(Radiographics. 2000;20:1263-1278.)
© RSNA, 2000
Complications of Endovascular Repair for Thoracic and Abdominal Aortic Aneurysm: An Imaging Spectrum1
Toshifumi Mita, MD,
Takeshi Arita, MD ,
Naofumi Matsunaga, MD, PhD ,
Matakazu Furukawa, MD ,
Nobuya Zempo, MD ,
Kensuke Esato, MD and
Masunori Matsuzaki, MD
1 From the Department of Radiology (T.M., T.A., N.M., M.F.), First Department of Surgery (N.Z., K.E.), and Second Department of Internal Medicine (M.M.), Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan. Presented as a scientific exhibit at the 1999 RSNA scientific assembly. Received March 3, 2000; revision requested March 29 and received May 9; accepted May 12. Address correspondence to T.M. (e-mail: mitafumi@mx51.tiki.ne.jp).
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Abstract
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Endovascular stent-graft implantation is an alternative to conventional open surgery for the treatment of aortic aneurysm. Forty-nine consecutive patients with aortic aneurysm (thoracic, n = 17; infrarenal, n = 32) were treated with endovascular stent-graft implantation. Complications occurred in 25 patients (two patients had two complications): endoleak (n = 13), graft thrombosis (n = 5), graft kinking (n = 2), pseudoaneurysm caused by graft infection (n = 1), graft occlusion (n = 1), shower embolism (n = 1), perforation of mural thrombus by means of inadvertent penetration of delivery system (n = 1), colon necrosis (n = 1), aortic dissection (n = 1), and hematoma at the arteriotomy site (n = 1). Imaging findings were analyzed for spiral computed tomography, plain abdominal radiography, transesophageal echocardiography, and digital subtraction angiography. Since some of these complications are fatal, radiologists need to instantly and accurately recognize them. Awareness and understanding of possible complications should help ensure a safe, successful procedure.
Index Terms: Aneurysm, aortic, 94.731, 94.732, 98.731, 98.732 • Angiography, 94.1211, 94.1222, 98.1211, 98.1222 • Arteries, CT, 94.12911, 94.12912, 94.12914, 94.12915, 98.12911, 98.12912, 98.12914, 98.12915 • Arteries, grafts and prostheses, 94.1268, 98.1268 • Computed tomography (CT), comparative studies, 94.12911, 94.12912, 94.12914, 94.12915, 98.12911, 98.12912, 98.12914, 98.12915
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Introduction
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Since the reports by Parodi et al (1) in 1991 for abdominal aortic aneurysm and Dake et al (2) in 1994 for thoracic aortic aneurysm, endovascular stent-graft implantation has been used as an alternative to conventional open surgery in the treatment of aortic aneurysm, especially in high-risk patients. Advantages of endovascular procedures are less blood loss, shorter stays in intensive care units and subsequent hospitalization, and quicker recovery (3). Many studies show that endovascular stent-graft therapy is safe and effective (1–12), although complications related to this treatment are also recognized. A few investigators report complications of endovascular stent-graft therapy for aortic aneurysm in the nonradiology literature (13,14), but the description of imaging findings is limited. The purpose of this article is to present imaging findings and the clinical outcomes of common (endoleak, graft thrombosis, graft kinking) and rare (pseudoaneurysm caused by graft infection, graft occlusion, shower embolism, perforation of mural thrombus by means of inadvertent penetration of the delivery system, colon necrosis, aortic dissection, hematoma at the arteriotomy site) fatal or nonfatal complications. The causes of each of these complications are also discussed.
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Materials and Methods
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Patient Population
Between September 1997 and September 1999, 49 consecutive patients (37 men and 12 women; mean age, 73.7 years; age range, 52–88 years) with aortic aneurysm (thoracic, n = 17; infrarenal, n = 32) were treated with endovascular stent-graft implantation.
Stent-Graft Implantation
Stent-grafts were constructed from self-expandable Gianturco Z-stents with thin-walled woven Dacron grafts (Ube Graft; Ube, Japan). Straight stent-grafts were used in all patients with thoracic aortic aneurysm. In patients with abdominal aortic aneurysm, a straight stent-graft was used in 11 and a bifurcated stent-graft in four. The remaining 17 patients were treated by implanting a tapered aortouniiliac stent-graft and performing contralateral iliac artery occlusion with a blind-ended stent-graft (occluded stent-graft) and ilioiliac or femorofemoral crossover bypass grafting. All procedures were performed with general anesthesia in an operating room by a team of vascular surgeons and interventional radiologists. To deploy the stent-graft, an 18–24-F delivery system was introduced via the external iliac artery by using the "tug-of-wire" technique with C-arm fluoroscopic guidance. In all cases of thoracic aortic aneurysm, transesophageal echocardiography was performed during the procedure.
Follow-up Imaging
Spiral CT (Somatom Plus 4; Siemens Medical Systems, Erlangen, Germany) was performed in all patients. The first follow-up study was performed within 7 days of the procedure and before discharge, with further follow-up studies every 3 months. Spiral CT was performed with use of 100 mL of nonionic contrast material (Optiray 320; Yamanouchi, Tokyo, Japan) in a concentration of 320 mg of iodine per milliliter with flow rate of 2.5 mL/sec, scanning delay of 25–30 seconds, 3.0-mm collimation, table speed of 6.0 mm per rotation, and reconstruction interval of 3.0 mm. Shaded surface display, multiplanar reconstruction, and curved-planar reconstruction images were produced with standard software. When complications were suspected on the basis of spiral CT findings, plain abdominal radiography (one patient) or digital subtraction angiography (two patients) were also performed.
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Results
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Twenty-five patients experienced complications. Complications were divided into two groups: common and rare. Common complications included endoleak (n = 13), graft thrombosis (n = 5), and graft kinking (n = 2). Rare complications included pseudoaneurysm caused by graft infection (n = 1), graft occlusion (n = 1), shower embolism (n = 1), perforation of mural thrombus by means of inadvertent penetration of the delivery system (n = 1), colon necrosis (n = 1), aortic dissection (n = 1), and hematoma at the arteriotomy site (n = 1). Most of the rare complications were serious, and one patient had a fatal outcome.
