Intermediate-term outcome of carotid endarterectomy with bovine pericardial patch closure compared with Dacron patch and primary closure

From the New England Society for Vascular Surgery

Intermediate-term outcome of carotid endarterectomy with bovine pericardial patch closure compared with Dacron patch and primary closure Karen J. Ho, MD, Louis L. Nguyen, MD, MBA, MPH, and Matthew T. Menard, MD, Boston, Mass Objective: Multiple studies have established that patch angioplasty following carotid endarterectomy (CEA) reduces the risk of subsequent stroke and restenosis compared with primary closure. Previous reports have also demonstrated bovine pericardium to be associated with similar rates of postoperative complications and restenosis compared with other patch materials. Due to favorable handling and sonographic properties, bovine pericardium has become increasingly popular as a patch option in recent years. However, the intermediate- and long-term performance of this material remains incompletely defined. Through a retrospective analysis of our carotid endarterectomy experience, we sought to compare the bleeding, infection, and pseudoaneurysm rates with bovine pericardium patch closure to those with Dacron patch and primary closure. In this study, 1331 primary carotid endarterectomies performed in our institution between 1996 and 2008 were grouped according to the method of arteriotomy closure: primary closure (PC) (216, 16.3%), Dacron patch angioplasty (DPA) (642, 48.2%), and bovine pericardial patch angioplasty (BPA) (457, 34.3%). Demographic variable and postoperative outcome measures collected real-time via a designated database manager were assessed by univariate and multivariate analysis. Results: Mean follow-up for the entire cohort was 46.1 months. There were no statistically significant differences in rates of postoperative wound infection, hematoma, pseudoaneurysm formation, or 30-day stroke or 30-day mortality among the three groups. Combined 30-day stroke and death was significantly lower in the PC cohort (0.5% vs 2.3% DPA vs 2.4% BPA; P ⴝ .94, BPA vs DPA; P ⴝ .001, BPA vs PC; P ⴝ .001, DPA vs PC), while 5-year restenosis after both DPA (2.0% ⴞ 0.6%) and BPA (1.1% ⴞ 0.6%) was significantly lower compared with PC (5.2% ⴞ 1.6%) (P ⴝ .03, DPA vs PC; P ⴝ .008, BPA vs PC; P ⴝ .14, BPA vs DPA). Five-year survival following BPA (77.9% ⴞ 3.6%) was significantly improved compared with PC (66.9% ⴞ 3.5%) and DPA (60.8% ⴞ 2.1%) in univariate analysis (P ⴝ .24, DPA vs PC; P ⴝ .01, BPA vs PC; P ⴝ .03, BPA vs DPA), with statin use (P ⴝ .004) and male gender (P ⴝ .05) being positive predictors of enhanced survival on multivariate analysis. Conclusions: This single-institution, retrospective review represents the largest reported experience with BPA after CEA to date and is the only report comparing outcomes after BPA to PC or to DPA. Our experience further demonstrates that patch angioplasty is protective against restenosis after CEA compared with PC. Equivalent rates of perioperative bleeding, infection, and pseudoaneurysm formation were seen with each closure strategy in this study. ( J Vasc Surg 2012;55:708-14.)

The gold standard treatment of critical internal carotid artery stenosis remains carotid endarterectomy (CEA), which has been shown in multiple studies to reduce the risk of stroke and death in patients with both symptomatic and asymptomatic lesions.1-4 Autologous saphenous vein patch closure after CEA was described as early as 1962.5 Based on an extensive literature accumulated subsequently, patch angioplasty closure has become the standard of care given its proven association with lower rates of recurrent carotid stenosis and stroke.6-9 From the Division of Vascular and Endovascular Surgery, Brigham and Women’s Hospital. Competition of interest: none. Presented at the Thirty-sixth Annual Meeting of the New England Society for Vascular Surgery, Boston, Mass, October 3, 2009. Reprint requests: Matthew T. Menard, MD, Division of Vascular and Endovascular Surgery, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115 (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 competition of interest. 0741-5214/$36.00 Copyright © 2012 by the Society for Vascular Surgery. doi:10.1016/j.jvs.2011.10.007

