(1):78-85. Moro E et al. Eur Heart J. 1988 Sep;9(9):1010-7. Flachskampf FA et al. J Am Coll Cardiol. 1990 Aug;16(2):396-404.
• Nonlinear Doppler velocity curves
Gonzalez MA, et al Am J Cardiol 1987;60:327-32
• Pregnancy
Rokey R el al. Obstet Gynecol. 1994;84(6):950-5.
Case Study
•80 year old woman, S/P open mitral commissurotomy 39 years ago, now presents with progressive DOE with mild exertion
BP = 124/56 mmHg
HR = 80-90 bpm (atrial fibrillation)
BSA = 1.65 cm2