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Aortic valve regurgitation (AR) occurs when the aortic valve fails to close properly, allowing blood to flow backward from the aorta into the left ventricle. This backflow can result in two distinct clinical presentations: acute and chronic AR, each characterized by its own set of symptoms and physical findings.
Acute Aortic Regurgitation
Acute AR presents with a sudden onset of severe symptoms. Patients typically experience profound dyspnea (shortness of breath), chest pain, and signs of left ventricular failure. This abrupt failure of the aortic valve can lead to cardiogenic shock, a life-threatening condition where the heart cannot pump enough blood to meet the body's needs. The rapid increase in left ventricular volume due to regurgitant flow overwhelms the heart's compensatory mechanisms, leading to these severe clinical manifestations.
Chronic Aortic Regurgitation
Chronic AR develops more slowly, allowing the left ventricle to adapt to the increased volume load. Symptoms in chronic AR include fatigue, exertional dyspnea (shortness of breath with physical activity), orthopnea, and paroxysmal nocturnal dyspnea (PND). Chronic AR can lead to a characteristic physical finding known as the water hammer or Corrigan's pulse, where the pulse is bounding and forceful due to the increased stroke volume.
Auscultatory Findings
Auscultation in AR reveals several characteristic murmurs. A soft, high-pitched diastolic murmur is typically heard, indicating the backflow of blood during diastole. This murmur is best heard at the left sternal border at the third or fourth intercostal space. Additionally, an Austin Flint murmur may be present. This low-pitched rumbling sound is heard at the apex of the heart and is believed to result from the regurgitant jet striking the anterior leaflet of the mitral valve, causing it to vibrate.
Diagnostic Testing
Diagnostic testing starts with echocardiography, the primary diagnostic tool.
- A transthoracic echocardiogram (TTE) assesses regurgitation severity, evaluates left ventricular size and function, and identifies underlying causes such as a bicuspid valve or infective endocarditis.
- If the TTE is inconclusive, a transesophageal echocardiogram (TEE) is used to visualize the aortic valve and root better.
- A chest X-ray can reveal signs of cardiomegaly, pulmonary congestion in acute cases, and aortic root dilation.
- An electrocardiogram (ECG) may show left ventricular hypertrophy, left atrial enlargement, and atrial fibrillation in advanced disease.
- A cardiac MRI provides detailed information on left ventricular function, the aortic root, and the ascending aorta.
- At the same time, a CT scan helps assess the aortic root and ascending aorta, especially if an aortic dissection is suspected.