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A variety of carotid patches have been utilized over time. While saphenous vein offers excellent results, the need for a second incision and the occasional experience with catastrophic patch blowout with distal saphenous vein10,11 spurred periods of experimentation with jugular and cervical veins and cryopreserved saphenous vein as alternative options. Prosthetic patches offer the considerable advantage of being readily available, though they carry the risk of enhanced thrombogenicity and increased infection and bleeding complications compared with autogenous tissue. Dacron and polytetrafluoroethylene (PTFE) are the most commonly used prosthetic patches12,13; Dacron remains in wider use currently given the prolonged suture line bleeding associated with PTFE.14 Biasi et al15 first reported the use of bovine pericardium for carotid patch angioplasty in 1996. Due in part to a perception that it is more resistant to infection than prosthetic material, bovine pericardium has also increasingly been used for patch angioplasty in other vascular beds.16-19 Proponents of bovine pericardium have highlighted its excellent handling characteristics,20,21 relative compliance, low thrombogenicity, and minimal associated suture line

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BPA DPA

Percent carotid endarterectomy operations

PC 100.0

80.0

60.0

40.0

20.0

0.0

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Fig 1. Institutional distribution of carotid endarterectomy arteriotomy closure method over time. BPA, Bovine pericardial patch angioplasty; DPA, Dacron patch angioplasty; PC, primary closure.

bleeding.21 Several reports have documented low rates of infection, pseudoaneurysm, and other complications with its use,22,23 and acceptable associated postoperative mortality and morbidity.22-25 Concerns over contraction of bovine spongiform encephalopathy from use of bovine pericardium have to date proven unfounded.9 We began using bovine pericardial patches on a trial basis at our institution when the price became comparable to that of Dacron and have used it almost exclusively since 2003 (Fig 1). We were particularly attracted by the ease of insonation through the patch and have recently shown that routine completion duplex following CEA has significantly lowered our rate of carotid restenosis.26 The literature comparing bovine pericardial patches with other patch material or primary closure remains quite limited, however,21,24,25,27 and the long-term stability and durability of bovine pericardium patches has yet to be firmly established. We were particularly interested in assessing the comparative rates of infection, bleeding, and pseudoaneurysm formation when bovine pericardial patch angioplasty was compared with other arteriotomy closure strategies. Herein, we present our short- and intermediate-term outcomes using bovine pericardium in over 450 patients over 12 years, which represents the largest published experience to date. METHODS In this study, 1331 primary carotid endarterectomies performed in a continuous fashion at the Brigham and Women’s Hospital between January 1, 1996 and December 31, 2008 were entered prospectively real-time into a long-standing registry. Procedures were divided into 3 groups depending on the method of closure of the arteriotomy after endarterectomy: primary closure of the carotid arteriotomy (PC), Dacron patch angioplasty (DPA), and bovine pericardial patch angioplasty (BPA). All procedures

were carried out under general anesthesia by attending vascular surgeons in standard fashion; no eversion endarterectomies were performed. Carotid shunting was performed on a selective basis based on preoperative clinical status and intraoperative electroencephalogram monitoring findings. Demographic factors and comorbid conditions in the entire cohort and in each group were recorded and evaluated. Renal failure was defined as dialysis-dependence, history of renal transplant, or serum creatinine ⬎2.0 mg/dL. Coronary artery disease (CAD) was defined as a history of myocardial infarction, angina, coronary artery bypass grafting prior to CEA, or preoperative documentation of CAD by a cardiologist. For patients who underwent CEA with BPA, a processed bovine pericardial patch (either VascuGuard; Synnovis Surgical Innovations, St. Paul, Minn [cost $131] or No-React; Shelhigh, Union, NJ prior to a Food and Drug Administration [FDA] recall request in 2007) was used. The patch was rinsed in sterile saline solution according to the manufacturer’s instructions prior to use. The Dacron patch used almost exclusively was the Hemashield Platinum Finesse (Maquet, Inc, Wayne, NJ [cost $91]). Patch repair was typically performed using two strands of 6-0 prolene suture in a running fashion. It has been our practice since 2000 to perform intraoperative completion duplex following patch closure to assess for technical problems.26 Standard antiplatelet therapy was routinely used following carotid endarterectomy, and surveillance carotid duplex was typically performed 1 month postoperatively and yearly thereafter to assess for carotid restenosis. Endpoints of perioperative infection, neck hematoma, pseudoaneurysm, 30-day stroke, 30-day mortality, combined 30-day stroke and death, 5-year restenosis, and 5-year survival were assessed. Infection was defined as a positive neck wound culture or need for intravenous antibiotics or neck exploration for infection. A neck hematoma was defined as a clinically significant fluid collection visual-

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Table I. Patient characteristics and indications for CEA

