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Endoluminal repair of abdominal aortic aneurysms — state of the art
European Journal of Radiology 39 (2001) 16 – 21 www.elsevier.nl/locate/ejrad
Endoluminal repair of abdominal aortic aneurysms — state of the art James May a,*, Geoffrey H. White b, John P. Harris b b
a Department of Surgery, Uni6ersity of Sydney DO6, Sydney, NSW 2006, Australia Department of Vascular Surgery, Royal Prince Alfred Hospital, Sydney, NSW 2006, Australia
Received 16 October 2000; accepted 16 November 2000
Abstract This paper considers the historical aspects of endovascular aneursym repair; the major findings of our Departments experience over an 812-year period and reviews recent developments in endovascular prostheses. Analysis of 400 patients undergoing primary repair of abdominal aortic aneurysm between 1992 and 2000 revealed a perioperative mortality rate of 2.7% and primary conversion rate of 5%. With sequential studies it was shown that the outcome was better with bifurcated/aorto uni iliac grafts than tube grafts; better with second generation prostheses than first generation protheses and that survival in consecutive patients treated concurrently by open repair and endoluminal repair was superior in the endoluminal group. Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for continued careful follow-up. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Aortic aneurysm; Endovascular; Endoluminal repair
1. Introduction In addressing the topic ‘Endoluminal repair of abdominal aortic aneurysm — state of the art’ we will consider the historical aspects of endovascular aneurysm repair, our departments experience over an 812year period and review the recent developments in endovascular prostheses. The endovascular treatment of patients with aortic aneurysms is not new. As early as 1864, Moore is credited by Keen with the introduction of large masses of intraluminal wire into an aneurysm in an attempt to precipitate thrombosis [1]. In preantibiotic days, the majority of aneurysms were syphilitic in origin and saccular in morphology (Fig. 1), which made them more amenable to treatment by wiring than the fusiform variety seen today. Saccular, syphilitic aneurysms were extremely painful and associated with a * Corresponding author. Tel.: + 61-2-93513358; fax: + 61-293517075.
poorer prognosis than the current fusiform ones. Approximately 90% of patients with syphilitic aneurysms died within 1 year from the onset of symptoms [2]. This rather desperate scenario explains why surgeons were prepared to offer the procedure of wiring of aneurysms and why patients were prepared to accept this unreliable form of treatment. In 1879, Corradi modified the wiring process by passing an electric current along an insulated wire in an attempt to induce thrombosis [1]. In 1915, Colt, while working as a house surgeon, developed a self-expanding wire umbrella that could be introduced via a trocar into an aneurysm (Fig. 2) [3]. The loading capsule and delivery system had many similarities with current endovascular systems. Blakemore and King [4] revived the use of wiring in 1938. Electrothermic coagulation of aortic aneurysms by wiring was used up until 1953, when graft replacement of aneurysms was introduced. The relatively high morbidity and mortality rates for graft replacement of aortic aneurysms, particularly in high-risk patients, maintained the interest of researchers
0720-048X/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 7 2 0 - 0 4 8 X ( 0 1 ) 0 0 3 3 8 - 2
J. May et al. / European Journal of Radiology 39 (2001) 16–21
17
sheep model of aortic aneurysm. The first radiographically guided aortic graft implantations were reported in 1987 by Lawrence et al. [6] who used a chain of stainless steel Gianturco Z-stents (Cook, Indianapolis, IN) within a tube of woven polyester; however, not until 1991 did Parodi et al. [7] report the first clinical use in humans of transfemoral, endovascular grafting to exclude aortic aneurysms. Their concept was the use of balloon-expandable, vascular stents to replace sutures and secure the proximal and distal ends of a fabric graft within the lumen of the aorta.
