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Experience with endovascular grafts in the treatment of infrarenal aortic aneurysms associated with proximal aortic dissection
Experience with Endovascular Grafts in the Treatment of Infrarenal Aortic Aneurysms Associated with Proximal Aortic Dissection Michael L. Marin, MD, New York, New York, Ross T. Lyon, MD, Bronx, New York, Larry H. Hollier, MD, David B. Kaplan, MD, New York, New York
BACKGROUND: Chronic abdominal and thoracic aortic dissections often present with concomitant infrarenal aortic dilatation. We conducted a retrospective review of 6 patients treated with endovascular stent grafts for coexisting aortic dissection and infrarenal aneurysm. METHODS: Six patients with suprarenal aortic dissections and infrarenal aortic aneurysms (AAA) had their AAAs treated with endovascular grafts. Grafts were constructed of balloon expandable Palmaz stents and expanded polytetrafluoroethylene graft. The device was inserted transfemorally and deployed under fluoroscopy. RESULTS: Successfully primary AAA exclusion was achieved in 5 patients. One patient required a supplemental stent placed above the endograft and into the true lumen to seal the endoleak. No aneurysm has enlarged, and all remain thrombosed for 9 to 24 months (mean 20). One type III dissection enlarged 2 weeks after endograft insertion. One patient had uncomplicated cephalad fenestration of a dissection by the endograft. CONCLUSIONS: Endovascular grafts may be used to treat coexisting AAA and aortic dissection. Attention to the site or sites of reentry of a dissection is essential to insure full aortic aneurysm exclusion. The fate of a chronic aortic dissection cephalad to an endovascularly treated AAA is unclear and will require longer follow-up. Am J Surg. 1999;177:102–106. © 1999 by Excerpta Medica, Inc.
A
cute dissection of the aorta is a surprisingly common problem associated with a significant morbidity and mortality.1– 4 Following aortic dissection, aneurysmal dilatation of the diseased vessel may occur with an alarming 20% risk of rupture.5,6 Incidental coexistence of atherosclerotic aneurysmal disease may also be present with the resulting combined lesion suggesting strong consideration for surgical repair.7 Endovascular repair of ab-
From the Department of Surgery (MLM, LHH, DBK), Mount Sinai Medical Center, New York, New York, and the Montefiore Medical Center (RTL), Bronx, New York. Requests for reprints should be addressed to Michael L. Marin, MD, Department of Surgery, Mount Sinai Medical Center, 5 East 98th Street, Box 1273, New York, New York 10029-6574. Manuscript submitted August 12, 1998, and accepted in revised form October 16, 1998.
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© 1999 by Excerpta Medica, Inc. All rights reserved.
dominal aortic aneurysms is currently undergoing clinical trials with generally favorable results.8 –10 Application of this technology to patients with coexisting aortic dissection and AAA has been suggested with clearly identified concerns relevant to mural fixation of the endograft to diseased aorta adjacent to or within the true or false lumen of the artery.11 We analyzed our experience with a balloon expandable aortic endograft in the treatment of AAA in the setting of aortic dissection to determine the feasibility of this procedure as an alternative to open repair.
