Injury of a native coronary vessel during coronary artery bypass grafting (CABG) is very rare. We report on a 76-year-old patient who developed a large pseudoaneurysm of the left anterior descending artery (LAD) following CABG. The patient was then successfully treated by polytetrafluorethylene (PTFE)-stent graft implantation and percutaneous coil embolization. A coronary artery pseudoaneurysm caused by intraoperative damage has not been described previously. The incidence of coronary artery aneurysm (> 1.5 times normal arterial diameter) has been shown to be 0.3% to 4.9% in patients with suspected coronary artery disease.1 Only a few papers have described pseudoaneurysms of native coronary arteries. Almost all of these were associated with mechanically-induced vessel trauma during catheter-based interventions.2–6 False aneurysms after CABG are usually related to saphenous vein grafts (SVG).7 To the best of our knowledge, pseudoaneurysm of a native coronary artery early after CABG has not been described previously. We report on a patient with coronary artery pseudoaneurysm involving the proximal left anterior descending artery (LAD) early after CABG that was successfully managed by percutaneous graft stent implantation and coil embolization. Case Report. A 76-year-old male with a history of diabetes mellitus hypertension, and peripheral artery occlusive disease presented with Canadian Cardiovascular Society Class III–IV angina. Three weeks earlier, he had undergone uncomplicated CABG with full cardiopulmonary bypass support (Figure 1). At that time, he had received a left internal thoracic artery (LIMA) graft to the LAD, and SVGs to the first obtuse marginal artery, the distal circumflex coronary artery (CFx) and the posterior descending artery (PDA). A coronary angiography had been performed at the referring hospital. Cardiac catheterization demonstrated a patent LIMA graft and a functioning SVG as well. However, the angiogram revealed a large pseudoaneurysm (diameter 18 x 17 x 20 mm) in the proximal portion of the LAD (Figure 2). A decision was made to seal the false aneurysm percutaneously by the use of a covered stent. The attempt to place a covered stent was unsuccessful because it was impossible to advance a 0.014 inch HT Balance guidewire (Guidant Corp., Indianapolis, Indiana) into the distal LAD. Subsequently, the patient was transferred to our hospital for further evaluation and treatment. There was some concern about the risk of a surgical approach in such a short timeframe after CABG because the preoperative logistic EuroSCORE8 predicted a 21% mortality rate for this patient. We therefore decided to perform a second interventional procedure. After inserting a 6 Fr sheath (St. Jude Medical, Inc., St. Paul, Minnesota) into the right femoral artery, 10,000 units of heparin were administered. Angiography with multiple projections and selective contrast injections into the left main artery (LM), the LIMA and the right coronary artery (RCA) was performed in order to precisely locate the blood supply of the aneurysm. The angiogram revealed a significant antegrade and retrograde inflow into the aneurysm and no significant septal collaterals via the RCA. The first step was to occlude the LAD ostium by the use of a PTFE-coated stent. The retrograde blood supply needed to be interrupted using a coil embolization technique. The ostium of the LM was cannulated with a 6 Fr Extra Support backup guiding catheter (Medtronic, Inc., Minneapolis, Minnesota), and a 0.014 inch BMW guidewire (Guidant) was placed into the CFx artery. Then a 16 mm PTFE-coated GraftMaster coronary stent graft (Abbott Laboratories, Redwood City, California) was deployed in the LM and the proximal CFx. The stent was postdilated with a 3.0 x 15 mm Powersail® PTCA balloon (Guidant) at 16 atm. As expected, the PTFE layer effectively acted as a mechanical barrier, and subsequent angiography confirmed successful sealing of the LAD ostium (Figures 3 A and B). Next, a 6 Fr IMA-type guiding catheter (Medtronic) was inserted through the left radial artery. A 3 Fr Tracker-18 soft catheter (Boston Scientific Corp., Natick, Massachusetts) was advanced through the LIMA into the LAD. A complex helical fiber platinum coil (Boston Scientific) was then passed into the LAD distal to the aneurysm in order to occlude the artery. Because dye injection through the guiding catheter revealed residual staining, a second and third coil were passed proximal to the first one. Final angiography revealed complete obliteration of the large pseudoaneurysm (Figure 4). The intervention was uneventful and the hemodynamic status of the patient remained stable during the procedure as well. Discussion. A pseudoaneurysm is a dilatation that involves disruption of one or