Echo assessment of Aortic Stenosis

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Echo assessment of Aortic Stenosis

  1. 1. ECHOCARDIOGRAPHICASSESSMENT OF AORTIC VALVE STENOSIS Dr Ranjith MP
  2. 2. Normal Aortic valve Three cusps, crescent shaped 3 commissures 3 sinuses supported by fibrous annulus3.0 to 4.0 cm2Node of Arantius
  3. 3. 2D Echo-Long axis view Diastole Systole
  4. 4. 2D Echo-Short axis view Diastole SystoleY or inverted Mercedes-Benz sign
  5. 5. 2D - Apical five chamber view
  6. 6. 2D – Suprasternal view
  7. 7. M Mode- Normal aortic valve
  8. 8. CAUSES AND ANATOMIC PRESENTATION
  9. 9. Aortic stenosis- CausesMost common :- Bicuspid aortic valve with calcification Senile or Degenerative calcific AS Rheumatic ASLess common:- Congenital Type 2 Hyperlipoproteinemia Onchronosis
  10. 10. Anatomic evaluation Combination of short and long axis images to identify Number of leaflets Describe leaf mobility, thickness, calcificationCombination of imaging and doppler allows the determination of the level of obstruction; subvalvular, valvular, or supravalvular.Transesophageal echocardiography may be helpful when image quality is suboptimal.
  11. 11. Calcific Aortic Stenosis Nodular calcific masses on aortic side of cuspsNo commissural fusionFree edges of cusps are not involvedstellate-shaped systolic orifice
  12. 12. Calcific Aortic StenosisParasternal long axis view showing echogenic and immobile aortic valve
  13. 13. Calcific Aortic StenosisParasternal short-axis view showing calcified aortic valve leaflets. Immobility of the cusps results in only a slit like aortic valve orifice in systole
  14. 14. Bicuspid Aortic valve Fusion of the right and left coronary cusps (80%) Fusion of the right and non-coronary cusps(20%) Schaefer BM et al. Am J Cardiol 2007;99:686–90 Schaefer BM et al.Heart 2008;94:1634–1638.
  15. 15. Bicuspid Aortic valveTwo cusps are seen in systole with only two commissures framing an elliptical systolic orifice(the fish mouth appearance).Diastolic images may mimic a tricuspid valve when a raphe is present.
  16. 16. Bicuspid Aortic valveParasternal long-axis echocardiogram may show an asymmetric closure line  systolic doming  diastolic prolapse of the cuspsIn children, valve may be stenotic without extensive calcification.In adults, stenosis typically is due to calcific changes, which often obscures the number of cusps, making determination of bicuspid vs. tricuspid valve difficult
  17. 17. Calcific Aortic Stenosis Calcification of a bicuspid or tricuspid valve, the severity can be graded semi-quantitatively as 0 1+ 2+ 3+ 4+ Schaefer BM et al.Heart 2008;94:1634–1638. The degree of valve calcification is a predictor of clinical outcome. Rosenhek R et al. N Engl J Med 2000;343:611–7.
  18. 18. Aortic sclerosisThickened calcified cusps with preserved mobilityTypically associated with peak doppler velocity of less than 2.5 m/sec
  19. 19. Rheumatic aortic stenosisCharacterized by Commissural fusion Triangular systolic orifice thickening & calcificationAccompanied by rheumatic mitral valve changes.
  20. 20. Rheumatic aortic stenosisParasternal short axis view showing commissural fusion, leaflet thickening and calcification, small triangular systolic orifice
  21. 21. Subvalvular aortic stenosis(1) Thin discrete membrane consisting of endocardial fold and fibrous tissue(2) A fibromuscular ridge(3) Diffuse tunnel-like narrowing of the LVOT(4) accessory or anomalous mitral valve tissue.
  22. 22. Supravalvular Aortic stenosisType I - Thick, fibrous ring above the aorticvalve with less mobility and has the easilyidentifiable hourglass appearance of the aorta.
