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Difficulty: MediumCardiovascular System

During a routine follow-up appointment, a 6969-year-old man is evaluated in the outpatient clinic for a 11-month history of steadily increasing abdominal girth and swelling in both legs. He has a known history of severe chronic obstructive pulmonary disease (COPD) and is adherent to an inhaled corticosteroid, a long-acting beta-agonist, and a long-acting muscarinic antagonist. He quit smoking 33 years ago after a 4545-pack-year history. The patient reports worsening exertional fatigue but explicitly denies waking up gasping for air at night or having trouble breathing when lying flat. Vital signs reveal a blood pressure of 126/80126/80 mm Hg, a heart rate of 9292/min, and a respiratory rate of 1818/min. Pulse oximetry shows an oxygen saturation of 87%87\% on room air. Physical examination demonstrates distended neck veins. Lung auscultation reveals globally decreased breath sounds and a prolonged expiratory phase, with no crackles appreciated. Cardiac examination shows a prominent parasternal impulse and a holosystolic murmur at the left lower sternal border that augments in intensity during inspiration. Abdominal exam is notable for a tender, palpable liver edge 44 cm below the right costal margin. Bilateral 3+3+ pitting edema is present up to the knees. Which of the following interventions is most likely to slow the progression of this patient's underlying cardiac condition and improve long-term survival?

  1. Supplemental oxygen therapyAnswer
  2. B
    Oral lisinopril
  3. C
    Oral metoprolol succinate
  4. D
    Oral furosemide
  5. E
    Oral sildenafil

Answer

Supplemental oxygen therapy
This patient's presentation of prominent jugular venous distention, a holosystolic murmur that augments with inspiration (tricuspid regurgitation), pulsatile hepatomegaly, and lower extremity edema in the absence of pulmonary crackles or orthopnea strongly indicates isolated right-sided heart failure. In the context of severe chronic obstructive pulmonary disease (COPD) and resting hypoxemia, this points to a diagnosis of cor pulmonale. The pathogenesis of cor pulmonale involves chronic alveolar hypoxia, which triggers hypoxic pulmonary vasoconstriction. Over time, this generalized vasoconstriction increases pulmonary vascular resistance, resulting in pulmonary hypertension and subsequent right ventricular hypertrophy and failure. Long-term supplemental oxygen therapy is the most appropriate disease-modifying intervention. It directly reverses the hypoxic vasoconstriction, thereby reducing pulmonary artery pressures, slowing the progression of cor pulmonale, and significantly improving long-term survival. Indications for long-term oxygen therapy in COPD include a resting arterial oxygen tension (PaO2\text{PaO}_2) of ≤55\leq 55 mm Hg or an oxygen saturation (SaO2\text{SaO}_2) of ≤88%\leq 88\%, or a PaO2\text{PaO}_2 of ≤59\leq 59 mm Hg with evidence of cor pulmonale or polycythemia.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and physical examination findings.
The patient exhibits signs of isolated right-sided heart failure: jugular venous distention, a holosystolic murmur of tricuspid regurgitation, pulsatile hepatomegaly, and peripheral edema. He lacks signs of left-sided heart failure, such as orthopnea or pulmonary crackles.
Differentiating between right and left heart failure is critical for establishing the underlying etiology and determining the correct disease-modifying therapy.
2
Identify the primary etiology of the patient's heart failure.
Given the history of severe COPD, chronic resting hypoxemia (SaO2\text{SaO}_2 87%87\% on room air), and isolated right heart failure, the diagnosis is cor pulmonale.
Chronic alveolar hypoxia from advanced COPD causes hypoxic pulmonary vasoconstriction, leading to pulmonary hypertension and subsequent right ventricular hypertrophy and failure.
3
Determine the optimal intervention to improve survival for this specific etiology.
Long-term supplemental oxygen therapy is the most appropriate intervention.
Oxygen relieves the hypoxic pulmonary vasoconstriction, which lowers pulmonary artery pressures, slows the progression of cor pulmonale, and is proven to improve mortality in patients with COPD and resting hypoxemia (SaO2\text{SaO}_2 ≤88%\leq 88\%).

Key Concept

Cor pulmonale secondary to COPD and the mortality benefit of long-term supplemental oxygen therapy
Estimated Time:1m 30s
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Topics

Cardiovascular System

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