A previously well 3½-month-old presents with poor feeding, diaphoresis during feeding, and poor growth. Vital signs reveal respirations of 70, pulse of 175, and blood pressure of 90/65 mm Hg in the upper and lower extremities. The cardiac examination reveals a palpable parasternal lift and a systolic thrill. A grade 4 holosystolic murmur and a mid-diastolic rumble are noted. The chest radiograph reveals cardiomegaly. The most likely diagnosis is

A previously well 3½-month-old presents with poor feeding, diaphoresis during feeding, and poor growth. Vital signs reveal respirations of 70, pulse of 175, and blood pressure of 90/65 mm Hg in the upper and lower extremities. The cardiac examination reveals a palpable parasternal lift and a systolic thrill. A grade 4 holosystolic murmur and a mid-diastolic rumble are noted. The chest radiograph reveals cardiomegaly. The most likely diagnosis is

A 12-year-old male tries out for a middle school hockey team. He has a history of a heart murmur as an infant, but the doctor thought it would go away. During the tryout, he experiences severe dyspnea and becomes light-headed. At your office, he has a normal rhythm, pulse, and blood pressure and is no longer dizzy. There is a grade 4/6 systole ejection murmur that radiates to the neck. There is also an ejection click. An ECG reveals left ventricular hypertrophy. The next approach to his management includes

The patient experiences a headache and is unable to move the left side of his body. The most likely cause is

Patients at risk for bacterial endocarditis include those with all of the following EXCEPT