  23. 23. Supravalvular Aortic stenosisType II - Thin, discrete fibrous membrane located above the aortic valveThe membrane usually mobile and may demonstrate doming during systole Type III- Diffuse narrowing
  24. 24. HOW TO ASSESS AORTIC STENOSIS
  25. 25. Doppler assessment of ASThe primary haemodynamic parameters recommended (EAE/ASE Recommendations for Clinical Practice 2008) Peak transvalvular velocity Mean transvalvular gradient  Valve area by continuity equation.
  26. 26. Peak transvalvular velocityContinuous-wave Doppler ultrasoundMultiple acoustic windows  Apical and suprasternal or right parasternal most frequently yield the highest velocity  rarely subcostal or supraclavicular windows may be requiredThree or more beats are averaged in sinus rhythm, with irregular rhythms at least 5 consecutive beats
  27. 27. Peak transvalvular velocityAS jet velocity is defined as the highest velocity signal obtained from any window after a careful examinationAny deviation from a parallel intercept angle results in velocity underestimationThe degree of underestimation is 5% or less if the intercept angle is within 15⁰ of parallel.‘Angle correction’ should not be used because it is likely to introduce more error given the unpredictable jet direction.
  28. 28. Peak transvalvular velocity The velocity scale adjusted so the spectral doppler signal fills on the vertical axis, and with a time scale on the x-axis of 100 mm/s Wall filters are set at a high level and gain is decreased to optimize identification of the velocity curve. Grey scale is used A smooth velocity curve with a dense outer edge and clear maximum velocity should be recorded
  29. 29. Peak transvalvular velocityThe shape of the CW Doppler velocity curve is helpful in distinguishing the level and severity of obstruction.With severe obstruction, maximum velocity occurs later in systole and the curve is more rounded in shapeWith mild obstruction, the peak is in early systole with a triangular shape of the velocity curve
  30. 30. Peak transvalvular velocityThe shape of the CWD velocity curve also can be helpful in determining whether the obstruction is fixed or dynamicDynamic sub aortic obstruction shows a characteristic late- peaking velocity curve, often with a concave upward curve in early systole
  31. 31. Mean transvalvular gradient The difference in pressure between the left ventricle and aorta in systole Gradients are calculated from velocity information The relationship between peak and mean gradient depends on the shape of the velocity curve.
  32. 32. Mean transvalvular gradientBernoulli equations ΔP =4v²The maximum gradient is calculated from maximum velocity ΔP max =4v² maxThe mean gradient is calculated by averaging the instantaneous gradients over the ejection period
  33. 33. Mean transvalvular gradientThe simplified Bernoulli equation assumes that the proximal velocity can be ignoredWhen the proximal velocity is over 1.5 m/s or the aortic velocity is ,3.0 m/s, the proximal velocity should be included in the Bernoulli equation ΔP max =4 (v² max- v2proximal)
  34. 34. Sources of error for pressure gradient calculationsMalalignment of jet and ultrasound beam.Recording of MR jet
  35. 35. Sources of error for pressure gradient calculationsNeglect of an elevated proximal velocity.Any underestimation of aortic velocity results in an even greater underestimation in gradients, due to the squared relationship between velocity and pressure differenceThe accuracy of the Bernoulli equation to quantify AS pressure gradients is well established
  36. 36. Pressure recoveryThe conversion of potential energy to kinetic energy across a narrowed valve results in a high velocity and a drop in pressure.Distal to the orifice, flow decelerates again. Kinetic energy will be reconverted into potential energy with a corresponding increase in pressure, the so-called PR
  37. 37. Pressure recoveryPressure recovery is greatest in stenosis with gradual distal wideningAortic stenosis with its abrupt widening from the small orifice to the larger aorta has an unfavorable geometry for pressure recovery PR= 4v²× 2EOA/AoA (1-EOA/AoA)
  38. 38. Comparing pressure gradients calculated from doppler velocities to pressures measured at cardiac catheterization.