Common Complications
Endoleak.—The most common complication after stent-graft implantation is leakage into the aneurysm. Rates of leakage after endovascular repair of aortic aneurysm are 2.4%–45.5% (15). Leakage is classified according to the site of origin as proximal, distal, or middle graft (16). The causes of proximal or distal endoleak are incomplete fixation of the stent-graft to the aortic wall and of middle graft endoleak are graft defects or retrograde blood flow via patent arteries. Axial CT findings on the basis of the configuration and location of the leakage in relation to the stent-graft and the aneurysm indicate the cause of leakage (17).
In our series, endoleak occurred in nine of the 17 patients with thoracic aortic aneurysm: middle graft endoleak in two and proximal endoleak in seven. In six of the latter seven patients, the proximal neck of the aneurysm was less than 2 cm long (Fig 1). The aneurysm in three of the nine patients with endoleak was enlarged, and one of the three patients died of a rupture. This patient had undergone emergent stent-graft implantation to avert impending rupture and died 8 days later.
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Figure 1a. Proximal endoleak due to a short proximal neck of the aneurysm in a 72-year-old man with a distal arch aneurysm. (a) Preprocedural multiplanar reconstruction image (oblique sagittal view) shows a distal arch aneurysm with a short proximal neck. (b) Follow-up multiplanar reconstruction image (sagittal view) obtained 1 week after stent-graft implantation show proximal endoleak (arrows).
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Figure 1b. Proximal endoleak due to a short proximal neck of the aneurysm in a 72-year-old man with a distal arch aneurysm. (a) Preprocedural multiplanar reconstruction image (oblique sagittal view) shows a distal arch aneurysm with a short proximal neck. (b) Follow-up multiplanar reconstruction image (sagittal view) obtained 1 week after stent-graft implantation show proximal endoleak (arrows).
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Persistent proximal endoleak occurred in only two of the 32 patients with infrarenal aortic aneurysm. The proximal necks of the aneurysms in these two patients were the most tortuous. In one of the two patients, additional stent-graft implantation was performed after 15 months because the aneurysm enlarged. No leakage was confirmed after this procedure. In this patient, multiplanar reconstruction images obtained before the additional stent-graft implantation clearly demonstrated insufficient attachment of the stent-graft to the aortic wall (Fig 2). In the other patient, graft occlusion occurred 14 days after the procedure, and emergent open surgery was performed.
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Figure 2a. Persistent proximal endoleak due to a tortuous proximal neck of the aneurysm in a 68-year-old woman with an infrarenal abdominal aortic aneurysm. (a, b) Curved-planar reconstruction (a) and sagittal multiplanar reconstruction (b) images obtained 12 months after stent-graft implantation show proximal endoleak (arrows). The angle of the proximal neck of the aneurysm is acute. (c) Magnified image of b clearly demonstrates insufficient attachment of the proximal end of the stent-graft to the aortic wall (arrows).
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Figure 2b. Persistent proximal endoleak due to a tortuous proximal neck of the aneurysm in a 68-year-old woman with an infrarenal abdominal aortic aneurysm. (a, b) Curved-planar reconstruction (a) and sagittal multiplanar reconstruction (b) images obtained 12 months after stent-graft implantation show proximal endoleak (arrows). The angle of the proximal neck of the aneurysm is acute. (c) Magnified image of b clearly demonstrates insufficient attachment of the proximal end of the stent-graft to the aortic wall (arrows).
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Figure 2c. Persistent proximal endoleak due to a tortuous proximal neck of the aneurysm in a 68-year-old woman with an infrarenal abdominal aortic aneurysm. (a, b) Curved-planar reconstruction (a) and sagittal multiplanar reconstruction (b) images obtained 12 months after stent-graft implantation show proximal endoleak (arrows). The angle of the proximal neck of the aneurysm is acute. (c) Magnified image of b clearly demonstrates insufficient attachment of the proximal end of the stent-graft to the aortic wall (arrows).
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Distal endoleak occurred 3 months after surgery in one patient who had undergone tapered stent-graft implantation from the aorta to the left iliac artery (Fig 3). A curved-planar reconstruction image obtained 1 week after the procedure revealed that the stent-graft was too short, and the left internal iliac artery originating from the aneurysm was patent (Fig 3b). An additional stent-graft implantation was performed, and the endoleak disappeared.
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Figure 3a. Distal endoleak developed 3 months after tapered stent-graft implantation from the aorta to the left iliac artery combined with right common iliac artery occlusion and ilioiliac bypass grafting in an 83-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural curved-planar reconstruction image shows an infrarenal aortic aneurysm extending into the left common iliac artery. (b) Curved-planar reconstruction image obtained 1 week after stent-graft implantation shows no endoleak, but the distal end of the stent-graft is within the mural thrombus of the aneurysm (small arrow), and the internal iliac artery is patent (arrowhead). Occlusion stent-graft is placed in the right common iliac artery (large arrow). (c) Curved-planar reconstruction image obtained 3 months after stent-graft implantation reveals development of distal endoleak (arrows).
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Figure 3b. Distal endoleak developed 3 months after tapered stent-graft implantation from the aorta to the left iliac artery combined with right common iliac artery occlusion and ilioiliac bypass grafting in an 83-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural curved-planar reconstruction image shows an infrarenal aortic aneurysm extending into the left common iliac artery. (b) Curved-planar reconstruction image obtained 1 week after stent-graft implantation shows no endoleak, but the distal end of the stent-graft is within the mural thrombus of the aneurysm (small arrow), and the internal iliac artery is patent (arrowhead). Occlusion stent-graft is placed in the right common iliac artery (large arrow). (c) Curved-planar reconstruction image obtained 3 months after stent-graft implantation reveals development of distal endoleak (arrows).
