Multicenter pivotal trial results of the Lifepath System for endovascular aortic aneurysm repair☆

Article Outline

• Abstract
• Methods
  • Device
  • Device insertion procedure
  • Patient selection
  • Device selection
  • Follow-up evaluation
  • Statistical analysis
• Results
  • Patients and procedures
  • Mortality
  • Complications and secondary procedures
  • Wireform fractures and migration
  • Aneurysm diameter and volume before and after evar
• Discussion
• Conclusion
• APPENDIX. 
• References
• Copyright

Abstract 

Purpose

This study was undertaken to assess the results of endovascular aortic aneurysm repair with the Lifepath abdominal aortic aneurysm (AAA) graft system.

Method

In a prospective clinical trial, 23 centers used the Lifepath System balloon-expandable, modular bifurcated stent graft for elective endovascular aortic aneurysm repair. Stent grafts were sized according to computed tomographic angiography–based diameter measurements. All repairs were performed in the operating room through bilateral surgically exposed femoral arteries. Results were assessed with contrast agent–enhanced computed tomography scans and plain abdominal x-ray films at 1, 6, 12, 24, 36, and 48 months postoperatively.

Results

Over 52 months (mean follow-up, 11 months), 227 patients (206 men, 21 women) were enrolled. Technical implant success rate was 98.7%. There were five (2.2%) conversions to open surgery: two emergently because of aortic perforation; to treat refractory endoleak, immediate in one and at 12 months in one; and to replace a device with wireform fractures that had migrated at 12 months, resulting in a proximal endoleak. The perioperative mortality rate was 1.3%. There was one operative death during a secondary procedure to repair perforation of the aorta. There were two perioperative deaths, from postoperative myocardial infarction (n = 1) and pulmonary embolus (n = 1). There were 12 late deaths, from coronary artery disease (n = 4), cancer (n = 2), respiratory failure (n = 2), sepsis (n = 1), or unknown cause (n = 3). Median length of stay was 2 days (mean, 4 days). There have been no AAA ruptures after successful implantation of the device, no graft limb thromboses, and no limb dislocations. At the time of operation endoleak was noted in 43 (19%) patients, but by 6 months this was reduced to 8 (5.9%) patients (type I, n = 1; type II, n = 7). There were no type III or type IV endoleaks. Secondary interventions to treat endoleaks included open conversion (n = 2), placement of extension cuffs (n = 4), repeated balloon dilation (n = 3), and coil embolization (n = 6). The two remaining secondary interventions were emergent treatment of postoperative bleeding from a groin incision, and a colon resection because of postoperative colonic ischemia, for a 12-month secondary intervention rate of 7.5%. Wireform fractures were noted in the first generation Lifepath device in 37 of 79 (47%) patients. Graft migration (>10 mm) was observed in five patients (2.2%), each of whom also had two or more fractures of the proximal anchoring wireforms. Migration resulted in a proximal attachment endoleak in one patient. In response to wireform fractures, the device was modified after the initial 79 patients were enrolled. Wireform fracture has been observed in six patients since this modification (4%), and in only one patient did this involve fracture of a proximal anchoring wireform; none of these patients has had endoleak or graft migration. By 12 months, mean aneurysm diameter was noted to decrease by 9 mm (P < .0001), and mean aneurysm volume by 42 mL (P < .0001) from the preoperative visit.

Conclusion

The Lifepath System demonstrates a low endoleak and secondary intervention rate and high sac regression rate, compared with other devices. The unique balloon-expandable design offers the advantages of precise placement and high radial force. The device appears to be highly resistant to limb thrombosis and modular component separation. Patients were protected from AAA rupture after successful device implantation, and demonstrated significant reduction in AAA diameter and volume. Fractures of the wireforms of the main body of the device have been observed. Careful long-term follow-up is necessary.