Mean age Male gender

Entire cohort n ⫽ 1331

PC n ⫽ 216 (16.3%)

DPA n ⫽ 642 (48.2%)

BPA n ⫽ 457 (34.3%)

70 ⫾ 6.8

72.1 ⫾ 8.1

68.9 ⫾ 9.3

69.4 ⫾ 9.4

786 (59%)

137 (63.4%)

366 (57%)

273 (59.7%)

African American

19 (1.4%)

4 (1.8%)

10 (1.6%)

5 (1.1%)

Diabetes mellitus

554 (26.6%)

51 (23.6%)

161 (25.1%)

138 (30.2%)

Smoking

297 (22.3%)

36 (16.7%)

152 (23.7%)

105 (23%)

Hypertension

980 (73.6%)

156 (72.2%)

439 (68.4%)

376 (82.3%)

CAD

627 (47.1%)

123 (56.9%)

306 (47.7%)

190 (41.6%)

COPD

117 (8.8%)

17 (7.9%)

58 (9.0%)

37 (8.1%)

Renal failure

41 (3.1%)

6 (2.8%)

16 (2.5%)

19 (4.2%)

Arrhythmia

10 (7.7%)

11 (5.1%)

43 (6.7%)

45 (9.8%)

Asymptomatic

780 (58.6%)

125 (57.9%)

354 (55.1%)

292 (63.9%)

TIA

256 (19.3%)

45 (20.8%)

Amaurosis fugax

160 (12.0%)

26 (12%)

83 (13%)

48 (10.5%)

Recent stroke

135 (10.1%)

20 (9.3%)

70 (10.9%)

44 (9.6%)

135 (21%)

73 (16%)

P value .001 (BPA vs PC) .41 (BPA vs DPA) .001 (DPA vs PC) .36 (BPA vs PC) .37 (BPA vs DPA) .098 (DPA vs PC) .42 (BPA vs PC) .514 (BPA vs DPA) .77 (DPA vs PC) .08 (BPA vs PC) .06 (BPA vs DPA) .67 (DPA vs PC) .06 (BPA vs PC) .79 (BPA vs DPA) .03 (DPA vs PC) .003 (BPA vs PC) .001 (BPA vs DPA) .29 (DPA vs PC) .001 (BPA vs PC) .05 (BPA vs DPA) .02 (DPA vs PC) .92 (BPA vs PC) .59 (BPA vs DPA) .60 (DPA vs PC) .23 (BPA vs PC) .12 (BPA vs DPA) .88 (DPA vs PC) .04 (BPA vs PC) .06 (BPA vs DPA) .40 (DPA vs PC) .13 (BPA vs PC) .004 (BPA vs DPA) .49 (DPA vs PC) .12 (BPA vs PC) .04 (BPA vs DPA) .95 (DPA vs PC) .55 (BPA vs PC) .22 (BPA vs DPA) .74 (DPA vs PC) .88 (BPA vs PC) .49 (BPA vs DPA) .50 (DPA vs PC)

BPA, Bovine pericardial patch angioplasty; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; DPA, Dacron patch angioplasty; PC, primary closure; TIA, transient ischemic attack.

ized on ultrasound or computerized tomography (CT) believed by the reporting attending physician to be consistent with a hematoma, or reoperation for evacuation of hematoma. All pseudoaneurysms were diagnosed by ultrasound or CT at the time of reoperation. A postoperative stroke was defined as any major neurologic deficit supported by a confirmatory attending physician note and/or head CT. Restenosis was defined as the presence of significant restenosis (⬎75% stenosis at the endarterectomy site on an imaging study with a confirmatory attending surgeon note) or occlusion (documented on an imaging study or at the time of reoperation for thrombectomy). In our vascular laboratory, a peak systolic velocity ⬎325 cm/s or an internal carotid artery:common carotid artery ratio of 4:1 corresponds to ⬎75% stenosis.28

Continuous variables are expressed as mean ⫾ standard deviation. Five-year survival and patency rates were calculated with the life-table method and compared using the log-rank life-test. Dichotomous variables were compared using ␹2 analysis and continuous variables were compared using the Student t test. Multivariate analysis was performed using the Cox proportional hazard model with stepwise backwards elimination. As most procedures using DPA were performed prior to 2002 and most procedures using BPA were performed after 2002, we also analyzed the effect of treatment date both as a dichotomous and continuous variable in our Cox proportional hazard models. In all comparisons, a P value of ⬍.05 was considered the threshold for statistical significance.