METHODS Patients Patients selected for endovascular repair of AAA were determined to be at high risk for conventional aortic repair by two independent nonsurgical medical specialists in accordance with the Institutional Review Board of the Mount Sinai Medical Center and an investigator-sponsored Investigational Device Exemption from the US Food and Drug Administration. After medical screening, all patients underwent preoperative spiral computed tomography (CT) scanning and aortic and pelvic arteriography. The 6 patients included in this analysis were found to have dissections of the thoracic and/or abdominal aorta coexisting with infrarenal AAAs .6 cm. In each patient preprocedural angiography was performed in an attempt to identify the origin and reentry points of dissections. Devices and Endografting Procedures All patients in this study were treated with an aorto-iliofemoral bypass, contralateral iliac occlusion, and femoralfemoral crossover graft. Endografts were constructed from custom tapered expanded polytetrafluoroethylene (ePTFE) graft (Impra Inc./Bard Inc., Tempe, Arizona) 28 to 8 mm, which were sutured at four sites to a Palmaz Balloon expandable stent (P5014 Cordis Endovascular; Johnson & Johnson Co., Miami Lakes, Florida; Figure 1). A radiographic gold marker was sutured to the proximal margin of the graft to facilitate proper positioning. Endografts were inserted transfemorally over a stiff 0.038-inch guide wire contained within a specialized delivery sheath (Figure 2). Following insertion and sheath retraction, aortic endografts were deployed by balloon inflation of the aortic attachment system. Each tapered endograft was extended to the ipsilateral common femoral artery where it was sutured to the inside of the vessel with 6-8-6-0 prolene “U” stitches. The ipsilateral common femoral arteriotomy overlying the endovascular graft served as the site of the origin of the femoral femoral bypass. An occlusion device was constructed from a Palmaz stent partially covered with 0002-9610/99/$–see front matter PII S0002-9610(98)00312-2
EXPERIENCE WITH ENDOVASCULAR GRAFTS/MARIN ET AL
in association with aortic dissection, the endograft was positioned fully below the dissection, if the neck of the aneurysm did not contain a dissection, or within the true lumen of the dissected aortic necks, compressing and thereby uniting the true and false lumens with the aortic endograft attachment system.
Figure 1. A tapered expanded polytetrafluoroethylene endovascular graft for aortic aneurysm repair. S 5 stent; G 5 tapered endograft.
Patient Follow-up Each patient underwent full completion angiography after endograft insertion to look for full aneurysm exclusion. Duplex ultrasonography and spiral CT scanning was performed in each patient immediately following endografting and at 3, 6, and 12 months, followed by annual examinations thereafter. Mean follow-up was 17 months (range 15 to 24).
RESULTS
Figure 2. An endovascular aorto-ilio-femoral repair for abdominal aortic aneurysm. The ipsilateral (right) internal iliac artery may be embolized with coils (arrow) to prevent retrograde flow. An endograft is then inserted over a guide wire through the right common femoral artery (curved arrow) and advanced into the infrarenal aorta. The balloon expandable endovascular stent (“s”) is deployed, when possible below the distal reentry point of an aortic dissection. If the dissection extends into the aneurysmal sac, the deployment must be across the true and false lumens rupturing the septum and fusing the two channels. A contralateral common iliac occluder is inserted (open arrow) prior to femoralfemoral bypass, completing the reconstruction.
ePTFE material and sealed distally so as to create a “wind sock.” The occluder was inserted into the contralateral common iliac artery to prevent retrograde flow into the aortic aneurysm (Figure 2). In each patient with an AAA
Aortic dissections originated from the proximal descending thoracic aorta in 4 patients and the distal descending thoracic aorta in 2 patients. In only 2 patients was the age of the dissection known (6 and 7 years), whereas in the remaining 4 patients, there was no history defining when the dissection occurred. In 3 patients the dissection terminated above the neck of the AAA, and in the remaining 3 patients the false lumen reentered into the AAA sac independently. The AAAs ranged in size between 6 and 7 cm (6.8 mean). Successful primary exclusion (complete seal) of AAA was achieved in 5 of the 6 patients with coexisting dissections (Figure 3). In 1 patient, a persistent endoleak was detected immediately postoperatively that originated from the reentry site of the false lumen terminating into the aneurysmal sac (Figure 4). This was successfully treated by the insertion of a supplemental stent into the true and false, which compressed true and false lumens together sealing the leak. AAAs have remained fully excluded and thrombosed without evidence of AAA enlargement or rupture during follow-up ranging from 9 to 24 months (mean 20). Proximal aortic dissections have remained unchanged from preoperative images on follow-up CT scans in 4 of the 6 patients. In 1 patient, stent compression of the false channel (Figure 4) resulted in a more cephalad reentry point. This has not been associated with a change in the size or appearance of the remaining segments of thoracic dissection. One patient with a DeBakey type III dissection developed back pain 2 weeks after AAA endograft repair that was associated with a widening of the dissection. This lesion stabilized and is currently being observed.
