(Radiology. 1999;211:317-324.)
© RSNA, 1999
Vascular and Interventional Radiology |
Synthetic Interposition Grafts of the Thoracic Aorta: Postoperative Appearance on Serial CT Studies1
Leslie Eisenbud Quint, MD,
Isaac R. Francis, MD,
David M. Williams, MD,
Hilary M. Monaghan, BSN and
G. Michael Deeb, MD
1 From the Departments of Radiology (L.E.Q., I.R.F., D.M.W.) and Surgery (H.M.M., G.M.D.), University of Michigan Medical Center, 1500 E Medical Center Dr, Ann Arbor, MI 49109-0030. Received March 18, 1998; revision requested June 10; revision received October 2; accepted November 19. Address reprint requests to L.E.Q.
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Abstract
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PURPOSE: To determine the normal postoperative appearance of thoracic aortic interposition grafts on serial CT studies and to document CT detectable complications.
MATERIALS AND METHODS: The 235 CT studies in 114 patients with one or more thoracic aortic interposition grafts were analyzed for the presence or absence of felt rings, felt pledgets, low-attenuation material surrounding the graft, pseudoaneurysm, and dissection flap. A graft was present in the ascending aorta in 93 patients, in the descending aorta in 25, and in the arch in 11.
RESULTS: Low-attenuation material was seen adjacent to the ascending graft in 55%–82% of patients and adjacent to the descending graft in 60%–79% of patients, showing diminishing frequency and thickness over time. CT scans in 30 of 53 patients showed residual low-attenuation material adjacent to the graft more than 1 year after surgery. CT scans in four of 93 patients with ascending grafts and one of 25 patients with descending grafts showed a pseudoaneurysm.
CONCLUSION: CT studies obtained after aortic interposition grafting show characteristic findings. Knowledge of the type of operative procedure and typical location and CT appearance of surgical materials used is important to correctly diagnose or exclude postoperative complications following thoracic aortic interposition grafting.
Index terms: Aorta, CT, 941.12912, 941.12915, 942.12912, 942.12915, 943.12912, 943.12915 • Aorta, grafts and prostheses, 941.4522, 942.4522, 943.4522 • Aorta, surgery, 941.458, 942.458, 943.458
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Introduction
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Computed tomography (CT) has been advocated as a tool for following up patients after thoracic aortic reconstruction (1). However, to our knowledge there is little written in the radiologic or the surgical literature regarding the normal postoperative CT appearance (1,2). Occasionally, normal postoperative imaging findings may simulate complications or complications may be overlooked, leading to inappropriate patient care. The appearance of the mediastinum on postoperative CT studies depends on the type of surgery that has been performed and the type of graft that has been used. The purpose of this study was to determine the normal postoperative appearance of synthetic interposition grafts of the thoracic aorta on serial CT studies and to document the spectrum of CT detectable complications such as pseudoaneurysm and hematoma.
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MATERIALS AND METHODS
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All patients undergoing thoracic aortic reconstruction with a synthetic interposition graft (without graft-inclusion technique) between January 1, 1994, and April 25, 1997, were identified by using a computerized thoracic surgery database. Of the 188 patients identified, 114 had undergone one or more postoperative CT examinations. This study analyzed the findings on 235 postoperative CT studies obtained in these 114 patients.
The ascending aorta was reconstructed by means of a median sternotomy (with or without partial arch replacement) in 93 of the 114 patients. The descending aorta was reconstructed by means of a left thoracotomy in 25 of the 114 patients. Four of the 114 patients had both ascending and descending aortic grafts. In 11 of the 114 patients, there was a complete arch graft in addition to an ascending aortic graft (n = 9), a descending graft (n = 1), or both (n = 11).