2. Royal Prince Alfred Hospital — University of Sydney experience with endoluminal repair of abdominal aortic aneurysm
Fig. 1. Clinical characteristics of syphilitic and arteriosclerotic aneurysms. (Modified from Bahnson HT. Considerations in the excision of aortic aneurysms. Ann Surg 1953;138:377 –382 with permission).
in developing an endovascular method of repair. Balko et al. [5] can probably be credited with the first reported experimental use of a stent-graft combination for the treatment of animals with artificial aneurysm. In their experiments, a novel form of nitinol Z-stent was combined with a sleeve of polyurethane and tested in a
Between May 1992 and October 2000 the endoluminal method was used for primary repair of AAA in 400 patients. There were 368 males and 32 females with a mean age of 72 years. The procedures were performed in the operating room with the patient draped and prepared for open operation in the event of failed endoluminal repair. Access was gained through the common femoral artery or the iliac arteries via an extra-peritoneal approach. Fluoroscopy was used to deliver and deploy the endograft. Sizing of the endograft was based on pre-operative, contrast-enhanced, computed tomography (CT) and aortography performed with a calibrated catheter. An on-table, post-procedure angiogram was obtained in all patients. Follow-up consisted of physical examination and contrast-enhanced CT within one week of the operation, at 6, 12 and 18 months after the operation, and annually thereafter.
Fig. 2. Colt’s apparatus for wiring aneurysms. (From Power D’A. The palliative treatment of aneurysms by ‘wiring’ with Colt’s apparatus. Br J Surg 1921;9:27 – 31 with permission).
18
J. May et al. / European Journal of Radiology 39 (2001) 16–21
Fig. 3. Kaplan – Meier curves comparing graft failure for endoluminal AAA repair using bifurcated, aorto-iliac and tube prostheses. Reproduced with permission from Eur J Vasc Endovasc Surg.
Fig. 4. Kaplan – Meier curves comparing graft failure following endoluminal AAA repair using first and second generation prostheses. Reproduced with permission from J Vasc Surg.
2.1. Results Successful endoluminal repair was achieved in 380 of 400 patients (95%). The remaining 20 patients required primary conversion to open repair at the original operation. Seventeen patients required secondary conversion on a subsequent occasion for; rupture (seven patients) persistent endoleak (four patients), inadvertent covering of the renal arteries with the endograft (three patients); and increasing size of AAA in the absence of endoleak in three patients. The overall perioperative mortality rate was 11 in 400 patients (2.75%). Analysis of the outcome according to the configuration of the endografts revealed a significantly larger number of failures with tube compared with non-tube (bifurcated and tapered aorto-uni-iliac) configuration using Fisher’s Exact Test [8]. Life table analysis by log rank test did not reveal a significant difference, despite widely divergent Kaplan–Meier curves, due to the disproportionately greater number of tube endo-
grafts early in the study and bifurcated grafts later in the study (Fig. 3). In mid 1995 second generation prostheses became available. These were characterised by low profile delivery systems, modular construction and metallic frame support throughout the length of the prosthesis. Comparison of 118 patients whose AAA were treated by first generation prostheses with 148 patients whose AAA were treated by second generation prostheses revealed similar perioperative mortality rates but a statistically significant difference between the survival curves of the two generations which favoured the second generation group (P = 0.012) [9]. There was also a significant (PB 0.001) difference between the two generations of patients in their probability of graft failure was considered. Second generation patients were at a lower risk of graft failure than first generation patients (Fig. 4). A study was also undertaken to compare the outcome of consecutive patients with AAA treated concurrently by open repair and endoluminal repair using
J. May et al. / European Journal of Radiology 39 (2001) 16–21
19
Fig. 5. Kaplan – Meier curves for survival following open repair and endoluminal repair of AAA. Reproduced with permission from J Vasc Surg.
second generation prostheses by the same surgeons during a defined interval [10]. Between May 1995 and December 1998 second generation endoprostheses were implanted in 148 patients and together with 135 patients treated concurrently by open repair during the same period, comprised the study group of 283 patients. Minimum period of follow-up for all patients was 18 months. Perioperative mortality was 5.9% in the open group and 2.7% in the endoluminal group (n.s.). There was a statistically significant difference between the survival curves of the two groups in favour of the endoluminal group when analysed by log rank test (P =0.004) (Fig. 5). The Kaplan– Meier curve for graft failure for the endoluminal repair group revealed a 3-year graft success probability of 82%. Survival probability with successful repair in the open group at 3 years was 85%.
