Ann Thorac Surg 2005;80:724-726
© 2005 The Society of Thoracic Surgeons
Case report
Rupture of a Saphenous Vein Coronary Artery Bypass Graft Due to Aspergillus Necrotizing Vasculitis
Jutta Draganov, MD
a
,
H. Michael Klein, MD
b
,
*
,
Ali Ghodsizad, MD
b
,
Martin Gehrke, MD
c
,
Emmeran Gams, MD
b
a Department of Anesthesiology, Heinrich-Heine-University, Duesseldorf, Germany
b Department of Cardiovascular and Thoracic Surgery, Heinrich-Heine-University, Duesseldorf, Germany
c Department of Pathology, Heinrich-Heine-University, Duesseldorf, Germany
Accepted for publication February 6, 2004.
* Address reprint requests to Dr Klein, Department of Cardiovascular and Thoracic Surgery, Heinrich-Heine-University, Moorenstr 5, Duesseldorf 40225, Germany (Email: kleinhm{at}med.uni-duesseldorf.de).
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Abstract
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We present the first, unusual case of a lethal mediastinal hemorrhage caused by rupture of a saphenous vein aortic coronary bypass graft due to Aspergillus species necrotizing vasculitis in an immunocompetent patient 18 days after redo coronary artery bypass surgery. The patient had neither signs for mediastinitis nor for another source of Aspergillus infection.
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Introduction
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Rupture of a saphenous vein graft with mediastinal hemorrhage is a rare but highly lethal complication after cardiac surgery. Graft rupture has been reported secondary to mediastinitis, bacterial infection within the wall of the vein, or secondary to trauma from sternal edges or veins eroded by mediastinal drainage tubes. There is no reported case of saphenous vein rupture due to Aspergillus species infection. Endovascular infections with Aspergillus are extremely rare and associated with high mortality rate of more than 80%. Only a few cases of Aspergillus infections of thoracic and abdominal aortic grafts, aortitis, endocarditis, and mycotic aneurysms have been reported, but there has been no reported case of Aspergillus infection of a saphenous vein graft.
A 79-year-old man presented with recurrent chest pain for repeat coronary artery bypass surgery. His medical history was significant for coronary heart disease, multiple myocardial infarctions of the posterior wall, multiple angioplasty and stenting of the left anterior descending artery (LAD) and both bypass grafts, arterial hypertension, obesity, renal insufficiency (preoperative urea 65 mg/dL, creatinine 1.8 mg/dL), and atrial fibrillation. His first coronary artery bypass grafting (CABG) surgery was performed 17 years earlier with venous grafts on the right coronary artery (RCA) and the first marginal branch. Cardiac catheterization showed progressive three-vessel-disease, high-grade stenosis of both bypass grafts, mild aortic stenosis (
p 30 mm Hg), and poor left ventricular function.
In the present instance, one saphenous vein and the left internal mammary artery graft, both of good quality, were used to bypass the posterior descending branch of the RCA and the LAD using an on-pump technique. The old grafts were left in situ. Massive calcification of the ascending aorta precluded the replacement of the aortic valve. There were no intraoperative or immediate postoperative complications, and the patient was successfully extubated. On postoperative day 4, renal function worsened, and the first dialysis was performed. On postoperative day 9, fever developed in the patient and signs of progressive pulmonary insufficiency requiring reintubation and ventilation. Chest radiography showed right lower lobe pneumonia, microbiological examination of the tracheal secretion revealed some Staphylococcus aureus and sporadic Candida albicans, blood culture results were negative, clinical analysis showed leukocytosis of 16/nL, and an increase of C-reactive protein to 24 mg/dL. Antibiosis with Piperacillin was started. On postoperative day 11, the patient underwent dilation tracheotomy to facilitate weaning from the respirator. Pulmonary function improved progressively over the following days, and the patient was weaned to spontaneous breathing. There were no radiographic signs for pneumonia, but the patient still had fever without leukocytosis and an increase of C-reactive protein to 30 mg/dL. Blood cultures and examination of the tracheal secretion showed no bacterial or fungal growth. On postoperative day 18, the patient suddenly suffered from massive intrathoracic bleeding with hemorrhagic shock leading to cardiovascular collapse. All attempts to stabilize cardiopulmonary function failed, and the patient died.
