- Email: [email protected]
Low-profile versus standard-profile multibranched thoracoabdominal aortic stent grafts
From the Western Vascular Society
Low-profile versus standard-profile multibranched thoracoabdominal aortic stent grafts Bala Ramanan, MBBS, MS, Charlene C. Fernandez, BS, Julia D. Sobel, BS, Warren J. Gasper, MD, Shant M. Vartanian, MD, Linda M. Reilly, MD, Timothy A. M. Chuter, DM, and Jade S. Hiramoto, MD, MAS, San Francisco, Calif Objective: This study compared midterm results using low-profile stent grafts (LPSGs; 18F) and standard-profile stent grafts (SPSGs; 22F-24F) for endovascular pararenal and thoracoabdominal aortic aneurysm (TAAA) repair. Methods: From July 2005 to March 2015, 134 asymptomatic patients underwent endovascular repair of a pararenal or TAAA using multibranched aortic stent grafts. In March 2011, we started using a LPSG with nitinol stents and thinwalled polyester fabric. Prospectively collected data on operative repair, complications, and outcomes were compared between the two groups. Results: LPSGs were used in 37 patients (8 women [21.6%]; mean 6 standard deviation age, 72.5 6 8 years) and SPSGs in 97 patients (25 [26%] women; mean age, 73 6 8 years). Medical comorbidities, aneurysm size, and aneurysm extent were similar in the LPSG and SPSG groups. Mean follow-up time was longer in the SPSG group (3.1 6 2 years) than in the LPSG group (1.3 6 0.9 years; P < .001). Operative time, renal failure, stroke, myocardial infarction, and perioperative death were not significantly different between the two groups (P > .05). Aneurysm-related death, rupture, stent graft migration, type I or III endoleaks, aneurysm enlargement >5 mm, branch vessel occlusion, and reintervention rates were similar between the two groups (P > .05). However, the combined outcome of conduit use or access artery injury occurred at a lower rate in the LPSG group than in the SPSG group (16% vs 36%; P [ .03). Women experienced significantly higher rates of conduit use and access artery injury than men after repair with SPSGs (64% vs 26%, respectively; P [ .001) but similar rates after repair with the LPSG (25% vs 14%, respectively; P [ .45). Conclusions: LPSGs had similar safety profile and midterm outcomes compared with the SPSGs for treatment of pararenal and TAAA. The substitution of LPSGs for SPSGs lowered the number of patients who required conduit insertion to avoid access artery injury, especially in women, thereby reducing an otherwise striking gender difference. (J Vasc Surg 2016;-:1-7.)
Despite improvements in perioperative care during the past two decades, open repair of thoracoabdominal aortic aneurysm (TAAA) remains a formidable procedure with high rates of morbidity and mortality.1,2 Multibranched endovascular aneurysm repair (MBEVAR) has evolved during the past decade as a less invasive treatment of pararenal aortic aneurysms (PRAA) and TAAA.3,4 However, in the absence of an iliac artery bypass or conduit, this technique is only applicable to those with iliac arteries large enough to admit the necessary delivery system. Concomitant iliac artery occlusive disease is present in w36% of patients
with aortic aneurysms, which increases the risk for arterial injury of the access vessel at the time of EVAR.5 Low-profile stent grafts (LPSGs) were developed in response to the need for smaller delivery systems for MBEVAR. The first MBEVAR using a LPSG took place in March 2011. Since then, LPSGs have been used in >60% of the cases at University of California San Francisco. The current study compared the midterm outcomes of standard-profile stent grafts (SPSGs) and LPSGs for MBEVAR of PRAA and TAAA. METHODS
From the Division of Vascular and Endovascular Surgery, University of California, San Francisco. This study is registered at clinicaltrials.gov: NCT00483249. Author conflict of interest: T.A.M.C. and J.S.H. receive royalties from licensed patents and research funding from Cook Medical Inc, the manufacturer of the multibranched thoracoabdominal stent graft. Presented at the Thirtieth Annual Meeting of the Western Vascular Society, Wailea, Maui, Hawaii, September 19-22, 2015. Correspondence: Jade S. Hiramoto, MD, MAS, Division of Vascular and Endovascular Surgery, University of California, San Francisco, 400 Parnassus Ave, Ste A-581, Box 0222, San Francisco, CA 94143 (e-mail: [email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2016 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2016.01.038
Study design and operative technique. This is a single-center, prospective nonrandomized clinical trial of endovascular repair of TAAA and PRAA with a modular multibranched thoracoabdominal endograft (Cook Australia, Brisbane, Queensland, Australia) in asymptomatic patients. Urgent or emergency cases were excluded from the analysis. A physician-sponsored investigational device exemption was approved by the U.S. Food and Drug Administration and the University of California San Francisco Committee on Human Research. All patients gave informed consent. The study design, inclusion and exclusion criteria, and surgical technique have been previously described.6 Briefly, bilateral open femoral artery and left brachial artery access was obtained. Modular aortic components were inserted through the femoral arteries, which were then closed. After 1
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Fig 1. The top graft is the standard-profile stent graft (SPSG). The top delivery system is the larger delivery system of the SPSG, and the lower is the smaller delivery system of the low-profile stent graft (LPSG). The lower graft is the LPSG.