2.2. Discussion What can we learn from this experience? The improved survival following endoluminal AAA repair using second generation prostheses compared with open repair is probably the most important finding. This must be weighed against the significantly greater graft failure rate with the endoluminal compared with the open method. These findings raise the question of reducing the minimal diameter at which endoluminal AAA repair may be recommended. This is important since the chances of a AAA being suitable for endoluminal repair are inversely related to the diameter of the aneurysm. Reports of device failure (Table 1) and recent reports of unexpected and unpredictable rupture following endoluminal AAA repair [11,12], however, make this suggestion premature.
3. New prostheses and modifications of existing prostheses The first-in-man study of the Cordis (Cordis/Johnson and Johnson, Warren, NJ) endoluminal AAA prosthesis was undertaken in 1999 [13]. Although modular in construction, this device has a unique design. It has a ‘gasket’, which is deployed in the proximal neck of the aneurysm (Fig. 6). Two self-expanding endolimbs are deployed within the gasket, the function of which is to provide a seal between the D-shaped configuration of the limbs (Fig. 7). The gasket and both endolimbs have 12F delivery catheters, making the device of potential use in the percutaneous treatment of AAA without the need for closure devices. The Anaconda™ (Sulzer Vascutek Ltd., Inchinnan, UK) has a unique ring stent in saddle configuration with high hoop strength, which both seals and anchors without the need for hooks or barbs. Both suprarenal fixation and repositioning of the device, when deployed, are possible. An innovative magnet system is used to aid limb replacement. The device features specially woven polyester and 16/18F introducers. Clinical trials of this device are ongoing. Table 1 AAA device failure Prosthesis
Manufacturer
Failure mode
EVT
Endovascular Technologies Mintec
Hook fractures
Stentor Vanguard AneuRx Lifepath
Boston Scientific Corporation Medtronic Baxter
Fabric defects, seam failure Fabric defects, tie breaks Modular dislocation Wireform fracture
20
J. May et al. / European Journal of Radiology 39 (2001) 16–21
Fig. 6. (a) Nitinol and polyurethane ‘gasket’. One of three components of the Cordis endoluminal prosthesis for percutaneous abdominal aortic aneurysm repair; it is deployed below the renal arteries. (b) One of two self-expanding endolimbs of the Cordis prosthesis; they are deployed within the gasket.
reductions in size of the aneurysm sac without kinking. It will also have limbs and extensions up to 15 mm in diameter. The modified AneuRx (Medtronic, Santa Rosa, CA) prosthesis will have a filaform nose cone in place of the hemispherical shape of the current model. It will also have a new deployment mechanism built into the delivery catheter and discard the current clip-on ‘fishing-rod’ system. Cook have now released a new three-piece configuration of the Zenith prosthesis. This provides a wider range of diameters and lengths for the limbs but increases the potential for modular dislocation. It should also reduce the need for custom-built prostheses which currently make up 40–50% of this company’s output. An infrarenal model of the Zenith is also planned for those interventionalists who prefer to avoid the obligatory covering of the renal ostia with the uncovered upper stent of the standard model. 4. Summary Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for caution and continued careful follow-up. References
Fig. 7. Postoperative CT scan of a Cordis prosthesis showing the D-shaped configuration of the two endolimbs deployed within the gasket in the proximal neck of the abdominal aortic aneurysm.
