Aortic insufficiency (AI), or aortic regurgitation, is a heart valve disease where the aortic valve does not close completely. This allows blood pumped into the aorta to leak backward into the left ventricle during diastole. This backward flow forces the left ventricle to handle increased volume, making the heart work harder to maintain forward flow. Over time, this volume overload causes the left ventricle to enlarge and thicken, eventually leading to heart muscle weakening and heart failure.
Underlying Causes of Aortic Insufficiency
The conditions leading to AI are separated into those affecting the valve leaflets directly and those causing the aortic root (the base of the aorta) to widen. Damage timing dictates severity: acute AI is sudden and life-threatening, while chronic causes progress gradually.
The most common cause of chronic AI in developed nations is gradual deterioration and calcification related to aging. The leaflets become stiff or retracted, preventing a proper seal. Congenital abnormalities, such as a bicuspid aortic valve (two leaflets instead of three), are frequent causes, as this structure is prone to wear or associated aortic root dilation.
Infectious processes, particularly infective endocarditis, damage the valve leaflets, often leading to acute, severe AI. Historically, rheumatic fever was a cause, though it is less common now. Conditions that weaken the aortic wall, such as Marfan syndrome or high blood pressure, can cause the aortic root to dilate, pulling the leaflets apart and preventing closure.
Recognizing the Signs
The presentation of AI varies depending on whether the condition is acute or chronic. Individuals with chronic, mild-to-moderate AI may remain asymptomatic for years because the left ventricle adapts to volume overload by gradually enlarging. During this compensated phase, the patient may not notice changes in physical capabilities.
As the condition progresses and compensatory mechanisms fail, symptoms emerge. Patients may first experience fatigue and shortness of breath only with physical exertion. Palpitations or a forceful heartbeat may be noted, particularly when lying down. Signs of heart failure, such as difficulty breathing when lying flat (orthopnea) or waking up short of breath (paroxysmal nocturnal dyspnea), indicate advanced disease.
Acute severe AI, often caused by sudden events like an aortic dissection or severe infection, presents as a medical emergency. Since the left ventricle has not had time to adapt, the sudden volume overload causes a rapid rise in pressure inside the heart. This leads to sudden and severe shortness of breath, often accompanied by pulmonary edema, and potentially progressing quickly to cardiogenic shock.
Diagnostic Procedures
The evaluation begins with a physical examination, where a clinician listens to the heart with a stethoscope. The characteristic finding is a high-pitched, decrescendo diastolic murmur—the sound of blood flowing backward through the leaky valve. The physical exam may also reveal a widened pulse pressure (the difference between systolic and diastolic blood pressure) due to the rapid runoff of blood back into the ventricle.
Echocardiography is the primary tool for diagnosing AI and determining its severity. This ultrasound allows clinicians to visualize the aortic valve’s structure, identify the cause of the leak, and measure the amount of blood regurgitating into the left ventricle. The test also provides information about the size and function of the left ventricle, which helps guide treatment decisions.
Other imaging tests support diagnosis and surgical planning. A Chest X-ray can show if the heart is enlarged or if there is fluid buildup in the lungs. An electrocardiogram (ECG) measures the heart’s electrical activity and can indicate if the left ventricle has thickened or if rhythm problems are present. Cardiac MRI or CT scans provide detailed images of the aortic root and measure its size, which is important if dilation is the underlying cause.
Management and Intervention Strategies
Management depends on the severity of the leak, symptoms, and the condition of the left ventricle. For patients with mild or moderate AI who are asymptomatic and have normal heart function, the strategy is watchful waiting. This involves regular monitoring with physical exams and echocardiograms to track disease progression and ventricular size.
Medical management controls symptoms and manages risk factors, but it cannot fix the faulty valve. Vasodilators (e.g., ACE inhibitors or calcium channel blockers) may be prescribed to lower blood pressure and reduce the resistance the heart must pump against, minimizing backflow. Diuretics are often used to manage fluid retention and reduce symptoms of heart failure.
Surgical intervention is the definitive treatment for severe AI and is recommended for all symptomatic patients. It is also indicated for asymptomatic patients if imaging reveals a decline in left ventricular function or significant enlargement of the heart chamber. The timing of surgery is carefully considered, as operating before irreversible heart damage occurs is necessary to achieve the best long-term outcome.
Aortic Valve Replacement (AVR) is the most common surgical procedure, replacing the damaged valve with a prosthetic valve. Patients typically receive either a mechanical valve (durable, requires lifelong blood-thinning medication) or a bioprosthetic (tissue) valve (avoids long-term anticoagulation but may require replacement). If the aortic root is dilated, a valve-sparing root replacement procedure may be performed, preserving native leaflets while replacing the enlarged section of the aorta.