Valvular Disease Assessment on Stress Echocardiography

Understanding Valvular Disease Assessment on Stress Echocardiography

Stress echocardiography provides dynamic assessment of valve function, revealing how valves behave under stress and explaining symptoms that may not be apparent at rest. This specialized test is particularly valuable when there's a discrepancy between the severity of valve disease and the patient's symptoms.

Unlike standard stress testing for ischemia, valvular stress testing focuses on changes in valve hemodynamics, pulmonary pressures, and functional capacity to guide treatment decisions.

When Is Stress Echo Used for Valve Disease?

Clinical Scenarios

Aortic stenosis with low gradient:

• Severe stenosis on valve area but low gradient
• Question of true severity vs. pseudosevere
• Low-flow, low-gradient AS assessment
• Determines need for intervention

Symptomatic mitral regurgitation:

• Discrepancy between MR severity and symptoms
• Exercise-induced pulmonary hypertension
• Determining if symptoms are from valve disease

Dyspnea evaluation:

• Is dyspnea from valve disease?
• Exercise-induced symptoms
• Pulmonary hypertension evaluation

Prosthetic valve assessment:

• Prosthetic valve hemodynamics
• Exercise tolerance
• Valve dysfunction detection

Specific Applications

Low-Flow, Low-Gradient Aortic Stenosis

The challenge:

• Aortic valve area ＜ 1.0 cm² (suggests severe)
• Mean gradient ＜ 40 mmHg (suggests moderate)
• Stroke volume low
• Is AS truly severe or pseudosevere?

Dobutamine stress protocol:

• Low-dose dobutamine (5-20 mcg/kg/min)
• Increases stroke volume
• Measures how gradient and valve area change

Interpretation:

• True severe AS: Valve area remains ＜ 1.0 cm², gradient increases ＞ 40 mmHg
• Pseudosevere AS: Valve area increases ＞ 1.0 cm² (flow reserve present)
• No flow reserve: Unable to increase stroke volume (poor prognosis)

Exercise-Induced Mitral Regurgitation

Stress testing for mitral regurgitation:

Questions answered:

1. Is MR actually severe?
2. Are symptoms due to MR?
3. Is pulmonary pressure elevation exercise-induced?
4. What is surgical risk?

Exercise protocol:

• Supine bicycle ergometer preferred
• Continuous imaging during exercise
• Measures changes in MR severity

Abnormal responses:

• ＞ 15 mmHg increase in pulmonary artery systolic pressure
• Worsening MR severity with exercise
• Abnormal blood pressure response
• Limited exercise capacity

Exercise-Induced Pulmonary Hypertension

When suspected:

• Dyspnea out of proportion to resting valve severity
• Exertional symptoms with mild/moderate valve disease
• Preoperative risk assessment

Diagnostic criteria:

• PASP increase ＞ 60 mmHg with exercise
• Inappropriate increase for workload
• Associated with symptoms

Clinical Presentation

Typical Patient Scenarios

Symptoms Requiring Evaluation

When stress echo is indicated:

• Symptoms disproportionate to resting severity
• Unclear symptom origin
• Low-flow, low-gradient aortic stenosis
• Exercise-induced pulmonary hypertension
• Preoperative fitness assessment
• Prosthetic valve concerns

Differential Diagnosis

Management Based on Results

Decision-Making Impact

Treatment Pathways

Prognosis and Outcomes

Impact of Stress Findings

With flow contractile reserve (good prognostic sign):

• Better response to aortic valve replacement
• Lower surgical mortality
• Better survival with surgery vs. medical therapy
• More likely to have symptom improvement

Without flow reserve (poor prognostic sign):

• Higher surgical mortality
• Limited functional improvement
• Poorer long-term survival
• Requires careful risk-benefit assessment

Special Populations

Prosthetic Valves

Stress echo for prosthetic valves:

• Assess valve hemodynamics under stress
• Detect patient-prosthesis mismatch
• Evaluate exercise tolerance
• Guide need for intervention

Pregnancy

Valve disease in pregnancy:

• Exercise stress echo may be safer than pharmacologic
• Assesses ability to tolerate pregnancy hemodynamics
• Guides monitoring and delivery planning

Frequently Asked Questions

Why do I need stress echo if I already had an echocardiogram?

Resting echocardiogram shows your valve function at rest, but stress echo shows how your valves and heart respond to physical activity. This is important when your symptoms occur with activity but appear mild on resting echo. Stress echo can reveal exercise-induced changes that guide treatment decisions.

What is low-flow, low-gradient aortic stenosis?

Low-flow, low-gradient aortic stenosis is a challenging form where the valve area suggests severe disease but the gradient is lower than expected. This occurs when stroke volume is low (often due to LV dysfunction). Stress echo helps determine if the stenosis is truly severe or appears worse than it actually is.

References

1. American Society of Echocardiography. Guidelines for Valvular Disease with Stress Echocardiography. 2023.
2. Lancellotti P, et al. Stress Testing in Valvular Heart Disease. Eur Heart J Cardiovasc Imaging. 2022.
3. Pibarot P, et al. Low-Flow, Low-Gradient Aortic Stenosis. J Am Coll Cardiol. 2023.

Medical Disclaimer: This information is educational only. Always discuss findings with your healthcare provider for personalized medical advice.