A 17-year-old boy presents to his primary care physician to discuss shortness of breath while playing basketball, which has worsened over the past few years. Past medical history is noncontributory, and he takes no medications. Family medical history is significant for the sudden death of the patient’s father (who was otherwise healthy) at age 36. Physical examination reveals a cardiac murmur. Electrocardiogram reflects normal sinus rhythm with a left axis deviation. An echocardiogram confirms the presence of left ventricular hypertrophy.
B) Crescendo-decrescendo systolic murmur at the lower left sternal border
This describes the murmur of hypertrophic cardiomyopathy (HCM), which is often accompanied by a family history of sudden death in young individuals during periods of activity. This murmur may radiate to the axilla and base but usually not into the neck. Pathogenesis is related to asymmetric ventricular hypertrophy (reflected by a left axis deviation on electrocardiogram) which results in reduced cardiac output. Treatment is with beta blockers or calcium channel blockers, which allow the heart more time to fill.
Answer choice A: Crescendo-decrescendo systolic murmur at the right upper sternal border, is incorrect. This describes the murmur of aortic stenosis. Although aortic stenosis may also present with dyspnea, a family history of sudden cardiac death at a young age suggest HCM.
Answer choice C: Decrescendo diastolic murmur at the left upper sternal border, is incorrect. This describes the murmur of valvular aortic regurgitation. Causes of valvular aortic regurgitation include infective endocarditis and myxomatous degeneration, among others.
Answer choice D: Midsystolic murmur with wide and fixed S2 splitting, is incorrect. These findings are characteristic of an atrial septal defect. Although atrial septal defects can be linked to certain genetic conditions such as Down syndrome and Turner syndrome, they do not typically cause sudden death in young people.
Answer choice E: Soft and delayed aortic component of S2, is incorrect. This finding is present with aortic stenosis, which also presents with a crescendo-decrescendo systolic murmur best heard at the right upper sternal border.
Key Learning Point
Hypertrophic cardiomyopathy (HCM) often presents with dyspnea in patients who have a family history of sudden death in young individuals. Asymmetric ventricular hypertrophy may present as a left axis deviation on electrocardiogram. Physical exam will reveal a crescendo-decrescendo systolic murmur best heard at the mid-left sternal border, which is in contrast to the murmur of aortic stenosis that is best heard at the right upper sternal border.
