A 39-year-old man was admitted to the hospital because of calcifications around the aortic root, a recent myocardial infarction, and subsequent congestive heart failure, with increasing aortic regurgitation.The patient had been well until six years earlier, when progressive renal insufficiency with hypertension was found. A low-protein diet and enalapril were begun. He was subsequently well until four months before admission, when chest pain developed and he entered another hospital. The urea nitrogen concentration was 143 mg per deciliter (51.1 mmol per liter), and the creatinine concentration was 9.4 mg per deciliter (830 m mol per liter). An electrocardiogram showed an acute myocardial infarct. A transthoracic cardiac ultrasonographic examination revealed a mass around the aortic root that was suspected to represent an aneurysm of the sinus of Valsalva. A transesophageal cardiac ultrasonographic examination at another hospital showed a multilobulated mass with a highly reflective surface and a sonolucent center encircling the anterior aspect of the aortic root and right coronary artery. Dense echogenic material extended onto the base of the anterior mitral leaflet. The aortic valve was tricuspid, with mild stenosis and regurgitation. The peak systolic aortic gradient by continuous-wave Doppler study was 40 mm Hg. The left ventricular size and ejection fraction were normal; the inferior segments of the left ventricle appeared slightly hypokinetic. A magnetic resonance imaging (MRI) scan of the heart also disclosed an extensive mass that involved the aortic root and the myocardial surface of the right ventricle, without obvious invasion of the ventricle. Serologic tests for brucella and coxiella microorganisms were negative. The patient was afebrile, and multiple blood-culture specimens were ster-ile. It was decided not to perform a surgical procedure. The urea nitrogen concentration declined to 88 mg per deciliter (31 mmol per liter), and the creatinine concentration to 8.8 mg per deciliter (780 m mol per liter). The patient was discharged, with arrangements made for extracorporeal hemodialysis.The patient felt well until two weeks before admission, when he began to have bouts of dyspnea, usually after dialysis. Four days before admission he was treated for congestive heart failure at another hospital. There was evidence of increasing aortic regurgitation. Episodes of intermittent atrioventricular dissociation, with a ventricular rate of 40 to 50, were observed, and on the fourth hospital day a sequential dual-chamber electronic pacemaker was implanted. The patient was transferred to this hospital.The patient was unmarried and lived alone. He was a veterinarian who treated dogs and cats predominantly. He traveled to England in the summer and frequently took cruises to the Caribbean and South America. His father had died at the age of 41 years of a ruptured intracranial mycotic aneurysm due to bacterial endocarditis on a bicuspid aortic valve. There was no family history of renal disease. The patient's medicatio...