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Figure 3c. Distal endoleak developed 3 months after tapered stent-graft implantation from the aorta to the left iliac artery combined with right common iliac artery occlusion and ilioiliac bypass grafting in an 83-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural curved-planar reconstruction image shows an infrarenal aortic aneurysm extending into the left common iliac artery. (b) Curved-planar reconstruction image obtained 1 week after stent-graft implantation shows no endoleak, but the distal end of the stent-graft is within the mural thrombus of the aneurysm (small arrow), and the internal iliac artery is patent (arrowhead). Occlusion stent-graft is placed in the right common iliac artery (large arrow). (c) Curved-planar reconstruction image obtained 3 months after stent-graft implantation reveals development of distal endoleak (arrows).
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Graft Thrombosis.—On contrast materialenhanced CT scans, graft thrombosis is recognized as an intraluminal, parietal, circular, or semicircular area within the stent-graft not enhanced (18). Parietal thrombi within the stent-graft are reported to occur at rates of 3%–19% (18–20). The prognosis for these parietal thrombi varies from spontaneous shrinkage to development of complete thrombosis; therefore, follow-up studies at short intervals are necessary.
Intraluminal circular or semicircular, 1.0–6.5-mm-wide thrombus formations were seen within the stent-graft at follow-up CT in five patients. All had undergone endovascular stent-graft implantation to treat infrarenal abdominal aortic aneurysm. In one of these patients, the 2-week follow-up CT scan showed a 6.5-mm-wide semicircular thrombus within the stent-graft (Fig 4a). Three months later, the thrombus had shrunk to 2.6 mm wide without any treatment (Fig 4b). At follow-up CT in the other four patients, the thrombus showed no significant change in size. The cause of graft thrombosis in these patients was unclear.
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Figure 4a. Graft thrombosis after stent-graft implantation in a 79-year-old man with an infrarenal aortic aneurysm. (a) Axial CT image obtained 2 weeks after stent-graft implantation shows a 6.5-mm-wide, crescent-shaped thrombus within the stent-graft. (b) Axial CT image obtained 3 months after the procedure reveals that the thrombus has shrunk without any treatment.
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Figure 4b. Graft thrombosis after stent-graft implantation in a 79-year-old man with an infrarenal aortic aneurysm. (a) Axial CT image obtained 2 weeks after stent-graft implantation shows a 6.5-mm-wide, crescent-shaped thrombus within the stent-graft. (b) Axial CT image obtained 3 months after the procedure reveals that the thrombus has shrunk without any treatment.
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Graft Kinking.—When large aneurysms decrease in diameter after endovascular repair, they also decrease in length (8,21). This shortening may lead to the development of a kink in the stent-graft (21). Axial CT images cannot depict the shape of the stent-graft adequately, but maximum intensity projection or multiplanar reconstruction images can clearly demonstrate the graft kinking. Chuter et al (8) reported graft kinking caused by shortening of the aneurysm after successful stent-graft implantation. White et al (9) described graft kinking associated with regression of the abdominal aortic aneurysm after complete exclusion of the aneurysm. The stent-grafts implanted in these patients were not fully supported by the stent; thus, graft kinking occurred at the unsupported portion of the stent-graft.
The stent-grafts we used were fully supported by Z-stents from one end to the other, and graft kinking occurred in two patients with infrarenal abdominal aortic aneurysm after complete exclusion of the aneurysm. In one of these two patients, graft kinking occurred 12 months after implantation (Fig 5). We believe that shortening of the aneurysm and a decrease in diameter caused the graft kinking (Fig 5b). In the other patient, graft kinking associated with distal migration of the proximal end of the stent-graft was seen 3 months after implantation (Fig 6). Follow-up curved-planar reconstruction images revealed no decrease in diameter or length of the aneurysm (Fig 6b).
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Figure 5a. Graft kinking after stent-graft implantation in a 74-year-old man with an infrarenal abdominal aortic aneurysm. (a) Sagittal multiplanar reconstruction image obtained 7 months after stent-graft implantation shows no endoleak or graft kinking. The proximal end of the aneurysm is at the level of the upper end (arrow) of the second lumbar spine (L2). (b) Sagittal multiplanar reconstruction image obtained 12 months after the procedure shows an apparent decrease in diameter of the aneurysm and development of graft kinking. A decrease in length of the aneurysm is also indicated by caudal deviation of the proximal end of the aneurysm (arrow).
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Figure 5b. Graft kinking after stent-graft implantation in a 74-year-old man with an infrarenal abdominal aortic aneurysm. (a) Sagittal multiplanar reconstruction image obtained 7 months after stent-graft implantation shows no endoleak or graft kinking. The proximal end of the aneurysm is at the level of the upper end (arrow) of the second lumbar spine (L2). (b) Sagittal multiplanar reconstruction image obtained 12 months after the procedure shows an apparent decrease in diameter of the aneurysm and development of graft kinking. A decrease in length of the aneurysm is also indicated by caudal deviation of the proximal end of the aneurysm (arrow).
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Figure 6a. Graft kinking after straight stent-graft implantation in a 77-year-old man with an infrarenal aortic aneurysm. (a) Curved-planar reconstruction image obtained 6 days after implantation shows no endoleak or graft kinking. (b) Curved-planar reconstruction image obtained 3 months after the procedure shows a kink and caudal displacement of the proximal end of the stent-graft. No change is seen in the maximum diameter of the aneurysm.
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Figure 6b. Graft kinking after straight stent-graft implantation in a 77-year-old man with an infrarenal aortic aneurysm. (a) Curved-planar reconstruction image obtained 6 days after implantation shows no endoleak or graft kinking. (b) Curved-planar reconstruction image obtained 3 months after the procedure shows a kink and caudal displacement of the proximal end of the stent-graft. No change is seen in the maximum diameter of the aneurysm.
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Tillich et al (22) recently reported that kinks of bifurcated stent-grafts fully supported by stents were observed in six of 33 patients 3–18 months after implantation. In three of the six patients, the kink was associated with distal migration of the proximal portion of the stent-graft. No details were given regarding the cause of graft kinking in the remaining patients.
