Aortic regurgitation (AR) is incompetency of the aortic valve causing flow from the aorta into the left ventricle during diastole. Causes include idiopathic valvular degeneration, rheumatic fever, endocarditis, myxomatous degeneration, congenital bicuspid aortic valve, aortic root dilatation or dissection, and connective tissue or rheumatologic disorders. Symptoms include exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, palpitations, and chest pain. Signs include widened pulse pressure and an early diastolic murmur. Diagnosis is by physical examination and echocardiography. Surgical treatment is aortic valve replacement.
Etiology
AR may be acute or chronic. The primary causes of acute AR are infective endocarditis and dissection of the ascending aorta. Mild chronic AR in adults is most often caused by a bicuspid or fenestrated aortic valve (2% of men and 1% of women), especially when severe diastolic hypertension (pressure ≥ 110 mm Hg) is present. Moderate to severe chronic AR in adults is most often caused by idiopathic degeneration of the aortic valves or root, rheumatic fever, infective endocarditis, myxomatous degeneration, or trauma. In children, the most common cause is a ventricular septal defect with aortic valve prolapse. Rarely, AR is caused by seronegative spondyloarthropathies (ankylosing spondylitis, reactive arthritis, psoriatic arthritis), RA, SLE, arthritis associated with ulcerative colitis, luetic (syphilitic) aortitis, osteogenesis imperfecta, thoracic aortic aneurysm, aortic dissection, supravalvular aortic stenosis, Takayasu's arteritis, rupture of a sinus of Valsalva, acromegaly, and temporal (giant cell) arteritis. AR due to myxomatous degeneration may develop in patients with Marfan syndrome or Ehlers-Danlos syndrome.
Pathophysiology
In chronic AR, left ventricular (LV) volume and LV stroke volume gradually increase because the LV receives aortic blood regurgitated in diastole in addition to blood from the pulmonary veins and left atrium. LV hypertrophy compensates for the increase in LV volume over years, but decompensation eventually develops. These changes may ultimately cause arrhythmias, LV impairment, and heart failure (HF).
Symptoms and Signs
Acute AR causes symptoms of HF and cardiogenic shock. Chronic AR is typically asymptomatic for years; progressive exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and palpitations develop insidiously. Symptoms of HF correlate poorly with objective measures of LV function. Chest pain (angina pectoris) affects only about 5% of patients who do not have coexisting coronary artery disease (CAD) and, when it occurs, is especially common at night. Patients may present with endocarditis (eg, fever, anemia, weight loss, embolic phenomena) because the abnormal aortic valve is predisposed to bacterial seeding.
Signs vary by severity. As chronic disease progresses, systolic BP increases while diastolic BP decreases, creating a widened pulse pressure. With time, the LV impulse may become enlarged, sustained, increased in amplitude, and displaced downward and laterally, with systolic depression of the entire left parasternal area, giving a rocking motion to the left chest.
A systolic apical or carotid thrill may become palpable in later stages of AR; it is caused by large forward stroke volumes and low aortic diastolic pressure.
Auscultatory findings include a normal 1st heart sound (S1) and a nonsplit, loud, sharp or slapping 2nd heart sound (S2) caused by increased elastic aortic recoil. The murmur of AR is often unimpressive. The murmur is blowing, high-pitched, diastolic, and decrescendo, beginning soon after the aortic component of S2 (A2); it is loudest at the 3rd or 4th left parasternal intercostal space. The murmur is heard best with the diaphragm of the stethoscope when the patient is leaning forward, with breath held at end-expiration. It increases in volume in response to maneuvers that increase afterload (eg, squatting, isometric handgrip). If AR is slight, the murmur may occur only in early diastole. If LV diastolic pressure is very high, the murmur is short because aortic and LV diastolic pressures equalize earlier in diastole.
Other abnormal sounds include a forward ejection and backward regurgitant flow (to-and-fro) murmur, an ejection click soon after the S1, and an aortic ejection flow murmur. A diastolic murmur heard near the axilla or mid left thorax (Cole-Cecil murmur) is caused by fusion of the aortic murmur with the 3rd heart sound (S3), which is due to simultaneous filling of LV from the left atrium and AR. A mid-to-late diastolic rumble heard at the apex (Austin Flint murmur) may result from rapid regurgitant flow into the LV, causing mitral valve leaflet vibration at the peak of atrial flow; this murmur mimics the diastolic murmur of mitral stenosis.
Other signs are unusual; sensitivity and specificity are low or unknown. Visible signs include head bobbing (Musset's sign) and pulsation of the fingernail capillaries (Quincke's sign, best seen with slight pressure) or uvula (Müller's sign). Palpable signs include a large-volume pulse with rapid rise and fall (slapping, water-hammer, or collapsing pulse) and pulsation of the carotid arteries (Corrigan's sign), retinal arteries (Becker's sign), liver (Rosenbach's sign), or spleen (Gerhard's sign). BP findings may include popliteal systolic pressure ≥ 60 mm Hg higher than brachial pressure (Hill's sign) and a fall in diastolic BP of > 15 mm Hg with arm elevation (Mayne's sign). Auscultatory signs include a sharp sound heard over the femoral pulse (pistol-shot sound, or Traube's sign) and a femoral systolic bruit distal and a diastolic bruit proximal to arterial compression (Duroziez's murmur).
