Aortic Insufficiency

Outline• Epidemiology• Etiology• Pathophysiology• Clinical Presentation / Symptoms• Natural History• Diagnosis

– Physical Exam– Echocardiography

• Treatment– Medical– Surgical

• What’s new?

Epidemiology

• Prevalence– Framingham Offspring Study

• 13% in men; 8.5% in women• Advanced age and male gender associated with AR• Singh,et al. American Journal of Cardiology.1999:83:897-902

– Strong Heart Study (Native American Population)• 10% prevalence• Advanced age and aortic root diameter associated with AR• Lebowitz, et al. JACC. 2000;36:461-7.

– In both studies the majority of cases were mild

Etiology• Valvular vs. Aortic Root• Valvular

– Calcific AS in the elderly– Infective endocarditis– Congenital bicuspid

• More commonly stenosis• Incomplete closure/prolapse can lead to isolated regurgitation

– Rheumatic fever• Cusps become infiltrated with fibrous tissue and retract

preventing cusp apposition during diastole– Less Common

• Congenital: quadricuspid• Inflammatory conditions: SLE, RA, AS, Whipple’s Disease, Takayasu• Anorectic drugs

Etiology

• Aortic Root Disease– Age related (degenerative) aortic dilation

• HTN longstanding• HLD

– Cystic medial necrosis (+/- Marfans)– Aortic dilation related to bicuspid valve– Osteogenesis imperfecta– Syphilitic aortitis – AS, Bechets, Psoriatic arthritis, GCA

Pathophysiology

• Regurgitant flow produces increase in LVEDV– Thereby raising wall tension (via Lapace’s law)– Wall stress proportional to (Intraventricular pressure x radius)/wall

thickness

• LV responds by compensatory eccentric hypertrophy of myocytes– Replication in series and elongation of myocytes and myocardial

fibers (Different from AS) Dilation

• Chronic compensated AR: sufficient wall thickening occurs so that ratio of wall thickness to cavity radius remains normal.

– Maintains End diastolic wall stress normal

Pathophysiology (con’t)• During chronic compensated AR LV is able to

adapt to increase in diastolic volume without increasing LV EDP.

• LV produces a larger total SV to compensate for regurgitant flow

• Over time progressive interstitial fibrosis reduces LV compliance leading to chronic decompensated phase.

• Chronic volume overload results in impaired LV emptying, increasing LVEDP and LVEDV causing further dilation and decreasing EF

Pathophysiology

• Patients with severe chronic AR have the largest LVEDV of those with any form of heart disease (cor bovinum)

• In contrast to AR, AS has pressure overload induced hypertrophy (concentric) with replication in parallel

• This leads to increased ratio of wall thickness to radius

Symptoms• Exertional dyspnea• Orthopnea• Parosxysmal nocturnal dyspnea• Angina pectoris

– Late in clinical course• Uncomfortable awareness of heartbeat

– Laying down– Thoracic pain

• PVCs great heave of volume loaded LV during post extrasystolic beat cause distress

• Complaints may be present for many years before symptoms of overt LV dysfunction manifest

Natural History of Chronic AR• Asymptomatic patients with normal EF

– No large scale studies evaluating this population– Current ACC recs derived from 9 published series involving 593 patients

with mean F/U 6.6 years• Progression to symptoms and/or LV dysfunction: <6%/yr• Progression to asymptomatic dysfunction: <3.5%/yr• Sudden Death: <0.2%/yr

• Two multivariate analysis identified two independent predictors of outcome (symptoms, death of LV dysfunction.)– Age– LVEDV

• EDV > 50 mm 19% annual• EDV 40-49 mm 6%/yr• EDV < 40 mm <1%/yr

Natural History of Chronic AR• Patients with asymptomatic LV Dysfunction

– Most develop symptoms requiring AVR in 2-3 years– Symptom onset 25% annually

• Patients with symptomatic AR– No long term studies on this population as most

proceed to AVR– Mortality rate of 10% annually if pt has angina– Mortality rate of 20% annually if pt has heart failure

Bonow, Circulation 1991, 84:1296-302

Physical Exam• Palpation

– Apical impulse enlarged, displaced lateral to midclavicular line in 5th intercostal space– Diastolic thrill and systolic thrill in second intercostal space (increased aortic flow)

• Auscultation– Diminished S1 (prolonged PR, LV dysfunction, preclosure of MV)– S2 soft, maybe paradoxically split– S3 may be heard with LV dysfunction (indicating increased LV EDP)– S4 often present (LA contraction into poorly compliant LV)– Blowing diastolic decrescendo murmur starting immediately after A2.

