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Difficulty: EasyCardiovascular System

A 71-year-old man is evaluated at the ambulatory clinic due to worsening exertional dyspnea and lower extremity swelling over the past week. He has a history of long-standing hypertension and a 35-pack-year smoking history. For the last three nights, he has been sleeping in a reclining chair to breathe comfortably. Vital signs show a blood pressure of 160/92 mm Hg, a pulse of 108/min, and a respiratory rate of 24/min. Physical examination demonstrates prominent jugular venous distention, a third heart sound (S3) gallop, bilateral basilar crackles, and scattered end-expiratory wheezes. Bilateral pitting edema is present up to the level of the knees. Which of the following is the most likely underlying cause of this patient's expiratory wheezing?

  1. Accumulation of fluid in the peribronchial interstitial spaceAnswer
  2. B
    Hypertrophy of bronchial mucinous glands
  3. C
    Irreversible enlargement of airspaces distal to terminal bronchioles
  4. D
    Hyperreactivity and smooth muscle constriction of the airways
  5. E
    Accumulation of purulent exudate within the alveolar spaces

Answer

Accumulation of fluid in the peribronchial interstitial space
The correct answer identifies that the patient's expiratory wheezing is due to the accumulation of fluid in the peribronchial interstitial space. This patient's classic presentation of orthopnea, elevated jugular venous distention, an S3 gallop, pulmonary crackles, and pitting edema strongly indicates acute decompensated heart failure (ADHF). In ADHF, left ventricular dysfunction leads to increased left atrial and pulmonary venous hydrostatic pressures. This pressure shift forces transudative fluid into the pulmonary interstitium. When this fluid accumulates in the peribronchial interstitial space, it causes external compression and narrowing of the small airways, leading to expiratory wheezing upon auscultation. This phenomenon is often referred to clinically as 'cardiac asthma'.

Step-by-Step Solution

1
Analyze the patient's presenting symptoms and physical examination findings.
The patient has orthopnea, elevated jugular venous pressure, an S3 gallop, bibasilar crackles, and severe lower extremity edema.
To establish the primary clinical syndrome driving the patient's presentation.
2
Synthesize the findings to formulate a primary diagnosis.
These findings are classic for acute decompensated heart failure (ADHF) characterized by both left-sided (crackles, orthopnea) and right-sided (JVD, peripheral edema) volume overload.
Identifying ADHF is necessary to correctly interpret the associated respiratory signs.
3
Determine the specific pathophysiology causing the wheezing in the context of heart failure.
In ADHF, elevated pulmonary capillary wedge pressure forces transudative fluid into the peribronchial interstitium, which physically compresses and narrows the small airways, leading to wheezing.
To directly answer the question regarding the exact etiology of the expiratory wheezes (cardiac asthma).

Key Concept

Wheezing in acute decompensated heart failure (often called cardiac asthma) is caused by peribronchial interstitial edema compressing the small airways, not by primary airway hyperreactivity or inflammation.
Estimated Time:1m 0s
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Topics

Cardiovascular System

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