Rare Complications
Pseudoaneurysm Caused by Graft Infection.—Graft infection, a rare event after endovascular stent-graft implantation, is associated with considerable mortality and morbidity rates. Although fever, leukocytosis, elevation of C-reactive protein, and perigraft air are frequently observed immediately after implantation, these findings do not represent evidence of systemic or graft infections (18,23). Sapoval et al (24) report transient periprosthetic thickening that occurred 2 months after stent-graft implantation in the iliac artery. This reaction was considered an inflammatory foreign body reaction against the graft material. Thus, periprosthetic thickening with soft-tissue attenuation at follow-up CT does not always indicate graft infection, and diagnosis of graft infections may be difficult (25).
Graft infection is occasionally observed sometime after the procedure (25,26). Heikkinen et al (25) report aortic stent-graft infection with Listeria monocytogenes that occurred 12 weeks after implantation. The outcome of no treatment of aortic stent-graft infection or treatment with exclusive antibiotics is invariably fatal. A combination of administration of systemic antibiotics and surgery is necessary to obtain successful results. The principle in such surgical treatment is total excision of the infected graft. In our series, a graft infection resulting in pseudoaneurysm formation occurred 2 months after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion and ilioiliac crossover bypass grafting. Abdominal radiography performed 2 weeks after the procedure revealed the occluded stent-graft at the left common iliac artery narrowed as the artery ran peripherally (Fig 7a). Two months later, the patient had fever, left inguinal swelling, and tenderness. Pelvic CT showed a soft-tissue-attenuating area around the distal end of the occluded stent-graft (Fig 7d). Graft infection was suspected on the basis of clinical symptoms and CT findings. Abdominal radiography performed at that time revealed the distal end of the Z-stent had expanded (Fig 7e). Digital subtraction angiography showed pseudoaneurysm at the distal end of the occluded stent-graft in the left common iliac artery (Fig 7f). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery, during which the distal end of the occluded stent-graft was observed to protrude from the external iliac artery. The ilioiliac bypass graft was not infected. The infected stent-graft was removed, and the left common iliac artery was resected.
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Figure 7a. Pseudoaneurysm caused by graft infection in an 82-year-old man with an infrarenal aortic aneurysm. (a) Abdominal radiograph obtained 2 weeks after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion, coil embolization of the left internal iliac artery, and ilioiliac bypass grafting reveals the occluded stent-graft placed at the narrowing of the left common iliac artery as it runs peripherally (arrows). (b) Digital subtraction angiogram obtained 2 weeks after the procedure shows no abnormal findings. (c) Axial CT image obtained 2 weeks after the procedure shows no abnormal findings at the distal end of the occluded stent-graft. (d) Axial CT scan obtained 2 months after the procedure shows development of a soft-tissue-attenuating area (arrows) around the distal end of the occluded stent-graft (arrowheads). The patient had fever, left inguinal swelling, and tenderness. (e) Abdominal radiograph obtained 2 months after the procedure shows expansion of the distal end of the occluded stent-graft (arrows). (f) Digital subtraction angiogram obtained 2 months after the procedure reveals pseudoaneurysmal formation around the distal end of the occluded stent-graft (arrows). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery when the distal end of the occluded stent-graft was seen to protrude from the external iliac artery.
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Figure 7b. Pseudoaneurysm caused by graft infection in an 82-year-old man with an infrarenal aortic aneurysm. (a) Abdominal radiograph obtained 2 weeks after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion, coil embolization of the left internal iliac artery, and ilioiliac bypass grafting reveals the occluded stent-graft placed at the narrowing of the left common iliac artery as it runs peripherally (arrows). (b) Digital subtraction angiogram obtained 2 weeks after the procedure shows no abnormal findings. (c) Axial CT image obtained 2 weeks after the procedure shows no abnormal findings at the distal end of the occluded stent-graft. (d) Axial CT scan obtained 2 months after the procedure shows development of a soft-tissue-attenuating area (arrows) around the distal end of the occluded stent-graft (arrowheads). The patient had fever, left inguinal swelling, and tenderness. (e) Abdominal radiograph obtained 2 months after the procedure shows expansion of the distal end of the occluded stent-graft (arrows). (f) Digital subtraction angiogram obtained 2 months after the procedure reveals pseudoaneurysmal formation around the distal end of the occluded stent-graft (arrows). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery when the distal end of the occluded stent-graft was seen to protrude from the external iliac artery.
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Figure 7c. Pseudoaneurysm caused by graft infection in an 82-year-old man with an infrarenal aortic aneurysm. (a) Abdominal radiograph obtained 2 weeks after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion, coil embolization of the left internal iliac artery, and ilioiliac bypass grafting reveals the occluded stent-graft placed at the narrowing of the left common iliac artery as it runs peripherally (arrows). (b) Digital subtraction angiogram obtained 2 weeks after the procedure shows no abnormal findings. (c) Axial CT image obtained 2 weeks after the procedure shows no abnormal findings at the distal end of the occluded stent-graft. (d) Axial CT scan obtained 2 months after the procedure shows development of a soft-tissue-attenuating area (arrows) around the distal end of the occluded stent-graft (arrowheads). The patient had fever, left inguinal swelling, and tenderness. (e) Abdominal radiograph obtained 2 months after the procedure shows expansion of the distal end of the occluded stent-graft (arrows). (f) Digital subtraction angiogram obtained 2 months after the procedure reveals pseudoaneurysmal formation around the distal end of the occluded stent-graft (arrows). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery when the distal end of the occluded stent-graft was seen to protrude from the external iliac artery.