The Lifepath abdominal aortic aneurysm (AAA) graft system is an adaptation of the White-Yu endovascular graft attachment device (GAD) described in 1994.1 The White-Yu device was constructed from a commercially available polyester prosthesis with a patented intrinsic wireform graft attachment system along the graft body. Initial bench model studies led to design enhancements that eventually allowed safe use in human beings. Three years of experience with the White-Yu Endovascular GAD graft was reported in 1997.2 In this latter series, the 30-day mortality rate for elective endoluminal AAA repair was 3.1%; primary endoleak occurred in five patients (5.4%), all during the first 15 months of the prototype clinical trial; and secondary endoleak was noted in three patients (3.2%). There were seven perioperative conversions (7.3%), because of causes unrelated to endoleak, and no late conversions in the bifurcated device implants. Decrease in the size of the aneurysm sac was consistently observed in the successfully treated cases. From this experience, it was concluded that the White-Yu device appeared to safely and effectively exclude aneurysms from blood flow. The success of this study led to development of the commercially designed and developed product by Edwards Lifesciences LLC (Irvine, Calif; formerly Baxter Cardiovascular Group). We report the results of a multicenter clinical trial of the Lifepath System for repair of nonruptured infrarenal aortic aneurysms.

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Methods 

A trial of the safety and efficacy of the Lifepath System was conducted at 23 centers (Appendix). This device is under Investigational Device Exemption in the United States in the context of a pivotal Food and Drug Administration trial. Each center obtained approval from its institutional review board for human subject investigations, and informed consent was obtained from all patients.

Device 

The Lifepath System is a modular, bifurcated, balloon-expandable endovascular graft. The stented endoskeleton is constructed from Elgiloy (Elgiloy Limited Partnership, Elgin, Ill), a metal alloy with high chromium content. Individual wireforms are interwoven through the graft material in concentric ring fashion, separated by regions of unsupported graft, to allow flexibility and sealing. The graft fabric is woven polyester, provided in a full, surgical-weight thickness. In addition to radial force alone, external metallic crimps help to achieve secure fixation. The main graft body consists of a balloon-expandable trunk with two self-expanding legs. The self-expanding legs are comprised of specially treated Elgiloy sewn externally on the polyester fabric (Fig 1, A). The iliac grafts are balloon-expandable in their entirety, and are comprised of independent concentric Elgiloy wireforms interwoven through the polyester graft fabric, with external crimps. Main body grafts are supplied in neck diameters from 21 to 29 mm, with aortic cuffs up to 31 mm, and are suitable for repair of aneurysms with neck diameters ranging from 19 to 27 mm. Main body grafts are uniform in diameter. Aortic necks of irregular or tapered diameter may be treated by combining a main body of one diameter with a proximal extender cuff of a different diameter, deploying the larger device into the smaller device to create a seal. Iliac limbs are straight or tapered in diameter along their length, with a common proximal end designed to securely dock with the main body graft, and a distal limb diameter chosen to seal appropriately in the desired distal iliac landing zone. Both proximal and distal extension cuffs, which are not tapered in diameter, are available. The grafts are supplied premounted on balloon catheters, and are delivered through highly flexible, hydrophilic sheaths: the main body through a 25F (outside diameter [OD]) sheath, and the iliac legs through a 19F (OD) sheath. Balloons in all sizes are also available separately.

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• Fig 1. 

  Lifepath System is a balloon-expandable, modular stent graft consisting of a main body (A) and docking limbs (not shown). Proximal and distal extension cuffs in various sizes are available. Grafts are premounted on balloons that have square shoulders, and are also supplied separately. Stent grafts are delivered through flexible, hydrophilic sheaths supplied in 25F and 19F (OD) sizes. B, A directional catheter, shown with a cut-away view of the main body stent graft, facilitates cannulation of the contralateral limb by means of a moveable tip, which can be deflected with a hand control located at the back of the catheter.

