Percutaneous Management of a Saphenous Venous Graft Leaking Pseudoaneurysm

Case report. A 73-year-old male with a previous history of four-vessel coronary artery bypass graft surgery (CABG; LIMA-LAD, SVG-OM3, sequential SVG to RPDA-RPL) in 1985 presented with chest pain consistent with unstable angina. Medical history was significant for hypertension, peripheral vascular disease with abdominal aortic aneurysm repair in 1988, and mesenteric artery venous bypass in 2002. His prior coronary revascularization included bare-metal stent placement in the distal portion of sequential vein graft to right posterior descending/posterolateral branch, and a distal left main stent extending into the ostium of the left circumflex artery eight months prior to this admission. The electrocardiogram (EKG) was essentially unchanged from his prior EKG in November, consisting of Q-waves in the inferior leads and poor R-wave progression in the precordial leads. He was subsequently ruled out for myocardial infarction by cardiac markers. After initial stabilization with intravenous heparin and glycoprotein IIb/IIIa receptor inhibitor therapy, coronary and graft angiography was performed. The previously placed left main stent was patent. The native left anteriordescending (LAD) artery had a 100% occlusion proximally. The left circumflex system was notable for complete occlusion of all obtuse marginal (OM) branches terminating into a small posterolateral branch. The native RCA was completely occluded in its mid-portion. The sequential SVG to the right posterolateral-posterior descending artery had a 40% proximal and 60% mid-ulcerated stenosis, with a patent distal stent site. The LIMA-LAD graft was also patent. The SVG-OM angiography revealed an eccentric proximal, hazy 70% stenosis (Figure 1), followed by a mid-graft body aneurysmal area and a small jet of dye extravasating in the peri-graft region, suggestive of a leaking pseudoaneurysm (Figure 2). After discussing various treatment options, including repeat CABG, the patient elected to be part of the SYMBIOT covered stent graft trial as a roll-in case. Using an 8 Fr JR5 guiding catheter (Medtronic, Santa Rosa, California) and a 0.014 inch Balanced Middle Weight wire (Guidant, Santa Clara, California), both the proximal and mid-lesions were crossed. The patient was anticoagulated with a total of 9,000 units of unfractionated heparin to achieve an ACT > 300 seconds. The leaking pseudoaneurysm was first covered with a 5 mm x 20 mm SYMBIOT covered, self-expanding stent (Boston Scientific, Natick, Massachusetts). Next, the proximal lesion was covered with a second 5 mm x 20 mm SYMBIOT covered stent. Both stent grafts were post-dilatedwith a 4 mm x 15 mm Quantum Maverick balloon (Boston Scientific) inflated to 7 atm. This resulted in no residual stenosis with brisk antegrade flow. The pseudoaneurysm showed no further leak (Figure 3). He tolerated the procedure well, with no complications, and was discharged home the next day with optimal medical therapy, including aspirin and clopidogrel. Follow-up angiography at eight months per the SYMBIOT trial protocol revealed widely patent stent graft sites with a persistent sealing of the pseudoaneurysm (Figure 4). Discussion The present case describes the successful treatment of a saphenous venous graft leaking pseudoaneurysm with a self-expanding covered stent graft. Pseudoaneurysms can occur both early and late following bypass graft surgery.^1–3 The exact pathophysiology is not clear, but infection, inflammation, iatrogenic trauma, and gradual weakening of the vessel wall have been proposed as potential mechanisms.^3–6 Iatrogenic pseudoaneurysms at the proximal or distal anastomosis of the vein graft occur relatively early in the post-operative course. The occurrence of a false aneurysm after coronary angioplasty and stenting of the saphenous vein graft and native coronary artery has been described.^6–8 Pseudoaneurysms occurring in the weeks or months following the bypass procedure are usually associated with wound infection,⁴ and intrinsic or iatrogenic weakness (vein harvest trauma) of the venous wall. Inherent weak points in the venous graft are at valve sites or at branch points where the normal circumferential arrangement of the smooth muscle layers in the media takes on a longitudinal orientation, thereby creating a weak point against the stress generated by the arterial pressure waveform.¹ The feared complication of anastomotic aneurysms is dehiscence of the anastmosis site with life-threatening hemorrhage. Indeed, such aneurysms can present with massive hemorrhage in the post-operative period, as early as ten days after the surgery.^5,9 Aside from rupture, an aneurysm can lead to distal embolization, as a majority of them are at least partially thrombosed. Other well-reported complications of venous graft aneurysms include fistula formation to the right atrium, right ventricle, and chest wall.¹⁰ Although traditionally treated with repeat bypass graft surgery, multiple percutaneous techniques can now be applied for SVG pseudoaneurysm exclusion. Intravascular coiling, injection of thrombin, and multiple bare stent implantations are viable, but less often used treatment modalities.^11–15 With the availability of covered stent grafts, many SVG pseudoaneurysms can be treated percutaneously. The balloon-expandable JoStent, a two-stent sandwich with a PTFE membrane (Abbott Vascular, Redwood City, California), has been used successfully for the treatment of bypass graft-related pseudoaneurysms.^3,16 The SYMBIOT is a self-expanding nitinol, multi-segmented stent encased within a thin porous ePTFE polymer found to be durable at eight-month follow-up in our patient. A self-expanding covered stent graft provides an additional treatment option for patients with bypass graft pseudoaneurysm, and may cause less distal embolization by avoiding balloon inflation during stent deployment.

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