  39. 39. Comparing pressure gradients calculated from doppler velocities to pressures measured at cardiac catheterization. Currie PJ et al. Circulation 1985;71:1162-1169
  40. 40. Aortic valve areaContinuity equation
  41. 41. Aortic valve area Aortic valve areaContinuity equation concept that the stroke volume ejected through the LV outflow tract all passes through the stenotic orifice AVA= CSA LVOT×VTILVOT / VTIAVCalculation of continuity-equation valve area requires three measurements  AS jet velocity by CWD  LVOT diameter for calculation of a circular CSA  LVOT velocity recorded with pulsed Doppler.
  42. 42. Aortic valve area Continuity equationLVOT diameter and velocity should be measured at the same distance from the aortic valve.When the PW sample volume is optimally positioned, the recording shows a smooth velocity curve with a well-defined peak.
  43. 43. Aortic valve area Continuity equationThe VTI is measured by tracing the dense modal velocity throughout systoleLVOT diameter is measured from the inner edge to inner edge of the septal endocardium, and the anterior mitral leaflet in mid-systole
  44. 44. Aortic valve area-Continuity equation Level of EvidenceWell validated - clinical & experimental studies. Zoghbi WA et al. Circulation 1986;73:452-9. Oh JK et al. J Am Coll Cardiol 1988;11:1227-34.Measures the effective valve area, the weight of the evidence now supports the concept that effective, not anatomic, orifice area is the primary predictor of clinical outcome. Baumgartner et al. J Am Society Echo 2009; 22,1 , 1-23.
  45. 45. Limitations of continuity- equation valve areaIntra- and interobserver variability AS jet and LVOT velocity 3 to4%. LVOT diameter 5% to 8%.When sub aortic flow velocities are abnormal SV calculation at this site are not accurateSample volume placement near to septum or anterior mitral leaflet
  46. 46. Limitations of continuity- equation valve areaObserved changes in valve area with changes in flow rateAS and normal LV function, the effects of flow rate are minimalThis effect may be significant in presence concurrent LV dysfunction.
  47. 47. Left ventricular systolic dysfunctionLow-flow low-gradient AS includes the following conditions: Effective orifice area < 1.0 Cm2 LV ejection fraction < 40%  Mean pressure gradient < 30–40 mmHgSevere AS and severely reduced LVEF represent 5% of AS patients Vahanian A et al. Eur Heart J 2007;28:230–68.
  48. 48. Dobutamine stress EchoProvides information on the changes in aortic velocity, mean gradient, and valve area as flow rate increases.Measure of the contractile response to dobutamineHelpful to differentiate two clinical situations Severe AS causing LV systolic dysfunction Moderate AS with another cause of LV dysfunction
  49. 49. Dobutamine stress EchoA low dose starting at 2.5 or 5 ủg/kg/min with an incremental increase in the infusion every 3– 5 min to a maximum dose of 10–20 ủg/kg/minThe infusion should be stopped as soon as Positive result is obtained Heart rate begins to rise more than 10–20 bpm over baseline or exceeds 100bpm
  50. 50. Dobutamine stress EchoRole in decision-making in adults with AS is controversial and the findings recommend as reliable are Stress findings of severe stenosis AVA<1cm² Jet velocity>4m/s Mean gradient>40mm of Hg Nishimura RA et al. Circulation 2002;106:809-13. Lack of contractile reserve- Failure of LVEF to ↑ by 20% is a poor prognostic sign Monin JL et al. Circulation 2003;108:319-24..
  51. 51. Serial measurementsDuring follow-up any significant changes in results should be checked in detail: Make sure that aortic jet velocity is recorded from the same window with the same quality (always report the window where highest velocities can be recorded).  when AVA changes, look for changes in the different components incorporated in the equation.  LVOT size rarely changes over time in adults.
  52. 52. Alternate measures of stenosis severity(Level 2 EAE/ASE Recommendations )
  53. 53. Simplified continuity equation.Based on the concept that in native aortic valve stenosis the shape of the velocity curve in the outflow tract and aorta is similar so that the ratio of LVOT to aortic jet VTI is nearly identical to the ratio of the LVOT to aortic jet maximum velocity. AVA= CSA LVOT×VLVOT / VAVThis method is less well accepted because results are more variable than using VTIs in the equation.
