DESCRIPTION 
Aortic valve incompetence allows diastolic flow from the aorta into the LV.
EPIDEMIOLOGY
Prevalence
The prevalence of moderate to severe aortic regurgitation (AR) ranges from 0.5–2.7% in the Framingham and Strong Heart Studies, respectively.
RISK FACTORS
Risk factors for AR include increasing age, male sex, HTN, and connective tissue disorders. See "Etiology."
Genetics
AR can be associated with several genetic diseases such as Marfan syndrome, familial thoracic aortic aneurysm with or without bicuspid aortic valve, and other connective tissue disorders.
PATHOPHYSIOLOGY
- Chronic AR:
- The response of the LV to chronic AR depends on the regurgitant volume. With moderate to severe AR, LV size increases to accommodate the additional stroke volume. Chronic AR causes a volume load on the LV leading to LV dilation, but also a pressure overload, since the LV must eject a large stroke volume into the high pressure aorta. The large stroke volume causes a high systolic arterial pressure. Compensatory mechanisms of LV dilation, peripheral vasodilation, and normal or increased ejection fraction allow patients with severe AR to maintain normal forward cardiac output for many years, but eventually systolic failure ensues (CHF). Diastolic arterial pressure is often low in the compensated state.
- Acute AR:
- The pathophysiology of acute aortic insufficiency is quite different from chronic AR. A sudden increase in diastolic volume causes a marked increase in LV diastolic pressure and in turn increased LA pressure, pulmonary venous pressure, which causes pulmonary edema. Because forward output cannot be readily augmented, hypotension and compensatory peripheral vasoconstriction usually occur. Thus, systemic diastolic pressure is normal, not low.
ETIOLOGY
- Diseases involving the aortic valve:
- Rheumatic disease
- Infective endocarditis (IE)
- Congenital AV abnormalities (unicommissural, bicuspid, quadricuspid)
- Calcific degeneration
- Traumatic injuries to the aortic valve
- Rheumatoid arthritis
- Subaortic stenosis causing high velocity wear and tear to the valve
- Ventricular septal defects (VSD) with prolapse of an aortic cusp
- Less common:
- Takayasu disease
- Systemic lupus erythematosus
- Diseases involving the aortic root:
- Systemic HTN
- Familial thoracic aortic aneurysm
- Ascending aortic dissection
- Giant cell arteritis
- Ehlers-Danlos syndrome
- Marfan syndrome
- Bechet syndrome
- Syphilitic aortitis
- Osteogenesis imperfecta
- Spondyloarthropathies (psoriasis, ankylosing spondylitis, ulcerative colitis, Reiter)
- Relapsing polychondritis
Outline
History
- Chronic AR is often asymptomatic until the 4th or 5th decade of life:
- Dyspnea, orthopnea and paroxysmal nocturnal dyspnea
- Decreased effort tolerance
- Palpitations due to increased stroke volume
- Acute severe AR:
- Fever in IE
- Severe abrupt chest pain in aortic dissection.
- Pulmonary edema or cardiogenic shock
Physical Exam
- Chronic AR:
- Hyperdynamic, laterally displaced apical impulse
- Classically, the diastolic murmur is heard best in the 3rd or 4th intercostal space at the left sternal border with valve disease and along the right sternal border with aortic root disease. It may be heard at the apex.
- High-pitched holodiastolic decrescendo murmur starts after A2; severity of AI not reflected by length of murmur and not intensity. In severe, wide-open AR with little turbulence, the murmur may be very soft. Auscultate with patient sitting, leaning forward at end-expiration; exam in the supine position only may miss many AR patients.
