|Home | About | Journals | Submit | Contact Us | Français|
Infection after aortic root replacement is uncommon, and it can be fatal. Herein, we present the case of a patient who underwent aortic root replacement with a valved conduit and coronary reimplantation. Prosthetic valve endocarditis and left ventricular cutaneous fistula ensued. Either condition alone could have been fatal. The fistula coursed from the valved conduit through the left ventricular outflow tract, behind the left main coronary artery, and to the skin at the upper sternum. Safe surgical entry into the chest was crucial, due to the free communication between the left ventricle, mediastinum, and skin. We discuss our surgical approach to this unusual combination of conditions, and the postoperative treatment of the patient.
Endocarditis after aortic valve replacement is rare and has a high mortality rate. Ventricular disruption after aortic root replacement with a valved conduit is even more unusual, and the condition is usually fatal. Here, we present the case of a patient who developed prosthetic valve endocarditis after aortic root replacement with a valved conduit, which resulted in aortic ventricular disruption from a left ventricular cutaneous fistula.
In December 2008, a 65-year-old man presented with severe aortic insufficiency, moderate aortic stenosis, and a 5.5-cm aortic root aneurysm. Repair involved constructing a valved conduit, by use of a 27-mm stented porcine valve and a 30-mm Dacron graft. The main coronary ostia were mobilized by use of Carrel's technique, and the coronary arteries were implanted as individual buttons. After the surgery, the patient developed atrial fibrillation, for which warfarin was administered. On postoperative day 9, he developed a large pericardial effusion with right-heart collapse as seen upon echocardiography, and he underwent a subxiphoid pericardial window procedure without incident. His subsequent recovery was uneventful except for thrombosis in a right forearm vein at the site of an intravenous port. He was discharged from the hospital on a 5-day course of minocycline as therapy for the forearm thrombosis. He was seen in the clinic 2 weeks later and was doing well, except for persistence of the atrial fibrillation. Six weeks postoperatively, he experienced the sudden onset of fever (103°F) with shaking chills. He came to the clinic the next day and noted that, when he had awakened that morning, there was a large “bump” at the upper end of the sternal incision. Needle aspiration yielded a dark fluid, consistent with old blood, which grew coagulase-negative Staphylococcus aureus in the laboratory. Computed tomography of the chest revealed what appeared to be a fistula that originated from the lower end of the graft near the aortic annulus (Fig. 1). He was given intravenous vancomycin (1 g every 12 hr), rifampin (300 mg every 12 hr), and cefepime (1 g every 12 hr). Surgical exploration was planned.
At surgical exploration, a transesophageal echocardiogram, performed after the induction of anesthesia, showed a fistula that originated below the valved conduit through the left ventricular outflow tract (Fig. 2). The right axillary artery was cannulated for arterial outflow with use of an 8-mm Dacron graft. Venous drainage was attained via a right femoral percutaneous 21F venous cannula. Cardiopulmonary bypass (CPB) was instituted and the sternum was opened without difficulty. A large amount of clotting was seen around the aortic root, but the distal ascending graft was isolated without difficulty. A sump was placed into the left atrium through the right superior pulmonary vein, and a retrograde cardioplegia cannula was placed through the right atrial wall into the coronary sinus. The distal ascending graft was cross-clamped, and retrograde cold-blood cardioplegia was started as the graft was opened. Cold-blood cardioplegic solution was then delivered antegrade directly into the coronary ostia, and cardioplegic arrest was achieved. Obvious vegetations emanated from below the prosthetic valve. A right-angle clamp was passed below the junction of the noncoronary and left coronary cusps to exit posterior to the aorta, for the purpose of examining the fistula's track. The fistula coursed from the valved conduit through the left ventricular outflow tract, behind the left main coronary artery, and to the skin at the upper sternum. The old graft was excised and the coronary buttons were mobilized. The annular abscess was extensively débrided of all infected tissue. A new valved conduit (a 27-mm porcine valve in a 30-mm Dacron graft) was constructed and then sutured into place with interrupted pledgeted 2-0 Ticron sutures, and the coronary buttons were directly reimplanted into the graft. The cross-clamp was then moved distally to permit excision of the old distal graft and to enable distal anastomosis of the new graft. The patient was successfully weaned from CPB. A necklace of 34 antibiotic-impregnated methyl-methacrylate beads was placed around the new aortic graft, the mediastinum was packed with lap sponges, and only the skin was closed.