insertion of the brachiofemoral wire, stent grafts were used to bridge the cuffs on the aortic components to the visceral and renal arteries through a brachial artery approach. Devices. The multibranched component refers to the tapered cuff that bears the aortic component. All multibranched components of the SPSG were made of stainless steel stents with conventional woven polyester fabric. The inner diameter of the device delivery system was 22F to 24F (Fig 1). The LPSG was made of self-expanding nitinol stents with thin-walled polyester fabric, enabling delivery of all the multibranched components through an 18F inner-diameter delivery system (Fig 1). An off-theshelf device was used in 38% (51 of 134) patients and a custom device was implanted in 62% (83 of 134). All the LPSGs were considered to be custom devices. Additional proximal and distal components were used to treat more extensive aneurysms, and covered and uncovered stents were used to bridge the aortic cuffs and the visceral and renal branches (Table I). Low-profile multibranched components were combined with low-profile proximal thoracic extensions. Proximal extensions measuring 32 to 38 mm in diameter were inserted through an 18F delivery system. Proximal extensions measuring 40 to 46 mm in diameter were inserted through a 20F delivery system. Device selection and conduit use. Preoperative imaging with computed tomography angiography and OsiriX MD three-dimensional reconstructive software (Pixmeo, Bernex, Switzerland) was used for anatomic assessment of
Table I. Stent graft extensions and branches Extensions
Branches a
Covered stents Zenith TX2 Zenith TX2 with Proform Fluency stentsd: 6-10 mm proximal thoracic extensionsa diameters, 60-80 mm Gore TAG thoracic lengths b endoprostheses Viabahn stentsb: 6-8 mm Gore c-TAG thoracic diameters, 50-100 mm endoprosthesesb lengths Custom made thoracic Uncovered stents c endoprostheses Wallstentse: 7-10 mm Zenith bifurcated aortoiliac diameters, 36-39 mm stent graftsa lengths Zenith RENU devicesa Zilver stentsa: 6-8 mm Custom-made infrarenal diameters, 60-120 mm componentsc lengths a
Cook Medical Inc, Bloomington, Ind. W. L. Gore and Associates, Flagstaff, Ariz. c Cook Australia, Brisbane, Queensland, Australia. d C. R. Bard, Inc, Tempe, Ariz. e Boston Scientific Corp, Natick, Mass. b
the access vessels and the aortic pathology. Patients were considered candidates for a SPSG if the diameter of the iliac artery was at $8 mm. Before the availability of the LPSG, an iliac conduit was used when the diameter of the iliac artery was <8 mm. After LPSGs became available, we lowered the threshold for conduit use to iliac arteries that were <6 mm in diameter. Access artery injury was defined
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Table II. Demographics of 134 patients who underwent endovascular repair with low-profile stent grafts (LPSGs) compared with standard-profile stent grafts (SPSGs) Variablesa
All SPSG LPSG P (N ¼ 134) (n ¼ 97) (n ¼ 37) value
Age, years 73 6 8 Male 101 (75) Caucasian 112 (84) History of 74 (55) Heart diseaseb 70 (52) Lung diseasec Smoking 121 (90) Stroke/TIA 28 (21) PVD 33 (25) Hypertension 127 (95) Dialysis 4 (3) Diabetes 16 (12) Aneurysm extentd Type I, II, III, and V 60 (45) Type IV and 74 (55) pararenal Maximum aortic 67 6 9 diameter, mm
73 6 8 72 (74) 84 (87)
73 6 8 29 (78) 28 (76)
.86 .62 .13
50 46 86 20 21 91 3 9
24 24 35 8 12 36 1 7
.17 .07 .30 .90 .19 .42 .91 .12 .87
(52) (47) (89) (21) (22) (94) (3) (9)
(65) (65) (95) (22) (32) (97) (3) (19)
43 (44) 54 (56)
17 (46) 20 (54)
67 6 10
67 6 8
.90
PVD, Peripheral vascular disease; TIA, transient ischemic attack. a Continuous data are shown as mean 6 standard deviation and categoric data as number (%). b Includes angina, myocardial infarction, congestive heart failure, arrhythmia, atrial fibrillation, cardiac bypass surgery, cardiac valve repair, balloon angioplasty, cardiac stenting procedure, and pacemaker placement. c Includes bronchitis, emphysema, asthma, and other lung conditions. d Aneurysm extent based on the Crawford classification for thoracoabdominal aortic aneurysm (TAAA).
as intraoperative or postoperative evidence of access artery dissection, thrombosis, occlusion, or rupture. Open iliofemoral conduits were generally designed as permanent bypasses and constructed in a manner that avoided competitive flow and preserved perfusion of the internal iliac artery. All conduits were constructed with 10-mm woven polyester grafts, and 80% were performed in a staged fashion. Follow-up. Patient demographics, comorbid conditions, imaging results, procedural details, and adverse events were recorded prospectively. Postoperative followup for all patients included a clinical evaluation and computed tomography angiography imaging at 1, 6, and 12 months, and then yearly thereafter. Data on complications and clinical outcomes were collected prospectively. Data analysis. Statistical analysis was performed with Stata/SE 13.1 software (StataCorp LP, College Station, Tex). Measured values are reported as percentages or mean 6 standard deviation. Mean values of continuous variables were compared using the Student t-test. Categoric variables were compared using the c2 and Fisher exact tests. A P value of <.05 was considered statistically significant. RESULTS From July 2005 to March 2015, 134 asymptomatic patients (101 men [75%]) underwent endovascular repair of a PRAA or TAAA using multibranched aortic stent
Table III. Outcomes of 134 patients who underwent endovascular repair with a low-profile stent graft (LPSG) compared with a standard-profile stent graft (SPSG) Variablesa
All (N ¼ 134)
SPSG (n ¼ 97)
Follow-up, years 2.6 6 1.9 3.1 6 2 Iliac conduit use 41 (31) 35 (36) or access artery injury Operative complexity Contrast 131 6 88 138 6 99 volume, mL Operative time, 8.4 6 2.2 8.4 6 2.4 hours Fluoroscopy 261 261 time, hours Operative 505 6 534 535 6 581 blood loss, mL Early postoperative events Perioperative 5 (4) 4 (4) death Renal failure 13 (10) 9 (9) requiring dialysis Stroke 3 (2) 2 (2) Paraplegia 7 (5) 4 (4) Myocardial 5 (4) 3 (3) infarction Late postoperative events Aneurysm12 (9) 9 (9) related death Rupture 2 (2) 1 (1) Conversion to 1 (1) 1 (1) open repair Migration 1 (1) 1 (1) Dilatation 7 (5) 6 (6) Endoleak type 11 (8) 10 (10) I or type III Visceral/renal 28/491 (6) 20/352 (6) branch occlusionb
LPSG (n ¼ 37)
P value
1.3 6 0.9 .0001 6 (16) .03
113 6 45 .15 8.5 6 1.7 .76 2 6 0.7 .69 426 6 374 .30
1 (3) .70 4 (11) .79 1 (3) .82 3 (8) .35 2 (5) .53 3 (8) .83 1 (3) .48 0 (0) .53 0 (0) .53 1 (3) .42 1 (3) .15 8/139 (6) .97
a Continuous data are shown as mean 6 standard deviation and categoric data as number (%). b Visceral/renal branch occlusion was counted per branch.