COMMENTS The coexistence of acute dissection of the aorta and atherosclerotic aneurysm of the abdominal aorta is uncommon in autopsy and clinical reviews of aortic pathology.12,13 An estimate based on a 20-year review of 325 cases demonstrated an incidence of 5%.7 Despite the relatively rare nature of this problem, concern over aneurysm rupture may be increased in patients with combined lesions. The use of endovascular grafts to treat abdominal aortic aneurysm has demonstrated favorable midterm results in select patients with optimum aortic anatomy.8 –10 This less-invasive approach allows for the reconstruction of the aorta without direct aortic exposure, resulting in reduced
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Figure 3. Endovascular repair of an abdominal aortic aneurysm in a man with a stable thoracic dissection for 7 years. A. Preoperative angiography demonstrates the saccular infrarenal aortic aneurysm. Bilateral renal artery stenoses (arrows) have been present and stable without progression since the dissection was diagnosed. B. A preoperative computed tomography scan of the aneurysm demonstrated two flow channels within the sac. Note calcification within the thrombus (arrow). C. Computed tomography scan following insertion of an endovascular graft. The aneurysm has thrombosed, and flow is seen only within the endograft.
morbidity and procedure related mortality. As endovascular techniques are advanced for the treatment of aortic pathology, a clear understanding of the potential interactions between variant aortic pathology and endovascular devices will be essential if wider application of these devices is anticipated. The insertion of an endovascular graft anchored in the region of an acute or chronic dissection for repair of an AAA raises several important concerns. Although it appears intuitively obvious to attempt to anchor the prosthesis within the true lumen of the aorta, such positioning may be difficult to insure when the identity of individual flow channels is unclear. In the present study, fixation to true lumen at the target site was planned in each case. However, the determination of the precise site for implantation was made on the basis of angiography only, which may not have always been correct. It is recognized that intravascular ultrasound may be a more effective tool for sorting out complex aortic pathology with dissections and may help to guide precise device positioning. Such analyses were not performed during this study. Based on the present experience, the true and false lumen should be tightly opposed to one another after deployment of the stent attachment system if both channels fill the aortic sac. If the dissection terminates cephalad to the aortic neck, then it appears preferable to avoid intervention on the dissection. Another important concern regarding endografts seated within aortic dissections relates to the ability of the aortic wall to “heal” following stent deployment. In order for long-term sealing to be achieved with resulting permanent aneurysm exclusion, the endograft must inseparably fix to the aortic neck. Incomplete healing at this site is thought 104
to be responsible for caudad endograft migration.14 Although migration of endografts was not seen in the present study during a mean follow-up of 20 months, a full understanding of endograft healing will require histopathologic analysis, and long-term follow-up. Finally, there is reason for concern about the fate of a proximal aortic dissection following caudad insertion of an aortic endograft. Alteration of the reentry site of an aortic dissection may potentially alter the forces exerted upon the vessel wall within the dissection, leading to expansion, extension, or even rupture of the dissected aorta. This may be of greatest concern when total obstruction of the reentry site from the false lumen occurs after fixation of the stent to the aortic neck. One patient in this series sustained the acute symptomatic widening of an aortic dissection within 2 weeks of endograft repair. While alternative etiologies for this event must be considered (guidewire injury to the vessel; unrelated events in association with the patients known chronic hypertension), the temporal relationship to endograft insertion must be considered the prevailing etiology. These concerns for widening and rupture of a proximal dissection must also be considered during clamping of the infrarenal aorta during conventional repair when coexisting AAA and dissection exist.5 Endovascular grafts are presently completing phase II trials in the United States in anticipation for treatment of abdominal aortic aneurysms. Although the benefits of a less-invasive therapy for treating combined aortic dissection and AAA is clear, caution must be exercised during device insertion and deployment. Based on a limited experience, we recommend aortic endograft fixation caudad to a reentry site of a chronic false lumen when a sufficient