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Figure 7d. Pseudoaneurysm caused by graft infection in an 82-year-old man with an infrarenal aortic aneurysm. (a) Abdominal radiograph obtained 2 weeks after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion, coil embolization of the left internal iliac artery, and ilioiliac bypass grafting reveals the occluded stent-graft placed at the narrowing of the left common iliac artery as it runs peripherally (arrows). (b) Digital subtraction angiogram obtained 2 weeks after the procedure shows no abnormal findings. (c) Axial CT image obtained 2 weeks after the procedure shows no abnormal findings at the distal end of the occluded stent-graft. (d) Axial CT scan obtained 2 months after the procedure shows development of a soft-tissue-attenuating area (arrows) around the distal end of the occluded stent-graft (arrowheads). The patient had fever, left inguinal swelling, and tenderness. (e) Abdominal radiograph obtained 2 months after the procedure shows expansion of the distal end of the occluded stent-graft (arrows). (f) Digital subtraction angiogram obtained 2 months after the procedure reveals pseudoaneurysmal formation around the distal end of the occluded stent-graft (arrows). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery when the distal end of the occluded stent-graft was seen to protrude from the external iliac artery.
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Figure 7e. Pseudoaneurysm caused by graft infection in an 82-year-old man with an infrarenal aortic aneurysm. (a) Abdominal radiograph obtained 2 weeks after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion, coil embolization of the left internal iliac artery, and ilioiliac bypass grafting reveals the occluded stent-graft placed at the narrowing of the left common iliac artery as it runs peripherally (arrows). (b) Digital subtraction angiogram obtained 2 weeks after the procedure shows no abnormal findings. (c) Axial CT image obtained 2 weeks after the procedure shows no abnormal findings at the distal end of the occluded stent-graft. (d) Axial CT scan obtained 2 months after the procedure shows development of a soft-tissue-attenuating area (arrows) around the distal end of the occluded stent-graft (arrowheads). The patient had fever, left inguinal swelling, and tenderness. (e) Abdominal radiograph obtained 2 months after the procedure shows expansion of the distal end of the occluded stent-graft (arrows). (f) Digital subtraction angiogram obtained 2 months after the procedure reveals pseudoaneurysmal formation around the distal end of the occluded stent-graft (arrows). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery when the distal end of the occluded stent-graft was seen to protrude from the external iliac artery.
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Figure 7f. Pseudoaneurysm caused by graft infection in an 82-year-old man with an infrarenal aortic aneurysm. (a) Abdominal radiograph obtained 2 weeks after tapered stent-graft implantation from the aorta to the right iliac artery combined with left common iliac artery occlusion, coil embolization of the left internal iliac artery, and ilioiliac bypass grafting reveals the occluded stent-graft placed at the narrowing of the left common iliac artery as it runs peripherally (arrows). (b) Digital subtraction angiogram obtained 2 weeks after the procedure shows no abnormal findings. (c) Axial CT image obtained 2 weeks after the procedure shows no abnormal findings at the distal end of the occluded stent-graft. (d) Axial CT scan obtained 2 months after the procedure shows development of a soft-tissue-attenuating area (arrows) around the distal end of the occluded stent-graft (arrowheads). The patient had fever, left inguinal swelling, and tenderness. (e) Abdominal radiograph obtained 2 months after the procedure shows expansion of the distal end of the occluded stent-graft (arrows). (f) Digital subtraction angiogram obtained 2 months after the procedure reveals pseudoaneurysmal formation around the distal end of the occluded stent-graft (arrows). Infection of the occluded stent-graft and pseudoaneurysm were confirmed in an emergent surgery when the distal end of the occluded stent-graft was seen to protrude from the external iliac artery.
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Graft Occlusion.—Stenosis of the iliac graft limb is reported in a series of bifurcated grafts not fully supported by stents (27), but graft occlusion is a relatively rare event after stent-graft implantation. Blum et al (12) reported occlusion of the iliac graft limb due to emboli from the left atrium. Dorffner et al (18) reported thrombogenic occlusion of the left iliac limb of the bifurcated stent-graft by means of local thrombolysis, which led to reopening of the graft. The aortic portion of the bifurcated stent-graft occluded 4 months after implantation, however, and was associated with distal kinking of the left iliac limb.
In our series, a straight stent-graft occluded in a 72-year-old man with a 46-mm-diameter infrarenal aortic aneurysm (Fig 8). Preprocedural images showed the proximal neck of the aneurysm with an acute angle of 87° (Fig 8a). Follow-up curved-planar reconstruction images revealed that the stent-graft did not bend along the tortuous proximal neck of the aneurysm. Proximal endoleak was also observed (Fig 8b). Enhancement that was weaker inside the stent-graft than in the endoleak indicated less blood flow into the stent-graft (Fig 8b). After 14 days, the patient suddenly experienced pain in the lower abdomen and both lower extremities. Both legs were pale, and a femoral pulse was not detected. Digital subtraction angiography revealed occlusion of the stent-graft (Fig 8c). Complete thrombosis of the stent-graft was confirmed at emergent open surgery. We believe that decreased blood flow into the stent-graft, caused by the inability of the stent-graft to bend along the acute angle, led to graft occlusion.
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Figure 8a. Graft occlusion after tapered stent-graft implantation from the aorta to the right iliac artery in a 72-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural curved-planar reconstruction image shows an infrarenal abdominal aortic aneurysm with a tortuous proximal neck of the aneurysm. (b) Follow-up curved-planar reconstruction image obtained 3 days after the procedure reveals that the stent-graft does not bend along the tortuous proximal neck of the aneurysm. Note weaker enhancement inside than outside the stent-graft (proximal endoleak [arrows]). (c) Digital subtraction angiogram obtained 14 days after the procedure shows occlusion of the stent-graft. Both of the patient's legs were pale, and a femoral pulse was not detected.
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Figure 8b. Graft occlusion after tapered stent-graft implantation from the aorta to the right iliac artery in a 72-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural curved-planar reconstruction image shows an infrarenal abdominal aortic aneurysm with a tortuous proximal neck of the aneurysm. (b) Follow-up curved-planar reconstruction image obtained 3 days after the procedure reveals that the stent-graft does not bend along the tortuous proximal neck of the aneurysm. Note weaker enhancement inside than outside the stent-graft (proximal endoleak [arrows]). (c) Digital subtraction angiogram obtained 14 days after the procedure shows occlusion of the stent-graft. Both of the patient's legs were pale, and a femoral pulse was not detected.
