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Difficulty: MediumCardiovascular System

An evaluation is requested for a 59-year-old man who comes to the outpatient clinic complaining of a progressive decline in his exercise tolerance over the past six months. He reports having to stop and catch his breath after walking just one block. The patient also notes a persistent dry cough, which frequently wakes him up at night. His medical history includes untreated hypertension and a 35-pack-year smoking history. Vital signs show a blood pressure of 162/98 mm Hg, a heart rate of 88/min, and an oxygen saturation of 94% on room air. On physical examination, the apical impulse is laterally displaced and sustained. Cardiac auscultation reveals a low-frequency diastolic sound just after S2 and a blowing, holosystolic murmur at the cardiac apex. Lung auscultation demonstrates bilateral basilar crackles without wheezing. In-office spirometry reveals a forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) ratio of 0.82. Which of the following is the most likely underlying mechanism for this patient's respiratory symptoms?

  1. Increased left ventricular end-diastolic pressureAnswer
  2. B
    Progressive destruction of alveolar walls and capillary beds
  3. C
    Chronic inflammation and narrowing of the small airways
  4. D
    Hypoxic pulmonary vasoconstriction leading to right ventricular dilation
  5. E
    Accumulation of fibrotic tissue reducing lung compliance

Answer

Increased left ventricular end-diastolic pressure
The correct answer identifies the underlying pathophysiology of left-sided heart failure. The patient's long-standing untreated hypertension has led to left ventricular failure, evidenced by the laterally displaced and sustained apical impulse, an S3 gallop, and a murmur of functional mitral regurgitation. As the left ventricle fails, the left ventricular end-diastolic pressure (LVEDP) rises. This elevated pressure is transmitted backward into the left atrium and pulmonary veins, causing pulmonary venous congestion and extravasation of fluid into the alveolar spaces. This fluid accumulation manifests as paroxysmal nocturnal dyspnea, exertional dyspnea, a dry cough (cardiac asthma), and bibasilar crackles on examination.

Step-by-Step Solution

1
Identify the primary cardiac physical exam findings.
The patient has a laterally displaced apical impulse, a third heart sound (S3), and a holosystolic murmur at the apex.
These findings are classic for left ventricular dilation and dysfunction, likely with secondary functional mitral regurgitation.
2
Evaluate the pulmonary symptoms and spirometry results.
The patient has dyspnea, orthopnea, and crackles, but spirometry shows a normal FEV1/FVC ratio of 0.82.
A normal FEV1/FVC ratio effectively rules out obstructive lung diseases such as COPD, despite the patient's substantial smoking history.
3
Synthesize the mechanism connecting the cardiac dysfunction to the respiratory symptoms.
Left ventricular failure leads to elevated left ventricular end-diastolic pressure, which backs up into the pulmonary circulation.
This elevated hydrostatic pressure in the pulmonary capillaries causes transudation of fluid into the alveoli, resulting in pulmonary edema, crackles, and dyspnea.

Key Concept

Respiratory symptoms in left-sided heart failure are caused by elevated left ventricular end-diastolic pressure leading to pulmonary venous congestion and subsequent pulmonary edema.
Estimated Time:1m 30s
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Topics

Cardiovascular System

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