THE AMERICAN JOURNAL OF SURGERY® VOLUME 177 FEBRUARY 1999
EXPERIENCE WITH ENDOVASCULAR GRAFTS/MARIN ET AL
Figure 4. A 78-year-old man had a previous proximal repair of a DeBakey type I dissection and presented 6 years later with a large infrarenal aneurysm. A. Computed tomography scan demonstrated a 7.5 cm infrarenal aneurysm. B. Aortography defined the aneurysm and its relationship with the proximal aortic dissection (large arrow). C, D, E. Computed tomography scans through corresponding regions labeled on the aortogram in Figure 4B. F. Intraoperative angiogram depicting the alignment of the proximal stent (“s”) attachment system in the neck of the aorta. G. Computed tomography scan of the aortic neck after stent deployment demonstrating flow in the endograft (E) as well as within the false lumen (F). H. Further expansion of the endovascular stent graft resulted in the obliteration of the false lumen. I. Follow-up computed tomography scan demonstrates flow in the endograft (E) and thrombosis of the aneurysmal sac. THE AMERICAN JOURNAL OF SURGERY® VOLUME 177 FEBRUARY 1999
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neck for sealing exists. This strategy will prevent disruption of a stable false channel with possible enlargement or thrombosis, which could lead to occlusion of essential side branches. When the false lumen communicates with the aneurysmal sac, fusion of the lumen by the endograft attachment system is required with proximal fenestration. Additional follow-up will be necessary to determine the long-term fate of false channels cephalad to an infrarenal aortic graft.
REFERENCES 1. Wheat MW, Palmer RF. Dissecting aneurysms of the aorta. Curr Prob Surg. 1971;1:43. 2. Bickerstaff LK, Pairolero PC, Hollier LH, et al. Thoracic aortic aneurysms: a population-based study. Surgery. 1982;92:1103. 3. Borst HG, Heineman MK, Stone CD. Surgical Treatment of Aortic Dissection. New York: Churchill Livingstone; 1996. 4. Cambria RP, Brewster DC, Gatler J, et al. Vascular complications associated with spontaneous aortic dissection. J Vasc Surg. 1988;7:199 –209. 5. DeBakey ME, McCollun CH, Crawford ES, et al. Dissection and dissecting aneurysms of the aorta: twenty-year follow-up of five hundred twenty-seven patients surgically. Surgery. 1982;92:1118 – 1133. 6. Cambria RP, Brewster MD, Ashby C, et al. Spontaneous aortic
106
dissection in the presence of coexistent or previously repaired atherosclerotic aortic aneurysm. Ann Surg. 1988;208:619 – 624. 7. Moore WS, Vescera CL. Repair of abdominal aortic aneurysms by transfemoral endovascular graft placement. Ann Surg. 1994;220: 331–341. 8. Marin ML, Veith FJ, Cynamon J, et al. Initial experience with transluminally placed grafts for the treatment of complex vascular lesions. Ann Surg. 1995;222:449 – 469. 9. Blum U, Voshage V, Lammer J, et al. Endoluminal stent grafts for infrarenal abdominal aortic aneurysms. NEJM. 1997;336:13–20. 10. May J, White G, Yu W, et al. Endoluminal repair of atypical dissecting aneurysm of the descending thoracic aorta and fusiform aneurysm of the abdominal aorta. J Vasc Surg. 1995;22:67–172. 11. Hirst AE, Johns VJ, Kime SW. Dissecting aneurysm of the aorta: a review of 505 cases. Medicine. 1958;37:217–279. 12. Miller DC, Mitchell RS, Oyer PE, et al. Independent determinates of operative mortality for patients with aortic dissection. Circulation. 1984;70:153–164. 13. Yusef SW, Baker DM, Chuter TAM, Whitaker SC. Transfemoral endoluminal repair of abdominal aortic aneurysms with bifurcated graft. Lancet. 1995;344:350 –351. 14. Ivancev K, Malina M, Lindblad B, et al. Abdominal aortic aneurysms: experience with the Ivancev-Malmo endovascular system for aortomonoiliac stent grafts. J Endovasc Surg. 1997;4:242– 251.