grafts. The patients were a mean age of 73 6 8 years. LPSGs were used in 37 patients (eight women [22%]; mean age, 72.5 6 8 years) and SPSGs in 97 patients (25 women [26%]; mean age, 73 6 8 years). Common comorbid conditions included hypertension (95%), cardiac disease (55%), and pulmonary disease (52%). There were no significant differences in the demographics of patients undergoing SPSG compared with LPSG (P > .05, Table II). The overall mean aneurysm diameter was 67 6 9 mm and was similar between the LPSG and SPSG groups (Table II). Of the patients in this cohort, 55% were treated for a type IV TAAA or PRAA. Nine patients had associated chronic aortic dissections, and the remaining patients were treated for atherosclerotic aneurysm disease. Access artery diameter is the lowest diameter of the largest external iliac artery. The mean access artery diameter was 8.1 mm (range, 4-13 mm). Iliac artery conduits were
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Freedom from composite endpoints by device profile
1.00
0.75
0.50
0.25
0.00
0
1
3
2
4
5
24
11
0
0
Time (Years) Patients at Risk SPSG LPSG
97 37
68
52
11
6
37 0
Standard ProfileStentGrafts
--- Low Profile StentGrafts
Fig 2. Composite outcome of freedom from perioperative death, aneurysm-related death, rupture, and visceral branch occlusion.
placed in 30 of the 134 patients (22%) to deliver the multibranched stent graft. The iliac conduit in six of these 30 patients (20%) was placed on the same day of the MBEVAR. The conduits in 24 patients (80%) were placed as a staged procedure at an average of 23 6 22 days before the definitive aortic aneurysm repair. Iliac endoconduits were placed in two patients, and open iliofemoral bypasses were constructed using polyester grafts in the remainder. Conduit infection developed in two patients. A femoral pseudoaneurysm developed in one patient 3 years after the construction of the conduit, soon after an episode of Salmonella enteritis. The infected iliofemoral conduit was replaced with contralateral great saphenous vein. Conduit infection developed in the other patient before stent graft implantation. The infected conduit was replaced with cadaveric femoral vein. All stent grafts and visceral branches were deployed as intended, with no immediate conversions to open repair. Operative and fluoroscopy times, contrast volume used, and blood loss during the procedure were similar in the LPSG and SPSG groups (Table III). Early and late postoperative events did not differ significantly between the SPSG and LPSG groups (P > .05). The main difference between the LPSG and SPSG is structuralddifferent fabric, different stents. We would expect that any difference in long-term performance would be reflected in the rates of structural failure such as migration, stent fracture, component separation, and type III endoleak. We saw none of these, and other modes of failure, such as branch occlusion, were too infrequent for individual analysis. Instead we performed Kaplan-Meier estimates for the composite outcome of freedom from
perioperative death, aneurysm-related death, rupture, and visceral branch occlusion, which showed no difference between the two groups (P ¼ .6, Fig 2). The combined outcome of conduit use or access artery injury occurred at a higher rate in the SPSG group than in the LPSG group (36% vs 16%; P ¼ .03, Table III). Women experienced significantly higher rates of conduit use and access artery injury than men after repair with the SPSG, but similar rates after repair with the LPSG (Table IV). Access artery injuries occurred in 13 patients, and in 11 of these, the access artery injury was recognized and managed at the time of the primary procedure. The injury in two patients was recognized postoperatively, and they underwent definitive repair in the operating room (Table V). No lower extremity tissue loss or amputations occurred postoperatively. Patients with access artery injury had a higher perioperative mortality rate of 15% compared with 2% in the patients without access artery injury (P ¼ .02). DISCUSSION In 2005, we began a physician-sponsored investigational device exemption trial to treat high-risk patients with PRAA and TAAA using custom-designed multibranched stent grafts. The device proved to be safe, effective, and durable but required the use of a large delivery system, which limited its applicability. A number of patients subsequently became suitable candidates, but only after construction of an iliac artery conduit. This prompted the development of a lowerprofile stent graft constructed of nitinol stents and thinwalled polyester and delivered through an 18F sheath. After introduction of this device in March 2011, LPSGs have
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Table IV. Comparison of conduit use and access artery injury by gender and device profile Device
No.
Female, No. (%)
Male, No. (%)
SPSG Iliac conduit Access artery injury Iliac conduit or access artery injury LPSG Iliac conduit Access artery injury Iliac conduit or access artery injury
97 26 11 35
(n ¼ 25) 12 (48) 6 (24) 16 (64)
(n ¼ 72) 14 (19) 5 (7) 19 (26)
.005 .02 .001
37 4 2 6
(n ¼ 8) 1 (12.5) 1 (12.5) 2 (25)
(n ¼ 29) 3 (10) 1 (3.5) 4 (14)
.86 .32 .45
P value
LPSG, Low-profile stent graft; SPSG, standard-profile stent graft.