The Endologix-Bard (CR Bard, Inc., Haverhill, MA) prosthesis, a one-piece, fully supported, bifurcated endoluminal graft was also released in 1999. This device goes against the trend of modular prostheses, which have been trialled in the past 5 years. It differs from the other one-piece EVT/Guidant (Endovascular Technologies, Menlo Park, CA) prosthesis, having PTFE fabric rather than polyester and a fully supported metallic frame rather than proximal and distal stent support. Modifications have been made to a number of existing prostheses. Vanguard III (Boston Scientific, Natick, MA) has a new metallic frame with smaller ‘zigs’ in the body of the endograft and greater capacity to adapt to
[1] Keen WW. Surgery: Its Principles and Practice. Philadelphia: WB Saunders, 1921:216 – 349. [2] Kampmeier RH. Saccular aneurysm of the thoracic aorta: a clinical study of 633 cases. Ann Intern Med 1938;12:624 –51. [3] Power D’A Sir. The palliative treatment of aneurysm by wiring with Colt’s apparatus. Br J Surg 1921;9:27. [4] Blackmore AH, King BG. Electrothermic coagulation of aortic aneurysms. J Am Med Assoc 1938;111:1821 – 938. [5] Balko A, Piasecki GJ, Shah DM, et al. Transfemoral placement of intraluminal polyurethane prosthesis for abdominal aortic aneurysm. J Surg Res 1986;40:305 – 9. [6] Lawrence DD, Charnsangavej C, Wright KC, et al. Percutaneous endovascular graft: experimental evaluation. Radiology 1987;163:357 – 60. [7] Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysm. Ann Vasc Surg 1991;5:491 – 9. [8] May J, White GH, Yu W, Waugh R, Stephen MS, Arulchelvam M, et al. Importance of graft configuration in outcome of endoluminal aortic aneurysm repair: a 5-year analysis by the life table method. Eur J Vasc Endovasc Surg 1998;15:406 – 11. [9] May J, White GH, Waugh R, Stephen MS, Chaufour X, Arulchelvam M, Harris JP. Comparison of first and second generation prostheses for endoluminal repair of abdominal aortic aneurysms: a 6-year study with life table analysis. J Vasc Surg 2000;32:124 – 9.
J. May et al. / European Journal of Radiology 39 (2001) 16–21 [10] May J, White GH, Waugh R, Ly CN, Stephen MS, Jones MA, Harris JP. Improved survival following endoluminal repair with second generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a five-year concurrent comparison by life table method. J Vasc Surg, 2001;33:S21-6 [11] Zarins CK, White RA, Fogarty TJ. Aneurysm rupture after endovascular repair using the AneuRx stent graft. J Vasc Surg
.
21
2000;31:960 – 70. [12] Politz JK, Newman VS, Stewart MT. Late abdominal aortic aneurysm rupture after AneuRx repair: a report of three cases. J Vasc Surg 2000;31:599 – 606. [13] May J. Technological progress with endovascular repair of abdominal aortic aneurysms. In: Davies A, editor. Vascular Surgery Highlights 1999 – 2000. Oxford: Fast Facts Health Press, 1999.
Endoluminal repair of abdominal aortic aneurysms — state of the art James May a,*, Geoffrey H. White b, John P. Harris b b
a Department of Surgery, Uni6ersity of Sydney DO6, Sydney, NSW 2006, Australia Department of Vascular Surgery, Royal Prince Alfred Hospital, Sydney, NSW 2006, Australia
Received 16 October 2000; accepted 16 November 2000
Abstract This paper considers the historical aspects of endovascular aneursym repair; the major findings of our Departments experience over an 812-year period and reviews recent developments in endovascular prostheses. Analysis of 400 patients undergoing primary repair of abdominal aortic aneurysm between 1992 and 2000 revealed a perioperative mortality rate of 2.7% and primary conversion rate of 5%. With sequential studies it was shown that the outcome was better with bifurcated/aorto uni iliac grafts than tube grafts; better with second generation prostheses than first generation protheses and that survival in consecutive patients treated concurrently by open repair and endoluminal repair was superior in the endoluminal group. Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for continued careful follow-up. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Aortic aneurysm; Endovascular; Endoluminal repair
1. Introduction In addressing the topic ‘Endoluminal repair of abdominal aortic aneurysm — state of the art’ we will consider the historical aspects of endovascular aneurysm repair, our departments experience over an 812year period and review the recent developments in endovascular prostheses. The endovascular treatment of patients with aortic aneurysms is not new. As early as 1864, Moore is credited by Keen with the introduction of large masses of intraluminal wire into an aneurysm in an attempt to precipitate thrombosis [1]. In preantibiotic days, the majority of aneurysms were syphilitic in origin and saccular in morphology (Fig. 1), which made them more amenable to treatment by wiring than the fusiform variety seen today. Saccular, syphilitic aneurysms were extremely painful and associated with a * Corresponding author. Tel.: + 61-2-93513358; fax: + 61-293517075.