• LUSB, diaphragm of stethoscope• Sitting up and leaning forward• Full expiration• Severity correlates with length/duration not intensity of murmur

– May hear second diastolic murmur at apex in severe AR• Austin Flint: middle to late diastolic rumble

– May hear short midsystolic ejection murmur at base radiating to neck reflecting increased ejection rate (don’t confuse with AS)

– Maneuvers• Increase: isometric exercise, squatting, inotrope infusion• Decrease: standing from squatting, valslava, inhalation of amyl nitrite

Physical Exam: Peripheral Pulses– Rapid upstroke followed by quick collapse

• Water-hammer/Corrigan’s pulse

– Head bob with each heartbeat• De Musset’s sign

– Pistol shot sounds heard over femoral arteries in systole and diastole• Traube’s sign

– Systolic pulsation of the uvula• Muller’s sign

– Capillary pulsation visible in nailbed• Quincke’s sign

– Popliteal cuff systolic pressure exceeding brachial cuff systolic pressure by > 60 mm hg

• Hill’s Sign

– Arterial pulsations visible in retinal arteries and pupils• Becker’s sign

Laboratory Evaluation

• EKG and CXR• Echocardiogram gold standard

– Two dimensional: cause of AR• Rheumatic: thickening and retraction of leaflet tips

failure of cusp apposition• Endocarditis: leaflet fibrosis and retraction, leaflet

perforation or flail of the valve cusp• Aortic root seen on parasternal long axis

– Symmetric dilatation causes central jet– Focal dilatation results in eccentric jet

Echocardiogram• M- Mode

– May reveal premature closure of the mitral valve (Fluttering in diastole)

– Diastolic opening of aortic valve (severe, acute)

Echocardiogram• Color Flow

– Assessment of jet origin, size and direction– Parasternal long axis and short axis (TTE)– LVOT view (135 degree transducer position of TEE)– Sensitivity 95%, specificity near 100% (Feigenbaum)– FN rare: can occur in setting of increased HR (short diastole),

should use CW for detection• Max length of jet poorly correlated with angiographic

severity of AR• Short axis regurgitant jet area relative to short axis area

of LVOT at aortic annulus correlates best with angiographic severity of AR

Echocardiography• Continuous wave allows for measurement of:

– Density of jet (qualitative indication of the volume of regurgitation)

– Velocity– Rate of deceleration

• Because AR jet invariably high velocity, continuous wave necessary for contour of envelope

• CW does well to differentiate between MS and AR

Echocardiogram

• Pulse wave Doppler relies on demonstration of turbulent flow during diastole in LVOT

• Highly sensitive but requires methodical and careful search for jet using multiple views and windows

• False positive: mitral stenosis or prosthetic mitral valve where turbulent diastolic flow can be mistaken for AR

ACC Guidelines on Echocardiogram• Class I indications (LOA)

– Confirm presence and severity of acute or chronic AR (B)– Diagnosis and assessment of cause of chronic AR and

assessment of LV hypertrophy, EDV, and EF (B)– Patient with enlarged aortic root to assess for regurgitation (B)– Radionuclide angiography or MRI indicated for initial and serial

assessments of LV volume and function at rest in pts with suboptimal TTE (B)

– Re-evaluate mild, moderate or severe AR in patient with new or changing symptoms (B)

Evaluating Severity of AR on ECHO• Multiple methods for measuring AR, each with its own

limitations• Important to obtain multiple measurements in multiple

views• Size and extent of jet within LV• Jet Width/LVOT diameter• Jet area/LVOT diameter• Pressure Half Time• Quantify regurgitant volume and regurgitant fraction• PISA• Diastolic Flow Reversal

Severity: Color Flow• Most common is to examine size of regurgitant jet

and regurgitant volume• Length of jet conveys unreliable information about

overall severity.• Important to examine at its origin (immediately

downstream of AoV)– Parasternal long axis– Height (width) of jet just below valve measured– Can also be expressed as percentage of LVOT dimension

• Limitations– Eccentric jets– Changes in gain, color scale, transducer frequent, wall

filters– Changes in View (apical vs. parasternal)

Severity Color Flow

Severity: Continuous Wave• Compares density of envelope of the antegrade

aortic flow and regurgitant jet– Larger the volume the darker the jet

• Mild AR– Compliant LV allows slow and modest increase in LVP and

aortic diastolic pressure is maintained throughout– Regurgitant velocity remains high = flat envelope (Long

Pressure half time)• Severe AR

– Increase LVP and rapid decrease in aortic pressure leads to rapid deceleration of regurgitant jet velocity

– Steep slope of Doppler wave (Pressure Half Time)

Severity: Continuous Wave

Severity Pulse Wave• Pulse wave can be used to assess diastolic flow

reversal in descending aorta– Dependent of vessel compliance and stroke volume– Holosystolic flow reversal in proximal descending

aorta is diagnostic of severe AR

Severity: Other

• Can use PISA to calculate ERO– Technical challenges of visualizing isovelocity shells

• Quantifying regurgitant volumes – All four valves in series, SV across each is equal– Total SV across AoV = Regurg Vol .+ Forward Vol.– SV = CSA x TVI– CSA = (pi)r2 = 0.785 x diameter2