Table V. Types of access artery injury and their management Types of access artery injury R CFA dissection with plaque L CIA dissection with embolization to L SFA R EIA rupture Dissection R EIA L EIA injury R CFA dissection R CFA dissection L EIA dissection
come to displace SPSGs from our practice (Fig 3). They have not only decreased the use of conduits and the frequency of arterial access injury but are also easier to orient and deploy, especially in the presence of iliac artery tortuosity and calcification. The change in the type of stents (stainless steel to nitinol) and nature of the fabric (standard vs thin-walled polyester) in the LPSG did not appear to affect the nature of the operation. All stent grafts and their branches were inserted as planned, and operative measures did not differ significantly between the LPSG and SPSG groups. In the midterm, it appears that the LPSG is safe and performs as well as the SPSG, as evidenced by the lack of any significant differences in late aneurysm-related outcomes, including death, rupture, migration, endoleaks, and branch occlusion. However, the follow-up time in the LPSG group was significantly shorter than the SPSG group. Longer follow-up in this cohort is needed. The iliac arteries of approximately one-third of the patients in the study were <8 mm in diameter; hence, the high rate of conduit use (22%). Many of these were women. Women accounted for 25% of the study population but 43% of conduits. The higher rate of conduit use and access artery injury in patients treated with a SPSG compared with a LPSG is not surprising. Several reports have shown that the use of a conduit during EVAR is associated with increased operative time, blood loss, perioperative complications, and mortality.7,8 Operative times and blood loss are even higher when the conduits are performed urgently as an unplanned procedure.9 MBEVAR is a long operation requiring prolonged anticoagulation. If this operation follows immediately after conduit creation, the retroperitoneal site of conduit creation continues to ooze throughout the remainder of the operation. During the early phase of this study (2005-2007), we constructed the iliac conduit during the same operation as the MBEVAR. Six cases were performed in this fashion, and an intraoperative complication (excessive blood loss) occurred in four of the six cases. Moreover, these patients have multiple comorbidities and need time to recover from conduit creation before undergoing the rest of the
R iliac occlusion R CFA dissection with thrombosis R iliofemoral occlusion R EIA occlusion
L CFA thrombosis due to local dissection
Management Repair of R CFA Embolectomy of L SFA Covered stent insertion into R EIA followed by R iliofemoral bypass Wallstenta insertion L iliofemoral conduit during definitive surgery Resection of R CFA with interposition graft Repair R CFA for local dissection/transection flap Small dissection which required no treatment R iliofemoral thrombectomy, R CFA patch R CFA endarterectomy and patch angioplasty R iliofemoral thrombectomy and R CFA patch R CFA endarterectomy with great saphenous vein patch and aortogram with R EIA stent placement R CFA endarterectomy with patch angioplasty
CFA, Common femoral artery; EIA, external iliac artery; L, left; R, right; SFA, superficial femoral artery. a Boston Scientific Corp, Natick, Mass.
MBEVAR. These factors prompted us to change our practice, and all cases subsequent to 2007 that required construction of an iliac conduit were performed as a separate procedure. Definitive MBEVAR was performed later, in a staged fashion. Because we found a significantly higher 30-day mortality rate in patients who had an arterial access site injury (compared with those who did not), we believe that careful preoperative arterial assessment and consideration of conduit placement is an important aspect of planning the MBEVAR. Coil embolization and coverage of one or both the internal iliac arteries for endovascular aortic aneurysm repair has been described in the literature10-12; we prefer to construct our conduits in a way that maintains hypogastric artery perfusion. The internal iliac artery is a significant pathway of collateral flow to the spinal cord, and several reports have shown the association of spinal cord ischemia with internal iliac artery coverage after endovascular thoracic and thoracoabdominal aortic surgeries.13-16 Prior studies have reported higher rates of conduit use in women than in men undergoing EVAR.7,17 In our study, women especially benefitted from the use of the LPSG because they experienced significantly higher rates of conduit use and access artery injury than men after repair with SPSG but similar rates after repair with LPSG. Having an off-the-shelf low-profile standard stent graft would not
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Fig 3. Changing practice patterns. AAI, Access artery injury; LPSG, low-profile stent graft; SPSG, standard-profile stent graft.
only eliminate manufacturing delays but also obviate the need for a conduit in patients with small-diameter access vessels. Our study has some limitations. The sample size is small and the event rates are low, which can cause a type II error. There is an inherent selection bias for the use of LPSGs in patients with small access arteries. Although the SPSG and LPSG groups had similar midterm outcomes, the follow-up period is significantly longer for the SPSG group. CONCLUSIONS The LPSG had similar safety profile and midterm outcomes compared with SPSGs for treatment of PRAA and TAAA. The substitution of LPSG for SPSG lowered the number of patients who required conduit insertion to avoid access artery injury, especially in women, thereby reducing an otherwise striking gender difference.
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AUTHOR CONTRIBUTIONS Conception and design: BR, JS, SV, WG, LR, TC, JH Analysis and interpretation: BR, CF, TC, LR, JH Data collection: BR, JS, CF, TC, LR, JH Writing the article: BR, TC, JH Critical revision of the article: BR, SV, WG, LR, TC, JH Final approval of the article: BR, CF, JS, SV, WG, LR, TC, JH Statistical analysis: CF, JS Obtained funding: TC, JH Overall responsibility: JH
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REFERENCES 1. Goodney PP, Travis L, Lucas FL, Fillinger MF, Goodman DC, Cronenwett JL, et al. Survival after open versus endovascular thoracic
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aortic aneurysm repair in an observational study of the medicare population. Circulation 2011;124:2661-9. LeMaire SA, Price MD, Green SY, Zarda S, Coselli JS. Results of open thoracoabdominal aortic aneurysm repair. Ann Thorac Surg 2012;1: 286-92. Reilly LM, Rapp JH, Grenon SM, Hiramoto JS, Sobel J, Chuter TA. Efficacy and durability of endovascular thoracoabdominal aortic aneurysm repair using the caudally directed cuff technique. J Vasc Surg 2012;56:53-63. Gasper WJ, Reilly LM, Rapp JH, Grenon SM, Hiramoto JS, Sobel JD, et al. Assessing the anatomic applicability of the multibranched endovascular repair of thoracoabdominal aortic aneurysm technique. J Vasc Surg 2013;57:1553-8. Henretta JP, Karch LA, Hodgson KJ, Mattos MA, Ramsey DE, McLafferty R, et al. Special iliac artery considerations during aneurysm endografting. Am J Surg 1999;178:212-8. Chuter TA, Rapp JH, Hiramoto JS, Schneider DB, Howell B, Reilly LM. Endovascular treatment of thoracoabdominal aortic aneurysms. J Vasc Surg 2008;47:6-16. Gupta PK, Sundaram A, Kent KC. Morbidity and mortality after use of iliac conduits for endovascular aortic aneurysm repair. J Vasc Surg 2015;62:22-6. Nzara R, Rybin D, Doros G, Didato S, Farber A, Eslami MH, et al. Perioperative outcomes in patients requiring iliac conduits/access for endovascular abdominal aortic aneurysm repair. Ann Vasc Surg 2015;29:1548-53. Abu-Ghaida AM, Clair DG, Greenberg RK, Srivastava S, O’Hara PJ, Ouriel K. Broadening the applicability of endovascular aneurysm repair: the use of iliac conduits. J Vasc Surg 2002;36:111-7. Halloul Z, Bürger T, Grote R, Fahlke J, Meyer F. Sequential coil embolization of bilateral internal iliac artery aneurysms prior to endovascular abdominal aortic aneurysm repair. J Endovasc Ther 2001;8: 87-92. Criado FJ, Wilson EP, Velazquez OC, Carpenter JP, Barker C, Wellons E, et al. Safety of coil embolization of the internal iliac artery in endovascular grafting of abdominal aortic aneurysms. J Vasc Surg 2000;32:684-8. Luo H, Huang B, Yuan D, Yang Y, Xiong F, Zeng G, et al. 8-year long-term outcome comparison: two ways to exclude the internal iliac artery during endovascular aorta repair (EVAR) surgery. PLoS One 2015;10:e0130586. Cheung AT, Pochettino A, McGarvey ML, Appoo JJ, Fairman RM, Carpenter JP, et al. Strategies to manage paraplegia risk after
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endovascular stent repair of descending thoracic aortic aneurysms. Ann Thorac Surg 2005;80:1280-9. 14. Chang CK, Chuter TA, Reilly LM, Ota MK, Furtado A, Bucci M, et al. Spinal arterial anatomy and risk factors for lower extremity weakness following endovascular thoracoabdominal aortic aneurysm repair with branched stent-grafts. J Endovasc Ther 2008;15: 356-62. 15. Roselli EE, Greenberg RK, Pfaff K, Francis C, Svensson LG, Lytle BW. Endovascular treatment of thoracoabdominal aortic aneurysms. J Thorac Cardiovasc Surg 2007;133:1474-82.