Device insertion procedure 

The device is delivered via surgically exposed femoral arteries. Initially, wire access through the aneurysm to the thoracic aorta is established. After completion of the arterial exposure, heparin is administered for systemic anticoagulation. Through ipsilateral femoral access, the 25F sheath is fluoroscopically guided over a stiff guide wire into the abdominal aorta to a level slightly proximal to the renal arteries. Through the contralateral femoral access route a flush angiographic catheter is placed, and an arteriogram is obtained to identify the precise location of the renal arteries. After thorough flushing with a high-concentration heparin flush, the Lifepath System main body graft is placed over the wire and loaded into the sheath. It is fluoroscopically guided within the sheath into position at the level of the lowest renal artery. Once positioned properly with respect to both level of the renal arteries and orientation of left and right limb markers, the graft is unsheathed, allowing the self-expanding legs to open, but with the main body remaining crimped on the balloon (Fig 2, A). Fine adjustments may be made with respect to device positioning and rotation. Balloon inflation is performed in a slow, controlled fashion, allowing precise deployment at the renal artery level. Repeat balloon inflation is used to ensure full expansion of the wireforms and secure the graft to the aortic neck. The balloon is then withdrawn. A mechanism on the delivery catheter for lengthening the balloon (stretching), thereby reducing its deflated diameter, may be used to reduce the balloon profile after deflation and facilitate balloon removal. Contralateral limb wire access is established either retrograde, through cannulation of the main graft body leg from the contralateral femoral access, or antegrade, through retrieval of a wire passed down through the contralateral limb from the ipsilateral access route already established. This latter maneuver is facilitated by use of a directional catheter supplied with the Lifepath System (Fig 1, B). This dual-lumen catheter is passed over the established ipsilateral access wire and positioned above the flow divider of the main body of the stent graft. The deflecting tip of the directional catheter is then fully deflected to enable a flexible guide wire to be passed through the catheter, down and out the contralateral leg, to be retrieved through the contralateral access (snare or open femoral retrieval). Successful cannulation is confirmed by visualizing the wire exiting the contralateral leg. Once access to the contralateral leg has been established, a stiff wire exchange is performed. Sheaths are advanced over the stiff wires positioned through both the ipsilateral and contralateral legs of the main graft body, to prepare for docking the iliac graft limbs. On the ipsilateral side, the previously placed 25F sheath is advanced into the leg of the main body, and on the contralateral side a 19F sheath is advanced into the contralateral leg of the main body. After flushing with a high-concentration heparin solution to remove air from the system, the iliac stent grafts are advanced through their respective sheaths into position, fully within the main body legs (Fig 2, B). They are unsheathed, and deployed with balloon inflation. These legs may be deployed sequentially or with the kissing balloon technique. Repeat balloon inflation is performed to ensure full expansion of the wireforms. A final arteriogram is obtained. At the conclusion of the procedure, the sheaths are withdrawn, the arteriotomies created for the procedure are closed, and the heparinization may be reversed with administration of protamine sulfate, at the discretion of the operator.

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• Fig 2. 

  Device insertion procedure (see text for details). A, Main body deployment. The two legs of the main graft body are self-expanding. B, Iliac limb deployment with balloon inflation.

Patient selection 

Only patients with nonruptured infrarenal aortoiliac aneurysms who were candidates for conventional open AAA repair were enrolled. Inclusion and exclusion criteria are shown in Table I.

Table I. Inclusion and exclusion criteria

AAA, Abdominal aortic aneurysm; OD, outside diameter.

The anatomic suitability for endovascular repair was determined with computed tomographic angiography (CTA) for the first-generation design, and additionally with three-dimensional reconstruction by the central core laboratory (originally, Imaging Sciences Institute, University Hospital, Utrecht, The Netherlands; currently, Medical Media Systems, Lebanon, NH). Routine preoperative catheter angiography was not performed.

Device selection 

Preoperative measurements of the aneurysm neck diameter (intima-to-intima) were used to determine the appropriate diameter of the stent graft main body. Inasmuch as the device was balloon-expandable, minimal oversizing (10%-15%) was used. Graft selection was suggested by the core laboratory, but was ultimately at the discretion of the implanting surgeon. Graft length was chosen so as not to cover more than one, and preferably neither, hypogastric artery.

