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Tex Heart Inst J. 2004; 31(3): 306–308.
PMCID: PMC521777

Composite Graft Endocarditis

Repair with a Mechanical Prosthesis

Abstract

We report the case of a 64-year-old man who developed a mediastinal pseudoaneurysm due to severe endocarditis, 2 years after aortic root replacement with a prosthetic composite graft containing a mechanical valve. After a short period of stabilization and antibiotic therapy, the patient underwent surgery. The coronary buttons and the sewing ring of the composite graft were found to be detached from the graft and the annulus, respectively. Re-replacement with a prosthetic composite graft (Dacron graft with a mechanical valve) by the Cabrol procedure was performed.

Although the homograft is considered by many surgeons to be the best graft for aortic root replacement, the synthetic composite graft can also be used to treat composite graft endocarditis successfully. The technical aspects of homograft versus synthetic aortic root replacement in patients with endocarditis are discussed briefly.

Key words: Aortic root, endocarditis, bacterial/surgery, heart valve prosthesis, prosthesis-related infections/surgery, recurrence, reoperation/methods

Composite graft endocarditis after aortic root replacement can be life-threatening. Reoperation is frequently required, particularly in the presence of periannular tissue destruction, abscess, or pseudoaneurysm. The use of biological materials for re-replacement is generally accepted.1–3 However, favorable outcomes with synthetic material in the treatment of prosthetic valve endocarditis have been reported, and the superiority of biological materials has been questioned.4–6

We report the case of a 64-year-old man with composite graft endocarditis, in whom a synthetic valved conduit was used successfully for aortic root re-replacement.

Case Report

In October 2002, a 64-year-old man, who had undergone aortic root replacement with a composite graft (Dacron graft with a mechanical valve) 2 years earlier, presented with persistent fever, shivering, progressive fatigue, and dyspnea on exertion. The patient was febrile and in respiratory distress. The respiratory sounds were significantly diminished in the right lower zone. Chest radiography revealed cardiomegaly and a large hematoma or effusion compressing the right pleural cavity. Images obtained by thoracic computed tomographic scanning were consistent with a pseudoaneurysm of the mediastinum, which had ruptured into the right chest. Blood cultures were positive for Staphylococcus aureus, which was sensitive only to vancomycin and ciprofloxacin. Intravenous heparin, fluids, low-dose dopamine, and the above-mentioned antibiotics were administered to optimize the coagulation and the cardiovascular and renal status, and to control the sepsis. Trans-thoracic echocardiography revealed that the posterior wall of the ascending aortic graft was mobile. The patient was taken to surgery.

Surgical Technique

The right femoral artery and vein were dissected and cannulated after full heparinization. A median sternotomy was performed. The entire anteromedial mediastinum was pulsating, and the ascending aortic graft was within it. A cannula for retrograde cardioplegia was placed in the coronary sinus, and a vent cannula was placed in the right superior pulmonary vein. In order to clamp the ascending aorta, the mediastinal pseudoaneurysm had to be entered. To achieve this safely, we initiated cardiopulmonary bypass (CPB) and cooled the patient to 28 °C. After a short period of exsanguination and circulatory arrest, the pseudoaneurysm was entered and the graft was clamped. A clamp could then be placed distal to the native ascending aorta (Fig. 1). As the retrograde cardioplegia was being delivered, the pseudoaneurysm and the aortic root were explored. The superomedial portion of the pseudoaneurysm was in continuum with an abscess cavity. The right pleural cavity was obliterated. Both coronary buttons were found to be detached from the composite graft, and the pseudoaneurysm had originated from the remaining holes on the graft. We surmised that the coronary blood must have been supplied from the pseudoaneurysmal cavity. The sewing ring of the composite graft was found to be partially detached from the aortic annulus. The composite graft was removed. The left ventricular outflow tract (LVOT) and the aortic root were severely infected and necrotic. The aortic annulus was not definable.

figure 24FF1
Fig. 1 Drawing shows intraoperative appearance after entry into the pseudoaneurysmal cavity and clamping of the aorta. Both coronary buttons and part of the sewing ring were found to be detached from the graft.

We excised nearly the entire wall of the pseudoaneurysm and performed extensive débridement. What remained was a stiff aortic root and immobile coronary buttons. We decided to replace the aortic root by using the Cabrol button modification of the Bentall procedure. We used interrupted pledgeted horizontal mattress sutures to implant the composite graft (26-mm Dacron graft containing a 23-mm bileaflet mechanical valve; Sulzer Carbomedics Inc.; Austin, Tex) to the healthy-looking tissues of the LVOT, which were composed mostly of ventricular muscle. An 8-mm Dacron graft was anastomosed end-to-end to the left coronary button, and then to the composite graft in a side-to-side fashion (Fig. 2). The distal end of the composite graft was anastomosed to the ascending aorta. During warming, the free end of the 8-mm graft was anastomosed to the right coronary button. The patient was weaned from CPB with low-dose inotropic support. The duration of myocardial ischemia was 213 minutes, and the pump time was 263 minutes.

figure 24FF2
Fig. 2 Drawing shows the anastomoses of the 8-mm Dacron graft, which was anastomosed end-to-end to the left coronary button, and then side-to-side to the composite graft.