Two different types of synthetic ascending aortic interposition grafts were used. Hemashield (valveless) grafts (Meadox, Oakland, NJ) were composed of collagen- impregnated Dacron. Composite grafts contained a Dacron conduit and an attached mechanical aortic valve. Reconstruction with a composite graft required reimplanting the native coronary arteries into the conduit. A small portion of native aortic anulus was included with each coronary artery, which resulted in coronary artery buttons. Generally, these coronary arterial anastomoses were reinforced with felt rings. Drawings of the different types of grafting procedures used are shown in Figure 1 (3).
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Figure 1. Diagram of some of the different surgical procedures performed. A, Root replacement with the distal anastomosis at the level of the brachiocephalic (innominate) artery (I). Arrows = coronary artery anastomoses, C = left common carotid artery, S = left subclavian artery. B, Root, ascending aorta, and partial arch replacement. C, Complete arch replacement with reimplantation of the arch vessels as a single island. D, Complete root and arch replacement with the elephant trunk technique used as a staged procedure for complete replacement of the aorta. E, Same as D except each arch vessel was implanted separately. F, Descending aortic graft. G, Descending aortic graft with complete arch replacement and reimplantation of the arch vessels as a single island. Coronary arteries are anastomosed to the root graft in parts A, B, D,and E. (Frontal view; heart removed in F and G). (A–E reprinted, with permission, from reference 3.)
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For all types of aortic grafts, felt rings were often used to buttress an anastomosis. Felt pledgets were used to reinforce the graft or the native aortic wall at sites of intraoperative cannula placement. These felt rings and pledgets are generally visible on CT images due to their high attenuation.
All CT examinations were retrospectively analyzed by using a consensus reading of three experienced radiologists (L.E.Q., I.R.F., D.M.W.) for the presence or absence of the following findings: circumferential felt reinforcing ring at an anastomosis, felt pledget in the native aorta or in the aortic graft, tortuosity of the graft, dissection flap, gas within or adjacent to the graft, mediastinal lymph node enlargement, pseudoaneurysm, pleural effusion, pericardial effusion, and pericardial thickening. Also documented was the presence or absence of high-attenuation or low-attenuation material (compared with the attenuation of skeletal muscle) or soft-tissue–attenuation material adjacent to the graft. When present, the maximum diameter of this material was measured and recorded. In all patients, the native portions of the thoracic aorta were evaluated for clinically important disease. If clinically important findings were present, comparison was made with the preoperative study to assess for interval change. CT scans from patients with ascending grafts were also analyzed for the presence of anterior mediastinal fluid and/or soft tissue, coronary artery buttons, and coronary artery bypass grafts.
In patients with descending aortic grafts, the following findings were noted, when present: collapsed (excluded) native aorta medial to the graft, bovine pericardial wrap, posterior mediastinal surgical clips, extrapleural low-attenuation material, and left lower lobe atelectasis lateral to the graft.
In patients with aortic arch grafts, the CT scans were evaluated for the presence of an island of native aorta containing the origins of the great vessels that has been anastomosed to the graft and for an "elephant trunk" portion of the graft protruding into the native descending aorta. An "elephant trunk" may be placed in those patients who are likely to require future reconstruction of the descending aorta.
The computerized thoracic surgery database was used to identify those patients with a clinically important mediastinal complication related to the grafting procedure, such as mediastinal abscess, anastomotic dehiscence, or postoperative bleeding. Clinical findings were correlated with CT findings in these patients.
All but four CT examinations used intravenous contrast material. Of 235 scans, 230 were obtained with use of a helical technique with a HiSpeed Advantage scanner (GE Medical Systems, Milwaukee, Wis) with 3-mm collimation and 2:1 pitch, as described previously (4). Occasionally, multiplanar reconstructions or three-dimensional images were available; however, only the axial images were analyzed for this study. Most patients underwent routine scanning following surgery at approximately 3, 6, and 12 months, and then yearly. Occasionally a suspected clinical complication led to scanning at other time intervals.
