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How Can You Assess Aortic Stenosis Severity with Practical Tips in Different Clinical Scenarios GHA 10 / SHA 24 Joint Scientific Conference 13th-16th February 2013 Riyadh, Saudi Arabia


Aortic Stenosis Role of Echocardiography  

Assess severity of aortic stenosis Assess LV: Size  Hypertrophy  Systolic function 

  

Look for echocardiographic predictors of outcome Timing of surgery, importance of symptoms What to do with asymptomatic patients


Aortic Stenosis Normal LV Function 

 521950

62 years-old female with chest tightness and dyspnea SR with small volume, slow rising carotid pulse, and BP 110/60 ESM along LSE with soft S1.


Aortic Stenosis Normal LV Function      521950

Peak / Mean gradients = 76/43 mmHG AVA = 0.5 cm2 by CE Coronary angiography: 3 VD CABG and AVR with CEP bioprosthesis


Severe Aortic Stenosis Natural History   

0.02 - 0.3 cm2 / year decrease in area 7 mm Hg / year increase in mean gradient Faster progress:  The very elderly with degenerative AV  Hyperlipidemic patients  Chronic renal failure patients  Heavy calcification of the AV

Otto et al. Circulation 1997;95:2262-2270


Grading of Severity of AS

Bonow et al. J Am Coll Cardiol 2008; 52:e1-142


Grading of Severity of AS

Bonow et al. J Am Coll Cardiol 2008; 52:e1-142


Doppler Assessment Standard Measurements  

 

Aortic valve velocity Aortic valve peak and mean gradients (Simplified Bernoulli Equation) AVA (Continuity equation) Indexed AVA


Use of Multiple Windows: Jet Alignment Recommendations: ď Ž Apical window and at least another window ď Ž Use of stand-alone probe


Gradient Across Aortic Valve Technical Hints  

   

Cursor as parallel to direction of flow. Best view will be the view that will give the highest velocity. Trace round the densest part of the signal Avoid artifactual “hair” Avoid post-ectopic beat Average 5 beats in AF


Doppler Pressure Gradient Simplified Bernoulli Equation

P = 4V2    

Flow dependence Dependence on LV systolic function Dependence on technique Affected by arrhythmia: AF


AVA by Continuity Equation Measure 5-10 mm below base of cusps

LVOTD = 2 cm

LVOTVTI = 16.5 cm

AVVTI = 129 cm

AVA = 22 x 0.785 x 16.5 = O.4 cm2 29


AVA by Continuity Equation

  

Assume circular LVOT geometry Assume uniform veloity in LVOT Simultaneous measurement in time and location are not obtained


CWD Doppler Signal Morphology Measure ET and AT

Mild AS

Severe AS

CWD signal is asymmetrical

CWD signal is symmetrical

Peak velocity occurs in first 1/3 of systole

Peak velocity in mid systole

Initial slope of the descending limb is rapid

Almost identical ascending and descending limbs

Triangular shape

Arched shape

P Mean =1/2 PPeak

PMean = 2/3 PPeak

PPeak /PMean >1.7

PPeak /PMean <1.5

 Chambers et al. J Am Soc Echo 2005;18:674-8

ET AT


Dimensionless Index V LVOT / V AV If < 0.25, compatible with severe AS Oh et al. J Am Coll Cardiol 1988;11:1227

TVI LVOT / TVI AO If < 0.30, associated with AVA < 1.0 cm2 Otto et al. J Am Coll Cardiol 1986;7:509

Shape of signals should be same


Planimetery of AVA by TEE Reproducible and feasible in 83-95% of cases  Limitations  Heavy calcification: Acoustic shadowing  Overestimation if oblique view 

RVOT


Planimetry of AVA: RT3DTEE and 3DTTE

 No geometric assumptions like for AVA by CE!  Underestimates AVA by 0.06 cm2


Asymptomatic Aortic Stenosis Role of Exercise    

Supervised by a physician! Frequent observation: Every minute! Avoid protocols with high workload 2 minutes of cool down walk

Otto et al. Circulation 1997;95:2262 Das et al. J Am Coll Cardiol 2001;37:489 A Nylander et al. Br Heart J 1986;55:480 Atwood et al. Chest 1988;93:1083

No death 40% + symptoms


Asymptomatic Aortic Stenosis Role of Exercise 

Look for:  Symptoms: Earlier than expected  Poor exercise tolerance  Abnormal BP response:

 Failure to increase SBP by 10 mm Hg  > 10 mm Hg drop in SBP  Ventricular arrhythmia Otto et al. Circulation 1997;95:2262-2270 Das et al. J Am Coll Cardiol 2001;37:489 A