  54. 54. Velocity ratioAnother approach to reducing error related to LVOT diameter measurements is removing CSA from the simplified continuity equation.This dimensionless velocity ratio expresses the size of the valvular effective area as a proportion of the CSA of the LVOT. Velocity ratio= VLVOT/VAVIn the absence of valve stenosis, the velocity ratio approaches 1, with smaller numbers indicating more severe stenosis.
  55. 55. Aortic valve area -PlanimetryPlanimetry may be an acceptable alternative when Doppler estimation of flow velocities is unreliablePlanimetry may be inaccurate when valve calcification causes shadows or reverberations limiting identification of the orificeDoppler-derived mean-valve area correlated better with maximal anatomic area than with mean-anatomic area. Marie Arsenault, et al. J. Am. Coll. Cardiol. 1998;32;1931-1937
  56. 56. Aortic valve area - Planimetry
  57. 57. Experimental descriptors of stenosis severity(Level 3 EAE/ASE Recommendations -not recommended for routine clinical use)
  58. 58. Valve resistanceRelatively flow-independent measure of stenosis severityDepends on the ratio of mean pressure gradient and mean flow rate Resistance = (ΔPmean /Qmean) × 1333There is a close relationship between aortic valve resistance and valve areaThe advantage over continuity equation not established
  59. 59. Left ventricular stroke work lossLeft ventricle expends work during systole to keep the aortic valve open and to eject blood into the aorta SWL(%) = (100×ΔPmean)/ ΔPmean+SBPA cutoff value more than 25% effectively discriminated between patients experiencing a good and poor outcome. Kristian Wachtell. Euro Heart J.Suppl. (2008) 10 ( E), E16–E22
  60. 60. Energy loss index Damien Garcia.et al. Circulation. 2000;101:765-771.Fluid energy loss across stenotic aortic valves is influenced by factors other than the valve effective orifice area .An experimental model was designed to measure EOA and energy loss in 2 fixed stenoses and 7 bioprosthetic valves for different flow rates and 2 different aortic sizes (25 and 38 mm). EOA and energy loss is influenced by both flow rate and AA and that the energy loss is systematically higher (15±2%) in the large aorta. Damien Garcia.et al. Circulation. 2000;101:765-771.
  61. 61. Energy loss index Damien Garcia.et al. Circulation. 2000;101:765-771.Energy loss coefficient (EOA × AA)/(AA - EOA) accurately predicted the energy loss in all situations .It is more closely related to the increase in left ventricular workload than EOA.To account for varying flow rates, the coefficient was indexed for body surface area in a retrospective study of 138 patients with moderate or severe aortic stenosis.The energy loss index measured by Doppler echocardiography was superior to the EOA in predicting the end points An energy loss index #0.52 cm2/m2 was the best predictor of diverse outcomes (positive predictive value of 67%).