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RESULTS
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Composite Grafts
Sixty-eight patients had a composite interposition graft. The preoperative diagnosis was aneurysm in 48 patients, type A dissection in 19 patients, and traumatic tear in one patient. There were 143 postoperative CT examinations, with a mean of 2.1 examinations per patient (range, 1–5 examinations ± 1.1 [SD]). In one patient with both an ascending graft and a descending graft (placed at different times), the ascending graft was placed in 1983. Excluding this patient who had a 14-year follow-up CT study, total follow-up time for each patient ranged from 1 to 42 months (mean, 15.8 months ± 10.7 [SD]).
The following CT findings were noted in these 68 patients: felt ring (n = 65) (Figs 2, 3), felt pledget in native aorta (n = 17), felt pledget in graft (n = 45) (Fig 4), tortuous graft (n = 5) (Fig 4), coronary artery buttons (n = 65) (Fig 5), coronary artery bypass graft(s) (n = 13), dissection flap (n = 15) (Fig 4), well-circumscribed hematoma (n = 2), and small, thrombosed, anastomotic pseudoaneurysm (n = 1). In one patient, a prominent right coronary artery button simulated a pseudoaneurysm (Fig 6). No patients showed gas within or adjacent to the graft.
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Figure 2. Axial CT scan shows circumferential felt reinforcing ring (arrows) at the distal anastomosis of an ascending aortic interposition graft, 14 months after surgery.
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Figure 3a. (a, b) Contiguous axial CT scans show an interposition graft of the ascending aorta and aortic arch, 4 months after surgery. A felt reinforcing ring is noted at the distal anastomosis (arrowheads in a). This ring may be mistaken for a pseudoaneurysm (arrowheads) on the contiguous image in b. The circumferential nature of the ring on adjacent CT sections establishes the correct diagnosis. Note also portions of the felt ring (arrows in a and b) that surround the brachiocephalic artery island implanted into the arch graft.
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Figure 3b. (a, b) Contiguous axial CT scans show an interposition graft of the ascending aorta and aortic arch, 4 months after surgery. A felt reinforcing ring is noted at the distal anastomosis (arrowheads in a). This ring may be mistaken for a pseudoaneurysm (arrowheads) on the contiguous image in b. The circumferential nature of the ring on adjacent CT sections establishes the correct diagnosis. Note also portions of the felt ring (arrows in a and b) that surround the brachiocephalic artery island implanted into the arch graft.
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Figure 4. Axial CT scan shows composite graft of the aortic root and arch and dissection flap (black arrow) in the native descending aorta, 15 months after surgery. Note kinking and tortuosity of the graft (G) and high-attenuation felt pledget (white arrow) in the graft.
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Figure 5. Axial CT scan shows composite aortic root graft with right (R) and left (L) coronary artery buttons. Portions of the felt rings (arrows) surrounding the coronary artery buttons are visible. Dissection flap (arrowhead) is present in the descending aorta, 14 months after surgery.
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Figure 6. Axial CT scan shows low-attenuation material adjacent to the graft, four months after composite root replacement. Right coronary artery button (R) simulates a pseudoaneurysm.
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Two of 68 patients had a clinically important mediastinal complication that was not treated before scanning. One patient had a huge anastomotic pseudoaneurysm that was identified at CT and confirmed surgically (Fig 7). Another patient had infection and dehiscence at the proximal anastomosis. This finding was identified at transesophageal echocardiography but not visible at CT; surgical confirmation was obtained.
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Figure 7a. Large pseudoaneurysm 4 months after composite root grafting. (a) Axial CT scan and (b) parasagittal reconstruction image show low-attenuation material, consistent with hematoma (H), and extravasated contrast material (C) adjacent to the distal anastomosis (white arrow in b). Black arrow in a = dissection flap in descending aorta, arrowhead in b = prosthetic aortic valve, G = graft.
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Figure 7b. Large pseudoaneurysm 4 months after composite root grafting. (a) Axial CT scan and (b) parasagittal reconstruction image show low-attenuation material, consistent with hematoma (H), and extravasated contrast material (C) adjacent to the distal anastomosis (white arrow in b). Black arrow in a = dissection flap in descending aorta, arrowhead in b = prosthetic aortic valve, G = graft.
