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Difficulty: MediumPhysical Examination Findings

A 22-year-old man is evaluated in the cardiology clinic following a syncopal episode that occurred while he was playing a collegiate basketball game. Over the past three months, he has experienced occasional dyspnea on intense exertion. He has no significant past medical history and takes no medications. His family history is notable for the sudden cardiac death of his maternal uncle at age 25. His temperature is 37.0°C (98.6°F), blood pressure is 118/74 mmHg, pulse is 72/min, and respirations are 14/min. Based on the most likely underlying condition, which of the following physical examination findings are expected in this patient? (Select all that apply)

  1. A harsh crescendo-decrescendo systolic murmur at the left lower sternal border that increases in intensity during the Valsalva maneuverAnswer
  2. A rapid, biphasic carotid pulse with two distinct systolic peaksAnswer
  3. C
    A delayed and diminished carotid arterial pulse upstroke
  4. D
    A late-peaking systolic murmur that radiates broadly to the carotid arteries
  5. E
    An early diastolic decrescendo murmur best heard at the right upper sternal border

Answer

A harsh crescendo-decrescendo systolic murmur at the left lower sternal border that increases in intensity during the Valsalva maneuver AND a rapid, biphasic carotid pulse with two distinct systolic peaks.
The correct findings directly reflect the dynamic left ventricular outflow tract (LVOT) obstruction characteristic of hypertrophic cardiomyopathy (HCM). The harsh crescendo-decrescendo systolic murmur of HCM becomes louder with the Valsalva maneuver because decreased venous return leads to a smaller left ventricular cavity, which exacerbates the outflow obstruction. Furthermore, patients with HCM often exhibit a pulsus bisferiens (biphasic carotid pulse) due to a rapid initial ventricular ejection followed by a sudden drop in flow as the outflow tract dynamically narrows mid-systole.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and demographics.
The patient is a young athlete with exertional syncope, exertional dyspnea, and a family history of sudden premature cardiac death.
Identifying the classic triad of symptoms and family history strongly points toward hypertrophic cardiomyopathy (HCM) as the most likely diagnosis.
2
Determine the pathophysiological mechanism of the suspected disease.
HCM is characterized by asymmetric septal hypertrophy leading to a dynamic left ventricular outflow tract (LVOT) obstruction.
Understanding the dynamic nature of the obstruction is necessary to predict how the physical examination findings will present and change with physiologic maneuvers.
3
Correlate the pathophysiology with specific physical examination findings.
The dynamic LVOT obstruction produces a harsh systolic murmur that worsens when left ventricular volume decreases (e.g., during the Valsalva maneuver or standing). Additionally, the rapid initial ejection of blood followed by sudden obstruction creates a biphasic carotid pulse (pulsus bisferiens).
Selecting the findings that specifically match this dynamic physiology rules out other causes of exertional syncope like fixed aortic stenosis.

Key Concept

Hypertrophic cardiomyopathy typically presents with a harsh systolic murmur that increases in intensity with maneuvers that decrease preload (such as the Valsalva maneuver), and a biphasic carotid pulse (pulsus bisferiens).
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Physical Examination Findings

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