Workshop Facing the challenge of TAVI 2016

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1 Workshop Facing the challenge of TAVI 2016 Congrès annuel de la SSC Lausanne 15 Juin 2016 Pitfalls in the severity assessment of aortic stenosis by echocardiography Hajo Müller, unité d échocardiographie, service de cardiologie, Hôpitaux universitaires de Genève

2 Severity assessment of AOST Predictive value of peak aortic velocity Peak aortic > 4.0 m/s velocity : in most cases «surgicaldegree» stenosis m/sec: calculate AVA!! Mean pressure gradient < 3.0 m/s: in most cases mild to moderate stenosis Aortic valve area (Otto Arch Int Med 1988; 148: 2553)

3 Classification of the Severity of Valve Disease in Adults Critical aortic stenosis has been defined hemodynamically as a valve area <0.75 cm2 and/or an aortic jet velocity >5.0 m/sec. Indexing is controversial: But important in children, adolescent and small adults (BSA < 1.5 m2, BMI < 22kg/m2, height < 135 cm) Cave: in obese patients, valve area does not increase with excess body weight!

Assessment of Valve Stenosis: EAE/ASE Recommendations for

4 Recommendations for classification of AS severity aesc Guidelines 2007 b AHA/ACC Guidelines 2006 Echocardiographic Assessment of Valve Stenosis: EAE/ASE Recommendations for Clinical Practice ESC 2012 AHA/ACC 2014 Baumgartner et al. JASE Jan 2009; Vol 22

6 First pitfall Inconsistencies of grading criteria Inconsistencies between invasive and echo grading

N=3483 echocardiography studies with normal LV function On the basis of AVA, a higher proportion of patients is classified as having severe aortic valve

7 N=3483 echocardiography studies with normal LV function On the basis of AVA, a higher proportion of patients is classified as having severe aortic valve stenosis compared with mean pressure gradient and peak flow velocity. Discrepant grading in these patients may be partly due to reduced stroke volume Minners et al.

8 Inconsistencies also in hemodynamic grading N=333 Stroke volume and stroke volume index were significantly lower in inconsistently graded patients. However, 41/85 (48%) of inconsistently graded patients had a normal stroke volume index >35 ml/m2 N=85 Minners et al. Heart 2010

9 First pitfall Inconsistencies of grading criteria Inconsistencies between invasive and echo grading

10 Invasive vs non invasive assessment CO measurement Fick equation (assumed vs measured O2 consumption) Indicator dilution (Thermodilution) Okura et al. JACC 1997; 30:753

Modest correlation between AVA at echo and at

(ICC=0.47, bias 0.06 cm², LOA -0.32 to 0.

11 Modest correlation between AVA at echo and at cath using directly measured oxygen consumption with a small overall bias but wide, clinically relevant limits of agreement (ICC=0.47, bias 0.06 cm², LOA to 0.44 cm², p=0.01) ICC 0.47 Bias 0.06cm2, LOA to 0.44 cm2

12 Factors responsible for differences in the Doppler- and catheter-derived gradients A) Apparent overestimation by Doppler 1) Comparison of Doppler peak gradient with catheter peak to peak gradient 2) Failure to account for increased subvalvular velocity 3) Pressure recovery 4) Changing physiological conditions

Pressure curves in severe aortic stenosis Peak to peak gradient from the peak of the left ventricular pressure recording to the peak of the aortic pressure Peak gradient: the largest

13 Pressure curves in severe aortic stenosis Peak to peak gradient from the peak of the left ventricular pressure recording to the peak of the aortic pressure Peak gradient: the largest difference between the two instantaneous Mean gradient: summing the gradients measured at sequential time intervals during systole and dividing by the number of measurements made. Cath Echo Cath or Echo

14 Factors responsible for differences in the Doppler- and catheter-derived gradients A) Apparent overestimation by Doppler 1) Comparison of Doppler peak gradient with catheter peak to peak gradient 2) Failure to account for increased subvalvular velocity 3) Pressure recovery 4) Changing physiological conditions

15 Bernoulli equation: estimation of pressure gradients simplified vs modified equation Alignement du faisceau doppler! V1: PW doppler V2: CW doppler V2 4m/s and V1 1m/s: 4 x (16 1) = 60mmHg V2 4m/s and V1 2m/s: 4 x (16 4) = 48mmHg V2 4m/s 4 x (16) = 64mmHg

16 Factors responsible for differences in the Doppler- and catheter-derived gradients A) Apparent overestimation by Doppler 1) Comparison of Doppler peak gradient with catheter peak to peak gradient 2) Failure to account for increased subvalvular velocity 3) Pressure recovery 4) Changing physiological conditions

Pressure gradient and pressure recovery The pressure gradient at the vena contracta level is proportional to the transvalvular flow and degree of stenosis

17 Pressure gradient and pressure recovery The pressure gradient at the vena contracta level is proportional to the transvalvular flow and degree of stenosis Vena contracta In laminar flow the kinetic energy downstream the vena contracta is retransformed into potential energy. This phenomenon is called pressure recovery

