1. A 6-year-old patient presents with a fever, chest pain, and an elevated white blood cell count. An echocardiogram reveals vegetation on the mitral valve. Which of the following is the most likely diagnosis? A. Rheumatic fever B. Infective endocarditis C. Myocarditis D. Pericarditis Correct Answer: B. Infective endocarditis Rationale: The presence of vegetation on the mitral valve, along with systemic symptoms of infection, is indicative of infective endocarditis. 2. During a cardiac surgery, a 4-year-old patient develops a sudden drop in blood pressure, increased central venous pressure, and jugular venous distension. What is the most immediate postoperative complication? A. Cardiac tamponade B. Pulmonary embolism C. Acute myocardial infarction