Bicuspid Aortic Valve Murmur
An early systolic ejection sound (click) heard during both inspiration and expiration, often accompanied by a midsystolic murmur, is the characteristic auscultatory finding of a bicuspid aortic valve 1, 2.
Characteristic Murmur Features
The bicuspid aortic valve typically presents with:
Early aortic systolic ejection sound (click): This is the most specific finding, occurring synchronously with the final halting of the opening aortic valve cusps 3. Critically, this ejection sound is heard during both inspiration and expiration, which distinguishes it from pulmonic valve stenosis (where the ejection sound is heard only during expiration) 1, 2.
Midsystolic (ejection) murmur: Often present even without significant stenosis, typically grade 2-3/6, crescendo-decrescendo in configuration 1.
Location consideration: When the diastolic murmur of aortic regurgitation is louder in the third and fourth right intercostal spaces than in the left intercostal spaces, this suggests the AR results from aortic root dilatation rather than leaflet deformity alone 2.
Recommended Evaluation
All patients with known or suspected bicuspid aortic valves must undergo an initial transthoracic echocardiogram (TTE) to assess both valve function AND aortic dimensions 2.
Initial Diagnostic Workup (Class I Recommendations):
Transthoracic echocardiography to evaluate 2, 4:
- Valve morphology (number of cusps best seen in parasternal short-axis view during systole showing only two commissures and an elliptical orifice) 5
- Presence and severity of aortic stenosis or regurgitation
- Aortic root diameter at multiple levels (annulus, sinuses of Valsalva, sinotubular junction, mid-ascending aorta)
- Left ventricular size and function
Advanced imaging with cardiac MRI or CT angiography when 2, 6:
- TTE cannot adequately visualize the ascending aorta beyond 4-5 cm from the valve
- Morphology of aortic root or ascending aorta cannot be assessed accurately by echo
- CMR is preferred over CT to avoid radiation exposure in these typically younger patients who will require lifelong surveillance 6
Surveillance Strategy Based on Initial Findings:
The initial echocardiogram findings dictate all future surveillance intensity 7:
If Normal Valve Function and Aortic Diameter <4.0 cm:
- Repeat imaging every 3-5 years 8
- These patients have extremely low risk of intervention in childhood/early adulthood 7
If Aortic Diameter ≥4.0 cm:
- Annual imaging is required (TTE, CMR, or CT) 2, 6, 4
- More frequent imaging (every 6 months) if diameter >4.5 cm or rapid progression 6
If Any Degree of Aortic Stenosis Present Initially:
- These patients require closer surveillance as they have significantly higher risk of:
- Follow-up interval: every 6-12 months depending on severity 8
If Moderate-Severe Aortic Regurgitation:
- Every 6-12 months with assessment of LV size and function 8
- More frequent (3-6 months) if LV dimensions are increasing 8
Critical Pitfalls to Avoid:
Don't rely on M-mode echocardiography alone: Studies show M-mode is entirely normal in non-stenotic bicuspid valves and cannot diagnose the condition 9. The parasternal short-axis view during systole is essential for diagnosis 5.
Don't forget aortic screening: 20-40% of bicuspid valve patients have associated aortopathy, and this can progress independently of valve dysfunction 4, 10. Missing aortic dilation is a major oversight.
Screen first-degree relatives: Consider TTE screening in first-degree relatives, as 20-30% may also have bicuspid valves or aortopathy 6, 8, 4.
Don't assume benign course in infants/children: While those with normal valve function at initial diagnosis rarely need intervention early, any stenosis or aortic dilation at baseline predicts future problems and mandates closer follow-up 7.
Measure aorta at multiple levels: The ascending aorta can dilate at different segments (sinuses, sinotubular junction, mid-ascending), and missing one segment can lead to underestimation of risk 6, 4.