Ann Thorac Surg 2005;80:2376-2378
© 2005 The Society of Thoracic Surgeons
Case report
Off-Pump Repair of a Giant Pseudoaneurysm of a Distal Saphenous Vein Bypass Graft
Wilson J. Couto, MD,
James J. Livesay, MD
*
,
Akram Allam, MD
Section of Cardiovascular Surgery, Texas Heart Institute, Houston, Texas, USA
Accepted for publication June 25, 2004.
* Address correspondence to Dr Livesay, Section of Cardiovascular Surgery, Texas Heart Institute, PO Box 20345, Mail Code 3–258, Houston, TX77225-0345 (Email: jlivesay{at}heart.thi.tmc.edu).
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Abstract
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Pseudoaneurysm of a saphenous vein bypass graft is a rare occurrence after coronary artery bypass grafting but may have lethal consequences. We treated a giant pseudoaneurysm of a saphenous vein graft to the right coronary artery in an 80-year-old male Jehovah's Witness who had undergone coronary artery bypass grafting 4 and a half years earlier. His history revealed a recurrent sternal wound infection. By using a venous patch to close the damaged graft, we were able to perform a successful surgical repair without the need for extracorporeal circulation.
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Introduction
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Postoperative pseudoaneurysm formation is a rare, potentially serious complication that may affect saphenous vein grafts used for coronary artery bypass grafting (CABG). A pseudoaneurysm is a dilatation that involves disruption of one or more layers of the graft wall rather than expansion of all layers of the wall, as in a true aneurysm. Pseudoaneurysms lack an endothelial lining and may represent a focal distention involving a hematoma. They usually occur at the proximal or distal anastomosis of the saphenous vein graft but may occasionally affect the body of the graft. Pseudoaneurysms may produce lethal complications by causing rupture, bleeding, tamponade, and myocardial infarction.
We present a case involving a giant pseudoaneurysm of a saphenous vein graft to the right coronary artery (RCA). The leakage site was successfully repaired without the use of extracorporeal circulation.
An 80-year-old male Jehovah's Witness presented to our institution with chest pain and dyspnea of recent onset. Four and a half years earlier, at another hospital, he had undergone CABG with saphenous vein grafts to the right posterior descending, left anterior descending, and ramus coronary arteries. His recovery had been complicated by a recurring sternal wound infection that was treated with multiple courses of antibiotics and surgical drainage. Eighteen months after the CABG procedure, he was referred to our institution with a recurrent sternal infection caused by methicillin-sensitive Staphylococcus aureus and underwent partial sternal debridement, with placement of an omental flap. He remained free of infection and symptoms for 3 years, after which he returned with his current symptoms.
Computed tomography (CT) and magnetic resonance imaging (MRI) showed a giant (9 cm) pseudoaneurysm of the distal half of the saphenous vein graft to the RCA (Figs 1 and 2).
The diaphragmatic surface of the right ventricle was displaced by the pseudoaneurysm. Cardiac catheterization showed that all three grafts were patent, but contrast medium filled only the proximal portion of the RCA graft, owing to the pseudoaneurysm of the distal portion. The patient was at increased surgical risk because of his obesity (250 lb [114 kg]), chronic obstructive pulmonary disease, and a large ventral hernia. Because he was a Jehovah's Witness, he refused to undergo blood transfusion. Therefore, we elected to use an off-pump surgical approach for repairing the aneurysm.
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Fig 1. Computed tomography scan of the chest revealing a giant (9 cm) pseudoaneurysm along the right atrioventricular groove. Note the laminated thrombus within the pseudoaneurysm. The arrows designate the pseudoaneurysm.
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Fig 2. Magnetic resonance image, in the oblique sagittal section, showing a large, circular mass that displaces the contrast-filled right ventricle (RV) away from the diaphragm and liver. The arrows designate the pseudoaneurysm. (LV = left ventricle.)
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Anterior transsternal dissection was performed to mobilize the previous omental flap to obtain proximal control of the RCA bypass graft, and to facilitate exposure of the distal right coronary artery. After heparin (1 mg/kg) was given and the RCA graft occluded, the pseudoaneurysm was entered and a large hematoma evacuated. Cultures obtained from the hematoma were sterile. The pseudoaneurysm was found to originate from partial disintegration (15 mm) of the hood of the saphenous vein graft, which overlay the distal anastomosis to the right posterior descending coronary artery. Backbleeding from the distal vessel was controlled with a coronary occluder, and the defect was repaired with a venous patch graft. The patient remained hemodynamically stable throughout the procedure. His total blood loss was 700 mL. The ventral hernia was repaired with polypropylene mesh. The wound was closed with skin flaps, but these later dehisced and became secondarily infected by Staphylococcus epidermidis. Bilateral pectoralis major muscle flaps and antibiotic therapy with 2 weeks of vancomycin and 6 weeks of minocycline were required for eventual healing. The patient recovered completely and has been asymptomatic at follow-up examinations over the last 2 years.
