Which description best fits hypertrophic obstructive cardiomyopathy?

• A. Over 60 years old with chest pain; systolic murmur that decreases with Valsalva; absence of S4
• B. Neonate with cyanosis; diastolic murmur
• C. 40-Year-Old With Dyspnea; continuous murmur
• D. Under 35 years old, syncope during tachycardia; systolic crescendo-decrescendo murmur that increases with Valsalva; S4

Answer: (D)

In hypertrophic obstructive cardiomyopathy, the key ideas are a dynamic left ventricular outflow tract obstruction from asymmetric septal hypertrophy, a systolic murmur that changes with preload, and signs of a stiff, thickened ventricle such as an S4. This condition often presents in younger patients and can cause syncope during tachycardia when the heart has less time to fill and the obstruction worsens.

The described scenario fits best because a patient under 35 experiences syncope during tachycardia, which aligns with reduced diastolic filling and greater obstruction during rapid heart rates. The murmur is systolic and crescendo-decrescendo and increases with Valsalva (which decreases preload and enhances the obstruction). The presence of an S4 reflects a stiff, hypertrophied ventricle from the hypertrophic process.

This contrasts with the other scenarios: an older adult with chest pain and a murmur that diminishes with Valsalva points more toward a fixed outflow lesion like aortic stenosis; a neonate with cyanosis and a diastolic murmur suggests a congenital defect with non-systolic flow abnormalities; a middle-aged patient with a continuous murmur implies a left-to-right shunt such as a PDA, not dynamic LVOT obstruction.