Follow-up evaluation 

Patients underwent baseline abdominal plain radiography at device implantation and before hospital discharge. In addition to physical examination, abdominal four-view (anteroposterior, lateral, left and right anterior oblique) x-ray studies and CTA were performed at 1, 6, and 12 months, and annually thereafter. These studies were used to assess the integrity of the stent graft and the aneurysm repair (migration, wire fractures, endoleak, aneurysm size). Studies were evaluated at each local site as well as independently by the central core laboratory. Reporting of results complied with the reporting standards for endovascular AAA repair.3

Statistical analysis 

For continuous variables, means and ranges are presented; where appropriate, 95% confidence limits were computed with the t distribution, and groups were compared with the two-sample t test or paired-sample t test. For binary variables, confidence limits were computed with the exact binomial distribution, and groups were compared with the Fisher exact test. Kaplan-Meier survival analysis was performed with the log-rank test for significance. All computations were performed with SAS software (version 8.2; SAS Institute, Cary, NC); unless otherwise specified, the exact form of each algorithm is the SAS default.

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Results 

Patients and procedures 

Beginning in December 1998 and continuing over 52 months, endovascular repair of AAA was successfully performed in 224 of 227 (98.7%) patients with the Lifepath System. Patient demographic data are shown in Table II. After the initial 79 patients (“generation 1”) were enrolled, the trial was voluntarily suspended to allow strengthening of the System wireforms, in response to observed wireform fractures (see below). Enrollment was then resumed (“generation 2”) after an enrollment hiatus of 18 months. Overall follow-up ranged from 0 to 41 months (mean, 11 months). For generation 1, mean follow-up was 25 months (median, 24 months), and for generation 2 patients, mean follow-up was 3 months (median, 3 months).

Table II. Patient demographic data

CABG, Coronary artery bypass grafting; PTCA, percutaneous transluminal coronary angioplasty; COPD, chronic obstructive pulmonary disease; TIA, transient ischemic attack; ASA, American Society of Anesthesiologists.

There were five (2.2%) conversions to open surgery: emergently because of aortic perforation (one intraoperative, one several hours postoperative), to treat refractory endoleaks (one immediate, one at 6 months), and for replacement of a device with wireform fractures that had migrated, resulting in a proximal endoleak (one, at 12 months). The aortic perforations were thought to be related to excessive stretching of the aortic neck during balloon inflation, resulting in disruption. Devices used are listed in Table III. Proximal extension cuffs were placed in 40 (17.6%) patients, and distal extensions in 46 (20.3%) patients. Most of the proximal cuffs were planned placements, to accommodate irregularly shaped aneurysm necks rather than to treat endoleaks or malpositioning of the main body. Unplanned cuff placement for endoleak remediation is discussed below. The details of the operative procedures are shown in Table IV. Median length of stay (LOS) after endovascular aortic aneurysm repair was 2 days (mean, 4 days; range, 1-33 days).

Table III. Devices deployed

Table IV. Details of operative procedures

Mortality 

There were 15 deaths (3 perioperative, 12 late) during follow-up. Of the 3 perioperative deaths (1.3%), 1 resulted from aortic perforation, noted after transfer to the intensive care unit, necessitating immediate return to the operating room and open conversion, with fatal outcome. The remaining perioperative deaths were from myocardial infarction (n = 1) and pulmonary embolus (n = 1). The 12 late deaths were from coronary artery disease (n = 4), cancer (n = 2), respiratory failure (n = 2), sepsis (n = 1), or unknown cause (n = 3).

Complications and secondary procedures 

Perioperative complications are listed in Table V. There have been no aneurysm ruptures after successful placement of the LifePath System, and no limb thromboses or dislocations during follow-up.

Table V. Perioperative complications

Details of the number and type of endoleaks and the interventions used to treat them are shown in Table VI. Endoleak was noted at the operative procedure in 43 (19%) patients, but by 1 month this was reduced to 25 (12.2%) patients (type I, n = 7; type II, n = 18). All type I leaks noted at the initial procedure were treated with additional ballooning or placement of cuffs. All remaining type I endoleaks detected subsequently were treated with secondary interventions (placement of extension cuffs, n = 4; repeat balloon dilation, n = 3). Spontaneous sealing occurred in 6 of the type II endoleaks, and 5 were treated with secondary intervention (coil embolization, n = 4; open conversion of a type II endoleak that preoperatively was thought to be type I, n = 1), resulting in an endoleak rate of 5.9% at 6 months. By 12 months a new type I endoleak developed secondary to graft migration (see below), and was treated with open conversion. Of the remaining type II endoleaks, 2 were treated with coil embolization, and one patient died of late myocardial infarction. A single remaining type II endoleak is being observed. There were no type III or type IV endoleaks.

