National Board of Chiropractic Examiners (NBCE) Practice Test

What is the most likely cause of a pansystolic murmur?

1. Aortic stenosis

2. Mitral regurgitation

3. Tricuspid stenosis

4. Hypertrophic cardiomyopathy

The correct answer is: Mitral regurgitation

A pansystolic murmur, also known as a holosystolic murmur, is characterized by its continuous sound throughout the entire systole phase of the cardiac cycle. The most common and prominent cause of a pansystolic murmur is mitral regurgitation. In mitral regurgitation, the mitral valve does not close properly during systole, allowing blood to flow backward from the left ventricle into the left atrium. This backflow of blood creates turbulence, which is heard as a continuous murmur throughout systole. The other options correspond to different types of murmurs or conditions that do not typically produce a pansystolic murmur. For instance, aortic stenosis generally leads to a systolic ejection murmur that occurs between S1 and S2 and is not continuous throughout the systole. Tricuspid stenosis typically produces a diastolic murmur rather than a systolic one, and hypertrophic cardiomyopathy can cause systolic murmurs, but they are often not pansystolic in nature and can vary depending on the specific dynamics of blood flow in the condition. Therefore, the characteristics of mitral regurgitation clearly delineate it as the most common cause of a pans