**Question:** The ejection systolic murmur in hyperopic obstructive cardiomyopathy is diminished when a patient -

* Core Concept: Ejection systolic murmur in hyperopic obstructive cardiomyopathy is a heart murmur caused by turbulent blood flow in the mitral and/or aortic valves during systole due to impaired valve function.

* Why the Correct Answer is Right: In hyperopic obstructive cardiomyopathy, the heart muscle is thickened and stiff, causing the heart valves to close abnormally and restrict blood flow. This results in a systolic murmur, which is reduced when the cardiac output is decreased.

* Why Each Wrong Option is Incorrect:
1. **Option A:** Increased cardiac output (CO) - An incorrect option since the murmur is reduced, not increased, with decreased cardiac output.
2. **Option B:** Normal cardiac output - This option is incorrect because the murmur is reduced, not preserved, in normal cardiac output conditions.
3. **Option C:** Decreased cardiac output - This option is correct as the murmur is reduced when cardiac output is decreased.
4. **Option D:** Increased peripheral vascular resistance - This option is irrelevant to the question, as the focus is on the cardiac output and murmur, not vascular resistance.

* Clinical Pearl: In hyperopic obstructive cardiomyopathy, the murmur is reduced when the cardiac output is decreased, which helps differentiate it from other murmur patterns in various cardiac conditions.

**Correct Answer:** C. Decreased cardiac output.