poorer prognosis than the current fusiform ones. Approximately 90% of patients with syphilitic aneurysms died within 1 year from the onset of symptoms [2]. This rather desperate scenario explains why surgeons were prepared to offer the procedure of wiring of aneurysms and why patients were prepared to accept this unreliable form of treatment. In 1879, Corradi modified the wiring process by passing an electric current along an insulated wire in an attempt to induce thrombosis [1]. In 1915, Colt, while working as a house surgeon, developed a self-expanding wire umbrella that could be introduced via a trocar into an aneurysm (Fig. 2) [3]. The loading capsule and delivery system had many similarities with current endovascular systems. Blakemore and King [4] revived the use of wiring in 1938. Electrothermic coagulation of aortic aneurysms by wiring was used up until 1953, when graft replacement of aneurysms was introduced. The relatively high morbidity and mortality rates for graft replacement of aortic aneurysms, particularly in high-risk patients, maintained the interest of researchers
0720-048X/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 7 2 0 - 0 4 8 X ( 0 1 ) 0 0 3 3 8 - 2
J. May et al. / European Journal of Radiology 39 (2001) 16–21
17
sheep model of aortic aneurysm. The first radiographically guided aortic graft implantations were reported in 1987 by Lawrence et al. [6] who used a chain of stainless steel Gianturco Z-stents (Cook, Indianapolis, IN) within a tube of woven polyester; however, not until 1991 did Parodi et al. [7] report the first clinical use in humans of transfemoral, endovascular grafting to exclude aortic aneurysms. Their concept was the use of balloon-expandable, vascular stents to replace sutures and secure the proximal and distal ends of a fabric graft within the lumen of the aorta.
2. Royal Prince Alfred Hospital — University of Sydney experience with endoluminal repair of abdominal aortic aneurysm
Fig. 1. Clinical characteristics of syphilitic and arteriosclerotic aneurysms. (Modified from Bahnson HT. Considerations in the excision of aortic aneurysms. Ann Surg 1953;138:377 –382 with permission).
in developing an endovascular method of repair. Balko et al. [5] can probably be credited with the first reported experimental use of a stent-graft combination for the treatment of animals with artificial aneurysm. In their experiments, a novel form of nitinol Z-stent was combined with a sleeve of polyurethane and tested in a
Between May 1992 and October 2000 the endoluminal method was used for primary repair of AAA in 400 patients. There were 368 males and 32 females with a mean age of 72 years. The procedures were performed in the operating room with the patient draped and prepared for open operation in the event of failed endoluminal repair. Access was gained through the common femoral artery or the iliac arteries via an extra-peritoneal approach. Fluoroscopy was used to deliver and deploy the endograft. Sizing of the endograft was based on pre-operative, contrast-enhanced, computed tomography (CT) and aortography performed with a calibrated catheter. An on-table, post-procedure angiogram was obtained in all patients. Follow-up consisted of physical examination and contrast-enhanced CT within one week of the operation, at 6, 12 and 18 months after the operation, and annually thereafter.
Fig. 2. Colt’s apparatus for wiring aneurysms. (From Power D’A. The palliative treatment of aneurysms by ‘wiring’ with Colt’s apparatus. Br J Surg 1921;9:27 – 31 with permission).
18
J. May et al. / European Journal of Radiology 39 (2001) 16–21
Fig. 3. Kaplan – Meier curves comparing graft failure for endoluminal AAA repair using bifurcated, aorto-iliac and tube prostheses. Reproduced with permission from Eur J Vasc Endovasc Surg.
Fig. 4. Kaplan – Meier curves comparing graft failure following endoluminal AAA repair using first and second generation prostheses. Reproduced with permission from J Vasc Surg.
