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Difficulty: MediumPhysical Examination Findings

A healthy young adult male, aged 23, arrives at an occupational medicine office to undergo medical clearance for a new physically demanding job. He denies any history of exertional dyspnea, precordial discomfort, or lightheadedness. He maintains an active lifestyle, engaging in high-intensity interval training regularly without limitation. Vital signs demonstrate a temperature of 37.0°C (98.6°F), a blood pressure measurement of 110/70 mmHg, and a resting heart rate of 62/min. Evaluation of the precordium demonstrates a quiet, non-displaced apical impulse. Cardiac auscultation identifies a grade 2/6 crescendo-decrescendo mid-systolic murmur located at the left upper sternal border. When the clinician asks him to stand quickly from a supine position, the amplitude of the murmur significantly diminishes. A physiologic split of the second heart sound is appreciated during inspiration. The remainder of the physical assessment is entirely within normal limits. Based on these physical examination findings, which of the following is the most appropriate next diagnostic step?

  1. Clinical reassurance with no further diagnostic testingAnswer
  2. B
    Comprehensive transthoracic echocardiography
  3. C
    Diagnostic exercise stress testing
  4. D
    Measurement of serum N-terminal pro-B-type natriuretic peptide
  5. E
    Referral to cardiology for suspected hypertrophic cardiomyopathy

Answer

Clinical reassurance with no further diagnostic testing
The patient exhibits classic physical examination findings of an innocent (physiologic) flow murmur. These features include a grade ≤ 2/6 intensity, a mid-systolic crescendo-decrescendo pattern, location at the left sternal border, and normal splitting of the second heart sound in an asymptomatic, healthy individual. Crucially, the murmur decreases in intensity when the patient stands. Standing reduces venous return (preload) to the right heart. For most murmurs, including innocent flow murmurs, decreased blood volume across the valve leads to a softer sound. Because the history and physical examination findings confidently establish a benign diagnosis, clinical reassurance is the only appropriate step; no further diagnostic testing is warranted.

Step-by-Step Solution

1
Analyze the patient's baseline clinical status.
The patient is a healthy, asymptomatic 23-year-old with excellent exercise tolerance.
The absence of symptoms such as syncope, chest pain, or dyspnea lowers the pretest probability of structural heart disease.
2
Characterize the auscultated murmur.
The murmur is grade 2/6, mid-systolic, and located at the left upper sternal border with a normal S2 split.
These are classic baseline characteristics of an innocent (physiologic) flow murmur. Pathologic murmurs are more likely to be holosystolic, diastolic, or grade 3/6 and above.
3
Interpret the effect of dynamic physical maneuvers on the murmur.
The murmur's intensity diminishes upon standing.
Standing decreases venous return (preload). Less blood flowing across a normal valve produces a softer sound, confirming an innocent flow murmur. Conversely, the murmur of hypertrophic cardiomyopathy (HOCM) would increase in intensity when standing.
4
Determine the appropriate management.
Clinical reassurance is provided.
Current guidelines dictate that asymptomatic young patients with definitively innocent murmurs on physical examination require no further diagnostic imaging or laboratory workup.

Key Concept

Physical examination differentiation of innocent flow murmurs from pathologic murmurs using dynamic maneuvers
Estimated Time:1m 0s
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Topics

Physical Examination Findings

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