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Figure 8c. Graft occlusion after tapered stent-graft implantation from the aorta to the right iliac artery in a 72-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural curved-planar reconstruction image shows an infrarenal abdominal aortic aneurysm with a tortuous proximal neck of the aneurysm. (b) Follow-up curved-planar reconstruction image obtained 3 days after the procedure reveals that the stent-graft does not bend along the tortuous proximal neck of the aneurysm. Note weaker enhancement inside than outside the stent-graft (proximal endoleak [arrows]). (c) Digital subtraction angiogram obtained 14 days after the procedure shows occlusion of the stent-graft. Both of the patient's legs were pale, and a femoral pulse was not detected.
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Shower Embolism.—Shower embolism is one of the most serious, possibly fatal complications after conventional repair of infrarenal abdominal aortic aneurysm and is relatively rare. Shower embolism occurs more frequently after endovascular aneurysm repair than after conventional open surgery (28). Shower embolism after endovascular procedures is reported at rates of 4%–17% (5,28). All of these cases resulted in perioperative death.
In our series, shower embolism occurred in a 78-year-old woman with infrarenal abdominal aortic aneurysm. Preprocedural images showed irregular, shaggy mural thrombus in the abdominal aorta (Fig 9). During the procedure, a guide wire and an angiographic catheter were repeatedly introduced via the brachial artery through the aortic arch to the abdominal aorta or the external iliac artery. The stent-graft was deployed without difficulty. Two days after the procedure, the patient was unconscious and brain CT depicted cerebral infarction of the left parietal lobe. Three days after the procedure, the patient died of renal failure and disseminated intravascular coagulation. Shower embolism was confirmed at autopsy. We believe the shower embolism was caused by mural thrombus dispersed during the repeated introduction of the guide wire, angiographic catheter, and delivery systems. Preprocedural contrast-enhanced CT was not performed at the level of the thoracic aorta, but shaggy mural thrombus similar to that in the abdominal aorta might have been present in the thoracic aorta. The cause of the cerebral infarction may have been mural thrombus dispersed from the aortic arch.
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Figure 9a. Shower embolism after stent-graft implantation in a 78-year-old woman with an infrarenal aortic aneurysm. (a) Preprocedural axial CT scan obtained at the level of the suprarenal abdominal aorta shows intraluminal shaggy thrombus. (b) Preprocedural shaded surface display CT image shows an irregular surface of the flow lumen of the abdominal aorta caused by shaggy thrombus. The patient died of renal failure and disseminated intravascular coagulation 3 days after the procedure. Shower embolism was confirmed at autopsy.
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Figure 9b. Shower embolism after stent-graft implantation in a 78-year-old woman with an infrarenal aortic aneurysm. (a) Preprocedural axial CT scan obtained at the level of the suprarenal abdominal aorta shows intraluminal shaggy thrombus. (b) Preprocedural shaded surface display CT image shows an irregular surface of the flow lumen of the abdominal aorta caused by shaggy thrombus. The patient died of renal failure and disseminated intravascular coagulation 3 days after the procedure. Shower embolism was confirmed at autopsy.
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Perforation of Mural Thrombus by Means of Inadvertent Penetration of the Delivery System.—To our knowledge, perforation of mural thrombus associated with stent-graft implantation has not been reported. Castrucci et al (29) investigated the relationship between MR imaging findings and the macroscopic characteristics of mural thrombi in patients with abdominal aortic aneurysms. In their investigation, mural thrombi were classified on the basis of gross characteristics as organized, unorganized, or partially organized. Organized thrombi were homogeneously firm and removable as a whole piece from the aortic wall. Unorganized thrombi were composed of fresh blood clot, fluid, or both. Partially organized thrombi were composed of mostly organized thrombi with portions composed of fresh blood clot, fluid, or both; therefore, perforation may occur in partially organized thrombus.
In our series, mural thrombus was perforated in a 52-year-old man with an 80-mm-diameter distal arch aneurysm (Fig 10). Before the delivery system was inserted, the guide wire was introduced via the right brachial artery through the aortic arch to the right external iliac artery. The delivery system was then advanced into the aortic arch over the guide wire. Intraprocedural aortography prior to stent-graft deployment revealed that some parts of the delivery system were outside the opacified lumen (Fig 10a), but the stent-graft was placed as introduced by the delivery system. Postprocedural CT depicted perforation of the mural thrombus (Fig 10f). Clinical distal arterial thromboembolism did not occur. At transesophageal echocardiography, we found that the guide wire and the delivery system had penetrated into the mural thrombus (Fig 10b–10d).
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Figure 10a. Perforation of the mural thrombus by means of inadvertent penetration of the delivery system in a 52-year-old man with a distal arch aneurysm. (a) Intraoperative digital subtraction angiogram obtained immediately after insertion of the delivery system reveals that some parts of the delivery system are outside the opacified lumen (arrows). (b) Transesophageal echocardiogram obtained before introduction of the guide wire shows a moderate amount of mural thrombus in the aortic arch (arrows). (c) Transesophageal echocardiogram obtained after introduction of the guide wire reveals that the mural thrombus is partially torn by the guide wire (arrowhead). (d) Transesophageal echocardiogram shows the delivery system (arrows) within the mural thrombus. (e) Preoperative axial CT image shows a moderate amount of the mural thrombus in the aneurysm. (f) Postoperative axial CT image depicts perforation of the mural thrombus. Dorsal thrombus is transposed to the right side (arrows) by the stent-graft as placed in the mural thrombus with the delivery system.
