IMAGING CONFERENCE:

AORTIC REGURGITATION

September 16, 2009

Ali R. Rahimi, MD MPH

Patient A: What is the Story?

Patient B: What is the Story ?

Patient B:

Patient A:

Patient A:

Patient A:

Patient B:

Patient B:

Patient B:

Patient B:

Patient B:

Diagnosis

Patient A 48 yo M PMH cocaine induced aortic arch dissection s/p

repair c/b recurrent VRE AV (Bicuspid) Endocarditis and 2-3+ AR Mobile vegetation on LVOT side of Posterior Leaflet

Patient B 47 yo M PMH AV (Bicuspid) Endocarditis c/b 4+ AR

Two separate, mobile, moderate-sized vegetations (0.8cm x 0.5cm, 0.6cm x 0.6cm) located on the two leaflets of the aortic valve which prolapse across the LVOT during systole (larger vegetation on posterior leaflet)

Aortic Regurgitation

Diastolic reflux of blood from Aorta LV

Incidence of clinically significant AR increases with age Typical peak in 4th to 6th decade of life More common in men than women

Prevalence 4.9% in Framingham Heart Study Congenital or Acquired

Caused by abnormalities of aortic root or AV

Etiology

Dilation of Aortic Root and Annulus Hypertension Marfan Syndrome Syphilitic Aortitis Cystic Medial Necrosis Aortic Dissection Osteogenesis Imperfecta Ankylosing Spondylitis Ehlers-Danlos Syndrome

≥ 2mm dilation at sinotubular junction can cause AR

Etiology

Aortic Valve Bicuspid Aortic Valve Rheumatic Heart Disease Degenerative Calcific AV Disease Infective Endocarditis

Other Trauma Membranous Subaortic Stenosis Rheumatoid Arthritis Fenfluramine and Dexfenfluramine Deterioration of AVR Bioprosthesis

Acute Aortic Regurgitation

Most commonly due to endocarditis, aortic dissection, or blunt chest trauma

Sudden large regurgitant volume imposed on LV

Abrupt increase in LVEDV Rapid increase LVEDP & LAP

Inability of ventricle to develop compensatory chamber dilatation acutely results in a decrease in forward SV

Congestive Heart Failure, Myocardial Ischemia and/or Cardiogenic Shock

Chronic Aortic Regurgitation

Early Compensated Enlarged chamber size

↑ afterload hypertrophy of LV which preserves compliance normal filling pressures

LVH ↑ LV mass normal LV vol/mass ratio & EF

Progressive LV dilation and systolic HTN ↑ wall stress and vol/mass ratio

↑ wall stress eventually leads to overt LV dysfunction.

Decompensated LV systolic dysfunction

accompanied by decreased LV diastolic compliance due to hypertrophy and fibrosis

Leads to high filling pressures and CHF symptoms

Exertional dyspnea common; angina can occur due to reduced coronary flow reserve with predominantly systolic coronary flow

Courtesy: Ali Mahajerin, MD

Stages

Bekerdjian R, et al. Circulation 2005; 112: 125-134

Physical Exam - Auscultation A2 often soft/absent, P2 normal

S3 if LV function severely depressed

High frequency decrescendo diastolic murmur over the 3rd or 4th intercostal space at left sternal border Best heard sitting up, leaning

forward at end expiration

Austin Flint murmur: mid-to-late diastolic apical rumble, possibly due to vibration of anterior mitral leaflet as it is struck by a posteriorly directed AR jet.

Physical Exam - Peripheral Findings

Corrigan’s pulse – bounding “waterhammer” carotid pulse

deMusset’s sign – head bob with each heart beat Mueller’s sign – systolic pulsation of uvula Traube’s sign – pistol shot pulse over the femoral

artery Duroziez’s sign – systolic and diastolic bruits heard

when femoral artery partially compressed Becker’s sign – visible pulsations of retinal arteries and

pupils Hill’s sign – popliteal cuff systolic pressure exceeding

brachial pressure by more than 60 mmHg Mayne’s sign – more than 15 mmHg decrease in

diastolic blood pressure with arm elevation Rosenbach’s sign – systolic pulsations of the liver Gerhard’s sign – systolic pulsations of the spleen

Diagnosis and Initial EvaluationClass 1 Echo: confirm presence and severity of acute or chronic AR. (Level of

Evidence: B)

