How should a patient with a bicuspid aortic valve and a harsh systolic ejection murmur be evaluated and managed?

Evaluation and Management of Bicuspid Aortic Valve with Systolic Ejection Murmur

Order transthoracic echocardiography immediately to assess valve morphology, quantify stenosis or regurgitation severity, evaluate left ventricular function, and measure the ascending aorta dimensions. 1

Initial Diagnostic Evaluation

Physical Examination Findings to Document

• Murmur characteristics: A harsh systolic ejection murmur in bicuspid aortic valve typically indicates developing stenosis, though murmur intensity does not reliably correlate with severity—even severe stenosis can present with a soft murmur if cardiac output is reduced 1, 2
• Carotid pulse assessment: Look for parvus et tardus (slow-rising, diminished pulse), though this may be absent in elderly patients with arterial stiffening 2
• Second heart sound: An early systolic ejection click heard during both inspiration and expiration is pathognomonic for bicuspid aortic valve 1, 3; a soft or absent A2 suggests severe stenosis 2, 4
• Assess for symptoms: Specifically ask about exertional dyspnea, syncope, angina, and exercise tolerance—patients often under-report symptoms 2

Transthoracic Echocardiography Protocol

The echocardiogram must include: 1

• Valve morphology assessment: Determine cusp fusion pattern (right-left coronary cusp fusion is most common; right-noncoronary fusion associates with more aortic dilation) 1
• Stenosis quantification: Measure peak velocity, mean gradient, and aortic valve area by continuity equation 1
• Regurgitation severity: Assess using color Doppler, jet width, and vena contracta 1
• Left ventricular function and dimensions: Document ejection fraction, end-diastolic and end-systolic dimensions 1
• Aortic measurements at multiple levels: Annulus, sinuses of Valsalva, sinotubular junction, and mid-ascending aorta 1
• Descending aorta Doppler: Screen for associated coarctation 1

Critical Diagnostic Pitfalls

When Physical Exam and Echo Disagree

If the physical examination suggests severe stenosis (late-peaking murmur, absent A2, parvus et tardus) but echocardiography shows only mild stenosis, the echocardiogram has likely underestimated severity—proceed to cardiac catheterization for direct gradient measurement. 1

Common causes of echocardiographic underestimation include: 1

• Poor Doppler alignment with the stenotic jet
• Low-flow/low-gradient state masking true severity
• Pressure recovery phenomenon in small aortic roots

Low-Flow/Low-Gradient Aortic Stenosis

When echo shows valve area <1.0 cm² but mean gradient <40 mmHg: 1, 2

• Perform low-dose dobutamine stress echocardiography to differentiate true severe stenosis from pseudo-severe stenosis
• True severe stenosis: Valve area remains <1.0 cm² despite increased flow with dobutamine
• Pseudo-severe stenosis: Valve area increases >0.2 cm² with augmented contractility
• This distinction is critical because only true severe stenosis warrants intervention

Aortopathy Assessment

Advanced Imaging Indications

Order cardiac MRI or CT angiography if: 5

• Ascending aorta diameter >4.0 cm on echocardiography
• Echocardiographic visualization of the ascending aorta is incomplete (occurs in ~20-30% of patients) 1
• Any aortic dilation is detected, to establish baseline for surveillance

Cardiac MRI is preferred over CT in younger patients to avoid cumulative radiation exposure from serial surveillance imaging 5

Aortic Dilation Patterns

• 50% of bicuspid aortic valve patients have aortic root involvement 5
• Patients with right-noncoronary cusp fusion have higher prevalence of aortic dilation (68% vs 40%) and more commonly develop ascending aortic aneurysms extending to the transverse arch 1
• Bicuspid aortic valve patients are at increased risk for aortic dissection, with 15% of acute dissections occurring at diameters <5.0 cm 1

Surveillance Strategy

For Valve Dysfunction

Asymptomatic patients with bicuspid aortic valve require serial echocardiography: 5

• Severe stenosis: Annually
• Moderate stenosis: Every 1-2 years
• Mild stenosis or regurgitation: Every 3-5 years
• Any change in symptoms: Immediate echocardiography regardless of scheduled interval

For Aortopathy

Aortic imaging intervals: 5

• No dilation: Echocardiography alone for valve surveillance
• Mild dilation (<4.0 cm): MRI or CT every 3-5 years
• Moderate dilation (4.0-4.5 cm): Annual MRI or CT
• Severe dilation (>4.5 cm): Annual imaging and surgical evaluation

Family Screening

Screen all first-degree relatives with transthoracic echocardiography, as 9-20% of family members also have bicuspid aortic valve and/or thoracic aortic aneurysms—family members can have aortic aneurysms even without bicuspid valve. 1

Management Thresholds

Indications for Intervention

Aortic valve replacement is indicated when: 1

• Any symptoms (dyspnea, syncope, angina) develop with severe stenosis or regurgitation
• Severe stenosis (valve area <1.0 cm², mean gradient ≥40 mmHg) with left ventricular ejection fraction <50%
• Severe regurgitation with left ventricular end-systolic dimension >50 mm or ejection fraction <50%

Concomitant aortic surgery is indicated when: 5

• Ascending aorta diameter >4.5 cm at time of valve surgery
• Ascending aorta diameter >5.0 cm even without valve surgery indication

Special Consideration for Young Adults

In young adults with isolated aortic stenosis, balloon aortic valvuloplasty may serve as effective temporizing treatment before definitive valve replacement becomes necessary. 5