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Figure 10b. Perforation of the mural thrombus by means of inadvertent penetration of the delivery system in a 52-year-old man with a distal arch aneurysm. (a) Intraoperative digital subtraction angiogram obtained immediately after insertion of the delivery system reveals that some parts of the delivery system are outside the opacified lumen (arrows). (b) Transesophageal echocardiogram obtained before introduction of the guide wire shows a moderate amount of mural thrombus in the aortic arch (arrows). (c) Transesophageal echocardiogram obtained after introduction of the guide wire reveals that the mural thrombus is partially torn by the guide wire (arrowhead). (d) Transesophageal echocardiogram shows the delivery system (arrows) within the mural thrombus. (e) Preoperative axial CT image shows a moderate amount of the mural thrombus in the aneurysm. (f) Postoperative axial CT image depicts perforation of the mural thrombus. Dorsal thrombus is transposed to the right side (arrows) by the stent-graft as placed in the mural thrombus with the delivery system.
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Figure 10c. Perforation of the mural thrombus by means of inadvertent penetration of the delivery system in a 52-year-old man with a distal arch aneurysm. (a) Intraoperative digital subtraction angiogram obtained immediately after insertion of the delivery system reveals that some parts of the delivery system are outside the opacified lumen (arrows). (b) Transesophageal echocardiogram obtained before introduction of the guide wire shows a moderate amount of mural thrombus in the aortic arch (arrows). (c) Transesophageal echocardiogram obtained after introduction of the guide wire reveals that the mural thrombus is partially torn by the guide wire (arrowhead). (d) Transesophageal echocardiogram shows the delivery system (arrows) within the mural thrombus. (e) Preoperative axial CT image shows a moderate amount of the mural thrombus in the aneurysm. (f) Postoperative axial CT image depicts perforation of the mural thrombus. Dorsal thrombus is transposed to the right side (arrows) by the stent-graft as placed in the mural thrombus with the delivery system.
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Figure 10d. Perforation of the mural thrombus by means of inadvertent penetration of the delivery system in a 52-year-old man with a distal arch aneurysm. (a) Intraoperative digital subtraction angiogram obtained immediately after insertion of the delivery system reveals that some parts of the delivery system are outside the opacified lumen (arrows). (b) Transesophageal echocardiogram obtained before introduction of the guide wire shows a moderate amount of mural thrombus in the aortic arch (arrows). (c) Transesophageal echocardiogram obtained after introduction of the guide wire reveals that the mural thrombus is partially torn by the guide wire (arrowhead). (d) Transesophageal echocardiogram shows the delivery system (arrows) within the mural thrombus. (e) Preoperative axial CT image shows a moderate amount of the mural thrombus in the aneurysm. (f) Postoperative axial CT image depicts perforation of the mural thrombus. Dorsal thrombus is transposed to the right side (arrows) by the stent-graft as placed in the mural thrombus with the delivery system.
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Figure 10e. Perforation of the mural thrombus by means of inadvertent penetration of the delivery system in a 52-year-old man with a distal arch aneurysm. (a) Intraoperative digital subtraction angiogram obtained immediately after insertion of the delivery system reveals that some parts of the delivery system are outside the opacified lumen (arrows). (b) Transesophageal echocardiogram obtained before introduction of the guide wire shows a moderate amount of mural thrombus in the aortic arch (arrows). (c) Transesophageal echocardiogram obtained after introduction of the guide wire reveals that the mural thrombus is partially torn by the guide wire (arrowhead). (d) Transesophageal echocardiogram shows the delivery system (arrows) within the mural thrombus. (e) Preoperative axial CT image shows a moderate amount of the mural thrombus in the aneurysm. (f) Postoperative axial CT image depicts perforation of the mural thrombus. Dorsal thrombus is transposed to the right side (arrows) by the stent-graft as placed in the mural thrombus with the delivery system.
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Figure 10f. Perforation of the mural thrombus by means of inadvertent penetration of the delivery system in a 52-year-old man with a distal arch aneurysm. (a) Intraoperative digital subtraction angiogram obtained immediately after insertion of the delivery system reveals that some parts of the delivery system are outside the opacified lumen (arrows). (b) Transesophageal echocardiogram obtained before introduction of the guide wire shows a moderate amount of mural thrombus in the aortic arch (arrows). (c) Transesophageal echocardiogram obtained after introduction of the guide wire reveals that the mural thrombus is partially torn by the guide wire (arrowhead). (d) Transesophageal echocardiogram shows the delivery system (arrows) within the mural thrombus. (e) Preoperative axial CT image shows a moderate amount of the mural thrombus in the aneurysm. (f) Postoperative axial CT image depicts perforation of the mural thrombus. Dorsal thrombus is transposed to the right side (arrows) by the stent-graft as placed in the mural thrombus with the delivery system.
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Colon Necrosis.—Colon ischemia or necrosis is a feared complication of endovascular stent-graft implantation to treat infrarenal abdominal aortic aneurysm. Yusuf et al (10) report a case of colon ischemia necessitating sigmoid colectomy. In this patient, both internal iliac arteries and the inferior mesenteric artery were occluded by the stent-graft. Murphy et al (4) describe colon necrosis resulting in perioperative death. Autopsy findings documented a clot in the inferior mesenteric artery but patent internal iliac arteries.
In our series, patent inferior mesenteric arteries were seen in 12 of 32 patients with infrarenal abdominal aortic aneurysms depicted on preprocedural contrast-enhanced CT images. Colon necrosis occurred in one of the 12 patients after implantation of the endovascular stent-graft. A 71-year-old man with a 62-mm-diameter infrarenal abdominal aortic aneurysm underwent endovascular stent-graft implantation. Preprocedural CT revealed the patency of the large inferior mesenteric artery arising from the aneurysm (Fig 11a). Both internal iliac arteries were also patent. Implantation of a tapered stent-graft from the aorta to the right iliac artery was combined with occlusion of the left common iliac artery and ilioiliac crossover bypass grafting. When the delivery system was removed, its tip was trapped by the distal stent body although the stent-graft was correctly placed. Owing to this problem, the procedure took longer than expected and resulted in extended hypoperfusion of both internal iliac arteries. Although immediate postprocedural digital subtraction angiography revealed that the left internal iliac artery was patent, sigmoid colon necrosis occurred 2 days after the procedure, and emergent left hemicolectomy was performed (Fig 11b). We believe that the colon necrosis was a result of occlusion of the large inferior mesenteric artery, which could have been an indispensable source of colon perfusion. Blum et al (12) state that a widely patent inferior mesenteric artery is an exclusion criterion for endovascular treatment, but it is not clear whether all patients with a patent inferior mesenteric artery arising directly from the aneurysm should be excluded.
