American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the criterion for diagnosing severe mitral stenosis based on diastolic pressure half-time?

1. Less than 150 msec

2. More than 150 msec

3. Exactly 150 msec

4. Less than 100 msec

The correct answer is: More than 150 msec

To diagnose severe mitral stenosis, the diastolic pressure half-time is a critical measurement. It reflects how quickly the left atrial pressure decreases during diastole, which is influenced by the severity of the mitral valve obstruction. A half-time measurement of more than 150 milliseconds indicates significant mitral stenosis. In this scenario, blood flow is severely restricted, leading to prolonged diastolic pressure decay. This finding is crucial as it assists clinicians in assessing the need for potential interventions such as balloon mitral valvuloplasty or surgical mitral valve replacement. In contrast, a measurement of less than 150 milliseconds suggests less severe obstruction. While there are less severe classifications for mitral stenosis based on half-time measurements, those values do not meet the threshold for a diagnosis of severe stenosis. Therefore, the criterion reflects the degree of hemodynamic impact the stenosis has on the patient's cardiac function.