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Valveless Ascending Grafts
Twenty-five patients had a valveless interposition graft of the ascending aorta. The preoperative diagnosis was aneurysm in 12 patients and type A dissection in 13. There were 52 postoperative CT examinations with a mean of two examinations per patient (range, 1–5 examinations ± 1.2). Total follow-up time for each patient ranged from 0.5 to 42 months (mean, 11.0 months ± 10.1).
The following CT findings were noted in these 25 patients: felt ring (n = 20) (18 at the proximal anastomosis, 17 at the distal anastomosis), felt pledget in native aorta (n = 4), felt pledget in graft (n = 14), tortuous graft (n = 5), coronary artery bypass graft(s) (n = 1), dissection flap (n = 8), well-circumscribed hematoma (n = 1), and small anastomotic pseudoaneurysm (n = 1) (Fig 8). One patient showed a small pseudoaneurysm at the graft pledget. No patients showed gas within or adjacent to the graft. Except for the absence of a prosthetic aortic valve and coronary artery buttons, and the frequent presence of a felt ring at the proximal anastomosis, valveless grafts showed a similar appearance to composite grafts in the ascending aorta.
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Figure 8. Axial CT scan shows a small pseudoaneurysm (arrows) at the proximal anastomosis, 2 weeks after valveless interposition graft replacement of the ascending aorta. Note the low-attenuation material (*) adjacent to the graft and the dissection flap (arrowhead) in the descending aorta.
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None of these 25 patients had a clinically important mediastinal complication related to the grafting procedure.
Ascending Grafts: Combined
Among the 93 patients with either a composite or a valveless graft of the ascending aorta, scanning was performed between 1 and 6 months after surgery in 82 patients, between 7 and 12 months after surgery in 31 patients, and more than 12 months after surgery in 47 patients (Table 1). Eighteen of 93 patients underwent only one CT examination, and 75 underwent two or more CT examinations. Low-attenuation material was seen adjacent to the graft in 55%–82% of the patients scanned, soft-tissue attenuation material was seen in 6%–11%, and high-attenuation material was seen in 0%–2%, depending on the time period following surgery (Table 1). These findings diminished in frequency and thickness over time (Table 1). Pleural effusion, pericardial effusion, and pericardial thickening were occasionally identified, particularly within 12 months after surgery (Table 1). In no patient did a follow-up CT scan show new findings that were not apparent on the initial postoperative CT scan.
Forty-four of 93 patients underwent two or more serial examinations (range, two to five examinations) with total follow-up at least 12 months after surgery (range, 12–42 months). Thirty-four of the 44 patients had low-attenuation material adjacent to the graft on the initial CT scan; 29 of the 34 patients showed progressive decrease in low-attenuation material over time, which eventually resolved in 14. In five of 34 patients, low-attenuation material showed no change over time.
Thirty-seven of 44 patients with serial examinations had soft-tissue stranding and/or fluid in the anterior mediastinum on the initial CT scan; 25 of 37 patients showed progressive decrease in low-attenuation material over time, which resolved in 14. In 12 of 37 patients, mediastinal soft-tissue stranding and/or fluid showed no change over time.
There were 47 patients with at least one CT examination performed more than 1 year after surgery. Twenty-six of 47 patients showed residual low-attenuation material adjacent to the graft on these examinations (Fig 9).
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Figure 9. Axial CT scan shows low-attenuation material (*) adjacent to a composite graft, 30 months after surgery. Felt strips (arrows) are seen surrounding a pulmonary artery patch. Note the partially calcified left hilar lymph nodes (N).
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Aortic Arch Grafts
Eleven patients had an interposition graft of the aortic arch. There were 26 postoperative CT examinations, with a mean of 2.4 CT examinations per patient (range, 1–5 examinations ± 1.3). Total follow-up time for each patient ranged from 0.5 to 42 months (mean, 11.2 months ± 11.4).