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16. Khoynezhad A, Donayre CE, Bui H, Kopchok GE, Walot I, White RA. Risk factors of neurologic deficit after thoracic aortic endografting. Ann Thorac Surg 2007;83:S882-9. 17. Tsilimparis N, Dayama A, Perez S, Ricotta J. Iliac conduits for endovascular repair of aortic pathologies. Eur J Vasc Endovasc Surg 2013;45:443-8.
Submitted Oct 28, 2015; accepted Jan 19, 2016.
Low-profile versus standard-profile multibranched thoracoabdominal aortic stent grafts Bala Ramanan, MBBS, MS, Charlene C. Fernandez, BS, Julia D. Sobel, BS, Warren J. Gasper, MD, Shant M. Vartanian, MD, Linda M. Reilly, MD, Timothy A. M. Chuter, DM, and Jade S. Hiramoto, MD, MAS, San Francisco, Calif Objective: This study compared midterm results using low-profile stent grafts (LPSGs; 18F) and standard-profile stent grafts (SPSGs; 22F-24F) for endovascular pararenal and thoracoabdominal aortic aneurysm (TAAA) repair. Methods: From July 2005 to March 2015, 134 asymptomatic patients underwent endovascular repair of a pararenal or TAAA using multibranched aortic stent grafts. In March 2011, we started using a LPSG with nitinol stents and thinwalled polyester fabric. Prospectively collected data on operative repair, complications, and outcomes were compared between the two groups. Results: LPSGs were used in 37 patients (8 women [21.6%]; mean 6 standard deviation age, 72.5 6 8 years) and SPSGs in 97 patients (25 [26%] women; mean age, 73 6 8 years). Medical comorbidities, aneurysm size, and aneurysm extent were similar in the LPSG and SPSG groups. Mean follow-up time was longer in the SPSG group (3.1 6 2 years) than in the LPSG group (1.3 6 0.9 years; P < .001). Operative time, renal failure, stroke, myocardial infarction, and perioperative death were not significantly different between the two groups (P > .05). Aneurysm-related death, rupture, stent graft migration, type I or III endoleaks, aneurysm enlargement >5 mm, branch vessel occlusion, and reintervention rates were similar between the two groups (P > .05). However, the combined outcome of conduit use or access artery injury occurred at a lower rate in the LPSG group than in the SPSG group (16% vs 36%; P [ .03). Women experienced significantly higher rates of conduit use and access artery injury than men after repair with SPSGs (64% vs 26%, respectively; P [ .001) but similar rates after repair with the LPSG (25% vs 14%, respectively; P [ .45). Conclusions: LPSGs had similar safety profile and midterm outcomes compared with the SPSGs for treatment of pararenal and TAAA. The substitution of LPSGs for SPSGs lowered the number of patients who required conduit insertion to avoid access artery injury, especially in women, thereby reducing an otherwise striking gender difference. (J Vasc Surg 2016;-:1-7.)
Despite improvements in perioperative care during the past two decades, open repair of thoracoabdominal aortic aneurysm (TAAA) remains a formidable procedure with high rates of morbidity and mortality.1,2 Multibranched endovascular aneurysm repair (MBEVAR) has evolved during the past decade as a less invasive treatment of pararenal aortic aneurysms (PRAA) and TAAA.3,4 However, in the absence of an iliac artery bypass or conduit, this technique is only applicable to those with iliac arteries large enough to admit the necessary delivery system. Concomitant iliac artery occlusive disease is present in w36% of patients
with aortic aneurysms, which increases the risk for arterial injury of the access vessel at the time of EVAR.5 Low-profile stent grafts (LPSGs) were developed in response to the need for smaller delivery systems for MBEVAR. The first MBEVAR using a LPSG took place in March 2011. Since then, LPSGs have been used in >60% of the cases at University of California San Francisco. The current study compared the midterm outcomes of standard-profile stent grafts (SPSGs) and LPSGs for MBEVAR of PRAA and TAAA. METHODS
From the Division of Vascular and Endovascular Surgery, University of California, San Francisco. This study is registered at clinicaltrials.gov: NCT00483249. Author conflict of interest: T.A.M.C. and J.S.H. receive royalties from licensed patents and research funding from Cook Medical Inc, the manufacturer of the multibranched thoracoabdominal stent graft. Presented at the Thirtieth Annual Meeting of the Western Vascular Society, Wailea, Maui, Hawaii, September 19-22, 2015. Correspondence: Jade S. Hiramoto, MD, MAS, Division of Vascular and Endovascular Surgery, University of California, San Francisco, 400 Parnassus Ave, Ste A-581, Box 0222, San Francisco, CA 94143 (e-mail: [email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2016 by the Society for Vascular Surgery. Published by Elsevier Inc. http://dx.doi.org/10.1016/j.jvs.2016.01.038
Study design and operative technique. This is a single-center, prospective nonrandomized clinical trial of endovascular repair of TAAA and PRAA with a modular multibranched thoracoabdominal endograft (Cook Australia, Brisbane, Queensland, Australia) in asymptomatic patients. Urgent or emergency cases were excluded from the analysis. A physician-sponsored investigational device exemption was approved by the U.S. Food and Drug Administration and the University of California San Francisco Committee on Human Research. All patients gave informed consent. The study design, inclusion and exclusion criteria, and surgical technique have been previously described.6 Briefly, bilateral open femoral artery and left brachial artery access was obtained. Modular aortic components were inserted through the femoral arteries, which were then closed. After 1
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Fig 1. The top graft is the standard-profile stent graft (SPSG). The top delivery system is the larger delivery system of the SPSG, and the lower is the smaller delivery system of the low-profile stent graft (LPSG). The lower graft is the LPSG.