THE AMERICAN JOURNAL OF SURGERY® VOLUME 177 FEBRUARY 1999
BACKGROUND: Chronic abdominal and thoracic aortic dissections often present with concomitant infrarenal aortic dilatation. We conducted a retrospective review of 6 patients treated with endovascular stent grafts for coexisting aortic dissection and infrarenal aneurysm. METHODS: Six patients with suprarenal aortic dissections and infrarenal aortic aneurysms (AAA) had their AAAs treated with endovascular grafts. Grafts were constructed of balloon expandable Palmaz stents and expanded polytetrafluoroethylene graft. The device was inserted transfemorally and deployed under fluoroscopy. RESULTS: Successfully primary AAA exclusion was achieved in 5 patients. One patient required a supplemental stent placed above the endograft and into the true lumen to seal the endoleak. No aneurysm has enlarged, and all remain thrombosed for 9 to 24 months (mean 20). One type III dissection enlarged 2 weeks after endograft insertion. One patient had uncomplicated cephalad fenestration of a dissection by the endograft. CONCLUSIONS: Endovascular grafts may be used to treat coexisting AAA and aortic dissection. Attention to the site or sites of reentry of a dissection is essential to insure full aortic aneurysm exclusion. The fate of a chronic aortic dissection cephalad to an endovascularly treated AAA is unclear and will require longer follow-up. Am J Surg. 1999;177:102–106. © 1999 by Excerpta Medica, Inc.
A
cute dissection of the aorta is a surprisingly common problem associated with a significant morbidity and mortality.1– 4 Following aortic dissection, aneurysmal dilatation of the diseased vessel may occur with an alarming 20% risk of rupture.5,6 Incidental coexistence of atherosclerotic aneurysmal disease may also be present with the resulting combined lesion suggesting strong consideration for surgical repair.7 Endovascular repair of ab-
From the Department of Surgery (MLM, LHH, DBK), Mount Sinai Medical Center, New York, New York, and the Montefiore Medical Center (RTL), Bronx, New York. Requests for reprints should be addressed to Michael L. Marin, MD, Department of Surgery, Mount Sinai Medical Center, 5 East 98th Street, Box 1273, New York, New York 10029-6574. Manuscript submitted August 12, 1998, and accepted in revised form October 16, 1998.
102
© 1999 by Excerpta Medica, Inc. All rights reserved.
dominal aortic aneurysms is currently undergoing clinical trials with generally favorable results.8 –10 Application of this technology to patients with coexisting aortic dissection and AAA has been suggested with clearly identified concerns relevant to mural fixation of the endograft to diseased aorta adjacent to or within the true or false lumen of the artery.11 We analyzed our experience with a balloon expandable aortic endograft in the treatment of AAA in the setting of aortic dissection to determine the feasibility of this procedure as an alternative to open repair.
METHODS Patients Patients selected for endovascular repair of AAA were determined to be at high risk for conventional aortic repair by two independent nonsurgical medical specialists in accordance with the Institutional Review Board of the Mount Sinai Medical Center and an investigator-sponsored Investigational Device Exemption from the US Food and Drug Administration. After medical screening, all patients underwent preoperative spiral computed tomography (CT) scanning and aortic and pelvic arteriography. The 6 patients included in this analysis were found to have dissections of the thoracic and/or abdominal aorta coexisting with infrarenal AAAs .6 cm. In each patient preprocedural angiography was performed in an attempt to identify the origin and reentry points of dissections. Devices and Endografting Procedures All patients in this study were treated with an aorto-iliofemoral bypass, contralateral iliac occlusion, and femoralfemoral crossover graft. Endografts were constructed from custom tapered expanded polytetrafluoroethylene (ePTFE) graft (Impra Inc./Bard Inc., Tempe, Arizona) 28 to 8 mm, which were sutured at four sites to a Palmaz Balloon expandable stent (P5014 Cordis Endovascular; Johnson & Johnson Co., Miami Lakes, Florida; Figure 1). A radiographic gold marker was sutured to the proximal margin of the graft to facilitate proper positioning. Endografts were inserted transfemorally over a stiff 0.038-inch guide wire contained within a specialized delivery sheath (Figure 2). Following insertion and sheath retraction, aortic endografts were deployed by balloon inflation of the aortic attachment system. Each tapered endograft was extended to the ipsilateral common femoral artery where it was sutured to the inside of the vessel with 6-8-6-0 prolene “U” stitches. The ipsilateral common femoral arteriotomy overlying the endovascular graft served as the site of the origin of the femoral femoral bypass. An occlusion device was constructed from a Palmaz stent partially covered with 0002-9610/99/$–see front matter PII S0002-9610(98)00312-2
EXPERIENCE WITH ENDOVASCULAR GRAFTS/MARIN ET AL
in association with aortic dissection, the endograft was positioned fully below the dissection, if the neck of the aneurysm did not contain a dissection, or within the true lumen of the dissected aortic necks, compressing and thereby uniting the true and false lumens with the aortic endograft attachment system.