Echo: diagnosis and assessment of the cause of chronic AR (including valve morphology and aortic root size and morphology) and for assessment of LV hypertrophy, dimension (or volume), and systolic function. (Level of Evidence: B)

Echo: in patients with an enlarged aortic root to assess regurgitation and the severity of aortic dilatation. (Level of Evidence: B)

Echo: periodic re-evaluation of LV size and function in asymptomatic

patients with severe AR. (Level of Evidence: B)

Echo: re-evaluate mild, moderate, or severe AR in patients with new or changing symptoms. (Level of Evidence: B)

**Radionuclide angiography or MRI: initial and serial assessment of LV volume and function at rest in patients with AR AND suboptimal echocardiograms. (Level of Evidence: B)

Bonow, R. O. et al. J Am Coll Cardiol 2008;52:e1-e142

M-Mode Imaging

Aortic jet across anterior MV creates High-frequency fluttering requiring rapid sampling

rate

Increased duration between E and A peaks

Increased distance between the maximal anterior motion of MV in early diastole (E point) and the most posterior motion of the IVS (e.g., increased E-point septal separation)

Acute AR premature closure of MV Rapidly increasing LVEDP

M-Mode Imaging

2-Dimensional Imaging

Focus on AV and Root Endocarditis Dissection Dilation Perivalvular leaks around aortic prosthesis

Assessment of LV size and function Dilation Response to volume overload

2-Dimensional Imaging

AVR - Dilated Aortic Root Marfans - Dilated Aortic Root

2-Dimensional and Color Flow

Aortic Regurgitation due to AV Endocarditis

2-Dimensional and Color Flow

AV Prosthesis: Aortic Root Abscess and Perivalvular Regurgitation

2-Dimensional and Color Flow

LV Dilated-Spherical due to Chronic Severe Aortic Regurgitation

Doppler Imaging: Color Flow

Critical since 2-D may at times be “unremarkable” despite severe aortic regurgitation

Most common technique to visualize AR Sensitivity > 95%

False negatives can occur in tachycardia with mild AR Frame rate allows only a few diastolic frames to be displayed

Can be overcome by using CW -- has a higher sampling rate

Specificity ~100% Detects even trivial AR

Less than1% of normal subjects under age 40 10-20% of patients greater than age 60 Vast majority of individuals greater than age 80

Doppler Imaging: Color Flow

Composed of 3 distinct segments: Proximal flow convergence zone = area of flow

acceleration into the orifice Vena contracta = narrowest and highest velocity

region of the jet at or just downstream from the orifice The jet itself occurs distal to the orifice in the LV cavity

Measurement of the jet area or penetration into the LV cavity is not accurate in assessing AR severity, though: If jet width/LVOT width < 25% specific for mild AR If jet width/LVOT width > 65% specific for severe AR This works best when regurgitant orifice is relatively

round in shape.

Doppler Imaging: Vena Contracta

The narrowest diameter of flow stream Independent of volume flow rate and driving

pressure, relatively unaffected by instrument settings

Narrow range of values though, so care needed to obtain optimal images. Ideal sample is: Perpendicular to jet width In zoom mode Narrow sector Minimum depth

For AR, vena contracta can be measured in parasternal long-axis view preferably in zoom mode

Doppler Imaging: Vena Contracta

Vena contracta width of ≥ 6 mm correlates with severe AR (sensitivity 95%, specificity 90%)

Vena contracta width of < 3 mm specific for mild AR

Enriquez-Sarano M, et al. NEJM 2004; 351: 1539-1546.

Doppler Imaging: Color Flow

Mild Moderate Severe

Doppler Imaging: Color Flow

Jet Width/LVOT Width < 25%Mild MR

Jet Width/LVOT Width > 65%

Severe AR

Bekerdjian R, et al. Circulation 2005; 112: 125-134.

