A 25-year-old with cystic fibrosis presents with JVD and edema. The most likely diagnosis is:

• A. Left sided heart failure due to LV dysfunction
• B. Cor pulmonale due to CF
• C. Right ventricular infarction
• D. Pericardial tamponade

Answer: (B)

In cystic fibrosis, chronic lung disease leads to low oxygen levels that cause the pulmonary arteries to constrict and remodel, raising pulmonary vascular resistance. This pulmonary hypertension places a high afterload on the right ventricle, which over time hypertrophies and eventually fails. When the right side of the heart fails, blood backs up into the systemic circulation, producing signs like a neck vein distention and edema. This scenario—right-sided heart failure driven by lung disease—fits best with cor pulmonale due to CF.

Left-sided heart failure would more often show pulmonary congestion and crackles from fluid backing up into the lungs, not the prominent systemic venous congestion described. Pericardial tamponade typically presents with hypotension and muffled heart sounds, not primarily JVD with edema from RV failure. Right ventricular infarction is unlikely in a young patient with CF unless there's an ischemic event; the presentation here aligns with chronic lung-driven RV failure rather than an acute coronary problem.