Table VI. Endoleaks and endoleak interventions

Additional secondary procedures, other than those described to treat endoleaks, included an emergent return to the operating room for treatment of bleeding from a groin incision, and a colon resection to treat postoperative colonic ischemia. The total secondary intervention rate was thus 7.5% at 12 months.

Wireform fractures and migration 

The LifePath System main body has four balloon-expandable wireforms. The first three of these create the anchoring seal to the aortic neck, and the fourth nonsealing wireform provides structural support for the self-expanding docking limbs during deployment. Integrity of the wireforms was evaluable with x-ray studies in 79 (100%) generation 1 patients and 117 (81%) generation 2 patients. Wireform fractures were noted in the first-generation Lifepath device in 37 of 79 (47%) patients. All fractures were noted to be in the balloon-expandable segment of the main body. Fractures were located in the first three anchoring wireforms in 33 of these 37 patients, and in the nonanchoring fourth wireform in 4 patients. No wireform fractures of the iliac limbs have been observed. Trial enrollment was voluntarily suspended, and the wireform thickness was increased. Wireform fractures have been noted in the main body components in 6 (4%) patients receiving the second-generation Lifepath System with the strengthened wireforms. Fractures were in the anchoring wireforms in only 1 patient, and in the nonanchoring fourth wireform in the remaining 5 patients. While there is no significant difference between generation 1 and generation 2 patients overall for wireform fracture-free survival, when only the critical anchoring wireforms are considered, generation 2 patients have significantly better fracture-free survival than do generation 1 patients (P = .0047; Fig 3).

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• Fig 3. 

  Kaplan-Meier analysis of anchoring wireform fractures for first-generation and second-generation Lifepath System.

Device migration (defined as movement >10 mm) was observed in the first-generation graft in five (2.2%) patients, each of whom also had two or more fractures of the proximal anchoring wireforms. Three migrations were noted at 12 months, and two migrations at 24-month follow-up. Of these five migrations, one resulted in a proximal attachment endoleak, and the remainder are not clinically significant. No migrations have been noted in patients receiving the second-generation Lifepath System.

Aneurysm diameter and volume before and after evar 

The average aneurysm diameter treated was 55 mm (range, 37-90 mm; median, 53 mm), and volume was 154 mL (range, 61-537 mL; median, 139 mL). Aneurysm diameter and volume reduction were significant at each assessment (Fig 4). Mean aneurysm diameter decreased by 3 mm at 6 months (P < .0001), an additional 4 mm at 12 months (P < .0001), and an additional 3 mm at 24 months (P < .0001). Similarly, mean aneurysm volume decreased by 10 mL at 6 months (P = .0012), an additional 12 mL at 12 months (P < .0001), and an additional 7 mL at 24 months (P < .0001). Overall, reduction of diameter was noted in 58% of aneurysms, and reduction of volume was noted in 84% at 12 months (Table VII). Enlargement of aneurysms was noted in 7 patients by diameter and in 18 patients by volume measurement at some point during follow-up. Wireform fractures were not observed in any of these patients with expanding aneurysms. However, endoleak was observed in most of these patients (5 diameter increases, 9 volume increases), and correction of these endoleaks resulted in subsequent sac shrinkage. All type I endoleaks resulted in AAA sac expansion. Expansion was observed in the absence of endoleak in 2 patients by diameter and in 9 patients by volume. Of the two diameter expansions without endoleak, one spontaneously regressed after 6 months, and the other increased by 5 mm at 1 year and is being observed. Of the nine volume expansions without endoleak, four spontaneously regressed after initial expansion, and five (increase by 4, 9, 10, 16, and 22 mL, respectively) are being observed.

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• Fig 4. 

