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Catheter estimation of stenotic valves

Catheter estimation of stenotic valves. Dr. DAYASAGAR RAO KIMS HYDERABAD. Stenotic valve orifice area-evaluation. Cardiac catheterization- gold standard? Echo doppler MRI based Clinical MDCT. Stenotic valve orifice area-evaluation.

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Catheter estimation of stenotic valves

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  1. Catheter estimation of stenotic valves Dr. DAYASAGAR RAO KIMS HYDERABAD

  2. Stenotic valve orifice area-evaluation • Cardiac catheterization- gold standard? • Echo doppler • MRI based Clinical • MDCT

  3. Stenotic valve orifice area-evaluation Is there role of catheter based assessment- stenotic valves in 2009?

  4. ACC/AHA guidelines valvular heart disease-evaluation 2008 • Discrepancy: clinical findings noninvasive data . • Technically unsatisfactory non invasive data (echo-doppler) operator dependent acoustic window TEE • Low flow- low gradient: aortic stenosis

  5. Catheter based – evaluation of stenotic orifice • Is it safe? tight/ critical stenosis cerebral embolism- calcific aortic stenosis Omran et al: LANCET 2003 152 patients aortic stenosis randomized: CAG only Vs CAG + crossing of aortic valve (retrograde)

  6. Stenotic orifice area (catheter based) • Brain MRI: diffusion imaging 22% focal diffusion imaging abnormalities 3% clinically apparent neurodeficit only in patients- crossing of aortic valve.

  7. Stenotic orifice area- catheter based • Aortic stenosis: retrograde approach antegrade Mitral stenosis: LV- PCW LV- LA

  8. Stenotic orifice areaAORTIC STENOSIS- (LV-AO)

  9. STENOTIC ORIFICE AREA • MITRAL STENOSIS • LV-PCW • LV-LA TRANSEPTAL • PROPER PCW PRESSURE: MEAN WEDGE- MEAN PA • ALIGNMENT MISMATCH- TIME DELAY 50-70 msec • REALIGNMENT- PEAK OF V WAVE BISECTED BY LV PRESSURE DOWNSTROKE.

  10. STENOTIC ORIFICE AREA

  11. VALVULAR STENOSIS- SEVERITY • Valvular disease cause of symptoms • Timing of intervention: symptomatic status natural history- symptoms

  12. Stenotic orifice area Geometric orifice area Effective orifice area Critical valve area

  13. DIAGRAM SHOWING Geometric / effective orifice area Contraction co efficient

  14. Contraction coefficient

  15. STENOTIC ORIFICE- VALVES Hemodynamic impact influenced by Cross sectional area Geometry of valve – flat valves have greater contraction co-efficient (for similar CSA and volume flow)

  16. Stenotic orifice area • Clinical implication: - Planimetry area • Effective orifice area (continuity/Gorlins) • EOA smaller than planimetered area- proportional contraction coefficient.

  17. PRESSURE RECOVERY • Fluid energy= pressure energy+ kinetic energy • Narrowed orifice (vena contracta) highest velocity • Downstream - flow stream expands • Deccleration (decreased velocity- kinetic) • Conversion- kinetic – pressure (pressure recovery)

  18. PRESSURE RECOVERY

  19. Clinical implication- pressure recovery • Doppler derived gradients- using CW doppler @ vena contracta • Catheter derived gradients- downstream vena contracta- pressure recovery GRADIENT DERIVED BY CATH IS LOWER THAN DOPPLER DERIVED GRADIENT

  20. PROSTHETIC VALVES Bileaflet valves • Side orifice velocities are less than central orifice velocities. (side orifice velocities is 85% of central orifice) • Pressure recovery occurs much further downstream in central orifice than side orifice. • Discrepancy measurement of gradients- over time.

  21. Stenotic orifice area- pressure recovery • Pressure recovery is more across aortic than at mitral prosthetic valve- native valve. • Pressure recovery- exaggerated in • Smaller aorta • Stiffer aorta • Hypertension • Discrepancy between catheter derived and doppler derived pressure data. (thus calculated valve area)

  22. Stenotic orifice area- pressure recovery(exaggeration- HTN)

  23. Stenotic valve area Torricelli’s law • F= A X V A=F/V A=F/V Cc F- Flow A- Valve area V- Velocity of flow Cc- coefficient of contraction

  24. Stenotic valve area • V2 = (CV)2 X 2Gh • V= (CV) x sq root 2Gh h = pressure gradient G = gravitational constant (980 cm/sec2) for conversion cmH2 to units pressure Cv- coefficient velocity for correcting energy loss (pressure energy- kinetic energy)

  25. Stenotic valve area • A= F/V F- flow (vol flow ml/sec) • Flow rate= cardiac output/ duration of systole or diastole (SEP/DFP X HR)

  26. Stenotic valve area • Valve area= cardiac output ÷ (HR X SEP) 44.3 X C X sq root of pressure gradient C- empirical constant calculated valve area (by Gorlin) actual valve area (at surgery) Mitral Valve = constant 0.7 (later changed 0.85) Aortic valve: assumed to be 1

  27. GORLINS FORMULA (AHJ 1951 Gorlin R, Gorlin G) Eleven patients Right heart catheterization- PCWP Assumed LV diastolic pressure- 5mmhg Duration diastole- peripheral arterial tracing Calculated mitral valve area Measured MVA at surgery

  28. GORLIN FORMULA Cardiac output Pressure gradient across valve (mitral/aortic) Duration of flow (DFP/SEP)- pressure tracing Constant (calculated-measured valve area)

  29. GORLIN FORMULA Empirical constant includes Conversion of cms H2o to units of pressure • Contraction co-efficient • Velocity co-efficient • Difference- valve area calculated- and valve area at surgery

  30. GORLIN FORMULA Problems • cardiac output Fick - oxygen consumption Thermodilution- low output state - significant TR • Duration of flow (SEP-DFP) • Alignment mismatch • Calibration errors

  31. GORLIN FORMULA • Modification: HAKKI cardiac output (L/ min) Sq root of MPG • Heart rate: 60- 100/ min

  32. Stenotic valve orifie area • Catheterization : gold standard ?(Grossman et al 2006) • Invasive procedure • Risk • Limitations – measured parameters - calibration -valvular regurgitation • Expensive ACC/AHA Guidelines

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