Figure 1. A tapered expanded polytetrafluoroethylene endovascular graft for aortic aneurysm repair. S 5 stent; G 5 tapered endograft.
Patient Follow-up Each patient underwent full completion angiography after endograft insertion to look for full aneurysm exclusion. Duplex ultrasonography and spiral CT scanning was performed in each patient immediately following endografting and at 3, 6, and 12 months, followed by annual examinations thereafter. Mean follow-up was 17 months (range 15 to 24).
RESULTS
Figure 2. An endovascular aorto-ilio-femoral repair for abdominal aortic aneurysm. The ipsilateral (right) internal iliac artery may be embolized with coils (arrow) to prevent retrograde flow. An endograft is then inserted over a guide wire through the right common femoral artery (curved arrow) and advanced into the infrarenal aorta. The balloon expandable endovascular stent (“s”) is deployed, when possible below the distal reentry point of an aortic dissection. If the dissection extends into the aneurysmal sac, the deployment must be across the true and false lumens rupturing the septum and fusing the two channels. A contralateral common iliac occluder is inserted (open arrow) prior to femoralfemoral bypass, completing the reconstruction.
ePTFE material and sealed distally so as to create a “wind sock.” The occluder was inserted into the contralateral common iliac artery to prevent retrograde flow into the aortic aneurysm (Figure 2). In each patient with an AAA
Aortic dissections originated from the proximal descending thoracic aorta in 4 patients and the distal descending thoracic aorta in 2 patients. In only 2 patients was the age of the dissection known (6 and 7 years), whereas in the remaining 4 patients, there was no history defining when the dissection occurred. In 3 patients the dissection terminated above the neck of the AAA, and in the remaining 3 patients the false lumen reentered into the AAA sac independently. The AAAs ranged in size between 6 and 7 cm (6.8 mean). Successful primary exclusion (complete seal) of AAA was achieved in 5 of the 6 patients with coexisting dissections (Figure 3). In 1 patient, a persistent endoleak was detected immediately postoperatively that originated from the reentry site of the false lumen terminating into the aneurysmal sac (Figure 4). This was successfully treated by the insertion of a supplemental stent into the true and false, which compressed true and false lumens together sealing the leak. AAAs have remained fully excluded and thrombosed without evidence of AAA enlargement or rupture during follow-up ranging from 9 to 24 months (mean 20). Proximal aortic dissections have remained unchanged from preoperative images on follow-up CT scans in 4 of the 6 patients. In 1 patient, stent compression of the false channel (Figure 4) resulted in a more cephalad reentry point. This has not been associated with a change in the size or appearance of the remaining segments of thoracic dissection. One patient with a DeBakey type III dissection developed back pain 2 weeks after AAA endograft repair that was associated with a widening of the dissection. This lesion stabilized and is currently being observed.