The patient was extubated 18 hours after the operation. The early postoperative course was uncomplicated. However, the right lung did not fully expand; therefore, 10 days after the cardiac operation, the patient underwent a right thoracotomy for decortication and evacuation of a pleural hematoma. He was given a 6-week course of antibiotic therapy, after which he was discharged from the hospital. A postoperative aortogram at the time of discharge showed a satisfactory repair (Fig. 3). When last seen in November 2003, the patient was asymptomatic, and echocardiography revealed good left ventricular and prosthetic valve function.

figure 24FF3
Fig. 3 Postoperative aortogram shows a satisfactory repair.

Discussion

Endocarditis of an aortic root prosthesis is a serious condition that can cause sepsis, cardiac failure, and rupture into the mediastinum and pleural cavities. Detachment of the coronary buttons, formation of abscesses, and destruction of the annulus can easily occur when the causative microorganisms are resistant staphylococci.

Débridement of all infected and necrotic tissues, re-replacement of the aortic root, and prolonged antibiotic therapy are all accepted strategies.3–6 However, there is no consensus regarding the advantages of using homografts for re-replacement and whether this approach provides an incremental benefit over the use of standard prostheses and synthetic material.3–6 Homografts are in short supply, and early calcification occurs in some patients. Moreover, homografts deteriorate progressively, and a technically challenging 2nd reoperation will eventually be required. When a long ascending graft has to be removed, 2 homografts are required to replace it.

When implanting a homograft, it is important to achieve a proximal suture line without distortion. After removal of the infected prosthesis and débridement, the aortic root is generally composed of soft, friable tissues on the inner surface and of dense adhesions on the outer surface. Safe anchoring of a prosthesis to such tissues often requires the placement of interrupted pledgeted sutures with large needles. Uneven tension caused by sutures of different depths is well tolerated by a prosthetic valved conduit. Re-attachment of immobile coronary buttons presents another technical problem. If the coronary buttons are distant from the aortic root, as they were in this case, the use of homografts can be problematic because of possible tension on the coronary anastomoses. The Cabrol procedure is a good option for use with a prosthetic valved conduit, because it enables coronary button anastomoses that are tension-free and easy to reach in case of bleeding.

An aortic root homograft may be preferable to a synthetic composite graft in some cases; however, it is not the only way to achieve success in the treatment of composite graft endocarditis. We report this case as a reminder to surgeons who cannot use a homograft in such situations: a synthetic valved conduit is a viable alternative.

Footnotes

Address for reprints: Dr. A.Z. Apaydin, Department of Cardiovascular Surgery, Ege University Medical School, Bornova – Izmir 35100, Turkey

E-mail: apaydina@med.ege.edu.tr

References

1. Niwaya K, Knott-Craig CJ, Santangelo K, Lane MM, Chandrasekeran K, Elkins RC. Advantage of autograft and homograft valve replacement for complex aortic valve endocarditis. Ann Thorac Surg 1999;67:1603–8. [PubMed]
2. Haydock D, Barratt-Boyes B, Macedo T, Kirklin JW, Blackstone E. Aortic valve replacement for active infectious endocarditis in 108 patients. A comparison of freehand allograft valves with mechanical prostheses and bioprostheses. J Thorac Cardiovasc Surg 1992;103:130–9. [PubMed]
3. Lytle BW, Sabik JF, Blackstone EH, Svensson LG, Pettersson GB, Cosgrove DM 3rd. Reoperative cryopreserved root and ascending aorta replacement for acute aortic prosthetic valve endocarditis. Ann Thorac Surg 2002;74:S1754–7; S1792–9. [PubMed]
4. Aagaard J, Andersen PV. Acute endocarditis treated with radical debridement and implantation of mechanical or stented bioprosthetic devices. Ann Thorac Surg 2001;71: 100–4. [PubMed]
5. Bauernschmitt R, Jakob HG, Vahl CF, Lange R, Hagl S. Operation for infective endocarditis: results after implantation of mechanical valves. Ann Thorac Surg 1998;65:359–64. [PubMed]
6. Hagl C, Galla JD, Lansman SL, Fink D, Bodian CA, Spielvogel D, Griepp RB. Replacing the ascending aorta and aortic valve for acute prosthetic valve endocarditis: is using prosthetic material contraindicated? Ann Thorac Surg 2002; 74:S1781–5; S1792–9. [PubMed]

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