Cardiovascular, Physiology, USMLE Step 1 - Full Vignette with Extended Explanations

Описание: A 57-year-old woman with a history of type 1 diabetes, ulcerative colitis, and IgG4-related disease presents with progressive exertional dyspnea, orthopnea, reduced exercise tolerance, and ankle swelling. Her physical exam shows bibasilar crackles and pitting edema, and labs reveal elevated NT-proBNP with normal troponin. What clinical findings and diagnostic clues should you focus on to identify the condition responsible for her symptoms in this complex patient?

VIDEO INFO
Category: Cardiovascular, Physiology, USMLE Step 1
Difficulty: Hard - Advanced level - Challenges experienced practitioners
Question Type: Diagnosis - Identify conditions based on clinical presentation
Case Type: Routine Visit - Standard clinical encounter in outpatient setting

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QUESTION
A 57-year-old woman presents to her primary care clinic for progressive exertional dyspnea, reduced walking distance, and ankle swelling over several months. She works in education and lives independently....

OPTIONS
A. Heart failure with preserved ejection fraction driven by impaired diastolic relaxation and elevated left-sided filling pressures.
B. Primary deconditioning with anxiety-related dyspnea and normal cardiopulmonary reserve.
C. Chronic thromboembolic pulmonary hypertension with segmental perfusion defects on ventilation-perfusion imaging, elevated pulmonary vascular resistance, and progressive right-ventricular dilation.
D. Moderate persistent asthma without airflow obstruction or bronchodilator response.

CORRECT ANSWER
A. Heart failure with preserved ejection fraction driven by impaired diastolic relaxation and elevated left-sided filling pressures.

EXPLANATION
Exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, bibasilar crackles, S4, obesity, diabetes, concentric LV hypertrophy, preserved LVEF (60%), enlarged left atrium, elevated E/e (17), and mildly increased pulmonary artery systolic pressure support heart failure with preserved ejection fraction (HFpEF) due to impaired diastolic relaxation and elevated left-sided filling pressures. Resting hypoxemia with exertional desaturation can accompany pulmonary congestion and secondary pulmonary hypertension.

Deconditioning with anxiety would not produce elevated E/e , LA enlargement, pulmonary congestion, or elevated natriuretic peptide. Chronic thromboembolic pulmonary hypertension requires mismatched perfusion defects and progressive RV dilation, which are not present. Moderate persistent asthma would show airflow obstruction or a bronchodilator response, neither of which is seen on spirometry.

In summary, the correct answer is Heart failure with preserved ejection fraction driven by impaired diastolic relaxation and elevated left-sided filling pressures. Echo and clinical findings are diagnostic in aggregate.

Primary teaching point: In HFpEF, preserved EF coexists with elevated filling pressures (eg, E/e greater than 15) and structural heart disease (LVH, LAE), supported by symptoms and natriuretic peptides.

Secondary teaching point: HFpEF commonly features obesity, diabetes, and pulmonary hypertension from chronic elevation of left-sided pressures.

Tertiary teaching point: Normal spirometry argues against asthma; absence of V/Q mismatch and RV changes argues against CTEPH.


Further reading:

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