Preoperative diagnosis was aneurysm in five and type A dissection in six. None of these patients had a clinically important mediastinal complication related to the grafting procedure.
In seven of 11 patients, an island of one or more great vessels was anastomosed to the arch graft, according to the surgical note. In five of seven patients, the margins of the island were visible at CT, separate from either the proximal or the distal graft anastomoses, due to the high attenuation of the circumferential felt reinforcing ring (Fig 10). The island was not visible in one patient with felt reinforcement or in one patient without felt reinforcement. In four of 11 patients, a flap or peninsula of aorta containing the origins of the great vessels was left attached to the descending aorta prior to anastomosis with the arch graft. No island was visible in these patients. Two of 11 patients showed an "elephant trunk" protruding into the descending aorta (Fig 10).
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Figure 10a. (a, b) Axial CT scans obtained 22 months after surgery show an aortic arch graft with a felt reinforcing ring at the margins of the great vessel island (arrows) and elephant trunk (E) protruding into aneurysmal, native descending aorta (D). The more cranial image in a shows the origins of the great vessels. The more caudal image in b shows additional portions of the anastomoses. Arrowheads = distal arch anastomosis, H = hematoma between elephant trunk and native descending aorta.
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Figure 10b. (a, b) Axial CT scans obtained 22 months after surgery show an aortic arch graft with a felt reinforcing ring at the margins of the great vessel island (arrows) and elephant trunk (E) protruding into aneurysmal, native descending aorta (D). The more cranial image in a shows the origins of the great vessels. The more caudal image in b shows additional portions of the anastomoses. Arrowheads = distal arch anastomosis, H = hematoma between elephant trunk and native descending aorta.
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One patient, with a preoperative diagnosis of type A dissection, showed progressive dilatation of the false lumen in the descending aorta on serial postoperative CT scans. On a study obtained 36 months postoperatively, there was a contained rupture of the false lumen.
Descending Grafts
Twenty-five patients had an interposition graft of the descending aorta. The preoperative diagnosis was aneurysm in 11 patients, type B dissection in four, penetrating ulcer in two, and traumatic tear in eight. There were 46 postoperative CT examinations, with a mean of 2.1 examinations per patient (range, 1–5 examinations ± 1.3). Total follow-up time for each patient ranged from 0.5 to 45 months (mean, 12.2 ± 13.5).
One of 25 patients had a large, postoperative mediastinal abscess detected at CT 6 weeks after surgery. The following CT findings were noted in these 25 patients: proximal felt ring (n = 10) (Fig 11), distal felt ring (n = 13) (Fig 11), tortuous graft (n = 3), dissection flap (n = 3), collapsed native aorta (n = 9) (Fig 12), bovine pericardial wrap (n = 15) (Fig 13), posterior mediastinal surgical clips (n = 19), mediastinal lymph node enlargement (n = 9). In one patient, there was a small pseudoaneurysm at the proximal anastomosis and puckering at the distal anastomosis (Fig 11). In general, the anastomoses were seen only when reinforced with felt. Sometimes, however, the location of an anastomosis could be inferred by an abrupt change in the caliber of the aorta and/or the sudden absence of atherosclerotic calcifications.
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Figure 11a. Four months after reconstruction of the descending aorta. (a, b) Contiguous axial CT scans show puckering of native aorta at distal anastomosis that simulates pseudoaneurysm and/or dissection flap. (c) Parasagittal reconstruction image more clearly displays the anatomic relationships and the pseudoflap (open arrow). Solid white and black arrows in a–c = felt rings, G = graft, P = pleural and/or extrapleural low-attenuation material consistent with old hematoma, S = coronary sinus.
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Figure 11b. Four months after reconstruction of the descending aorta. (a, b) Contiguous axial CT scans show puckering of native aorta at distal anastomosis that simulates pseudoaneurysm and/or dissection flap. (c) Parasagittal reconstruction image more clearly displays the anatomic relationships and the pseudoflap (open arrow). Solid white and black arrows in a–c = felt rings, G = graft, P = pleural and/or extrapleural low-attenuation material consistent with old hematoma, S = coronary sinus.