Two days later, the patient was returned to the operating room for mediastinal washout and removal of the lap sponges. The antibiotic beads were left in place, and again only the skin was closed. Two days thereafter, the beads were removed, and the omentum was mobilized on the gastroepiploic artery and vein and was transposed into the chest in order to wrap the graft completely and obliterate all space. Care was taken to keep the pedicle untwisted and to fill all spatial defects with omentum. BLAKE® drains (Ethicon, Inc., a Johnson & Johnson company; Somerville, NJ) were placed over and under the omentum, and the sternum was closed. The final operative cultures grew coagulase-negative S. aureus, and, 5 days after the initial repair, the patient's medication was changed to intravenous daptomycin (6 mg/kg every 8 hr). After a 4-week course, he was discharged from the hospital and underwent a 2-week outpatient course of intravenous trimethoprim/sulfamethoxazole. We then placed the patient on the oral form of this medication daily for life. The wound was completely healed at the time of hospital discharge. When the patient was seen 3 months postoperatively, he had returned to normal activity and showed no evidence of infection or cardiac dysfunction. During a telephone follow-up in February 2010, he reported no problems.
Prosthetic valve endocarditis is uncommon, occurring at a frequency of 0.3 to 0.6 per patient-year1 in patients who undergo valve replacement surgery; however, the infection has a mortality rate of 20% to 80%.2 Aortic root replacement after previous aortic root surgery also carries a high mortality rate of 17.9%.3 Aortocutaneous fistula has been reported in association with postoperative infections of the ascending aorta and aortic arch; these infections alone have an early mortality rate of 17%.4 Our patient had undergone previous aortic root replacement, and endocarditis of the prosthetic aortic valve ensued.
Cardiocutaneous fistula is reported infrequently, and it is usually the result of infected Dacron pledgets that have been used during ventricular aneurysm repair.5–8 This combination of factors in our patient mandated careful entry into the chest due to the free communication between the left ventricle, mediastinum, and skin. Axillary artery cannulation is a well-described approach to arterial inflow that we have routinely used in most type A dissections, and percutaneous venous access is commonly used in our minimally invasive cardiac approaches. In our patient, the use of the axillary artery and femoral vein enabled easy and safe preparation for immediate CPB before sternal re-entry, in the event that we encountered massive bleeding. After CPB and cardioplegic arrest were achieved, the graft could be opened in order to define the nature and extent of the disease.
Complete excision of the infected valved conduit and aggressive débridement of all infected annular tissue are imperative for infection control. After the new graft was implanted in our patient, he was weaned from CPB, and the ascending aorta was surrounded with a necklace of 34 antibiotic-impregnated methyl-methacrylate beads, for the timed release of local antibiotics.9 Because of diffuse coagulopathy, we packed our patient's chest with lap sponges and closed only the skin, in order to control the bleeding completely and to enable removal of the beads before final closure.
Omentum has been used extensively, with excellent results, in the treatment of infected sternal wounds.10–12 Surgeons have found that omentum is harvested easily, it fills spaces well because of its pliability, and it has been shown to potentially deliver vascular endothelial growth factor and promotes vascularization of the wound.13 There is also evidence that it contains a substantial number of immunologically active cells.14 After omental-flap transposition in mediastinitis, predictors of death include acute renal failure, prolonged ventilatory support, and methicillin-resistant staphylococcal infection.15 Complications that are attributed to omental muscle flaps include the spread of infection intra-abdominally and, later, herniation of the abdominal viscera into the mediastinum.10 Hultman and colleagues16 found an 18.5% rate of donor-site complications, including abdominal-wall infection, ventral hernia, gastrointestinal hemorrhage, small-bowel obstruction, and gastric outlet obstruction. Patients who were at increased risk of these complications were older, had higher transfusion requirements, and had previously undergone abdominal surgery or extensive adhesiolysis.16 In patients who undergo laparoscopic harvesting of the omental pedicle, there is less chance of donor-site complications such as ventral hernia, and no increase in flap loss or mortality rate has been identified.17,18
Pectoralis major muscle flaps are also commonly used to treat infections of deep sternal wounds.19 In a direct comparison of omental flaps and pectoralis muscle flaps in post-sternotomy mediastinitis, omental flaps were associated with shorter hospital stays and fewer early major complications, including respiratory failure, hemorrhage, persistent sepsis, renal failure, chronic wound drainage, subcutaneous infection, and flap failure. Specific disadvantages of pectoralis muscle flaps (particularly in the presence of sternal instability) include chronic pain, numbness, and weakness, which have reportedly occurred in 30% to 50% of patients.20 Therefore, many authors now favor the use of omental flaps instead of muscle flaps for infected deep sternal wounds. After surgical débridement and local control of infection, appropriate intravenous antibiotics should be administered to the patient for 6 weeks. In order to increase the probability of long-term suppression and eradication of infection, we recommend that the patient undertake a lifelong regimen of suppressive oral antibiotics.
Address for reprints: Michael J. Reardon, MD, Cardiovascular Surgery Associates, 6550 Fannin St., #1401, Houston, TX 77030