Independent Predictors of Cardiac Events Increase in mean gradient ≥ 18 mm Hg during exercise  AVA < 0.75 cm2  Abnormal exercise test  Angina  Dyspnea  ≥ 2 mm ST-segment depression  Fall on systolic BP  < 20 mm HG rise in systolic BP 

Lancellotti et al. Circulation 2005;112 (Suppl I):I-377-I-382


Tissue Doppler


Aortic Stenosis Indication for Surgery


Aortic Stenosis Doppler Mimickers      

Mitral regurgitation Hypertrophic obstructive cardiomyopathy Aortic arch branch vessel stenosis (SA) Subaortic membrane Supravalvar aortic stenosis Ventricular septal defect


Aortic Stenosis Doppler Mimickers    

MR jet is wider: ET + IVRT + IVCT Peak velocity of MR is higher than peak velocity of AS always MR jet is usually more symmetrical AS jet signal by PWD typically shows superimposed flow signal of LVOT.


Aortic Stenosis VS Mitral Regurgitation

Mitral Regurgitation

Aortic Stenosis


Aortic Stenosis with LV Dysfunction

     

63 years old man Class III dyspnoea SR with small volume slow-rising pulse ESM along LSE with soft S1 Bilateral basal crepitations Mean gradient of 35 mm Hg, with estimated AVA of 0.8 cm2


Severe Aortic Stenosis Definition 

 

Mean gradient > 40 mm HG Normal cardiac output Normal LV systolic function Valve area < 1.0 cm2 * Valve area index < 0.6 cm2 / m2

Bonow et al. J Am Coll Cardiol 2008;52:e1-143


Aortic Stenosis with LV Dysfunction

      

63 years old man Class III dyspnoea SR with small volume slow-rising pulse ESM along LSE with soft S1 Bilateral basal crepitations Impaired EF of < 20% Mean gradient of 35 mm Hg, with estimated AVA of 0.8 cm2


Aortic Stenosis with LV Dysfunction Problem

   

Surgery associated with significant operative mortality Surgery may fail to improve symptoms LV dysfunction may not improve postoperatively Worse long term survival


Aortic Stenosis with LV Dysfunction 

Those with high gradient  High but acceptable operative mortality (Connoly et al with 9%)  Worse long term survival  Improved symptoms  Improved ejection fraction and NYHA functional classification


Aortic Stenosis Impaired LV Function and Good Reserve


Aortic Stenosis with LV Dysfunction 

Those with low gradient = Low gradient low flow impaired ejection Fraction aortic stenosis  Significant operative risk  No improvement of symptoms  No improvement in LVF  Poor prognosis


Low Gradient Low Flow Impaired EF AS Definition At least two of the following haemodynamic Measurements:

< 1.0 cm2 (0.7-1.2) Mean Trans Ao Gradient < 30 mm Hg Vmax < 3.5 m/sec

LV Ejection fraction

 

Effective AVA

< 40%


Aortic Stenosis with LV Dysfunction     

Is this true aortic stenosis, or pseudo-severe aortic stenosis? If it was true aortic stenosis, should the patient have surgery? Can I determine which patient will fare better with surgery? What is the prognosis of surgery? When do you say no to surgery?


Aortic Stenosis with LV Dysfunction     

Is this true aortic stenosis, or pseudo-severe aortic stenosis? Low dose Dobutamine Echo If it was true aortic stenosis, should the patient have surgery? Contractile reserve! Can I determine which patient will fare better with surgery? Contractile reserve! What is the prognosis of surgery? When do you say no to surgery?


Low Gradient AS with LV Dysfunction 

True aortic stenosis  Inability of LV to cope with the greatly increased

after-load  Inability of LV to generate high gradient due to low SV 

Pseudo-severe aortic stenosis  Valve mildly stenotic  Concomitant cardiomyopathy with insufficient

force to open the valve


Low Gradient AS with LV Dysfunction Implications! ď Ž ď Ž

True Aortic stenosis: Likely to benefit from AVR Pseudo-severe aortic stenosis: Unlikely to benefit from AVR


Low Gradient AS With LV Dysfunction

Low dose Dobutamine Stress Echocardiography!