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Figure 11c. Four months after reconstruction of the descending aorta. (a, b) Contiguous axial CT scans show puckering of native aorta at distal anastomosis that simulates pseudoaneurysm and/or dissection flap. (c) Parasagittal reconstruction image more clearly displays the anatomic relationships and the pseudoflap (open arrow). Solid white and black arrows in a–c = felt rings, G = graft, P = pleural and/or extrapleural low-attenuation material consistent with old hematoma, S = coronary sinus.
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Figure 12. Axial CT scan obtained 27 months after reconstruction of the descending aorta. Note collapsed native aorta (A) medial to the graft (G).
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Figure 13. Axial CT scan obtained 29 months after reconstruction of the descending aorta. Arrows = bovine pericardial wrap.
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Among the 25 patients with a graft of the descending aorta, low-attenuation material was commonly seen, soft-tissue attenuation material was occasionally seen, and high-attenuation material was rarely seen adjacent to the graft (Table 2). These findings diminished in frequency and thickness over time (Table 2). Mediastinal lymph node enlargement and left lower lobe atelectasis were commonly seen, and left pleural effusion and left extrapleural low-attenuation material were occasionally identified, particularly within 12 months after surgery (Table 2) (Fig 11). No patients showed gas within or adjacent to the graft. In no patient did a follow-up CT scan show new findings that were not apparent on the initial postoperative CT scan.
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DISCUSSION
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Routine CT studies are generally obtained at our institution at 3 months, 6 months, 12 months, and then yearly following thoracic aortic reconstruction. Mediastinal complications, such as severe hemorrhage, in the immediate postoperative period are often clinically evident, and these patients may be treated without performing a CT examination. CT may permit detection of delayed mediastinal complications, such as anastomotic dehiscence, infection, and/or clinically important pseudoaneurysm formation; however, these complications were rarely seen in our study, either with use of CT or with other clinical means. Occasionally, CT showed new or progressing abnormality of the native aorta.
The postoperative CT and MR imaging appearances following aortic repair with the continuous-suture graft-inclusion technique have been previously described (2,5); with this technique, the native aorta is wrapped around the graft. In the study by Pracki et al (1), two of 39 patients developed pseudoaneurysms 3 or more months after composite graft replacement of the ascending aorta with the graft inclusion technique. The pseudoaneurysms were due to dehiscence at the proximal graft suture line. These authors suggested that routine, postoperative CT examinations were important in the long-term care of patients after composite grafting of the ascending aorta. To our knowledge, there are no studies in the literature describing the serial CT or MR imaging appearance following interposition aortic graft replacement without graft inclusion.
A large number of patients in our study showed low-attenuation or soft-tissue–attenuation material surrounding or adjacent to the aortic graft (including anterior mediastinum for ascending grafts and extrapleural for descending grafts) several months or years following surgery. In many patients, this material diminished over time, although in others it remained unchanged. The etiology of this material is subject to speculation. It may represent hematoma that has evolved into fibrous tissue; at reoperation, this tissue is generally hard in consistency. In any case, the presence of such material on postoperative CT studies should not be mistaken for evidence of leak or infection.
Many of the early postoperative CT studies showed pleural or pericardial effusion, mediastinal lymph node enlargement, and/or left lower lobe atelectasis. These findings diminished in frequency over time and presumably represented normal postoperative findings. A small amount of left lower lobe atelectasis may remain indefinitely, adjacent to a descending aortic graft. This appears to be an incidental postoperative finding, without any adverse clinical consequences.