insertion of the brachiofemoral wire, stent grafts were used to bridge the cuffs on the aortic components to the visceral and renal arteries through a brachial artery approach. Devices. The multibranched component refers to the tapered cuff that bears the aortic component. All multibranched components of the SPSG were made of stainless steel stents with conventional woven polyester fabric. The inner diameter of the device delivery system was 22F to 24F (Fig 1). The LPSG was made of self-expanding nitinol stents with thin-walled polyester fabric, enabling delivery of all the multibranched components through an 18F inner-diameter delivery system (Fig 1). An off-theshelf device was used in 38% (51 of 134) patients and a custom device was implanted in 62% (83 of 134). All the LPSGs were considered to be custom devices. Additional proximal and distal components were used to treat more extensive aneurysms, and covered and uncovered stents were used to bridge the aortic cuffs and the visceral and renal branches (Table I). Low-profile multibranched components were combined with low-profile proximal thoracic extensions. Proximal extensions measuring 32 to 38 mm in diameter were inserted through an 18F delivery system. Proximal extensions measuring 40 to 46 mm in diameter were inserted through a 20F delivery system. Device selection and conduit use. Preoperative imaging with computed tomography angiography and OsiriX MD three-dimensional reconstructive software (Pixmeo, Bernex, Switzerland) was used for anatomic assessment of
Table I. Stent graft extensions and branches Extensions
Branches a
Covered stents Zenith TX2 Zenith TX2 with Proform Fluency stentsd: 6-10 mm proximal thoracic extensionsa diameters, 60-80 mm Gore TAG thoracic lengths b endoprostheses Viabahn stentsb: 6-8 mm Gore c-TAG thoracic diameters, 50-100 mm endoprosthesesb lengths Custom made thoracic Uncovered stents c endoprostheses Wallstentse: 7-10 mm Zenith bifurcated aortoiliac diameters, 36-39 mm stent graftsa lengths Zenith RENU devicesa Zilver stentsa: 6-8 mm Custom-made infrarenal diameters, 60-120 mm componentsc lengths a
Cook Medical Inc, Bloomington, Ind. W. L. Gore and Associates, Flagstaff, Ariz. c Cook Australia, Brisbane, Queensland, Australia. d C. R. Bard, Inc, Tempe, Ariz. e Boston Scientific Corp, Natick, Mass. b
the access vessels and the aortic pathology. Patients were considered candidates for a SPSG if the diameter of the iliac artery was at $8 mm. Before the availability of the LPSG, an iliac conduit was used when the diameter of the iliac artery was <8 mm. After LPSGs became available, we lowered the threshold for conduit use to iliac arteries that were <6 mm in diameter. Access artery injury was defined
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Table II. Demographics of 134 patients who underwent endovascular repair with low-profile stent grafts (LPSGs) compared with standard-profile stent grafts (SPSGs) Variablesa
All SPSG LPSG P (N ¼ 134) (n ¼ 97) (n ¼ 37) value
Age, years 73 6 8 Male 101 (75) Caucasian 112 (84) History of 74 (55) Heart diseaseb 70 (52) Lung diseasec Smoking 121 (90) Stroke/TIA 28 (21) PVD 33 (25) Hypertension 127 (95) Dialysis 4 (3) Diabetes 16 (12) Aneurysm extentd Type I, II, III, and V 60 (45) Type IV and 74 (55) pararenal Maximum aortic 67 6 9 diameter, mm
73 6 8 72 (74) 84 (87)
73 6 8 29 (78) 28 (76)
.86 .62 .13
50 46 86 20 21 91 3 9
24 24 35 8 12 36 1 7
.17 .07 .30 .90 .19 .42 .91 .12 .87
(52) (47) (89) (21) (22) (94) (3) (9)
(65) (65) (95) (22) (32) (97) (3) (19)
43 (44) 54 (56)
17 (46) 20 (54)
67 6 10
67 6 8
.90
PVD, Peripheral vascular disease; TIA, transient ischemic attack. a Continuous data are shown as mean 6 standard deviation and categoric data as number (%). b Includes angina, myocardial infarction, congestive heart failure, arrhythmia, atrial fibrillation, cardiac bypass surgery, cardiac valve repair, balloon angioplasty, cardiac stenting procedure, and pacemaker placement. c Includes bronchitis, emphysema, asthma, and other lung conditions. d Aneurysm extent based on the Crawford classification for thoracoabdominal aortic aneurysm (TAAA).