At autopsy, the left pleural cavity showed 2,500 mL fresh and partially coagulated blood, which displaced the whole left lung. All parenchymal organs showed pallor caused by shock. The saphenous vein graft to the posterior descending branch was identified as the site of bleeding. The vein graft showed a 1-cm rupture on the ventral site 6 cm distal to aortal anastomoses at the site before the vessel turned to the posterior wall. The graft showed no aneurysmal or fibrotic areas. The sutures of the anastomoses were intact, and no dehiscence was detected. Macroscopically, a necrotizing vasculitis could be seen in the area of the vein rupture. Histologic examination of the ruptured bypass graft revealed a massive inflammatory reaction extending up to the surrounding epicardial fatty tissue and septated hyphae in the wall of the vein. In the lumen of the vein, necrotic tissue consisting of fibrin, granulocytes, and hyphae could be seen. High-grade necrotizing vasculitis had destroyed normal vascular layers (see Fig 1). Immunohistochemical examination of the Y-like branched, septated hyphae with monoclonal mouse anti-Aspergillus antibodies identified the hyphae as an Aspergillus species. The lungs were free from aspergilloma or other infections. There were no signs of sepsis or mediastinitis.
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Fig 1. (A) Cross section of the venous bypass graft showing transmural floride inflammation. (B) Detection of septated hyphae within the venous wall. (C) Aspergillus species identified with immunohistochemical staining (monoclonal mouse anti-Aspergillus antibodies).
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Comment
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Mediastinal hemorrhage caused by rupture of a saphenous vein coronary artery graft is a rare complication after cardiac surgery and is associated with a high mortality rate. In most cases, rupture of the saphenous vein is associated with mediastinitis [1], bacterial infection of the vein [2, 3], vein laceration secondary to trauma from the sternal edge [3], poor vein quality [3], vein erosion by a mediastinal drainage tube [4], or formation of a false aneurysm of the vein [5]. Rupture of the saphenous vein graft in our patient was caused by necrotizing vasculitis due to localized Aspergillus infection. There is only one case report dealing with Aspergillus infection of a saphenous vein graft resulting in thrombotic graft closure associated with an intimal mycotic abscess, not resulting in graft rupture [6].
Aspergillus infection is a rare but highly lethal complication after cardiovascular surgery. Endovascular infections with Aspergillus species usually present with endocarditis, aortitis, formation of mycotic aneurysms, or prosthetic graft infections [7, 8]. Most patients in whom Aspergillus infection develops are immunocompromised or receive chemotherapy or long-term steroid or antibiotic treatment. The route of infection can be a contamination, especially of prosthetic vascular grafts, in the operating room with the airborne fungal spores, or a hematogenous dissemination or embolization of fungal spores during the course of deep tissue infection or aspergilloma of the lungs. Our patient was immunocompetent with none of the known risk factors for an opportunistic Aspergillus infection. The unsettled question is how the patient got a localized Aspergillus infection of the saphenous vein graft: the Aspergillus organisms could already have invaded the saphenous vein before the saphenectomy was done, and the wall of the vessel destroyed before the vein was transplanted. The already infected vein and the high pressure in the arterial system consequently caused the rupture of the graft. Another possibility is that the vein was damaged at the site where it turned toward the posterior wall of the heart, with subsequent hematogenous dissemination of Aspergillus organisms causing local Aspergillus infection. The origin of a possible causative hyphemia could be an aspergilloma of the lung. This mode of infection seems unlikely, especially as at autopsy no other sources of Aspergillus infection could be found. The route of this localized Aspergillus infection remains unknown.
In summary, a necrotizing vasculitis due to Aspergillus infection of a saphenous vein coronary artery graft and subsequent rupture of the vein graft causing mediastinal hemorrhage is a rare, but highly lethal complication after cardiac surgery. Persistent fever at any time after cardiac surgery in the setting of sterile blood cultures and negative microbiological tests should always alert the physician to a possible fungal infection. Specific tests for fungal infections such as fungal polymerase chain reaction should be considered.
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References
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Abstract
Introduction
