American Board of Internal Medicine (ABIM) Certification Practice Exam

For patients with severe mitral regurgitation, which dimension for volume contraction is indicative?

1. Less than 30 mL/beat

2. 30-59 mL/beat

3. 60 mL/beat or greater

4. Exactly 40 mL/beat

The correct answer is: 60 mL/beat or greater

In patients with severe mitral regurgitation, assessing the effective forward volume contraction of the heart is important for understanding the hemodynamic impact of the condition. The volume contracted with each heartbeat indicates the efficiency of the heart's pumping capability. Typically, a left ventricular stroke volume of 60 mL/beat or greater signifies a more robust and effective contraction. In severe mitral regurgitation, even though there is a volume overload because of the backflow of blood into the left atrium, effective forward flow is crucial for maintaining adequate perfusion to the systemic circulation. When the forward volume is 60 mL/beat or greater, this suggests the left ventricle is compensating well despite the regurgitation. It indicates that the heart is still capable of generating an adequate output to meet the body's demands, which can be pivotal when determining treatment needs for these patients, such as surgical intervention. Volume contractions less than 60 mL/beat often suggest suboptimal forward flow, which could be a concern in severe mitral regurgitation cases as it may lead to symptoms of heart failure. Therefore, recognizing a stroke volume of 60 mL/beat or higher aligns with clinical expectations for volume contraction in this disease state.