A 24-year-old man is brought to the emergency department 15 minutes after he sustained a stab wound to the left chest. On arrival, he has rapid, shallow breathing and appears anxious. His pulse is 135/min, respirations are 30/min and shallow, and palpable systolic blood pressure is 80 mm Hg. Examination shows no active external bleeding. There is a 2.5-cm single stab wound to the left chest at the 4^th intercostal space at the midclavicular line. Cardiovascular examination shows muffled heart sounds and jugular venous distention. Breath sounds are normal. Further evaluation of this patient is most likely to show which of the following findings?

Two weeks after undergoing coronary artery bypass surgery for acute myocardial infarction, a 62-year-oldman comes to the physician because of a 4-day history of fever, sharp chest pain, and progressive fatigue. Initially, the pain was only present when he was lying supine, but now it is constant and only subsides when he leans forward. He has hypertension and mild mitral regurgitation. He has smoked one pack of cigarettes daily for 44 years but quit prior to surgery. Current medications include aspirin, clopidogrel, metoprolol, captopril, and atorvastatin. His temperature is 38.3°C (102°F), pulse is 84/min and regular, respirations are 16/min, and blood pressure is 132/86 mm Hg. During inspiration, the patient's blood pressure drops to 117/80 mm Hg. On physical examination, there are jugular venous pulsations 4 cm above the sternal angle. Heart sounds are faint. There is 2+ edema in the lower extremities. Which of the following additional findings is most likely to be present in this patient?

pericardial friction rub is the best heard at?