COMMENTS The coexistence of acute dissection of the aorta and atherosclerotic aneurysm of the abdominal aorta is uncommon in autopsy and clinical reviews of aortic pathology.12,13 An estimate based on a 20-year review of 325 cases demonstrated an incidence of 5%.7 Despite the relatively rare nature of this problem, concern over aneurysm rupture may be increased in patients with combined lesions. The use of endovascular grafts to treat abdominal aortic aneurysm has demonstrated favorable midterm results in select patients with optimum aortic anatomy.8 –10 This less-invasive approach allows for the reconstruction of the aorta without direct aortic exposure, resulting in reduced
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EXPERIENCE WITH ENDOVASCULAR GRAFTS/MARIN ET AL
Figure 3. Endovascular repair of an abdominal aortic aneurysm in a man with a stable thoracic dissection for 7 years. A. Preoperative angiography demonstrates the saccular infrarenal aortic aneurysm. Bilateral renal artery stenoses (arrows) have been present and stable without progression since the dissection was diagnosed. B. A preoperative computed tomography scan of the aneurysm demonstrated two flow channels within the sac. Note calcification within the thrombus (arrow). C. Computed tomography scan following insertion of an endovascular graft. The aneurysm has thrombosed, and flow is seen only within the endograft.
morbidity and procedure related mortality. As endovascular techniques are advanced for the treatment of aortic pathology, a clear understanding of the potential interactions between variant aortic pathology and endovascular devices will be essential if wider application of these devices is anticipated. The insertion of an endovascular graft anchored in the region of an acute or chronic dissection for repair of an AAA raises several important concerns. Although it appears intuitively obvious to attempt to anchor the prosthesis within the true lumen of the aorta, such positioning may be difficult to insure when the identity of individual flow channels is unclear. In the present study, fixation to true lumen at the target site was planned in each case. However, the determination of the precise site for implantation was made on the basis of angiography only, which may not have always been correct. It is recognized that intravascular ultrasound may be a more effective tool for sorting out complex aortic pathology with dissections and may help to guide precise device positioning. Such analyses were not performed during this study. Based on the present experience, the true and false lumen should be tightly opposed to one another after deployment of the stent attachment system if both channels fill the aortic sac. If the dissection terminates cephalad to the aortic neck, then it appears preferable to avoid intervention on the dissection. Another important concern regarding endografts seated within aortic dissections relates to the ability of the aortic wall to “heal” following stent deployment. In order for long-term sealing to be achieved with resulting permanent aneurysm exclusion, the endograft must inseparably fix to the aortic neck. Incomplete healing at this site is thought 104
to be responsible for caudad endograft migration.14 Although migration of endografts was not seen in the present study during a mean follow-up of 20 months, a full understanding of endograft healing will require histopathologic analysis, and long-term follow-up. Finally, there is reason for concern about the fate of a proximal aortic dissection following caudad insertion of an aortic endograft. Alteration of the reentry site of an aortic dissection may potentially alter the forces exerted upon the vessel wall within the dissection, leading to expansion, extension, or even rupture of the dissected aorta. This may be of greatest concern when total obstruction of the reentry site from the false lumen occurs after fixation of the stent to the aortic neck. One patient in this series sustained the acute symptomatic widening of an aortic dissection within 2 weeks of endograft repair. While alternative etiologies for this event must be considered (guidewire injury to the vessel; unrelated events in association with the patients known chronic hypertension), the temporal relationship to endograft insertion must be considered the prevailing etiology. These concerns for widening and rupture of a proximal dissection must also be considered during clamping of the infrarenal aorta during conventional repair when coexisting AAA and dissection exist.5 Endovascular grafts are presently completing phase II trials in the United States in anticipation for treatment of abdominal aortic aneurysms. Although the benefits of a less-invasive therapy for treating combined aortic dissection and AAA is clear, caution must be exercised during device insertion and deployment. Based on a limited experience, we recommend aortic endograft fixation caudad to a reentry site of a chronic false lumen when a sufficient