  Abdominal aortic aneurysm diameter and volume change after endovascular aortic aneurysm repair. Reduction in diameter and volume is significant at each follow-up. Mean (± SE) aneurysm diameter decreased by 3 mm at 6 months (P < .0001), an additional 7 mm at 12 months (P < .0001), and an additional 3 mm at 24 months (P < .0001). Similarly, mean (± SE) aneurysm volume decreased by 15 mL at 6 months (P = .0012), an additional 28 mL at 12 months (P < .0001), and an additional 12 mL at 24 months (P = .0002). See Table VII for details of diameter and volume change at each follow-up.

Table VII. Aneurysm diameter and volume change after EVAR*

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Discussion 

We conducted a multicenter trial of the Lifepath System for endovascular repair of AAA in 227 patients over 52 months, and achieved a technical success rate of 98.7%, perioperative mortality rate of 1.3%, and few serious complications. The Lifepath System was effective in protecting patients from AAA rupture after successful implantation, with no late ruptures during follow-up, and significant reduction in AAA diameter and volume at each follow-up examination.

The Lifepath System is unique among EVAR devices. It is balloon-expandable, which distinguishes it from all other currently available stent grafts. This feature enables the graft to be delivered with great precision to the desired location, as evidenced by the low rate of cuff placement to treat proximal attachment endoleaks at implantation (3.9%). The stent graft has extremely high radial force and hoop strength, as is generally associated with balloon- expandable stents. This may be responsible for the complete absence of iliac limb thrombosis, a phenomenon that has plagued other EVAR devices.4 The main body and the iliac graft limbs are supported by balloon-expandable stents, arranged in concentric rings, to enable both radial force and flexibility. This high radial force also enables tight apposition of modular components, as evidenced by the absence of any occurrences of component separation in this trial. In contrast, component separation was responsible for late AAA rupture after EVAR with other devices.5

We found that the graft performs well even in challenging angulated neck anatomy. In such cases, the balloon- expandable stents significantly straighten the angulated neck, providing a strong seal. Often with self-expanding stent grafts it is difficult to obtain a seal in angulated necks, and remedial procedures for leaking self-expanding stent grafts in such situations usually include use of a balloon-expandable stent or additional proximal cuff to provide added radial sealing force.6 The Lifepath System provides this additional force from the outset.

Because the stent graft is provided as a stented graft premounted on a balloon, components are delivered through sheaths. The sheaths provided with the System are extremely flexible and hydrophilic, with long, smoothly tapered dilators. The advantages of working through sheaths include decreased blood loss and the ability to negotiate tortuous or difficult anatomy with a flexible sheath rather than a more rigid stent-graft delivery system.

The Lifepath System also includes a directional catheter (Fig 1), which can greatly simplify the process of contralateral limb cannulation. This offers the operator the option of antegrade or retrograde access to the contralateral main body leg, depending on the particular patient's anatomy.

Sizing considerations are different for balloon-expandable stent grafts compared with self-expanding stent-grafts. Significant oversizing has been advocated for self-expanding stent grafts, as a hedge against late endoleak, chiefly on the basis of data from the EuroSTAR registry.7 However, oversizing may be associated with a higher incidence of late neck dilatation and subsequent graft migration.8 With a balloon- expandable stent graft, however, sizing is tailored to the internal diameter of the target vessel, with minimal oversizing. In this trial, the amount of oversizing was determined with preoperative CTA-based measurements. We have observed no instances of late-attachment endoleak with this strategy. Oversizing of a balloon-expandable device can result in aortic perforation, as occurred in two of our patients.

Endoleaks were noted in only 5.9% of patients at 6 months. It has recently been noted that endoleak rates are device- dependent,9 and with the Lifepath System we report one of the lowest endoleak rates described for any device to date.5, 10, 11, 12, 13, 14 The endoleaks that were noted to persist at 6 months were treatable with endovascular means in all but one case, which was treated with open conversion. It is important that there was no occurrence of type III or type IV endoleaks. The graft fabric consists of full-thickness surgical-weight woven polyester, traditionally used for open AAA repair, which has thus far not demonstrated any defects during follow-up.

