aortic insufficiency (AI)

Introduction

Insufficiency of the aortic valve during diastole.

Classification

• mild
  • vena contracta width < 0.3 cm
  • regurgitant oriface area < 0.10 cm2
  • regurgitant volume < 30 mL
  • normal LV ejection fraction
• moderate
  • vena contracta width 0.3-0.6 cm
  • regurgitant oriface area 0.10-0.29 cm2
  • regurgitant volume 30-59 mL
  • regurgitant fraction 30-49%
• severe
  • vena contracta width > 0.6 cm
  • regurgitant oriface area >= 0.30 cm2
  • regurgitant volume >= 60 mL
  • regurgitant fraction > 50%

Etiology

• abnormality in the aortic valve
  • rheumatic fever
  • endocarditis*
  • trauma
  • connective tissue diseases
  • congenital bicuspid aortic valve
    • seronegative arthritis
    • ankylosing spondylitis
    • rheumatoid arthritis
  • degenerative aortic valve disease (calcification)
  • radiation therapy
• dilation & distortion of the aortic root
  • systemic hypertension
  • ascending aortic dissection*
  • syphilis (uncommon)
  • cystic medionecrosis
  • Marfan's syndrome
  • ankylosing spondylitis
  • osteogenesis imperfecta
  • aneurysm of Valsalva sinus

* most common causes of acute aortic insufficiency

Pathology

• chronic AI
  • increased left ventricular end diastolic volume (LVEDV)
  • increased left ventricular end diastolic pressure (LVEDP)
  • left ventricular hypertrophy (LVH)
  • left ventricular dilatation
  • increased peripheral vascular resistance
    • systolic hypertension
• acute AI
  • marked increase in LVEDP
  • time course too acute for compensatory mechanisms

Clinical manifestations

• acute AI
  • severe heart failure
  • cardiogenic shock
  • pulmonary edema, inspiratory crackles
  • tachycardia
  • diastolic murmur
    • short, soft, sometimes inaudible at the cardiac base & mid stermum
    • may be masked by tachycardia
  • soft S1, S3
  • atrial gallop
  • normal pulse pressure
  • Traube's sign, de Musset's sign, Duroziez murmur present in chronic AI absent in acute AI
• chronic AI usually presents insidiously
  • angina pectoris
  • dyspnea on exertion
  • orthopnea
  • wide pulse pressure (chronic but not acute AI)
  • diastolic murmur
    • high-pitched decrescendo
    • radiation along left sternal border (aortic leaflets) or right sternal border (aortic root)
    • accentuated by leaning forward & exhalation
    • a low-pitched rumbling diastolic murmur may occur (Austin-Flint murmur)
    • murmur does not radiate
    • severity of AI difficult to determine by auscultation
  • rapid forceful carotid upstroke with marked collapse
    • bounding carotid pulse (Corrigan's pulse)
    • bounding peripheral pulse
  • head bobbing with each systole (de Musset's sign)
  • prominent pulsations of skin capillaries (Quincke's pulse)
  • popliteal artery pressure > brachial artery pressure (Hill's sign)
  • murmur heard over the femoral artery (Duroziez murmur)
  • 'pistol shot' sound over peripheral arteries (Traube's sign)
  • displaced & hyperdynamic point of maximum impulse (PMI)
    • enlarged, displaced apical impulse
  • soft S1, loud S3 or S4, soft or absent A2
  • paradoxical splitting of S2 may occur
  • dyspnea or fatigue with left ventricular failure
  • signs of chronic volume overload (congestive heart failure)
    • pulmonary crackles, jugular venous distension

Laboratory

• serologic tests for syphilis: RPR, VDRL (screening)

Diagnostic procedures

• electrocardiogram:
  • may show left ventricular hypertrophy
  • left axis deviation
  • conduction abnormalities suggest aortic root pathology
  • prolongation of PR interval suggests endocarditis that has extended into the aortic valve annulus
• echocardiography - Doppler
  • early mitral valve closure (acute AI)
  • diastolic flow reversal
  • presence & severity of AI
  • LV size & function
  • aortic root size
  • frequency of serial evaluation
    • every 5 years for asymptomatic patients with mild AI (regurgitant fraction < 30%)
    • every 1-2 years for asymptomatic patients with moderate AI (regurgitant fraction 30-50%)
    • every 6-12 months for asymptomatic patients with severe AI (regurgitant fraction >50%)
• cardiac catheterization

Radiology

• chest X-ray
  • cardiomegaly in chronic cases, normal with acute AI
  • pulmonary vascular congestion
  • aortic root dilatation
  • calcification of aortic root
  • double lumen sign when aortic dissection is present
• radionuclide ventriculography
• computed tomography if suspecting aortic dissection

Differential diagnosis

• consider aortic dissection
• ruptured sinus of Valsalva

Management

• stabilization of patients with acute AI before surgery
  • nitroprusside
  • inotropic agents
    • dobutamine
    • amrionone, milrinone
  • avoid beta-blockers d avoid intra-aortic balloon pump
• chronic, stable AI
  • treatment of underlying causes
  • prophylaxis for endocarditis;
    • no longer recommended
  • left ventricular dysfunction
    • restriction of strenuous physical activity
      • isometric exercise (i.e. weight-lifting) more detrimental than walking or swimming
    • fluid & salt restriction
    • diuretics
    • digoxin
    • afterload reduction (hypertension)
      • ACE inhibitor or ARB
      • dihydropyridine calcium channel blocker
      • vasodilators (nifedipine or enalapril) of no benefit in delaying surgery
• surgery
  • acute AI: aortic valve replacement
    • immediate aortic valve replacement (AVR)
    • repair of associated aortic root abnormalities (aortic dissection)
    • infective endocarditis - delay surgery for several days of antibiotics if patient can be medically stabilized
    • Ross procedure
  • chronic AI: aortic valve replacement
    • signs & symptoms of moderate heart failure (New York Heart Association class II-III), exercise intolerance
    • left ventricular dysfunction
      • LVEF < 50-55%, progressive LV dilation
      • reversibility of LV dysfunction depends upon:
        • duration of dysfunction
        • dilatation of left ventricle; LV end-systolic dimension > 5.0 cm
        • degree of systolic dysfunction
    • asymptomatic severe AI with LVEF < 50-55% & progressive LV dilation are at increased risk for heart failure & sudden death
    • symptomatic severe AI regardless of LVEF
  • transcatheter aortic valve replacement (TAVR) may be an option
    • in-hospital mortality similar with TAVR or surgical aortic valve replacement
  • moderate or severe aortic insufficiency if patient undergoes other cardiad surgery (CABG, mitral valve repair)
• follow-up (no indication for aortic valve replacement, yet)
  • clinical evaluation yearly
    • every 6 months if LV dilation or severe disease
  • echocardiogram (patient asymptomatic)
    • in 2-3 months to exclude rapidly progressive process
    • mild: every 2-3 years
    • moderate: every 1-2 years
    • severe: yearly
    • every 6-12 if LV dilation

Additional terms

• aortic valve