Which assessment finding does the nurse expect in a patient with pericarditis?

Pericarditis classically produces a pericardial friction rub, which is a high-pitched, scratching or grating sound best heard at the left lower sternal border with the patient leaning forward. Crucially, this rub is present during respiration and changes with the respiratory cycle because breathing alters the contact between the inflamed pericardial layers. The rub is caused by the roughened, inflamed visceral and parietal pericardial surfaces rubbing against each other as the heart moves. The option describing a rub that persists when the patient holds his breath is incorrect — a true pericardial friction rub is distinct from a pleural rub, but importantly the pericardial rub may actually diminish or change character with breath-holding because movement of the pericardial layers is altered. The options describing irregular heart rates — one that speeds up and slows down and one that skips every other beat — describe sinus arrhythmia and a regularly irregular rhythm such as bigeminy, respectively; neither is a hallmark finding of pericarditis. While pericarditis can cause dysrhythmias, the most characteristic and clinically tested physical examination finding is the pericardial friction rub that is heard during respiration, making that the best answer.