As evidence of successful aneurysm exclusion, reduction in sac diameter and volume was observed in most patients (84% with volume reduction at 1 year). This represents the highest rate of sac size regression reported for any device to date.15 These significant reductions continued to accrue through every follow-up interval. Only a few patients had observed increases in diameter or volume, and most of these were attributable to endoleaks noted at the same time. It is important that there were no late ruptures or aneurysm-related deaths over the 52-month study, attesting to the efficacy of aneurysm exclusion.

Wireform fracture has been a problem with the Lifepath System. Fractures have been without clinical sequelae in most patients. However, graft migration, while uncommon (2.2%), was seen only in first-generation patients with two or more fractures of the proximal three anchoring wireforms, and one endoleak, at the proximal attachment, was noted in association with one such migration. In response to this early observation the wireforms were strengthened. While there have been no clinically significant wireform fractures since this modification, follow-up of the second-generation of the LifePath System is too brief to draw firm conclusions. The incidence of observed fractures in the critical first three sealing wireforms has been significantly reduced. Clearly, careful follow-up is necessary to ensure the long-term integrity of the device.

Limitations of the Lifepath System include the relatively large size of the delivery system. The main body is delivered through a 25F (OD) sheath, requiring a minimum iliac access diameter of 8 mm on one side. The contralateral access requirement is 19F (OD). The flexible sheath will enable passage of the device through smaller iliac arteries, provided the vessels are not highly calcified. We have found anecdotally that uncalcified iliac arteries as small as 6 mm often are able to accommodate the 25F hydrophilic sheath with its long, tapered dilator.

The skills required for successful planning and use of the Lifepath System transfer readily from experience gained in placing balloon-expandable stents. There is a learning curve, both for sizing of grafts and implantation of devices, for operators whose EVAR experience has been exclusively with self-expanding stent grafts.

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Conclusion 

The Lifepath System demonstrates a low endoleak and secondary intervention rate and high sac regression rate compared with other devices. The unique balloon-expandable design offers the advantages of precise placement and high radial force. The device appears to be highly resistant to limb thrombosis and modular component separation. Patients were protected from AAA rupture after successful implantation of the device, and demonstrated significant reduction in AAA diameter and volume. Fractures of the wireforms of the main body of the device have been observed. Careful follow-up of patients after EVAR is necessary.

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APPENDIX. 

The Lifepath AAA Graft System Investigators. Jens Allenberg, MD, University of Heidelberg, Heidelberg, Germany; Alain Branchereau, MD, Hospital de la Timone, Marseille, France; Hugh G. Beebe, MD, Jobst Vascular Center, Toledo, Ohio; David C. Brewster, MD, Massachusetts General Hospital, Boston, Mass; Jeffrey P. Carpenter, MD, University of Pennsylvania, Philadelphia, Pa; John Crouch, MD, St. Luke’s Medical Center, Milwaukee, Wis; R. Clement Darling, MD, Albany Medical Center, Albany, NY; Mark Fillinger, MD, Dartmouth Hitchcock Medical Center, Lebanon, NH; Roy Fujitani, MD, University of California, Irvine, Calif; Berndt Glucklich, MD, Kreiskrankenhaus Rendsburg, Rendsburg, Germany; Roy Greenberg, MD, Cleveland Clinic Foundation, Cleveland, Ohio; Svante Horsch, MD, Krankenhaus Porz am Rhein, Koln, Germany; K. Craig Kent, MD, New York Hospital, New York, NY; Chris Kwolek, MD, University of Kentucky, Lexington, Ky; Werner Lang, MD, Klinikum der Friedrich-Alexander-Universitat, Erlangen, Germany; Graham Long, MD, William Beaumont Hospital, Detroit, Mich; Michel Makaroun, MD, University of Pittsburgh, Pittsburgh, Pa; John Martin, MD, Anne Arundel Vascular Institute, Prince Frederick, Md; Richard McCann, MD, Duke University, Durham, NC; William McKinsey, MD, University of Chicago, Chicago, Ill; Andre Nevelsteen, MD, Dienst Vaatheelkunde, Leuven, Belgium; Geoffrey White, MD, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Rodney White, MD, Harbor UCLA Medical Center, Torrance, Calif.

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