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Comment
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Pseudoaneurysm of a saphenous vein graft used for CABG was first reported by Riahi and colleagues [1] in 1975. This complication can occur either early or late postoperatively. It usually involves the proximal suture line but can also affect the distal suture line. Mediastinal sepsis is the major predisposing factor in more than half of the reported cases, especially those involving S aureus. Mycotic or infected pseudoaneurysms may result from direct extension to, or hematogenous seeding of, the anastomotic site, leading to suture-line dehiscence [2]. In noninfectious cases, the mechanism of pseudoaneurysm formation is often unclear, but the following factors have been implicated: (1) technical factors such as trauma during the harvesting and preparation of vein grafts; (2) operative factors that cause suture-line dehiscence through breakage of the suture material or tension on the anastomosis; and (3) host factors such as intrinsic weakness at the vein's side branches or around valves, mechanical stress related to hypertension, venous dissection, mycotic vasculitis, or atherosclerotic changes [3, 4].
In symptomatic cases, the patient presents with worsening dyspnea and recurrent chest pain, which may be caused by angina, a myocardial infarction, or aneurysmal rupture. Chest radiography or echocardiography may show a mediastinal mass or superior vena caval obstruction. The diagnosis is confirmed with subtraction angiography, transesophageal echocardiography, coronary angiography, or CT. Magnetic resonance imaging can provide views in multiple planes, allowing three-dimensional definition of the aneurysm. Rapid-beam CT is also a superior diagnostic tool, as cardiac motion does not harm the clarity of the image. In the past, coronary vein graft pseudoaneurysms have been treated by means of surgical correction [2–4]. More recently, successful treatment has been accomplished with transcatheter embolization [5] or insertion of a "covered" intracoronary stent [6]. Neither technique is advisable in the presence of an ongoing infection.
In our patient, pseudoaneurysm formation was probably the result of a postoperative wound infection involving a Staphylococcus organism. Chest pain and other symptoms of heart failure were related to progressive cardiac compression by the pseudoaneurysm. Our patient was at high risk because of his advanced age, chronic obstructive pulmonary disease, redo operative status, previous sternal infection, obesity, and need for concomitant ventral hernia repair. He was also a Jehovah's Witness and refused blood transfusion and blood products. Because of these factors, we chose to avoid the use of extracorporeal circulation. The off-pump approach expedited the repair, minimized blood loss, and prevented systemic complications.
Other surgeons have used cardiopulmonary bypass and deep hypothermic circulatory arrest in patients with pseudoaneurysms of coronary vein grafts, but this approach should be limited to patients with proximal pseudoaneurysms involving the ascending aorta [2]. Deep hypothermic circulatory arrest increases the complexity of the procedure and the risk of complications. In some cases, extracorporeal circulation and cardioplegia may be necessary to allow access to posterior vessels or to avoid perioperative ischemia. Avoidance of extracorporeal circulation was advantageous in our patient and permitted successful repair of the pseudoaneurysm.
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Acknowledgments
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The authors appreciate the contributions of Scott Flamm, MD, Director of Magnetic Resonance Imaging and MRI Research, Virginia Fairchild, senior medical editor, and Stephen Palmer, PhD, scientific medical writer at the Texas Heart Institute/St. Luke's Episcopal Hospital, Houston, Texas.
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References
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- Riahi M, Vasu CM, Tomatis LA, Schlosser RJ, Zimmerman G. Aneurysm of saphenous vein bypass graft to coronary artery J Thorac Cardiovasc Surg 1975;70:358-359.[Abstract]
- Smith JA, Goldstein J. Saphenous vein graft pseudoaneurysm formation after postoperative mediastinitis Ann Thorac Surg 1992;54:766-768.[Abstract/Free Full Text]
- Mohara J, Konishi H, Kato M, Misawa Y, Kamisawa O, Fuse K. Saphenous vein graft pseudoaneurysm rupture after coronary artery bypass grafting Ann Thorac Surg 1998;65:831-832.[Abstract/Free Full Text]
- deHann HPJ, Huysmans HA, Weeda HWH, Bosker HA, Buis B. Anastomotic pseudoaneurysm after aorto-coronary bypass grafting Thorac Cardiovasc Surg 1985;33:55-56.[Medline]
- Kim D, Guthaner DF, Wexler L. Transcatheter embolization of a leaking pseudoaneurysm of a saphenous vein aortocoronary bypass graft Cathet Cardiovasc Diagn 1983;9:591-594.[Medline]
- Mahy IR, Walton S. Successful treatment of false aneurysm of a saphenous vein bypass graft with fistula to the anterior chest wall using "covered" intracoronary stents Heart 1998;80:527-529.[Free Full Text]
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Abstract
Introduction
