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Question

Difficulty: EasyCardiovascular System

A 68-year-old man presents to the outpatient clinic reporting a three-week history of worsening swelling in his lower extremities and an uncomfortable sensation of abdominal fullness. He has a 45-pack-year smoking history and was diagnosed with severe chronic obstructive pulmonary disease (COPD) five years ago, for which he takes inhaled bronchodilators and corticosteroids. Vital signs show a blood pressure of 118/76 mmHg, a heart rate of 88/min, and an oxygen saturation of 89% on room air. Physical examination reveals prominent jugular venous distention and a palpable parasternal heave. Auscultation of the chest demonstrates distant breath sounds with a prolonged expiratory phase, but no crackles are heard. A holosystolic murmur is auscultated at the lower left sternal border that increases in intensity with inspiration. Tender hepatomegaly is noted on abdominal palpation. Which of the following pathophysiologic mechanisms is the most direct cause of this patient's cardiovascular findings?

  1. A
    Impaired left ventricular contractility due to coronary artery disease
  2. B
    Acute bacterial infection causing severe airway inflammation
  3. C
    Retrograde pressure transmission from primary aortic valve stenosis
  4. Chronic hypoxia-induced pulmonary arterial vasoconstrictionAnswer
  5. E
    Inadequate renal bicarbonate retention for acid-base compensation

Answer

Chronic hypoxia-induced pulmonary arterial vasoconstriction
The patient's presentation of jugular venous distention, parasternal heave, a murmur consistent with tricuspid regurgitation (holosystolic at the left sternal border increasing with inspiration), tender hepatomegaly, and peripheral edema in the setting of severe COPD without pulmonary crackles points directly to cor pulmonale (right-sided heart failure). In chronic lung diseases like COPD, chronic alveolar hypoxia leads to diffuse pulmonary vasoconstriction as the body attempts to shunt blood to better-ventilated areas. When the hypoxia is global, this vasoconstriction causes significant pulmonary hypertension, resulting in right ventricular pressure overload, hypertrophy, and eventual right-sided heart failure.

Step-by-Step Solution

1
Analyze the patient's physical examination findings.
The patient has jugular venous distention, a parasternal heave, a tricuspid regurgitation murmur (increases with inspiration), tender hepatomegaly, and peripheral edema.
These findings are classic signs of right-sided heart failure and systemic venous congestion.
2
Evaluate the pulmonary findings in the context of the cardiac examination.
The patient has severe COPD (prolonged expiration, hypoxemia) but lacks pulmonary crackles.
The absence of crackles indicates that the right-sided heart failure is not secondary to left-sided heart failure (which would cause pulmonary edema).
3
Link the chronic pulmonary disease to the isolated right-sided heart failure.
The diagnosis is cor pulmonale.
Chronic alveolar hypoxia from COPD causes widespread pulmonary vasoconstriction. Over time, this increases pulmonary vascular resistance, leading to right ventricular pressure overload and failure.

Key Concept

Cor Pulmonale Pathophysiology
Estimated Time:1m 0s
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Topics

Cardiovascular System

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