- A2 may be decreased (with valvular disease) or increased (with aortic root disease)
- Ejection clicks signal the presence of a congenitally bicuspid valve (usually in the younger patient)
- S3 may be present with a dilated LV and rapid LV filling
- Austin-Flint murmur: Mid to late diastolic apical rumble due to increased LV diastolic pressure and aortic jet across the anterior mitral leaflet
- Systolic ejection murmur often present due to increased forward flow across the AV
- Other signs (usually with chronic severe AR):
- Widened pulse pressure
- De Musset sign: Head bobbing with pulse
- Corrigan pulse: Water hammer pulse
- Bisferiens carotid pulse: Two systolic impulses
- Traube sign: Pistol-shot systolic and diastolic sounds over the femoral artery
- Duroziez sign: Femoral artery systolic murmur when it is compressed proximally and diastolic murmur when it is compressed distally
- Quincke sign: Capillary pulsations in fingertips
- Hill sign: Popliteal systolic BP exceeds brachial systolic BP by >60 mm Hg
- Acute severe AR:
- Signs of cardiovascular collapse: Tachycardia, marked hypotension vasoconstriction, cyanosis, pulmonary edema
- LV impulse usually normal, not laterally displaced
- Pulse pressure usually not widened since peripheral resistance is increased to compensate for decreased forward output
- Low-pitched early diastolic murmur
- Murmur of AR may or may not be present; in wide-open AR there is little turbulence
- Soft aortic component (A2) of 2nd heart sound (S2)
- Third (S3) heart sound and 4th (S4) are often present
DIAGNOSTIC TESTS & INTERPRETATION
Lab
ECG: In chronic AR, left axis deviation; LV hypertrophy with repolarization changes, widened QRS, LBBB
Imaging
- CXR:
- Acute AR: Normal heart size, pulmonary edema, widened mediastinum (with acute aortic dissection)
- Chronic AR: Cardiomegaly, pulmonary congestion, Kerley B lines, ascending aorta dilatation, calcified ascending aorta in syphilitic aortitis (now rare)
- Echo:
- Frequently identifies the cause of AR, number of valve cusps, calcium, dilated aortic root, vegetations, intimal flap, prolapsed cusp
- Doppler echo and color flow for evaluating AR severity
- LV dimensions, volumes, and systolic function
- Ascending aorta (size, presence of dissection)
- MRI:
- Very accurate for measuring regurgitant volumes, LV mass and segmental aortic sizes, presence of dissection
- Aortic root angiography has generally been replaced by echo.
DIFFERENTIAL DIAGNOSIS
- The AR murmur may be confused with the murmur of pulmonary regurgitation.
- Acute severe AR can mimic any disease process causing cardiogenic shock.
- The diastolic murmur in acute severe AR may be missed.
- Chronic severe AR may be asymptomatic or may mimic other causes of CHF.
- Austin-Flint murmur may be confused with mitral stenosis.
Outline
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
- Patients with mild to moderate AR and normal LV size and function should be followed by yearly exam and echo every 2–3 yr.
- Asymptomatic patients with chronic severe AR and normal LV size and function require an exam and echo every 6–12 mo. Exercise testing can be helpful in detecting asymptomatic deterioration of systolic function.
- AVR is indicated if the patient develops symptoms, decreased exercise capacity or abnormal LV size or function (LVEF <50% or LVEDD >75 mm or LVESD >55 mm).
- LV dimensions upon which these decisions are based should take into consideration patient size (BSA).
Pregnancy Considerations
- Patients with normal LV function and AR usually tolerate pregnancy well.
- Patients with severe AR and abnormal LV function (LVSF) are at risk for developing CHF and should have surgery prior to pregnancy.
- May treat AR acutely with nifedipine (pregnancy class C), hydralazine (C), furosemide (C), digoxin (C)
- To avoid fetal renal agenesis, avoid ACEI and ARBs.
- Controlled induced vaginal delivery preferred over Cesarean delivery for patients with AR.
- If patient has an aortic root diameter (ARD) >40 mm, pregnancy should be discouraged. If ARD is <40 mm, monitor via exams and ECGs during gestation. (No evidence to support this, extrapolated from recommendations for Marfan syndrome patients.)
PATIENT EDUCATION
Activity:
- Asymptomatic patients with normal LV function can participate in most activities.
- In severe AR or in cases of aortic root dilation, dilated ascending aorta, strenuous isometric exercise should be avoided.
PROGNOSIS
- Asymptomatic patients with chronic severe AR and normal LV function have an excellent prognosis: <6% per year progress to symptoms or LV dysfunction; <0.2% per year have sudden death.
- Patients with LVESD <40 mm are likely to be stable and can be monitored; when LVESD >50 mm, there is a 19% per year risk of developing CHF symptoms; LVESD >55 mm there is a risk of permanent LV dysfunction.
COMPLICATIONS
Possible complications of AR include IE, recurrent rheumatic carditis, LV remodeling, angina, CHF, cardiogenic shock and death.
Outline
CODES
ICD9
424.1 Aortic valve disorders
SNOMED
60234000 aortic valve regurgitation (disorder)
10 yr, at least until age 40 and sometimes life-long.