The patient was an 81-year-old male who visited our hospital with chief complaints of low back pain and fever. Four years before, he had undergone AVR with a 23-mm Carpentier-Edwards Perimount (CEP) valve (Edwards Lifesciences, Irvine, CA, USA) to treat aortic regurgitation (AR). He had developed low back pain at 14 days and fever at 10 days before admission to our hospital. Because the symptoms persisted even after medical treatment at a local physician, he visited the Department of Cardiology of our hospital. The following physical findings were observed during his visit: body temperature, 39.0 °C; blood pressure, 94/58 mmHg; pulse rate, 90/min; and no heart murmur on auscultation. A blood test revealed increases in the white blood cell count and C-reactive protein, and a mild increase in the hepatobiliary enzyme concentrations. Although computed tomography (CT) was immediately performed, no abscess formation or pneumonia was detected. Similarly, echocardiography revealed a trivial degree of mitral regurgitation, and negative findings for AR and tricuspid regurgitation. Because of his high fever and AVR history, he was emergently admitted to our hospital and treated with cefazolin (CEZ). Moreover, a continuous norepinephrine infusion was needed for the hypotension. On the next day, Staphylococcus bacteria were identified by blood culture tests performed on admission. Accordingly, teicoplanin (TEIC) was added along with CEZ. The second echocardiography evaluations detected a large vegetation measuring 16 mm × 9 mm in diameter (Fig. 1) on the prosthetic valve with increased transvalvular gradient (peak velocity, 4.4 m/s; peak pressure gradient, 79 mmHg), leading to a staphylococcal PVE diagnosis. Therefore, the patient was referred to our department for emergency surgery.
Surgical procedures
Redo sternotomy was performed, and a cardiopulmonary bypass (CPB) was established. Then, an antegrade-cardioplegia was delivered after aortic cross-clamping, and cardiac arrest was quickly achieved. A transverse incision was performed just above the previous incision on the proximal ascending aorta to expose the prosthetic valve, which was covered with vegetation (Fig. 2a, b). No defects were observed in the valve seating, which was covered with endothelial tissue, when viewed from the aortic side. Subsequently, the prosthetic valve, which had been implanted in the intra-annular position, was removed by cutting the sutures. It should be noted that pus leakage was observed from the commissure and annulus between the left coronary and noncoronary sinuses to the nadir of the two cusps. Therefore, the patient was diagnosed with aortic annular abscess. After complete prosthetic valve removal, large vegetation covering the left ventricular outflow tract was revealed (Fig. 2c, d). A visual inspection after aortic annular abscess removal demonstrated that the infection was limited to the annulus. Moreover, no further infection was detected between the left ventricular outflow tract and the mitral valve annulus. After copious irrigation of the abscess cavity, an aortic annulus reconstruction was carried out with a bovine pericardium patch using continuous 4-0 monofilament sutures (Fig. 3a, b). A new aortic annulus was sized to a 23-mm sizer, but it was slightly tight. Therefore, a 21-mm CEP valve was chosen. The part of the patch between the LCC and NCC was threaded from the outside of the aorta with the patch and sutured with interrupted sutures without a pledget (Fig. 3c, d). In the other parts, we used the everting sutures, and the artificial valve was attached to the intra-annular position. The aortic cross-clamping was released, and spontaneous beating resumed. The patient was smoothly weaned from the CPB.
Postoperative course
The patient had stable hemodynamics and respiratory function and was extubated on postoperative day 1. Because he was found to have aortic annular abscess, three antibiotics, including gentamicin (GM), TEIC, and CEZ, were administered. In addition, gamma globulin was also given for 3 days postoperatively. At that time, the infecting organism was identified as S. lugdunensis by a preoperative blood culture and intraoperative vegetation culture. Due to the high drug susceptibility, the CEZ dose was increased from 3 to 6 g/day, and the antibiotic treatment regimen was changed to CEZ, continuous GM, and oral rifampicin (RFP, 300 mg every 8 h). TEIC administration was stopped. After 4 weeks of postoperative continuous CEZ administration, the antibiotic treatment regimen was changed to oral RFP and sulfamethoxazole–trimethoprim (ST). At 5 weeks postoperatively, the patient was uneventfully discharged home. Outpatient echocardiography and CT follow-ups revealed no abnormalities, and the oral antibiotics were discontinued at 1 year postoperatively. The subsequent clinical course was uneventful. An outpatient follow-up conducted 5 years postoperatively showed no recurrence.