Doppler Imaging: Color Flow

Limitations as indicator for AR severity: Eccentric jets entrained along LV wall Jet is 3-D thus need multiple planes Changes in instrument gain, color scale,

transducer frequency and wall filters will affect AR appearance, independent of severity

ROA in chronic AR usually decreases during diastole Thus temporal variability Tendency to overestimate since visualized jet area

would reflect peak rather than mean orifice area

Doppler Imaging: Pulsed Wave

Relies on demonstration of turbulent flow in LVOT on ventricular side of AV

Due to high AR velocity, aliasing occurs, with prescence of turbulence establishing the diagnosis

Highly sensitive but requires methodical search for AR

False-Positive in setting of Mitral Stenosis or Prosthetic MV with turbulent diastolic flow

Assumption the AR is centrally located and can be tracked toward apex

Holodiastolic flow reversal in descending aorta correlated with severe AR

2-Dimensional and Doppler Imaging

Eccentric AR Jet Displacement of Anterior MV

Doppler Imaging: Continuous Wave Due to high velocity AR jet, CW necessary for

contour of the envelope to be recorded Density of jet ≈ volume of regurgitation

Approximation of number of RBCs being sampled Velocity of AR jet and Rate of Deceleration of

retrograde flow can be measured AR results in increased antegrade volume flow

rate across AV, which is reflected in an increase in the antegrade velocity across the valve The greater the severity of AR, the higher the

antegrade velocity across the AV Must also consider possibility of coexisting AS Helpful to distinguish AR from Mitral Stenosis Jet

Based on velocity and contour of jet

Doppler Imaging: Continuous Wave

Compare AR signal to Antegrade Flow

Weak mild

Equal severe

Antegrade

AR

Doppler Imaging: CW and PHT

AR velocity reflects pressure gradient between aorta and LV throughout diastole Early diastole – gradient is the highest with

velocity 4-6 m/sec, depending on BP Diastole progresses – gradient diminishes as

aortic pressure decreases and LV pressure increases

Mild AR – compliant LV allows a slow and modest increase in LVEDP and Ao EDP is maintained throughout AR velocity remains high and CW envelope

appears flat Severe AR – increasing LVEDP and more

rapid decrease Ao pressure leads to a more rapid decel of AR velocity

Doppler Imaging: CW and PHT Flat slope (P1/2 > 500 msec) mild AR Steep slope (P1/2 < 200 msec) severe AR

Limitations of pressure half-time assessment: Aortic compliance, BP, and LV size/compliance

will affect measures Pressure half-time sensitive to chronicity of AR

Acute AR leads to much shorter values than chronic AR when LV is dilated with increased compliance

Thus, a rapid P1/2 is more indicative of acuity than severity Pressure half-time varies with SVR

Vasodilators may shorten the pressure half-time even as the aortic regurgitant fraction improves.

Doppler Imaging: CW and PHTAcute AR due to Aortic Dissection

Chronic AR due to Ca AV disease

Doppler Imaging: Regurgitant Volume and Fraction

Can compare flow through AV versus MV or PV Stroke volume at any valve annulus is derived

as the product of CSA and TVI of flow at the annulus

In the absence of regurgitation, SV determinations at different sites should be equal

In the presence of regurgitation of one valve, without any intracardiac shunt the flow through the affected valve is larger than the other valves RV is the difference between the two flows RF = RV/ Forward SV through the regurgitant valve

Doppler Imaging: Regurgitant Volume and Fraction

Regurgitant Volume (fraction): Mild: < 30cc (< 30%) Mild-Moderate: 30-44cc (30-

39%) Mod-Severe: 45-59cc (40-49%) Severe: ≥60cc (≥50%)

Limitations: Assumes normal flow through

comparison valve Cannot be used in presence of

shunts Sensitive to small measurement

errors (measurement errors of the radius and tracing the VTI)

Summary:

Zoghbi WA, et al. JASE 2003; 16: 777-802

Serial Testing by Echocardiography

If chronic nature of lesion uncertain and no initial surgical indication, should repeat exam and echo within 2-3 months after initial evaluation

Asx, mild AR, little/no LV dilation, normal LV systolic function: see yearly, echo q2-3 years

Asx, severe AR, significant LV dilation (LVEDD > 60 mm), normal LV fx: echo q6-12 months

Asx, severe AR, severe LV dilation (LVEDD > 70 mm), normal LV fx: echo q4-6 months.

Repeat echo for onset of symptoms, equivocal history of changing symptoms or exercise tolerance, or clinical findings to suggest worsening regurgitation or progressive LV dilatation. Bonow RO, et al. J Am Coll Cardiol, 2008; 52:1-142

Copyright ©2008 American College of Cardiology Foundation. Restrictions may apply.

Bonow, R. O. et al. J Am Coll Cardiol 2008;52:e1-e142

Management Strategy for Patients With Chronic Severe Aortic Regurgitation

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