18 Pressure recovery PR (in mmhg) can be calculated from the Doppler gradient, the effective orifice area by the continuity equation (EOA) and the cross-sectional area (CSA) of the ascending aorta (AoA) by the following equation: Pressure recovery does occur under conditions of flow acceleration without turbulence PR = 4v 2 x 2EOA/AoA x (1 - EOA/AoA) Thus, PR is basically related to the ratio Turbulent of EOA/AoA flow Laminar flow Pressure recovery is greatest in stenoses with gradual distal widening since occurrence of turbulences is then reduced. Aortic stenosis with its abrupt widening from the small orifice to the larger aorta has an unfavourable geometry for pressure recovery (turbulences: energy loss)

19 Pressure recovery: key message For clinical purposes, aortic sizes, therefore, appear to be the key player and PR must be taken into account primarily in patients with a diameter of the ascending aorta < 30 mm In general cath gradient is underestimated by 5-10 mm Hg if too far from the valve

20 Factors responsible for differences in the Doppler- and catheter-derived gradients A) Apparent overestimation by Doppler 1) Comparison of Doppler peak gradient with catheter peak to peak gradient 2) Failure to account for increased subvalvular velocity 3) Pressure recovery 4) Changing physiological conditions

21 Effect of changing physiological conditions

22 Factors responsible for differences in the Doppler- and catheter-derived gradients B) Apparent underestimation by Doppler Poor Doppler signal Inappropriate alignment! Changing physiological conditions

23 Importance of correct Doppler alignment Angles greater than 30 result in major underestimation!! The Doppler equation solved for frequency shift Blood velocity = Doppler velocity / cosine angle

24 Systematic assessment of multiples acoustic windows Apical (maximal velocity in most) Suprasternal and/or right parasternal (up to 1 of 10 patient with maximal velocity!) Subcostal Other Use pencil probe!

25 Assessment of multiple acoustic windows: right parasternal V max 3.6 m/s. MG V max 4.15 m/s. MG 40 mmhg Calculated AOVA: 0.89 cm2 Right parasternal Apical

26 Assessment of multiple acoustic windows: subscapular in pleural effusion Pleural effusion LV AOV V max 3.6m/s V max 4.3 m/s V max 3.45m/sMG 41 mmhg Right parasternal Apical Left subscapular

27 Second pitfall: measurement errors LVOT diameter measurement Doppler alignment (underestimation of V max) LVOT PW Doppler (under/overestimation)

28 The continuity of flow equation «Flow-independent» index of severity: Valve opening area Three meaurements and one calculation! Continuity of forward flow. Flow that enters a cylinder is equal to the flow passing through an obstruction and exiting from the distal side

29 The continuity of flow equation: calculation of an effective orifice area CSA1 = π (Diam LVOT/ 2) 2 Errors are squared! Importance of precise LVOT diameter measurement!

30 Calculation of AVA corrected for distal pressure recovery: ELI (energy loss index)

31 Case: difficult LVOT measurement Hyperdynamic small LV. LVOT not well seen on TTE

32 Case: pressure recovery and ELI Small BSA 1.4 m2 Normal AOV opening Small LVOT 1.6 cm Small Aortic root STJ 2.6 cm V m/s. Max G 30mmHg MG 15 mmhg Accelerated V1 1.5 m/s ELI 1.1 cm2/m2 RPG 10.5 mmhg AOVA 1.2 cm2 (0.84cm2/m2)

33 Third pitfall: low flow states LV systolic dysfunction with low EF Severe MS/MR AF severe TR Small hypertrophied LV with preserved but less than expected EF and abnormal longitudinal function (GLS, MAPSE)

34 Adapted from Pibarot P et al. JACC Cardiovasc Imaging :400-3

35 Severe stenosis vs «pseudo-stenosis» Role of DSE best in classical LFLG AS Low gradient low flow severe AOST Dobutamine stress echo (DSE) Aortic valve area <1 cm 2 Low ejection fraction Low gradient (DP mean <30-40 mmhg) Afterload mismatch Myocardial damage «Pseudostenosis» Stroke volume DP mean >20% ( ) <20% ( ) Aortic valve area = = No contractile reserve (CR) = >0.3cm2 >1cm2l

36 Severely thickened AOV with reduced opening LV EF 25-30%

37 Fast progression of aortic stenosis in rheumatoid arthritis CR 25%% Conclusion: true severe AOST Normal LVEF after AOVR! Peyrou,.. Müller. ACVD 2009; 102:

38 TTE 3 months later Normal LVEF

39 Case: DSE in classical LFLG moderate - severe AOST DSE AVA 1.5 cm2, 0.81 cm2/m2 REST AVA 1.1 cm2, 0.59 cm2/m2 Conclusion: pseudo stenosis. True mild - moderate stenosis

First rule out underestimation of peak aortic jet velocity and/or PW LVOT velocity and measurement error of LVOT area which may lead to a similar constellation of measurements!