as intraoperative or postoperative evidence of access artery dissection, thrombosis, occlusion, or rupture. Open iliofemoral conduits were generally designed as permanent bypasses and constructed in a manner that avoided competitive flow and preserved perfusion of the internal iliac artery. All conduits were constructed with 10-mm woven polyester grafts, and 80% were performed in a staged fashion. Follow-up. Patient demographics, comorbid conditions, imaging results, procedural details, and adverse events were recorded prospectively. Postoperative followup for all patients included a clinical evaluation and computed tomography angiography imaging at 1, 6, and 12 months, and then yearly thereafter. Data on complications and clinical outcomes were collected prospectively. Data analysis. Statistical analysis was performed with Stata/SE 13.1 software (StataCorp LP, College Station, Tex). Measured values are reported as percentages or mean 6 standard deviation. Mean values of continuous variables were compared using the Student t-test. Categoric variables were compared using the c2 and Fisher exact tests. A P value of <.05 was considered statistically significant. RESULTS From July 2005 to March 2015, 134 asymptomatic patients (101 men [75%]) underwent endovascular repair of a PRAA or TAAA using multibranched aortic stent
Table III. Outcomes of 134 patients who underwent endovascular repair with a low-profile stent graft (LPSG) compared with a standard-profile stent graft (SPSG) Variablesa
All (N ¼ 134)
SPSG (n ¼ 97)
Follow-up, years 2.6 6 1.9 3.1 6 2 Iliac conduit use 41 (31) 35 (36) or access artery injury Operative complexity Contrast 131 6 88 138 6 99 volume, mL Operative time, 8.4 6 2.2 8.4 6 2.4 hours Fluoroscopy 261 261 time, hours Operative 505 6 534 535 6 581 blood loss, mL Early postoperative events Perioperative 5 (4) 4 (4) death Renal failure 13 (10) 9 (9) requiring dialysis Stroke 3 (2) 2 (2) Paraplegia 7 (5) 4 (4) Myocardial 5 (4) 3 (3) infarction Late postoperative events Aneurysm12 (9) 9 (9) related death Rupture 2 (2) 1 (1) Conversion to 1 (1) 1 (1) open repair Migration 1 (1) 1 (1) Dilatation 7 (5) 6 (6) Endoleak type 11 (8) 10 (10) I or type III Visceral/renal 28/491 (6) 20/352 (6) branch occlusionb
LPSG (n ¼ 37)
P value
1.3 6 0.9 .0001 6 (16) .03
113 6 45 .15 8.5 6 1.7 .76 2 6 0.7 .69 426 6 374 .30
1 (3) .70 4 (11) .79 1 (3) .82 3 (8) .35 2 (5) .53 3 (8) .83 1 (3) .48 0 (0) .53 0 (0) .53 1 (3) .42 1 (3) .15 8/139 (6) .97
a Continuous data are shown as mean 6 standard deviation and categoric data as number (%). b Visceral/renal branch occlusion was counted per branch.
grafts. The patients were a mean age of 73 6 8 years. LPSGs were used in 37 patients (eight women [22%]; mean age, 72.5 6 8 years) and SPSGs in 97 patients (25 women [26%]; mean age, 73 6 8 years). Common comorbid conditions included hypertension (95%), cardiac disease (55%), and pulmonary disease (52%). There were no significant differences in the demographics of patients undergoing SPSG compared with LPSG (P > .05, Table II). The overall mean aneurysm diameter was 67 6 9 mm and was similar between the LPSG and SPSG groups (Table II). Of the patients in this cohort, 55% were treated for a type IV TAAA or PRAA. Nine patients had associated chronic aortic dissections, and the remaining patients were treated for atherosclerotic aneurysm disease. Access artery diameter is the lowest diameter of the largest external iliac artery. The mean access artery diameter was 8.1 mm (range, 4-13 mm). Iliac artery conduits were
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Freedom from composite endpoints by device profile
1.00
0.75
0.50
0.25
0.00
0
1
3
2
4
5
24
11
0
0
Time (Years) Patients at Risk SPSG LPSG
97 37
68
52
11
6
37 0
Standard ProfileStentGrafts
--- Low Profile StentGrafts
Fig 2. Composite outcome of freedom from perioperative death, aneurysm-related death, rupture, and visceral branch occlusion.
placed in 30 of the 134 patients (22%) to deliver the multibranched stent graft. The iliac conduit in six of these 30 patients (20%) was placed on the same day of the MBEVAR. The conduits in 24 patients (80%) were placed as a staged procedure at an average of 23 6 22 days before the definitive aortic aneurysm repair. Iliac endoconduits were placed in two patients, and open iliofemoral bypasses were constructed using polyester grafts in the remainder. Conduit infection developed in two patients. A femoral pseudoaneurysm developed in one patient 3 years after the construction of the conduit, soon after an episode of Salmonella enteritis. The infected iliofemoral conduit was replaced with contralateral great saphenous vein. Conduit infection developed in the other patient before stent graft implantation. The infected conduit was replaced with cadaveric femoral vein. All stent grafts and visceral branches were deployed as intended, with no immediate conversions to open repair. Operative and fluoroscopy times, contrast volume used, and blood loss during the procedure were similar in the LPSG and SPSG groups (Table III). Early and late postoperative events did not differ significantly between the SPSG and LPSG groups (P > .05). The main difference between the LPSG and SPSG is structuralddifferent fabric, different stents. We would expect that any difference in long-term performance would be reflected in the rates of structural failure such as migration, stent fracture, component separation, and type III endoleak. We saw none of these, and other modes of failure, such as branch occlusion, were too infrequent for individual analysis. Instead we performed Kaplan-Meier estimates for the composite outcome of freedom from
perioperative death, aneurysm-related death, rupture, and visceral branch occlusion, which showed no difference between the two groups (P ¼ .6, Fig 2). The combined outcome of conduit use or access artery injury occurred at a higher rate in the SPSG group than in the LPSG group (36% vs 16%; P ¼ .03, Table III). Women experienced significantly higher rates of conduit use and access artery injury than men after repair with the SPSG, but similar rates after repair with the LPSG (Table IV). Access artery injuries occurred in 13 patients, and in 11 of these, the access artery injury was recognized and managed at the time of the primary procedure. The injury in two patients was recognized postoperatively, and they underwent definitive repair in the operating room (Table V). No lower extremity tissue loss or amputations occurred postoperatively. Patients with access artery injury had a higher perioperative mortality rate of 15% compared with 2% in the patients without access artery injury (P ¼ .02). DISCUSSION In 2005, we began a physician-sponsored investigational device exemption trial to treat high-risk patients with PRAA and TAAA using custom-designed multibranched stent grafts. The device proved to be safe, effective, and durable but required the use of a large delivery system, which limited its applicability. A number of patients subsequently became suitable candidates, but only after construction of an iliac artery conduit. This prompted the development of a lowerprofile stent graft constructed of nitinol stents and thinwalled polyester and delivered through an 18F sheath. After introduction of this device in March 2011, LPSGs have
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Table IV. Comparison of conduit use and access artery injury by gender and device profile Device
No.