  62. 62. Classification of AS severity (a ESC & bAHA/ACC Guidelines) Aortic Sclerosis Mild Moderate SevereAortic jet velocity (m/s) ≤ 2.5 m/s 2.6 -2.9 3.0 - 4 >4Mean gradient (mm Hg) < 20b(<30a) 20 – 40b (30 -50a) > 40AVA (cm²) > 1.5 1.0 - 1.5 < 1.0Indexed AVA (cm²/m²) > 0.85 0.60 – 0.85 < 0.6Velocity ratio > 0.50 0.25 – 0.50 < 0.25
  63. 63. Effects of concurrentconditions on assessment of severity
  64. 64. Effect of concurrent conditions ……Left ventricular systolic dysfunctionLeft ventricular hypertrophy Small ventricular cavity & small LV ejects a small SV so that, even in severe AS the AS velocity and mean gradient may be lower than expected.  Continuity-equation valve area is accurate in this situation
  65. 65. Effect of concurrent conditions contd…Hypertension 35–45% of patients primarily affect flow and gradients but less AVA measurements Control of blood pressure is recommended The echocardiographic report should always include a blood pressure measurement
  66. 66. Effect of concurrent conditions contd…Aortic regurgitation  About 80% of adults with AS also have aortic regurgitation High transaortic volume flow rate, maximum velocity, and mean gradient will be higher than expected for a given valve area In this situation, reporting accurate quantitative data for the severity of both stenosis and regurgitation
  67. 67. Effect of concurrent conditions contd…Mitral valve disease With severe MR, transaortic flow rate may be low resulting in a low gradient .Valve area calculations remain accurate in this setting A high-velocity MR jet may be mistaken for the AS jet. Timing of the signal is the most reliable way to distinguish
  68. 68. Effect of concurrent conditions contd…High cardiac output Relatively high gradients in the presence of mild or moderate AS The shape of the CWD spectrum with a very early peak may help to quantify the severity correctlyAscending aorta Aortic root dilation Coarctation of aorta
  69. 69. M Mode- Aortic StenosisMaximal aortic cusp separation (MACS) Vertical distance between right CC and non CC during systole Aortic valve area MACS Measurement Predictive value Normal AVA >2Cm2 Normal MACS >15mm 100% AVA>1.0 > 12mm 96% AVA< 0.75 < 8mm 97% Gray area 8-12 mm ….. DeMaria A N et al. Circulation.Suppl II. 58:232,1978
  70. 70. M Mode- Aortic Stenosis
  71. 71. M Mode- Aortic StenosisLimitations Single dimension Asymmetrical AV involvement Calcification / thickness ↓ LV systolic function ↓ CO status
  72. 72. Approach Valve anatomy, etiology Exclude other LVOTO Stenosis severity – jet velocity  mean pressure gradient  AVA – continuity equation LV – dimensions/hypertrophy/EF/diastolic fn Aorta- aortic diameter/ assess COA AR – quantification if more than mild MR- mechanism & severity Pulmonary pressure
  73. 73. MCQ -1Which is false about Severe AS? a) Aortic jet velocity > 4 m/s b) Velocity ratio > 0.50 c) Indexed AVA < 0.6 cm²/m² d) Mean gradient > 40 mm Hg e) None of the above
  74. 74. MCQ-2By definition Low-flow low-gradient AS includes the following conditions except a) Anatomic orifice area < 1.0 Cm2 b) LV ejection fraction < 40% c) Mean pressure gradient < 30–40 mmHg d) None
  75. 75. MCQ-3Characteristic feature of calcific aortic stenosis is …………. a) Nodular calcific masses on ventricular side of cusps b) Calcium deposition at free edges of the cusp c) Commissural fusion d) None of the above
  76. 76. MCQ- 4False about Maximal aortic cusp separation? a) MACS of normal aortic valve is >15 mm b) AVA <0.75 corresponds to MACS <8mm c) Vertical distance between right CC and non CC during systole d) Gray area is 8-12mm e) None of the above
  77. 77. MCQ 5All are true about standard dobutamine stress echocardiography for evaluation of AS severity in setting of LV dysfunction except? A) Uses low dose of dobutamine starting at 2.5 or 5ủg/kg/min B) Maximum dose of dobutamine used is 10–20 ủg/kg/min C) The infusion should be stopped when the heart rate begins to rise more than 10–20 bpm over baseline D) Failure of LVEF to ↑ by 40% is a poor prognostic sign e) None of the above
  78. 78. MCQ 6In a patient with aortic valve area of 0.6 sq cm(not a low flow low gradient AS) continuous wave Doppler velocity will be: a) 1-2 m/sec b) 2-3 m/sec c) 3-4 m/sec d) > 4 m/sec
