投稿者：February 15, 2007
A 53-year-old man with a prosthetic aortic valve was admitted to this hospital because of the recent onset of fatigue, dyspnea, weight loss, and sweats.
Approximately 4 years earlier, severe aortic insufficiency had developed. Echocardiography revealed a calcified, bicuspid aortic valve. Aortic-valve replacement was performed elsewhere, with a Medtronic Hall tilting-disk valve. Three months later, aortic insufficiency recurred, and the aortic valve was replaced with another Medtronic Hall valve at the same hospital. During the second operation, there was partial dehiscence of the prosthesis along a portion of the annulus, and although there was no abscess, inflammatory tissue was present at the surgical site. Pathological examination of the excised tissue disclosed a foreign-body giant-cell reaction; no organisms were identified.
Approximately 4 months before admission, the patient began to have anorexia, fatigue, and dyspnea on exertion, which gradually worsened, causing him to avoid climbing stairs. He reported profuse sweating during the day but no night sweats, fevers, or chills. He saw his primary care physician, who prescribed escitalopram for depression.
During the next 2 months, his symptoms continued, and he lost more than 22.7 kg in weight. He noticed that his mechanical heart sounds were less crisp than usual. One month before admission, he again saw his primary care physician. The results of laboratory tests are shown in Table 1. Orally administered iron supplementation was begun.
Two weeks before admission, the patient saw his cardiologist for a regularly scheduled visit and transthoracic echocardiography. The echocardiogram showed severe aortic insufficiency, with a poorly seated valve and a moderately enlarged aortic root. The ejection fraction was 40%, and there was diffuse hypokinesis. Two specimens of blood were sent for culture the next day; there was no bacterial growth after 5 days, at which time the cultures were discarded. A transesophageal echocardiogram, obtained at another hospital 3 days later, showed an echolucent area near the left coronary cusp that raised concern about the possibility of an annular abscess. The aortic root was dilated, at 48 mm, with a normal left atrium. Additional laboratory test results are shown in Table 1.
The patient declined immediate admission to the hospital because of business issues; instead, for 1 week vancomycin (1.5 g) was administered intravenously every 12 hours, and gentamicin (500 mg) and ceftriaxone (2 g) were given intravenously every day through a peripherally inserted central catheter. One day before admission, he was admitted briefly to another hospital, and on the next day he was transferred to this hospital.
The patient had a history of obstructive sleep apnea and used continuous positive airway pressure by face mask nightly. He had not had dental work in the past year. He was allergic to acetaminophenpropoxyphene and codeine. He had no family history of valvular heart disease or rheumatologic disease. His mother was alive and well; his father had died of complications from alcohol-induced liver disease at the age of 56 years.
The patient lived in Maine, was married, and had 8 children and 13 grandchildren. The family owned three cats but had no other pets; the patient had hunted in the past, but not for many years. He owned and operated a junkyard and tow-truck service. He had not traveled outside the country and had had no contact with ill persons. He had used alcohol and tobacco in the past, but had ceased using both approximately 30 years earlier. He did not use illicit drugs. Medications taken on a daily basis included warfarin, escitalopram, furosemide (20 mg, administered intravenously), folic acid, cobalamin, aspirin, and ferrous sulfate; he took hydroxyzine occasionally for allergy symptoms.
On examination, the temperature was 37.2, the pulse 99 beats per minute, and the blood pressure 115/57 mm Hg; the respirations were 18 per minute. The oxygen saturation was 95% while the patient was breathing ambient air. He appeared well. He was obese, with a protuberant abdomen. He had a ruddy facial complexion, and he was perspiring. Dentition was poor, with no abscesses or gingival tenderness. The conjunctivas were pale. There was no cervical lymphadenopathy. A well-healed sternotomy scar was noted. Auscultation of the chest revealed bibasilar rales. There was a mechanical second heart sound, a grade 2/6 systolic murmur, heard best at the apex, and a grade 2/4 diastolic murmur, heard best at the base. The point of maximal impulse was not displaced. The jugular venous pressure was 8 cm H2O. There were no Osler's nodes, Janeway's lesions, splinter hemorrhages, or peripheral edema. No erythema or drainage was evident at the catheter site.
The antibiotics were continued, and anticoagulation therapy with heparin was begun. A urine specimen was positive for proteinuria (1+) and blood (2+) but negative for nitrite. The sediment contained 10 to 20 red cells and 5 to 10 white cells per high-power field, many bacteria, and a few squamous cells. A culture of the urine showed no growth. Specimens of blood were sent for cultures for bacteria, mycobacteria, and fungi; the results were pending. Serum protein electrophoresis showed a moderate, diffuse increase in gamma globulin. No Bence Jones protein was detected, but trace amounts of albumin, alpha and beta globulin, and intact immunoglobulin were present. Serum levels of electrolytes, calcium, phosphorus, and bilirubin were normal, and renal function was also normal. The differential white-cell count was normal. An electrocardiogram showed normal sinus rhythm without prolongation of the PR interval but with ST-segment depressions in leads V3 through V6.
On the second hospital day, a chest radiograph showed evidence of a previous sternotomy and a slightly unusual position of the aortic valve, without other abnormalities. Computed tomographic (CT) scanning of the abdomen showed an enlarged spleen with focal abnormalities that were suggestive of tiny septic emboli and multiple small, low-density lesions in both kidneys. There were sigmoid diverticula and prominent retroperitoneal lymph nodes up to 1.6 by 1.0 cm in diameter, with minimal retroperitoneal stranding. CT scanning of the chest showed emphysema and paratracheal, prevascular, and subcarinal lymphadenopathy; the largest node in the right paratracheal region was 2 cm in diameter. The aortic valve appeared malpositioned, and there were several small pockets of contrast material adjacent to the aortic-valve annulus, between the aortic root and the pulmonary artery. Examination of a specimen from a bone marrow biopsy showed hypercellular bone marrow with trilineage hematopoiesis, erythroid predominance, and a reactive plasmacytosis.
Cardiac catheterization on the third day revealed a right-dominant system with normal coronary arteries. An aortogram showed preserved left ventricular function but severe aortic insufficiency. The prosthesis was noted to be rocking, tethered only on the left. The presence of an aortic-root abscess could not be ruled out. The two sets of blood culture specimens obtained on admission still exhibited no growth.
Carotid Doppler studies showed no stenosis. CT angiography of the chest on the fourth hospital day revealed an enlarged aortic root but a normal-size distal ascending aorta and aortic arch. Results of laboratory tests are shown in Table 1. A panoramic dental film obtained on the fifth day showed no evidence of periapical abscess, although many teeth were absent. A dental consultant noted the presence of a fractured tooth and two teeth containing caries.
On the sixth hospital day, transesophageal echocardiography showed that the mechanical aortic valve rocked excessively and moved into the left ventricular outflow tract during diastole. The valve was partly detached from the annulus; the detachment involved more than half the circumference of the valve. There was a large paravalvular leak, with severe aortic insufficiency. Although the left coronary sinus was dilated, there was no continuous flow into the left ventricular outflow tract. The left ventricle was dilated, with a normal ejection fraction.
A procedure was performed.
Table 1. Results of Laboratory Tests.