Cardiac Medicine Certification (CMC) Practice Exam

What is the significance of monitoring for a new-onset holosystolic murmur in lateral wall myocardial infarction?

1. Indicates an increase in heart rate

2. Signifies papillary muscle dysfunction

3. Represents decreased blood pressure

4. Shows improvement in renal function

The correct answer is: Signifies papillary muscle dysfunction

The presence of a new-onset holosystolic murmur in the context of lateral wall myocardial infarction is significant because it typically indicates papillary muscle dysfunction. In myocardial infarction, particularly involving the lateral wall, ischemia can compromise the structural integrity of the heart's muscle, including the papillary muscles, which are essential for normal valve function, particularly the mitral valve. When the papillary muscles are affected due to ischemic damage, they can no longer adequately support the mitral valve leaflets during systole. This dysfunction may lead to the development of mitral regurgitation, which is characterized by a holosystolic murmur, heard best at the apex and often radiating to the left axilla. This murmur reflects the abnormal backflow of blood from the left ventricle into the left atrium during systole, ultimately indicating a potential complication of the myocardial infarction that may require urgent intervention. The other options do not have a direct correlation to the development of a holosystolic murmur in this setting. An increase in heart rate, decreased blood pressure, or improvement in renal function do not inherently cause or indicate the presence of a new murmur due to papillary muscle dysfunction. Thus, recognizing