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Figure 11a. Colon necrosis after stent-graft implantation in a 71-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural axial CT image shows a large patent inferior mesenteric artery (arrow). (b) Intraoperative photograph shows necrosis of the sigmoid colon (arrows).
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Figure 11b. Colon necrosis after stent-graft implantation in a 71-year-old man with an infrarenal abdominal aortic aneurysm. (a) Preprocedural axial CT image shows a large patent inferior mesenteric artery (arrow). (b) Intraoperative photograph shows necrosis of the sigmoid colon (arrows).
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Aortic Dissection.—Dake et al (7) report aortic dissection caused by a retrograde injury from delivery system introduction. In our series, aortic dissection was observed at follow-up CT in a 71-year-old woman with a distal arch aneurysm. Stent-graft implantation was performed in conjunction with surgical resection of the abdominal aortic aneurysm. During the procedure, the delivery system was introduced by using the tug-of-wire technique through one limb of the bifurcated abdominal graft. Aortic dissection was not evident at preprocedural CT but was detected at follow-up CT (Fig 12). In this patient, the dissection was located between the distal end of the stent-graft and the proximal end of the bifurcated abdominal graft. We believe that the dissection was caused by a retrograde injury at the introduction of the delivery system. No treatment was applied since the patient had no symptoms and was hemodynamically stable.
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Figure 12. Aortic dissection in a 71-year-old woman. Axial CT image obtained 25 days after stent-graft implantation to treat a distal arch aneurysm shows dissection of the descending thoracic aorta and pleural effusion.
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Hematoma at the Arteriotomy Site.—Hematoma at the arteriotomy site usually develops under conditions of manifest hypocoagulability and often requires surgical repair (11). In our series, hematoma at the arteriotomy site occurred in the 78-year-old woman with shower embolism resulting from repair of an infrarenal abdominal aortic aneurysm. Pelvic CT performed 2 days after stent-graft implantation depicted a large high-attenuating area around the right external iliac artery (Fig 13), which represented hematoma at the arteriotomy site. In our case, disseminated intravascular coagulation caused by shower embolism may have made the arteriotomy site bleed easily.
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Figure 13. Hematoma at the arteriotomy site in a 78-year-old woman with an infrarenal abdominal aortic aneurysm. Follow-up axial CT image obtained 2 days after stent-graft implantation shows a large high-attenuating area (arrows) around the right external iliac artery.
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Conclusions
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Endovascular stent-graft implantation has been accepted as an alternative to conventional open surgery, but various complications may occur after treatment. Spiral CT is a fast, minimally invasive, initial procedure for the assessment of such complications. Shaded surface display, multiplanar reconstruction, and curved-planar reconstruction images often clarify the complex anatomy of the tortuous aorta. Preprocedural assessment of the length and tortuosity of the proximal neck of the aneurysm, mural thrombus irregularity, and inferior mesenteric artery patency may help predict complications such as endoleak, shower embolism, and colon ischemia. Endoleak and graft thrombosis are easily depicted at transverse contrast-enhanced CT. In addition, the degree of intraluminal enhancement of the stent-graft and existence of an abnormal attenuating area around the stent-graft or arteriotomy site should be carefully evaluated. Multiplanar reconstruction images help evaluate the configuration of the stent-graft, origin and cause of an endoleak, and longitudinal change in aneurysmal size. Plain radiography, digital subtraction angiography, and transesophageal echocardiography sometimes play an important role in the detection of serious complications. Since some of these complications are fatal, radiologists need to instantly and correctly recognize them. Awareness and understanding of possible complications should help ensure a safe and successful procedure.
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References
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Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysms. Ann Vasc Surg 1991; 5:491-499.[Medline]
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Dake MD, Miller DC, Semba CP, Mitchell RS, Walker PJ, Liddel RP. Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms. N Engl J Med 1994; 331:1729-1734.[Abstract/Free Full Text]
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Brewster DC, Geller SC, Kaufman JA, et al. Initial experience with endovascular aneurysm repair: comparison of early results with outcome of conventional open repair. J Vasc Surg 1998; 27:992-1005.[Medline]
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Murphy KD, Richter GM, Henry M, Encarnacion CE, Le VA, Palmaz JC. Aortoiliac aneurysms: management with endovascular stent-graft placement. Radiology 1996; 198:473-480.[Abstract/Free Full Text]
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Parodi JC. Endovascular repair of abdominal aortic aneurysms and other arterial lesions. J Vasc Surg 1995; 21:549-557.[Medline]
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Chuter TAM, Risberg B, Hopkinson BR, et al. Clinical experience with a bifurcated endovascular graft for abdominal aortic aneurysm repair. J Vasc Surg 1996; 24:655-666.[Medline]
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Dake MD, Miller DC, Mitchell RS, Semba CP, Moore KA, Sakai T. The first generation of endovascular stent-grafts for patients with aneurysms of the descending thoracic aorta. J Thorac Cardiovasc Surg 1998; 116:689-704.[Abstract/Free Full Text]
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Chuter TAM, Gordon RL, Reilly LM, et al. Abdominal aortic aneurysm in high-risk patients: short- to intermediate-term results of endovascular repair. Radiology 1999; 210:361-365.[Abstract/Free Full Text]
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White RA, Donayre CE, Walot I, Kopchok GE, Wilson EP, deVirgilio C. Regression of an abdominal aortic aneurysm after endograft exclusion. J Vasc Surg 1997; 26:133-137.[Medline]
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Yusuf SW, Whitaker SC, Chuter TAM, et al. Early results of endovascular aortic a
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Abstract
Introduction
