Download 9/09 Aortic Regurgitation

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
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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 Evaluation
Class 1

Echo: confirm presence and severity of acute or chronic AR. (Level of Evidence: B)
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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
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High-frequency fluttering requiring rapid sampling rate
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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

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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
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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
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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
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For AR, vena contracta can be measured in
parasternal long-axis view preferably in zoom mode
Doppler Imaging: Vena Contracta
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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
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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
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AR results in increased antegrade volume flow rate across
AV, which is reflected in an increase in the antegrade
velocity across the valve
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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
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Based on velocity and contour of jet
Doppler Imaging: Continuous Wave
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Compare AR signal to
Antegrade Flow
AR
Antegrade

Weak  mild
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Equal  severe
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

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Mild AR – compliant LV allows a slow and modest
increase in LVEDP and Ao EDP is maintained
throughout
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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
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Flat slope (P1/2 > 500 msec)  mild AR
Steep slope (P1/2 < 200 msec)  severe AR
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Limitations of pressure half-time assessment:

Aortic compliance, BP, and LV size/compliance will affect
measures
 Pressure half-time sensitive to chronicity of AR
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

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 PHT
Acute AR due to Aortic Dissection
Chronic AR due to Ca AV disease
Doppler Imaging:
Regurgitant Volume and Fraction
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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
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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
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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
Management Strategy for Patients With Chronic Severe Aortic Regurgitation
Bonow, R. O. et al. J Am Coll Cardiol 2008;52:e1-e142
Copyright ©2008 American College of Cardiology Foundation. Restrictions may apply.
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