With the interposition aortic grafting technique, felt strips are used to buttress the anastomosis in patients with a dissection or other disease of the aortic wall, rendering it fragile and likely to tear. Usually the high attenuation of the felt strips is the visual marker of the anastomosis at CT. In cases without a felt reinforcing ring, the anastomosis is usually difficult to discern. Sometimes the location of the anastomosis can be inferred by an abrupt change in aortic caliber or an abrupt transition between nonatherosclerotic- and atherosclerotic-appearing wall. Felt pledgets are often used at surgery to repair the bypass cannulation site in the native aorta and the air evacuation needle site in the graft. These pledgets appear as small, high-attenuation structures at CT. On occasion, the high-attenuation felt rings and pledgets may resemble contrast material and simulate a contained leak (Fig 3). Although the addition of nonenhanced scans might be helpful in such cases, precontrast imaging is not routinely done. Nonenhanced imaging would increase the time and cost of the examination and lead to potential tube cooling problems during the contrast material–enhanced portion of the examination. Some newer helical CT scanners, however, have improved tube cooling characteristics; with these scanners, the addition of noncontrast scans through a limited portion of the thorax may potentially add useful information without compromising the quality of the contrast-enhanced portion of the examination.
Another potential pitfall in the interpretation of postoperative CT scans after aortic root reconstruction with a composite graft lies in the variable appearance of the coronary artery anastomoses. The coronary arteries are generally anastomosed to the graft along with a button of native aortic root. These buttons can occasionally be rather prominent and simulate a pseudoaneurysm at the proximal graft anastomosis, if the interpreting radiologist is unaware of this hazard (Fig 6).
In summary, CT studies obtained after aortic interposition grafting show characteristic findings, often including high-attenuation felt strips or pledgets, low-attenuation hematoma or fibrous tissue surrounding the graft, and bulging at coronary artery anastomoses. Knowledge of the typical location and appearance of these structures is important in interpreting these studies. In cases with unusual findings, it may be crucial to obtain precise information regarding operative technique and materials, in order to correctly diagnose or exclude postoperative complications.
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Footnotes
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Author contributions: Guarantor of integrity of entire study, L.E.Q.; study concepts and design, L.E.Q., I.R.F., D.M.W.; definition of intellectual content, L.E.Q., I.R.F., D.M.W., G.M.D.; literature research, L.E.Q., I.R.F.; clinical studies, L.E.Q., I.R.F., D.M.W., H.M.M., G.M.D.; data acquisition, L.E.Q., I.R.F., D.M.W., H.M.M., G.M.D.; data analysis, L.E.Q.; statistical analysis, L.E.Q.; manuscript preparation, L.E.Q.; manuscript editing, L.E.Q., I.R.F., D.M.W., G.M.D.; manuscript review, L.E.Q., I.R.F., D.M.W., H.M.M., G.M.D.
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References
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Pracki P, Petri D, Kellner H, Struck E. Composite graft (Medtronic-Hall) replacement of the ascending aorta and aortic valve in aortic aneurysms: what is adequate follow-up?. Thorac Cardiovasc Surg 1995; 43:104-107.[Medline]
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Rofsky N, Weinreb J, Grossi E, et al. Aortic aneurysm and dissection: normal MR imaging and CT findings after surgical repair with the continuous-suture graft-inclusion technique. Radiology 1993; 186:195-201.[Abstract/Free Full Text]
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Deeb GM, Jenkins E, Bolling SF, et al. Retrograde cerebral perfusion during hypothermic circulatory arrest reduces neurologic morbidity. J Thorac Cardiovasc Surg 1995; 109:259-268.[Abstract/Free Full Text]
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Quint L, Francis I, Williams D, et al. Evaluation of thoracic aortic disease with the use of helical CT with multiplanar reconstructions: comparison with surgical findings. Radiology 1996; 201:37-41.[Abstract/Free Full Text]
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Dagenais F, Cartier R, Paquet E, Hudon G, Castonguay Y, Leclerc Y. Pseudoaneurysm after Bentall repair: magnetic resonance imaging assessment. Can J Cardiol 1993; 9:869-872.[Medline]
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Abstract
Introduction