40 First rule out underestimation of peak aortic jet velocity and/or PW LVOT velocity and measurement error of LVOT area which may lead to a similar constellation of measurements!!! Part Definition Prevalence of theses of 5-25% severe cases Paradoxical are real PLFLG Low Flow AS, part Low Small are Gradient hypertrophied only moderate (PLFLG) LV AOST stenosis (errors!) and Diastolic part have dysfunction a pseudostenosis component AOVA Preserved < 1cm2 but and less < than 0.6cm2/m2 expected EF and Mean abnormal gradient longitudinal <40 mmhg function (GLS, LV MAPSE) EF > 50% SVI Older < 35ml/m2 age, HTN, diabetics, women

41 Case PLFLG severe AOST MV MG 4 mmhg Elderly diabetic women with HTN and severe COPD Small hypertrophied LV with normal EF Reduced longitudinal function (GLS 16%, mean MAPSE 7 mm) Associated MAC with mild MS

42 Case PLFLG severe AOST V max 3.6 m/s, low gradient MG 28 mmhg BP 127/62 mmhg ZVA 5.4 mmhg/ml/m2 Low flow SVI <35ml/m2 SVI 29ml/m2 (Doppler) and 21ml/m2 (2D biplane) Double check low SVI! AVA 0.7cm2 and 0.46cm2/m2 Invasive assessment: low CO (Fick) 3.5 l/min (2.3l/min/m2) AVA 0.57cm2. Peak-to-peak G 27 mmhg. LVEDP 15 mmhg.

43 Case: DSE in PLFLG severe AOST 65 male, CAD, CKD, HTN Small LV with normal EF (65%) and slight hypertrophy (concentric remodeling)

44 Case: DSE in PLFLG severe AOST REST DSE Vmax 3,2 m/s, MG 24 mmhg Vmax 3,6 m/s, MG 28 mmhg Conclusion: pseudo severe stenosis TVI 17.8 cm EF 65% AVA 0.72cm2 and 0.46 cm2/m2 TVI 23.3 cm EF 75% AVA 1.2 cm2 and 0.69 cm2/m2 Contractile reserve 25%

45 Scanner/CT in low gradient severe AOST Can provide quantitative evaluation of the amount of valve calcification Degree of calcification correlates with stenosis severity by echocardiography and with clinical outcomes

46 Correlation between AVC score measured by EBCT and weight of calcium measured by tissue digestion aortic valve specimens Messika-Zeitoun, D. et al. Circulation 2004;110:

47 Clavel et al. JACC 2013 Clavel et al. EHJ 2014

48 Case: CT score in LFLG severe AS REST EF 30-35% Vmax 3.8 m/s MG 34 mmhg AVA 0.55cm2 TVI 13.4 cm

49 Case: CT score in LFLG severe AS DSE Vmax 4 m/s MG 38 mmhg Conclusion: true severe stenosis Follow-up 2 months later: TAVR - EF 45% AVA 0.8 cm2 EF 35-40% TVI 16.7cm (CR <20%) CT: important calcifications, Agatston score 2971

50 Other pitfalls Associated subvalvular dynamic gradient Excentrique MR/TR-jet Insufficient acoustic windows

51 Case associated dynamic gradient AVA calculation impossible Dynamic gradient up to 100 mmhg Small LV and LVOT with important basal-septal hypertrophy mm SAM and MR

52 Role of TEE In difficult acoustic windows (LVOT, AOV planimetry, 3D MPR) Search for sub aortic obstruction (membrane etc.)

53 Case associated dynamic gradient: TEE Biplane planimetry 1.5cm2 Trans-gastric view V max 2.5m/s. MG 12 mmhg Calculated AVA 1.5cm2 No SAM during TEE 3D MPR 1.5cm2

8 cm2) with discordance on echo continuity

54 Case role of 2D/3D TEE Multiples valve involvement Planimetry biplan TEE 1.2 cm2 Severe PLFLG AOST on invasive assessment with GORLIN (CO 3l/min, MG 21mmHg, 0.8 cm2) with discordance on echo continuity equation (1.1 cm2, MG 14 mmhg) Planimetry 3D MPR 1.1 cm2 Context: moderate MS and TR

55 Conclusion - 1 Discordances in echo severity criteria are frequent Most frequently due to measurement errors or difficulties in correct assessment Partly due to inconsistencies in grading criteria

56 Conclusion - 2 Assessment is difficult in multiples valve involvement In low flow states careful assessment is mandatory before concluding PLFLG AOST

57 Conclusion - 3 Role of stress echo, TEE and CT scan Assessment of complementary parameters (e.g. pressure recovery, ELI) introduces complexity but is sometimes useful

58 Merci pour votre attention

MAKING SENSE OF MODERATE GRADIENTS IN PATIENTS WITH SYMPTOMATIC AORTIC STENOSIS

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