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