Which statement is true regarding hypertrophic cardiomyopathy murmurs?

Which statement is true regarding hypertrophic cardiomyopathy murmurs?

• A. Heard in the 4th and 5th intercostal spaces and varies with standing or sitting
• B. Radiates to the carotids
• C. Is a diastolic murmur
• D. Is associated with a dilated ventricle

Answer: (A)

Hypertrophic cardiomyopathy murmurs are dynamic systolic murmurs caused by obstruction of the left ventricular outflow tract from asymmetric septal hypertrophy, and their loudness changes with preload. The murmur is best heard at the left lower sternal border, around the 4th to 5th intercostal spaces, and it fluctuates with body position because changing preload alters the degree of obstruction. When standing or performing maneuvers that reduce preload, the obstruction worsens and the murmur becomes louder; when you sit or squat and preload increases, the murmur softens. This pattern helps distinguish it from other murmurs. For example, radiating to the carotids is typical of aortic stenosis, not HCM. The murmur of HCM is systolic, not diastolic, and the ventricle is usually hypertrophied rather than dilated.

Hypertrophic cardiomyopathy murmurs are dynamic systolic murmurs caused by obstruction of the left ventricular outflow tract from asymmetric septal hypertrophy, and their loudness changes with preload. The murmur is best heard at the left lower sternal border, around the 4th to 5th intercostal spaces, and it fluctuates with body position because changing preload alters the degree of obstruction. When standing or performing maneuvers that reduce preload, the obstruction worsens and the murmur becomes louder; when you sit or squat and preload increases, the murmur softens.

This pattern helps distinguish it from other murmurs. For example, radiating to the carotids is typical of aortic stenosis, not HCM. The murmur of HCM is systolic, not diastolic, and the ventricle is usually hypertrophied rather than dilated.