Aortic Stenosis: Low Gradient AS With LV Dysfunction Resting Hemodynamics:  HR, BP, CO, VTILVOT, VTIAO and

gradient, AVA  Dobutamine at 5 u / kg / min  Increase by 5 u / kg / min every 3 min to maximum of 20: maximum inotropic  without chronotropic response  Repeat hemodynamics each time 


Aortic Stenosis: Low Gradient AS With LV Dysfunction End Points:      

20 u / kg / min Normalization of CO Decreased BP VT HR > 120 bpm, or > 10-20 bpm Symptoms


Aortic Stenosis: Low Gradient AS With LV Dysfunction Low gradient LV Dysfunction Dobutamine Stress

CO Gradient > 40 mm Hg Fixed AVA

Severe AS

Mild or CO Gradient Increased AVA > 0.3 cm2 Myocardial Dysfunction


Aortic Stenosis Impaired LV Function VTILVOT = 12 cm

Baseline

VTILVOT = 14.8 cm

At 20 Âľg Dobutamine


Aortic Stenosis Impaired LV Function VTIAV = 50 cm

Baseline Area = 0.68 cm2

VTIAV = 58 cm

At 20 Âľg Dobutamine Area = 0.7 cm2


Aortic Stenosis: Low Gradient AS With LV Dysfunction Dobutamine Stress Test  Confirm severity of aortic stenosis: True AS

vs pseudo-severe AS  Test for LV contractile reserve  Determine appropriate therapy  Risk-stratify patients


Contractile Reserve Definition With dobutamine Stress Test  Improvement in trans-valvular flow rate  Improvement in SV > 20% (VTILVOT)  

Increase of > 20 mm Hg in the mean transvalvular pressure gradient Increase in peak velocity of > 0.6 m/s


Group I = With Contractile Reserve Group II = Without Contractile Reserve


Median value

Individual Patients


Group I = With Contractile Reserve Group II = Without Contractile Reserve


Contractile Reserve   

Strong predictor of peri-operative mortality: 32% vs 5%* Strong predictor of long term survival Should not be used to preclude AVR: medical therapy is associated with3-year survival of < 15% Does not predict post operative functional class

* Monin et al. Circulation 2003;108:319-324 

Quere et al. Cirulation 2006;113:1738-1744


Paradoxical Low Flow Aortic Stenosis!  

    

78 years old female Increasing shortness of breath last 8 months. No chest pain Hypertensive SR Slow-rising pulse Loud ESM left sternal edge, late peaking Decreased intensity of aortic component of S2


PLFAS!


PLFAS!

AVA by CE = 0.9 cm2 indexed to 0.62 cm2


PLFAS! Corrected ET = 429 msec Peak and Mean Gradients of 49 and 33 mm HG


PLFAS! 

Paradoxical low flow aortic stenosis with normal ejection fraction  Severe AS by CE  Normal ejection

fraction  Paradoxically low mean gradient < 40 mm HG Minners et al. Eur Heart J 2008;29:1043-1048


PLFAS! 

Paradoxical low flow aortic stenosis with normal ejection fraction  Severe AS by CE  Normal ejection

fraction  Paradoxically low mean gradient < 40 mm HG Minners et al. Eur Heart J 2008;29:1043-1048


PLFAS! 

  

Normal ejection fraction is usually associated with high gradient Misinterpreted as moderate AS Surgery denied or deferred Worse prognosis


Overall Survival


Overall Survival Medical vs Surgical Treatment


Valvulo-Arterial Impedance

SAP MG SVI

= Systolic BP = Mean Gradient = Stroke Volume Index


Importance of LVOT Measurement  

Underestimation of LVOT diameter = False conclusion of severe AS by AVA Underestimation of LVOT diameter = false estimation of stroke volume and this false low-flow Use of TEE to get LVOT diameter


PLFAS Features         

Females Older age Concomitant HT Pronounced LV concentric remodeling Small LV Cavity = Smaller end diastolic volume Impaired LV filling Altered myocardial function = Higher degree of myocardial fibrosis Decreased mid-wall and longitudinal shortening Increased peripheral resistance


PLFAS Hemodynamic Features


Decreased Flow = Decreased SV Pronounced myocardial concentric remodeling  Decreased size  Decreased compliance  Decreased filling of the LV  LV systolic function is substantially reduced despite “apparent normal EF   Longitudinal shortening   Longitudinal velocity 


Take-Home Message!  

Look at the clinical picture Comprehensive Doppler echocardiographic evaluation Other diagnostic tests

Gradient AVA by CE Normal EF


Take Home Message      

Look carefully at LV for hypertrophy and systolic function Look for presence of associated aortic regurgitation Align cursor parallel with flow Look for gradient in all acoustic windows Careful measurement In case gradient and estimated AVA by continuity equation does not give the answer, look into other methods


SHA24/021002  

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