Aortic regurgitation (AR) is a common type of heart valve disease where the heart’s main outflow valve does not close correctly. This condition, also known as aortic insufficiency, prevents a tight seal between the heart and the body’s largest artery, the aorta. It is a progressive problem that can range from a trace amount of leakage to a severe condition affecting heart function over time.
Understanding the Aortic Valve and Regurgitation
The aortic valve is positioned between the heart’s main pumping chamber, the left ventricle, and the aorta, which distributes oxygenated blood to the rest of the body. Under normal conditions, this valve opens to allow blood to be ejected into the aorta during the heart’s contraction (systole). Once the heart relaxes (diastole), the valve closes completely to prevent blood from flowing backward into the left ventricle.
Aortic regurgitation occurs when the valve leaflets do not close tightly, allowing a portion of the ejected blood to leak back from the aorta into the left ventricle during diastole. This backward flow of blood creates a volume overload within the left ventricle. The heart must then pump this extra volume of blood, forcing the muscle to work harder. Over many years, this increased workload can cause the left ventricle to enlarge and thicken, which ultimately makes the heart less efficient.
Common Causes and Underlying Conditions
Aortic regurgitation can arise from problems with the valve leaflets themselves or from dilation of the aortic root, the section of the aorta where the valve is anchored. The causes are typically categorized by their onset, being either acute (sudden) or chronic (gradual). Acute AR is often a medical emergency, commonly resulting from infective endocarditis, a serious infection of the heart lining and valves, or from an aortic dissection, which is a tear in the aortic wall.
Chronic AR develops slowly over decades, giving the heart time to adapt to the volume overload. The most frequent cause of chronic AR is age-related degenerative changes or calcification of the valve tissue. A significant number of cases are also linked to a congenital defect called a bicuspid aortic valve, where the valve forms with only two cusps instead of the usual three.
Diseases that cause the aorta to widen, such as chronic high blood pressure (hypertension) or connective tissue disorders like Marfan syndrome, can also prevent the valve from closing properly. Inflammatory conditions affecting the aorta, including certain types of arthritis, may also lead to valve incompetence.
Symptoms and Diagnostic Methods
The symptoms experienced by a patient with AR depend heavily on the severity and the speed of its onset. Individuals with mild or even moderate chronic AR may remain without symptoms for many years as the left ventricle adapts to the leakage. The earliest sign of dysfunction is often a subtle reduction in exercise capacity or a feeling of fatigue.
As the condition progresses, a variety of symptoms related to heart failure may appear. Shortness of breath, medically termed dyspnea, is a common complaint, particularly during physical exertion. Fluid backing up into the lungs can also cause orthopnea, which is difficulty breathing when lying flat, and paroxysmal nocturnal dyspnea, a sudden awakening with breathlessness. Some patients report an uncomfortable awareness of their heartbeat, known as palpitations, or chest pain, especially at night.
The diagnostic process usually begins with a physical examination where a healthcare provider listens to the heart with a stethoscope. A characteristic finding of AR is a soft, blowing, high-pitched heart murmur heard during diastole, reflecting the sound of blood leaking backward. In chronic, severe cases, the difference between the systolic and diastolic blood pressure, called the pulse pressure, may become noticeably widened.
The primary tool for confirming a diagnosis and assessing the severity of AR is the echocardiogram, an ultrasound of the heart. This non-invasive test allows doctors to visualize the valve structure, measure the amount of backflow using Doppler technology, and assess the size and function of the left ventricle. Other tests, such as a chest X-ray to check for an enlarged heart or an electrocardiogram (EKG) to look for rhythm disturbances, may be used to gain a complete clinical picture.
Treatment and Management Strategies
The management of aortic regurgitation is determined by the severity of the leakage, the patient’s symptoms, and the degree of left ventricular dysfunction. For patients with mild or moderate AR who are asymptomatic and have normal heart function, the strategy is typically “watchful waiting”. This involves regular monitoring with physical exams and periodic echocardiograms to track any progression of the disease.
Medications have a limited role in treating the valve problem itself, as they cannot stop the blood leakage. However, certain drugs, such as Angiotensin-Converting Enzyme (ACE) inhibitors or Angiotensin II Receptor Blockers (ARBs), may be prescribed to manage high blood pressure and reduce the overall strain on the heart. Diuretics and other heart failure medications may also be used to alleviate symptoms like fluid retention and shortness of breath.
The definitive treatment for severe AR, or for cases where symptoms develop or the heart function begins to decline, is surgical intervention. Surgeons may perform an aortic valve repair, which is often possible when the valve tissue is of good quality and the problem is related to aortic root dilation. More commonly, the damaged valve is replaced with a prosthetic valve, which can be either a mechanical valve or a tissue valve made from animal or human donors.