2.1. Results Successful endoluminal repair was achieved in 380 of 400 patients (95%). The remaining 20 patients required primary conversion to open repair at the original operation. Seventeen patients required secondary conversion on a subsequent occasion for; rupture (seven patients) persistent endoleak (four patients), inadvertent covering of the renal arteries with the endograft (three patients); and increasing size of AAA in the absence of endoleak in three patients. The overall perioperative mortality rate was 11 in 400 patients (2.75%). Analysis of the outcome according to the configuration of the endografts revealed a significantly larger number of failures with tube compared with non-tube (bifurcated and tapered aorto-uni-iliac) configuration using Fisher’s Exact Test [8]. Life table analysis by log rank test did not reveal a significant difference, despite widely divergent Kaplan–Meier curves, due to the disproportionately greater number of tube endo-
grafts early in the study and bifurcated grafts later in the study (Fig. 3). In mid 1995 second generation prostheses became available. These were characterised by low profile delivery systems, modular construction and metallic frame support throughout the length of the prosthesis. Comparison of 118 patients whose AAA were treated by first generation prostheses with 148 patients whose AAA were treated by second generation prostheses revealed similar perioperative mortality rates but a statistically significant difference between the survival curves of the two generations which favoured the second generation group (P = 0.012) [9]. There was also a significant (PB 0.001) difference between the two generations of patients in their probability of graft failure was considered. Second generation patients were at a lower risk of graft failure than first generation patients (Fig. 4). A study was also undertaken to compare the outcome of consecutive patients with AAA treated concurrently by open repair and endoluminal repair using
J. May et al. / European Journal of Radiology 39 (2001) 16–21
19
Fig. 5. Kaplan – Meier curves for survival following open repair and endoluminal repair of AAA. Reproduced with permission from J Vasc Surg.
second generation prostheses by the same surgeons during a defined interval [10]. Between May 1995 and December 1998 second generation endoprostheses were implanted in 148 patients and together with 135 patients treated concurrently by open repair during the same period, comprised the study group of 283 patients. Minimum period of follow-up for all patients was 18 months. Perioperative mortality was 5.9% in the open group and 2.7% in the endoluminal group (n.s.). There was a statistically significant difference between the survival curves of the two groups in favour of the endoluminal group when analysed by log rank test (P =0.004) (Fig. 5). The Kaplan– Meier curve for graft failure for the endoluminal repair group revealed a 3-year graft success probability of 82%. Survival probability with successful repair in the open group at 3 years was 85%.
2.2. Discussion What can we learn from this experience? The improved survival following endoluminal AAA repair using second generation prostheses compared with open repair is probably the most important finding. This must be weighed against the significantly greater graft failure rate with the endoluminal compared with the open method. These findings raise the question of reducing the minimal diameter at which endoluminal AAA repair may be recommended. This is important since the chances of a AAA being suitable for endoluminal repair are inversely related to the diameter of the aneurysm. Reports of device failure (Table 1) and recent reports of unexpected and unpredictable rupture following endoluminal AAA repair [11,12], however, make this suggestion premature.
3. New prostheses and modifications of existing prostheses The first-in-man study of the Cordis (Cordis/Johnson and Johnson, Warren, NJ) endoluminal AAA prosthesis was undertaken in 1999 [13]. Although modular in construction, this device has a unique design. It has a ‘gasket’, which is deployed in the proximal neck of the aneurysm (Fig. 6). Two self-expanding endolimbs are deployed within the gasket, the function of which is to provide a seal between the D-shaped configuration of the limbs (Fig. 7). The gasket and both endolimbs have 12F delivery catheters, making the device of potential use in the percutaneous treatment of AAA without the need for closure devices. The Anaconda™ (Sulzer Vascutek Ltd., Inchinnan, UK) has a unique ring stent in saddle configuration with high hoop strength, which both seals and anchors without the need for hooks or barbs. Both suprarenal fixation and repositioning of the device, when deployed, are possible. An innovative magnet system is used to aid limb replacement. The device features specially woven polyester and 16/18F introducers. Clinical trials of this device are ongoing. Table 1 AAA device failure Prosthesis
Manufacturer
Failure mode
EVT
Endovascular Technologies Mintec
Hook fractures
Stentor Vanguard AneuRx Lifepath
Boston Scientific Corporation Medtronic Baxter
Fabric defects, seam failure Fabric defects, tie breaks Modular dislocation Wireform fracture
20
J. May et al. / European Journal of Radiology 39 (2001) 16–21
Fig. 6. (a) Nitinol and polyurethane ‘gasket’. One of three components of the Cordis endoluminal prosthesis for percutaneous abdominal aortic aneurysm repair; it is deployed below the renal arteries. (b) One of two self-expanding endolimbs of the Cordis prosthesis; they are deployed within the gasket.
