A bicuspid aortic valve (BAV) is a congenital heart condition where the aortic valve has two leaflets instead of the typical three. This valve is located between the heart’s main pumping chamber and the aorta, the body’s largest artery. Many individuals with a bicuspid aortic valve remain unaware of their condition for years, often until a doctor detects a heart murmur during a routine check-up. An echocardiogram, which uses sound waves to create images of the heart, is the primary tool for diagnosing and assessing this condition.
Why an Echocardiogram Is Used
An echocardiogram is a non-invasive and painless test that uses sound waves to produce moving pictures of the heart. This diagnostic tool does not involve radiation, making it a safe option for repeated examinations. During the procedure, a technician moves a probe across the chest for a standard transthoracic echocardiogram (TTE), which is typically the initial imaging study.
If the images from a TTE are not clear enough, or if more detailed visualization of the valve and aorta is needed, a transesophageal echocardiogram (TEE) may be performed. For a TEE, a small probe is passed down the throat to get closer to the heart, providing clearer and more accurate images, especially when the valve is calcified. Both types of echocardiograms visualize the heart’s internal structures, including the valves and blood flow, in real-time.
What the Echocardiogram Reveals
During an echocardiogram for a bicuspid aortic valve, the sonographer and cardiologist examine the heart’s structure and function. This assessment begins with identifying the valve’s morphology. A healthy aortic valve has three leaflets that open to form a triangular shape, allowing smooth blood flow.
In contrast, a bicuspid valve usually presents with two leaflets, often displaying a “fish mouth” appearance or a raphe (a ridge from fused leaflets). The most common type involves the fusion of the right and left coronary cusps. Identifying a bicuspid valve can be challenging, particularly if heavily calcified, as this can obscure the leaflet structure.
Beyond valve identification, the echocardiogram also assesses valve function using Doppler technology to evaluate blood flow. Two common problems are aortic stenosis and aortic regurgitation. Aortic stenosis is the narrowing or stiffening of the valve, which obstructs blood flow from the heart into the aorta. The echo measures the peak jet velocity and mean pressure gradient across the valve, and calculates the aortic valve area, to determine the severity of this obstruction.
Aortic regurgitation occurs when the valve fails to close properly, causing blood to leak backward into the heart’s left ventricle. Color Doppler imaging visualizes and quantifies this backflow. These measurements help determine the extent of the leak and its impact on heart function.
The echocardiogram also measures the size of the aorta, as a bicuspid aortic valve is frequently associated with aortic enlargement or aneurysm (aortopathy). The aorta’s diameter is measured at several points. This measurement is important for screening for related aortic conditions.
Interpreting Echo Results
Echocardiogram results provide a detailed picture of the valve’s condition and associated aortic health. Aortic stenosis and regurgitation, if present, are graded as mild, moderate, or severe based on specific measurements. For instance, severe aortic stenosis is indicated by a peak jet velocity greater than 4 meters per second, a mean pressure gradient exceeding 40 mmHg, and an aortic valve area less than 1.0 square centimeter.
The implications of these grades relate directly to the heart’s workload. Severe stenosis means the heart must exert more effort to pump blood through the narrowed valve, which can lead to the thickening and enlargement of the left ventricle and eventually heart failure. Similarly, severe aortic regurgitation increases the heart’s workload because a portion of the blood pumped forward leaks back, requiring the heart to re-pump that volume. Severe aortic regurgitation is suggested by a vena contracta greater than 6 mm or a pressure half-time less than 200 ms.
Regarding the aorta, its measured size is compared against established normal values to determine if an enlargement or aneurysm is present. Aortic dilation in individuals with a bicuspid aortic valve most commonly affects the ascending aorta. Surgical intervention for aortic enlargement is considered when the ascending aorta reaches a diameter greater than 5.0 centimeters, or at 4.5 centimeters if the patient is already undergoing aortic valve surgery. The rate of aortic growth in bicuspid aortic valve patients can vary, often ranging from 0.2 to 1.9 mm per year.
Monitoring and Follow-Up Care
Initial echocardiogram findings for a bicuspid aortic valve are important for the long-term management plan. Based on valve dysfunction and aortic dimensions, a cardiologist establishes a schedule for periodic surveillance echocardiograms. This monitoring tracks changes in valve function or aortic size over time.
For individuals with a well-functioning bicuspid aortic valve and a normal-sized aorta, follow-up echocardiograms are recommended every three to five years. If the aortic diameter measures greater than 40 millimeters, annual imaging is suggested. If the aorta remains stable after an initial follow-up, the frequency can be extended to every two to three years.
Patients with an aortic diameter exceeding 45 millimeters require annual echocardiographic surveillance. More frequent monitoring, every six months, may be warranted if there is rapid aortic growth (an increase greater than 3 millimeters per year) or if the diameter exceeds 50 millimeters. This regular assessment is important for identifying any progression of the condition and determining the appropriate timing for potential interventions, such as surgical repair or replacement.