THE AMERICAN JOURNAL OF SURGERY® VOLUME 177 FEBRUARY 1999
EXPERIENCE WITH ENDOVASCULAR GRAFTS/MARIN ET AL
Figure 4. A 78-year-old man had a previous proximal repair of a DeBakey type I dissection and presented 6 years later with a large infrarenal aneurysm. A. Computed tomography scan demonstrated a 7.5 cm infrarenal aneurysm. B. Aortography defined the aneurysm and its relationship with the proximal aortic dissection (large arrow). C, D, E. Computed tomography scans through corresponding regions labeled on the aortogram in Figure 4B. F. Intraoperative angiogram depicting the alignment of the proximal stent (“s”) attachment system in the neck of the aorta. G. Computed tomography scan of the aortic neck after stent deployment demonstrating flow in the endograft (E) as well as within the false lumen (F). H. Further expansion of the endovascular stent graft resulted in the obliteration of the false lumen. I. Follow-up computed tomography scan demonstrates flow in the endograft (E) and thrombosis of the aneurysmal sac. THE AMERICAN JOURNAL OF SURGERY® VOLUME 177 FEBRUARY 1999
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neck for sealing exists. This strategy will prevent disruption of a stable false channel with possible enlargement or thrombosis, which could lead to occlusion of essential side branches. When the false lumen communicates with the aneurysmal sac, fusion of the lumen by the endograft attachment system is required with proximal fenestration. Additional follow-up will be necessary to determine the long-term fate of false channels cephalad to an infrarenal aortic graft.
REFERENCES 1. Wheat MW, Palmer RF. Dissecting aneurysms of the aorta. Curr Prob Surg. 1971;1:43. 2. Bickerstaff LK, Pairolero PC, Hollier LH, et al. Thoracic aortic aneurysms: a population-based study. Surgery. 1982;92:1103. 3. Borst HG, Heineman MK, Stone CD. Surgical Treatment of Aortic Dissection. New York: Churchill Livingstone; 1996. 4. Cambria RP, Brewster DC, Gatler J, et al. Vascular complications associated with spontaneous aortic dissection. J Vasc Surg. 1988;7:199 –209. 5. DeBakey ME, McCollun CH, Crawford ES, et al. Dissection and dissecting aneurysms of the aorta: twenty-year follow-up of five hundred twenty-seven patients surgically. Surgery. 1982;92:1118 – 1133. 6. Cambria RP, Brewster MD, Ashby C, et al. Spontaneous aortic
106
dissection in the presence of coexistent or previously repaired atherosclerotic aortic aneurysm. Ann Surg. 1988;208:619 – 624. 7. Moore WS, Vescera CL. Repair of abdominal aortic aneurysms by transfemoral endovascular graft placement. Ann Surg. 1994;220: 331–341. 8. Marin ML, Veith FJ, Cynamon J, et al. Initial experience with transluminally placed grafts for the treatment of complex vascular lesions. Ann Surg. 1995;222:449 – 469. 9. Blum U, Voshage V, Lammer J, et al. Endoluminal stent grafts for infrarenal abdominal aortic aneurysms. NEJM. 1997;336:13–20. 10. May J, White G, Yu W, et al. Endoluminal repair of atypical dissecting aneurysm of the descending thoracic aorta and fusiform aneurysm of the abdominal aorta. J Vasc Surg. 1995;22:67–172. 11. Hirst AE, Johns VJ, Kime SW. Dissecting aneurysm of the aorta: a review of 505 cases. Medicine. 1958;37:217–279. 12. Miller DC, Mitchell RS, Oyer PE, et al. Independent determinates of operative mortality for patients with aortic dissection. Circulation. 1984;70:153–164. 13. Yusef SW, Baker DM, Chuter TAM, Whitaker SC. Transfemoral endoluminal repair of abdominal aortic aneurysms with bifurcated graft. Lancet. 1995;344:350 –351. 14. Ivancev K, Malina M, Lindblad B, et al. Abdominal aortic aneurysms: experience with the Ivancev-Malmo endovascular system for aortomonoiliac stent grafts. J Endovasc Surg. 1997;4:242– 251.
THE AMERICAN JOURNAL OF SURGERY® VOLUME 177 FEBRUARY 1999