  79. 79. MCQ-7True about doppler assessment of AS is all except ? a) With severe obstruction, maximum velocity occurs later in systole b) Angle correction is likely to reduce errors in measuring peak transvalvular gradient a) Apical and suprasternal windows most frequently yield the highest velocity c) None of the above
  80. 80. MCQ-8True a bout Bicuspid valve is? a) Fusion of the right and non-coronary cusps occurs in 80% of cases b) Fusion of the right and non-coronary cusps is more commonly associated with mitral vale myxomatous disease c) Parasternal short axis view in diastole always demonstrate bicuspid anatomy d) Calcification usually occurs along the edges of cusp
  81. 81. MCQ -9True about Supravalvular aortic stenosis is all? a) Type 2 shows doming in systole b) Type 3 hourglass appearance of aorta c) Type 1is thin discrete fibrous membrane d) Type 3 is localized disease just above aortic valve
  82. 82. MCQ- 10All are true except a) accuracy of the Bernoulli equation to quantify AS pressure gradients is well established b) The relationship between peak and mean gradient depends on the shape of the velocity curve. c) Gradients are calculated from velocity information d) Dynamic sub aortic obstruction shows a characteristic early peaking velocity curve e) None
  83. 83. MCQ -1Which is false about Severe AS? a) Aortic jet velocity > 4 m/s b) Velocity ratio > 0.50 c) Indexed AVA < 0.6 cm²/m² d) Mean gradient > 40 mm Hg e) None of the above
  84. 84. MCQ-2By definition Low-flow low-gradient AS includes the following conditions except a) Anatomic orifice area < 1.0 Cm2 b) LV ejection fraction < 40% c) Mean pressure gradient < 30–40 mmHg d) None
  85. 85. MCQ-3Characteristic feature of calcific aortic stenosis is …………. a) Nodular calcific masses on ventricular side of cusps b) Calcium deposition at free edges of the cusp c) Commissural fusion is common and early d) None of the above
  86. 86. MCQ- 4False about Maximal aortic cusp separation? a) MACS of normal aortic valve is >15 mm b) AVA <0.75 corresponds to MACS <8mm c) Vertical distance between right CC and non CC during systole d) Gray area is 8-12mm e) None of the above
  87. 87. MCQ 5All are true about standard dobutamine stress echocardiography for evaluation of AS severity in setting of LV dysfunction except? A) Uses low dose of dobutamine starting at 2.5 or 5ủg/kg/min B) Maximum dose of dobutamine used is 10–20 ủg/kg/min C) The infusion should be stopped when the heart rate begins to rise more than 10–20 bpm over baseline D) Failure of LVEF to ↑ by 40% is a poor prognostic sign e) None of the above
  88. 88. MCQ 6In a patient with aortic valve area of 0.6 sq cm(not a low flow low gradient AS) continuous wave Doppler velocity will be: a) 1-2 m/sec b) 2-3 m/sec c) 3-4 m/sec d) > 4 m/sec
  89. 89. MCQ-7True about doppler assessment of AS is all except ? a) With severe obstruction, maximum velocity occurs later in systole b) Angle correction is likely to reduce errors in measuring peak transvalvular gradient a) Apical and suprasternal windows most frequently yield the highest velocity c) None of the above
  90. 90. MCQ-8True a bout Bicuspid valve is? a) Fusion of the right and non-coronary cusps occurs in 80% of cases b) Fusion of the right and non-coronary cusps is more commonly associated with mitral vale myxomatous disease c) Parasternal short axis view in diastole always demonstrate bicuspid anatomy d) Calcification usually starts along the edges of cusp
  91. 91. MCQ -9True about Supravalvular aortic stenosis is all? a) Type 2 shows doming in systole b) Type 3 shows hourglass appearance of aorta c) Type 1 is thin discrete fibrous membrane d) Type 3 is localized disease just above aortic valve
  92. 92. MCQ- 10All are true except a) accuracy of the Bernoulli equation to quantify AS pressure gradients is well established b) The relationship between peak and mean gradient depends on the shape of the velocity curve. c) Gradients are calculated from velocity information d) Dynamic sub aortic obstruction shows a characteristic early peaking velocity curve e) None

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