Aortic Insufficiency: Etiology, Pathophysiology, and Clinical Presentation
Last updated: 01/04/2023
- Aortic insufficiency (AI) is caused by the failure of the aortic valve leaflets to close.
- Bicuspid aortic valves and primary diseases of the ascending aorta and sinuses of Valsalva are the main causes of chronic and severe AI in high-income countries. Rheumatic heart disease is the main cause of AI in lower-income countries.1
- AI is typically a chronic disease in most patients, which results in left ventricle ventricular dilation and eccentric hypertrophy.1
- AI occurs due to a failure of the aortic valve leaflets from fully closing (coapting) during diastole. The etiology of AI is broad and can be categorized in the following ways (Figure 1).
- Type 1: aortic root or aortic annular dilation
- Type 2: excessive aortic cusp motion
- Type 3: restricted leaflet motion or poor tissue quality leaflets
- The most common cause of chronic AI is congenital valvular disease (specifically bicuspid valve) and aortic dilation.1
- Causes of acute AI include endocarditis, aortic dissection, and prosthetic valve complications such as leaflet dysfunction, paravalvular leak, and valve dehiscence.2
- Other causes include age-related senile valvular calcification, age-related aortic dilation, systemic hypertension, myxomatous valve degeneration, aortitis, and aortic root dilation from syphilis or rheumatologic disease.2
- Trace AI as seen on echocardiography with color Doppler is very common and is seen even in healthy patients.3
- AI prior to age 50 is unusual and when present, typically progresses over time.3 It is estimated to occur in approximately 2% of the population older than 70 years, with men affected more commonly than women.3
- Bicuspid aortic valves are estimated to affect 0.5-3% of the general population, with prevalence being three times higher in males than females.4 Of these patients, between 13-30% will develop moderate to severe AI in their lifetimes, and up to 40% of these patients will also develop an aortopathy with enlargement of the sinuses of Valsalva or ascending aorta.4
- AI produces a predictable hemodynamic response. When the aortic valve leaflets fail to coapt during diastole, a fraction of the left ventricle (LV) stroke volume leaks from the aorta back into the LV. This causes an increase in LV end-diastolic volume and LV wall stress. In response, the LV adapts to the increased volume through eccentric hypertrophy and dilation.
- Initially, the LV increases total stroke volume and maintains forward flow. Through eccentric hypertrophy and LV dilation, which maintains LV compliance, LV end-diastolic pressure initially remains normal despite the increase in LV volume. Low aortic diastolic blood pressures and a widened pulse pressure result from the increasing regurgitant volume back into the LV.
- As the disease progresses, there is an eventual increase in LV wall stress and afterload, which result in progressive LV systolic dysfunction in the setting of dilated cardiomyopathy.
- To compensate for a reduction in cardiac output, there is further peripheral vasoconstriction to maintain blood pressure. This adaptation eventually becomes pathologic, further exacerbating the severity of regurgitation in advanced stages of aortic insufficiency.5
- Patients with chronic regurgitation may be asymptomatic for decades, even with evidence of ventricular remodeling.
- Those who develop severe disease have typical signs and symptoms of heart failure, including exertional dyspnea, angina, orthopnea, paroxysmal nocturnal dyspnea, and/or pulmonary edema. Of note, angina in these patients can be due to underlying atherosclerotic disease or poor coronary perfusion because of low diastolic aortic pressure.
- On auscultation, the classic decrescendo early diastolic murmur can be heard at the left upper sternal border.
- The pulse pressure is widened with a high systolic and low diastolic pressures.
- Bounding carotid pulses, head bobbing, retinal, and uvular pulsations are some of the peripheral signs of chronic AI.2
- Chest x-ray shows pulmonary congestion and cardiomegaly.
- Echocardiography is the gold standard in the evaluation of aortic regurgitation, providing valuable diagnostic information regarding severity, etiology, and pathologic maladaptations (Figure 3).
- The American Heart Association (AHA) stages AI based on symptoms, valve anatomy, severity of valve dysfunction, and degree of cardiac maladaptation or hemodynamic effects.5
- Stage A: No or trace AI
- Stage B: Mild to moderate regurgitation with normal systolic function and only mildly dilated LV volume
- Stage C: Asymptomatic, severe regurgitation: Stage C1 is characterized by normal LV systolic function with mild to moderately increased LV dilation, while stage C2 is characterized by a decreased LV systolic function as well as markedly increased LV systolic volume.
- Stage D: Symptomatic, severe aortic regurgitation, along with decreased systolic function and severely increased LV volume
- Acute AI is less common than chronic regurgitation and is poorly tolerated because the LV has not had time to adapt to the increase in LV end-diastolic volume. In these settings, the LV typically fails quickly, rapidly resulting in pulmonary edema and hemodynamic instability unless the underlying cause of insufficiency is addressed.
- Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease: A report of the American College of Cardiology/American Heart Association joint committee on clinical practice guidelines. Circulation. 2020; 143(5): e72-e227. PubMed
- Akinseye OA, Pathak A, Ibebuogu UN. Aortic valve regurgitation: A comprehensive review. Curr Probl Cardiol. 2018: 43(8): 315-34. PubMed
- Singh JP, Evans JC, Levy D, et al. Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Heart Study). Am J Cardiol. 1999: 83(6): 897-902. PubMed
- Masri A, Svensson LG, Griffin BP, et al. Contemporary natural history of bicuspid aortic valve disease: A systematic review. Heart. 2017; 103:1323-30. PubMed
- Zoghbi WA. Clinical manifestations and diagnosis of chronic aortic regurgitation in adults. In Otto CM (Ed). UpToDate. 2022. Accessed October 17th, 2022. Link
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