reductions in size of the aneurysm sac without kinking. It will also have limbs and extensions up to 15 mm in diameter. The modified AneuRx (Medtronic, Santa Rosa, CA) prosthesis will have a filaform nose cone in place of the hemispherical shape of the current model. It will also have a new deployment mechanism built into the delivery catheter and discard the current clip-on ‘fishing-rod’ system. Cook have now released a new three-piece configuration of the Zenith prosthesis. This provides a wider range of diameters and lengths for the limbs but increases the potential for modular dislocation. It should also reduce the need for custom-built prostheses which currently make up 40–50% of this company’s output. An infrarenal model of the Zenith is also planned for those interventionalists who prefer to avoid the obligatory covering of the renal ostia with the uncovered upper stent of the standard model. 4. Summary Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for caution and continued careful follow-up. References
Fig. 7. Postoperative CT scan of a Cordis prosthesis showing the D-shaped configuration of the two endolimbs deployed within the gasket in the proximal neck of the abdominal aortic aneurysm.
The Endologix-Bard (CR Bard, Inc., Haverhill, MA) prosthesis, a one-piece, fully supported, bifurcated endoluminal graft was also released in 1999. This device goes against the trend of modular prostheses, which have been trialled in the past 5 years. It differs from the other one-piece EVT/Guidant (Endovascular Technologies, Menlo Park, CA) prosthesis, having PTFE fabric rather than polyester and a fully supported metallic frame rather than proximal and distal stent support. Modifications have been made to a number of existing prostheses. Vanguard III (Boston Scientific, Natick, MA) has a new metallic frame with smaller ‘zigs’ in the body of the endograft and greater capacity to adapt to
[1] Keen WW. Surgery: Its Principles and Practice. Philadelphia: WB Saunders, 1921:216 – 349. [2] Kampmeier RH. Saccular aneurysm of the thoracic aorta: a clinical study of 633 cases. Ann Intern Med 1938;12:624 –51. [3] Power D’A Sir. The palliative treatment of aneurysm by wiring with Colt’s apparatus. Br J Surg 1921;9:27. [4] Blackmore AH, King BG. Electrothermic coagulation of aortic aneurysms. J Am Med Assoc 1938;111:1821 – 938. [5] Balko A, Piasecki GJ, Shah DM, et al. Transfemoral placement of intraluminal polyurethane prosthesis for abdominal aortic aneurysm. J Surg Res 1986;40:305 – 9. [6] Lawrence DD, Charnsangavej C, Wright KC, et al. Percutaneous endovascular graft: experimental evaluation. Radiology 1987;163:357 – 60. [7] Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysm. Ann Vasc Surg 1991;5:491 – 9. [8] May J, White GH, Yu W, Waugh R, Stephen MS, Arulchelvam M, et al. Importance of graft configuration in outcome of endoluminal aortic aneurysm repair: a 5-year analysis by the life table method. Eur J Vasc Endovasc Surg 1998;15:406 – 11. [9] May J, White GH, Waugh R, Stephen MS, Chaufour X, Arulchelvam M, Harris JP. Comparison of first and second generation prostheses for endoluminal repair of abdominal aortic aneurysms: a 6-year study with life table analysis. J Vasc Surg 2000;32:124 – 9.
J. May et al. / European Journal of Radiology 39 (2001) 16–21 [10] May J, White GH, Waugh R, Ly CN, Stephen MS, Jones MA, Harris JP. Improved survival following endoluminal repair with second generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a five-year concurrent comparison by life table method. J Vasc Surg, 2001;33:S21-6 [11] Zarins CK, White RA, Fogarty TJ. Aneurysm rupture after endovascular repair using the AneuRx stent graft. J Vasc Surg
.
21
2000;31:960 – 70. [12] Politz JK, Newman VS, Stewart MT. Late abdominal aortic aneurysm rupture after AneuRx repair: a report of three cases. J Vasc Surg 2000;31:599 – 606. [13] May J. Technological progress with endovascular repair of abdominal aortic aneurysms. In: Davies A, editor. Vascular Surgery Highlights 1999 – 2000. Oxford: Fast Facts Health Press, 1999.