– Regurg Volume = SV AV – SV MR

Classification of Severity

Cardiac Catherization

• For patients with poor echo images aortography provides semi quantitative assessment of AR severity– 1+ - mild – contrast incompletely opacifies LV but clears

with each beat– 2+ - moderate – faint complete opacification of LV, rapidly

clears– 3+ - mod-severe – opacification of LV matching aorta– 4+ - severe – opacification of entire LV on first beat, more

intense than aorta, slow clearing• Coronary angiography indicated prior to surgery in

patient’s > 50 years old

ACC Guidelines on Catherization in AR• Class I

– Assessment of severity of AR, EF, or aortic root size when noninvasive tests are inconclusive or discordant with clinical findings in patients with AR (B)

– Coronary angiography indicated before AR in patients at risk for CAD (C)

• Class III– Not indicated for assessment of EF, aortic root size,

or severity of AR before AVR when non-invasive tests are adequate and concordant (C)

– Not indicated for assessment of LV function and severity of AR in asymptomatic patients (C)

Management

Medical TherapySurgical Indications

Serial Follow Up

Medical Therapy• Vasodilating agent therapy designed to improved

forward SV and reduce regurgitant volume– Decrease LV EDV– Decrease wall stress– Decrease afterload

• Hydralazine, nitroprusside produce acute hemodynamic changes– Decrease EDV – Increase EF

• Nifedipine or felodipine– Inconsistent results

• Randomly assigned 95 patients with asymptomatic severe AR and normal LV EF to open label nifedipine, open label enalapril or placebo

• Mean 7 year follow up• Primary end points: LV dimension on TTE,

symptoms, need for surgery

Vasodilators?• Exclusion: EF< 50%, other

valvular disease, DBP > 90, Afib, Hx CAD

• Defined severe AR as:– Regurg fraction > 60% or– Jet width > 10 mm AND jet

area > 7 cm2• No reduction in

development of symptoms or LV dysfunction warranting surgery

• No difference in LV dimension, EF, or mass

Medical Therapy ACC Guidelines• Class I

– Vasodilator therapy indicated for chronic therapy in severe AR with symptoms or LV dysfunction when surgery not recommended

• Class IIa– Vasodilator therapy is reasonable for short term therapy to

improve hemodynamic profile prior to surgery

• Class IIb– Vasodilator therapy considered for long term therapy in

asymptomatic patients with severe AR, LV dilatation and normal systolic function

Medical Therapy: ACC Guidelines• Class III

– Vasodilator therapy not indicated in asymptomatic patients with mild to moderate AR and normal EF

– Not indicated in asymptomatic patients with LF systolic dysfunction who can undergo surgery

– Not indicated in patients with normal EF or mild to moderate LV systolic dysfunction who are candidates for AVR

Indications for Surgery• Indications for repair and replacement are the

same• Symptomatic Patients with normal EF (>50%)

– AVR for NYHA Class III or IV– AVR indicated for Canadian Class angina II – IV

• Symptomatic Patients with LV dysfunction– AVR indicated for NYHA class II-IV and EF 25-50%

• Class IV have worse post op survival

– NYHA IV and EF < 25% difficult management scenario• Some get meaningful LV recovery post op• Many have developed irreversible damage

Indications for Surgery

• Asymptomatic patients– Controversial topic– Generally agreed

• Indicated in patients with LV dysfunction on 2 consecutive measurements

– 1 month apart or– Two modalities

• Indicated for severe LV dilatation – EDD > 75 mm or ESD > 55 mm

• Aortic Root– Root > 5 cm in diameter and ANY degree of AR

Serial Follow Up• Goal is to detect changes in hemodynamic parameters

prior to symptoms• Asymptomatic patients with mild AR, little or no LV

dilatation, normal EF– Q1 year exams– No need for annual TTE

• Asymptomatic patients with normal EF but severe AR and LV dilation ( > 60 mm)– Q 6 month exam and echo

• Immediate TTE in any patient with onset of symptoms• Serial exercise testing, radionuclelide v-grams or MIR not indicated

What’s New in AI

• 642 consecutive bicuspid AoV patient presenting to Canadian Congenital Heart Clinic

• Followed for 9 years• Average age 35 (+/- 16 years)• Main Outcomes:

– All cause mortality– Cardiac death– Intervention on aortic valve or ascending aorta– CHF requiring hospitalization

JAMA 9/17/08 200(11): 1317-1325

Results• 161 had primary cardiac events (1 or more)

– 17 deaths– 142 interventions on aorta or AoV– 11 Aortic dissections or aneurysms– 16 CHF exacerbations requiring hospitalization

• Independent predictors of primary cardiac events• Age > 30 (Hazard ratio with CI: 3.01, 2.15-4.19)• Moderate to severe AS (5.67, 4.16-7.8)• Moderate to severe AR (2.68, 1.93-3.76)• 10 year survival not significantly different from

population estimates

References• 2008 Focus Update Incorporated into 2006

ACC/AHA guidelines for Management of Patients with Valvular disease. JACC. 2008:52 e1-e142.

• Braunwald et all. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine 8th edition.

• Feigenbaum et al. Echocardiography. p288-302• Oh et al. Basics in Echocardiography• Topol et al Manual of Cardiovascular Medicine. p

192-202.