Female, No. (%)
Male, No. (%)
SPSG Iliac conduit Access artery injury Iliac conduit or access artery injury LPSG Iliac conduit Access artery injury Iliac conduit or access artery injury
97 26 11 35
(n ¼ 25) 12 (48) 6 (24) 16 (64)
(n ¼ 72) 14 (19) 5 (7) 19 (26)
.005 .02 .001
37 4 2 6
(n ¼ 8) 1 (12.5) 1 (12.5) 2 (25)
(n ¼ 29) 3 (10) 1 (3.5) 4 (14)
.86 .32 .45
P value
LPSG, Low-profile stent graft; SPSG, standard-profile stent graft.
Table V. Types of access artery injury and their management Types of access artery injury R CFA dissection with plaque L CIA dissection with embolization to L SFA R EIA rupture Dissection R EIA L EIA injury R CFA dissection R CFA dissection L EIA dissection
come to displace SPSGs from our practice (Fig 3). They have not only decreased the use of conduits and the frequency of arterial access injury but are also easier to orient and deploy, especially in the presence of iliac artery tortuosity and calcification. The change in the type of stents (stainless steel to nitinol) and nature of the fabric (standard vs thin-walled polyester) in the LPSG did not appear to affect the nature of the operation. All stent grafts and their branches were inserted as planned, and operative measures did not differ significantly between the LPSG and SPSG groups. In the midterm, it appears that the LPSG is safe and performs as well as the SPSG, as evidenced by the lack of any significant differences in late aneurysm-related outcomes, including death, rupture, migration, endoleaks, and branch occlusion. However, the follow-up time in the LPSG group was significantly shorter than the SPSG group. Longer follow-up in this cohort is needed. The iliac arteries of approximately one-third of the patients in the study were <8 mm in diameter; hence, the high rate of conduit use (22%). Many of these were women. Women accounted for 25% of the study population but 43% of conduits. The higher rate of conduit use and access artery injury in patients treated with a SPSG compared with a LPSG is not surprising. Several reports have shown that the use of a conduit during EVAR is associated with increased operative time, blood loss, perioperative complications, and mortality.7,8 Operative times and blood loss are even higher when the conduits are performed urgently as an unplanned procedure.9 MBEVAR is a long operation requiring prolonged anticoagulation. If this operation follows immediately after conduit creation, the retroperitoneal site of conduit creation continues to ooze throughout the remainder of the operation. During the early phase of this study (2005-2007), we constructed the iliac conduit during the same operation as the MBEVAR. Six cases were performed in this fashion, and an intraoperative complication (excessive blood loss) occurred in four of the six cases. Moreover, these patients have multiple comorbidities and need time to recover from conduit creation before undergoing the rest of the
R iliac occlusion R CFA dissection with thrombosis R iliofemoral occlusion R EIA occlusion
L CFA thrombosis due to local dissection
Management Repair of R CFA Embolectomy of L SFA Covered stent insertion into R EIA followed by R iliofemoral bypass Wallstenta insertion L iliofemoral conduit during definitive surgery Resection of R CFA with interposition graft Repair R CFA for local dissection/transection flap Small dissection which required no treatment R iliofemoral thrombectomy, R CFA patch R CFA endarterectomy and patch angioplasty R iliofemoral thrombectomy and R CFA patch R CFA endarterectomy with great saphenous vein patch and aortogram with R EIA stent placement R CFA endarterectomy with patch angioplasty
CFA, Common femoral artery; EIA, external iliac artery; L, left; R, right; SFA, superficial femoral artery. a Boston Scientific Corp, Natick, Mass.
MBEVAR. These factors prompted us to change our practice, and all cases subsequent to 2007 that required construction of an iliac conduit were performed as a separate procedure. Definitive MBEVAR was performed later, in a staged fashion. Because we found a significantly higher 30-day mortality rate in patients who had an arterial access site injury (compared with those who did not), we believe that careful preoperative arterial assessment and consideration of conduit placement is an important aspect of planning the MBEVAR. Coil embolization and coverage of one or both the internal iliac arteries for endovascular aortic aneurysm repair has been described in the literature10-12; we prefer to construct our conduits in a way that maintains hypogastric artery perfusion. The internal iliac artery is a significant pathway of collateral flow to the spinal cord, and several reports have shown the association of spinal cord ischemia with internal iliac artery coverage after endovascular thoracic and thoracoabdominal aortic surgeries.13-16 Prior studies have reported higher rates of conduit use in women than in men undergoing EVAR.7,17 In our study, women especially benefitted from the use of the LPSG because they experienced significantly higher rates of conduit use and access artery injury than men after repair with SPSG but similar rates after repair with LPSG. Having an off-the-shelf low-profile standard stent graft would not
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Fig 3. Changing practice patterns. AAI, Access artery injury; LPSG, low-profile stent graft; SPSG, standard-profile stent graft.
only eliminate manufacturing delays but also obviate the need for a conduit in patients with small-diameter access vessels. Our study has some limitations. The sample size is small and the event rates are low, which can cause a type II error. There is an inherent selection bias for the use of LPSGs in patients with small access arteries. Although the SPSG and LPSG groups had similar midterm outcomes, the follow-up period is significantly longer for the SPSG group. CONCLUSIONS The LPSG had similar safety profile and midterm outcomes compared with SPSGs for treatment of PRAA and TAAA. The substitution of LPSG for SPSG lowered the number of patients who required conduit insertion to avoid access artery injury, especially in women, thereby reducing an otherwise striking gender difference.
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AUTHOR CONTRIBUTIONS Conception and design: BR, JS, SV, WG, LR, TC, JH Analysis and interpretation: BR, CF, TC, LR, JH Data collection: BR, JS, CF, TC, LR, JH Writing the article: BR, TC, JH Critical revision of the article: BR, SV, WG, LR, TC, JH Final approval of the article: BR, CF, JS, SV, WG, LR, TC, JH Statistical analysis: CF, JS Obtained funding: TC, JH Overall responsibility: JH
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Submitted Oct 28, 2015; accepted Jan 19, 2016.