more layers of the vessel wall, rather than expansion of all layers of the wall, as in a true aneurysm. The incidence and natural history of coronary pseudoaneurysms are not known.6 False aneurysms may produce lethal complications by causing rupture, bleeding, tamponade and myocardial infarction. Differentiation between a true aneurysm and a pseudoaneurysm is frequently possible from clinical presentation or by using conventional angiography. However, accurate diagnosis may require the use of intravascular ultrasound or electron beam computed tomography in addition to angiography.9 An increasing number of coronary aneurysms are currently being described following percutaneous coronary interventions (PCI) such as balloon angioplasty, stent implantation, atherectomy and brachytherapy.10–12 However, these mechanisms play no role in the patient described here because he had never undergone PCI. Pseudoaneurysms after CABG are primarily related to SVGs. They tend to develop early, within weeks to a few months, after surgery and may rupture with drastic clinical consequences, including sudden death. Pseudoaneurysms usually occur at the proximal or distal anastomoses of the SVG, but may occasionally affect the body of the graft.13 True SVG aneurysms, on the other hand, emerge many years after the initial CABG surgery.7 A pseudoaneurysm of a native coronary artery that occurs a few weeks after CABG has not been described previously. However, coronary vessel injury during a surgical procedure have been reported in several case studies. Borger et al reported on two cases of intraoperative fractures of calcified right coronary arteries due to compression of the right atrioventricular groove,14 requiring emergent CABG. In our case, the construction of the distal CFx anastomosis during CABG was very difficult because of the location of the target. Presumably, injury to the LAD had occurred secondary to a combination of vessel wall calcification and excessive compression during exposure of the CFx coronary artery. Considering this, we strongly suspect that damage of the LAD during surgery is the most probable cause of the pseudoaneurysm. Surprisingly, this adverse event went undetected during the surgical procedure. Indeed an aneurysm of the proximal LAD might be invisible on the heart’s surface during surgery because this region is covered with thick epicardial fat.15 Therefore, a coronary aneurysm can go unnoticed if the patient remains in stable hemodynamic condition and the operation course is uneventful. The indication for treatment and the best modality for aneurysm therapy remain to be defined.16 Initial treatment for an aneurysm should be based upon its size and rate of growth. Moreover, the type of aneurysm may be an important factor in the indication for a treatment strategy.15 Comorbid conditions of the patient which affect surgical risk need to be factored into the decision process as well. Obviously, simple observation was inappropriate in this case because large pseudoaneurysm had developed in a short period of time and there was a risk of spontaneous rupture. A surgical approach was also considered to be an inadequate option because the patient had undergone CABG a few weeks earlier. Furthermore, many coronary artery aneurysms can be managed safely with interventional techniques. PTFE-coated stents and autologous vein graft-coated stents have been reported to be efficacious for large proximal vessels,17–20 provided that these stents can be delivered to the site. Moreover, percutaneous coil embolization has been used in the treatment of coronary artery false aneurysms21 and coronary perforations.22,23 Considering the potential risk of rupture, a decision was made to proceed with interventional therapy. Because of sufficient bypass graft supply of the LAD and the CFx, disadvantages of PTFE-covered stents such as late thrombo-occlusive events and edge renarrowing,18,24 were of no relevance in this case. A placement of coils into the proximal LAD was obviated to ensure that the coils did not protrude or extend back into the aorta or left main coronary artery. Finally, retrograde coil embolization of the LAD caused the false aneurysm to disappear. We feel that this treatment strategy is highly effective for this complication, and the risk of significant myocardial damage is extremely low. To the best of our knowledge, this is the first reported case of a coronary artery pseudoaneurysm caused by intraoperative injury to a LAD artery during CABG that was successfully treated by PTFE-coated stent implantation and percutaneous platinum coil embolization. Acknowledgment. We wish to thank Anne M. Gale, Editor in the Life Sciences, for her editorial assistance.
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