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Difficulty: EasyCardiovascular System

A 75-year-old man presents to the emergency department with acute-onset, severe dyspnea that woke him from sleep. He has a history of a myocardial infarction 5 years ago and a 45-pack-year smoking history. His blood pressure is 165/95 mmHg, heart rate is 112/min, and respiratory rate is 28/min. Pulse oximetry is 88% on room air. He is visibly distressed, sitting on the edge of the stretcher, and coughing up pink, frothy sputum. Pulmonary auscultation reveals diffuse bilateral wheezes and scattered crackles. Which of the following physical examination findings would most strongly support a primary cardiac etiology for this patient's acute respiratory distress over a primary pulmonary exacerbation?

  1. A
    Prolonged expiratory phase on auscultation
  2. B
    Hyperresonance to lung percussion
  3. Presence of a third heart sound (S3)Answer
  4. D
    Increased anteroposterior chest diameter
  5. E
    Prominent use of accessory muscles of respiration

Answer

Presence of a third heart sound (S3)
The correct answer represents a highly specific physical examination finding for acute decompensated heart failure. A third heart sound (S3) occurs during early diastole and reflects rapid ventricular filling into a non-compliant or volume-overloaded left ventricle. In a patient with risk factors for both heart disease and chronic lung disease who presents with wheezing (which can be 'cardiac asthma' due to peribronchial airway edema), an S3 gallop is a definitive sign pointing toward a primary cardiac etiology.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient presents with severe dyspnea, orthopnea, hypoxemia, pink and frothy sputum, and bilateral wheezing.
To synthesize the clinical signs and recognize the acute life-threatening respiratory distress.
2
Distinguish between competing diagnoses based on risk factors.
The patient has significant risk factors for both acute decompensated heart failure (prior myocardial infarction) and a COPD exacerbation (heavy smoking history).
To narrow the differential diagnosis to the two most likely etiologies.
3
Identify the most specific differentiating clinical sign.
An S3 gallop is a highly specific indicator of increased left ventricular end-diastolic pressure and volume overload.
Wheezing can occur in heart failure due to peribronchial edema (cardiac asthma), meaning pulmonary signs alone may not differentiate the two conditions as clearly as a specific cardiac sign.

Key Concept

Differentiating acute decompensated heart failure (cardiac asthma) from chronic obstructive pulmonary disease (COPD) exacerbation using specific physical examination findings.
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Topics

Cardiovascular System

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