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Table II. Outcomes after CEA in entire cohort and according to type of arteriotomy closure Entire cohort n ⫽ 1331

PC n ⫽ 216 (16.3%)

DPA n ⫽ 642 (48.2%)

BPA n ⫽ 457 (34.3%)

5 (0.3%)

0

2 (0.3%)

3 (0.6%)

Neck hematoma

42 (3.2%)

5 (2.3%)

21 (3.3%)

13 (3.5%)

Pseudoaneurysm

3 (0.2%)

0

2 (0.3%)

1 (0.2%)

30-day stroke

21 (1.6%)

1 (0.5%)

14 (2.2%)

6 (1.3%)

30-day death

11 (0.8%)

0

5 (0.8%)

6 (1.3%)

Combined 30-day stroke and death

27 (2%)

1 (0.5%)

15 (2.3%)

11 (2.4%)

Infection

P value .23 (BPA vs PC) .73 (BPA vs DPA) .41 (DPA vs PC) .41 (BPA vs PC) .84 (BPA vs DPA) .48 (DPA vs PC) .49 (BPA vs PC) .77 (BPA vs DPA) .41 (DPA vs PC) .31 (BPA vs PC) .29 (BPA vs DPA) .096 (DPA vs PC) .38 (BPA vs DPA) .09 (BPA vs PC) .19 (DPA vs PC) .94 (BPA vs DPA) .001 (BPA vs PC) .001 (DPA vs PC)

BPA, Bovine pericardial patch angioplasty; DPA, Dacron patch angioplasty; PC, primary closure.

Table III. Restenosis and survival at 5 years

5-year restenosis 5-year survival

Entire cohort n ⫽ 1331

PC n ⫽ 216 (16.3%)

DPA n ⫽ 642 (48.2%)

BPA n ⫽ 457 (34.3%)

9.1 ⫾ 0.4

5.2 ⫾ 1.6

2.0 ⫾ 0.6

1.1 ⫾ 0.6

70.8 ⫾ 1.6

86.9 ⫾ 3.5

69.8 ⫾ 2.1

77.9 ⫾ 3.6

P value .03 (DPA vs PC) .008 (BPA vs PC) .15 (BPA vs DPA) .24 (DPA vs PC) .01 (BPA vs PC) .03 (BPA vs DPA)

BPA, Bovine pericardial patch angioplasty; DPA, Dacron patch angioplasty; PC, primary closure. All data shown as percent ⫾ SD.

RESULTS Demographic and comorbid variables for the entire cohort and defined subgroups are listed in Table I. Primary arteriotomy closure was performed in 216 cases (16.3%), DPA in 642 cases (48.2%), and BPA in 457 cases (34.3%). The graphic depiction of our adoption of bovine pericardium as a patch material over time is represented in Fig 1. Patients undergoing BPA were more likely to be hypertensive and asymptomatic at the time of CEA compared with those undergoing DPA, while patients who underwent PC were slightly older, more likely to have CAD, and less likely to smoke. Rates of intraoperative completion duplex were 19%, 48%, and 95% in the PC, DPA, and BPA groups, while rates of intraoperative completion angiography in the three groups were 67%, 43%, and 4%. Yearly duplex surveillance was available for 57% of those in the PC group, 64% in the DPA group, and 79% of the BPA group. Mean followup time for the entire cohort was 46.1 ⫾ 40.2 months (median 38.2, range 0-181.7 months). Subgroup mean follow-up times were PC, 46.1 ⫾ 48.2 months (median 38.2, range 0-181.7 months); DPA, 57.3 ⫾ 42.2 months (median 52.4, range 0-165.6 months); BPA, 24.6 ⫾ 21.2 months

(median 19.6, range 0-113.0 months). Seven percent of the BPA cohort, 29% of the DPA cohort, and 16% of the PC cohort were lost to follow-up. As shown in Table II, the overall rates of postoperative infection, neck hematoma, and pseudoaneurysm formation were low across each closure strategy. While there were no significant differences in either the rates of these complications or in 30-day stroke or 30-day death, the combined 30-day stroke and death rate was significantly lower in the PC cohort. Combined 30-day stroke and death was significantly lower in the PC cohort (0.5% vs 2.3% DPA vs 2.4% BPA; P ⫽ .94, BPA vs DPA; P ⫽ .001, BPA vs PC; P ⫽ .001, DPA vs PC). Patching was associated with improved 5-year restenosis compared with PC (Table III, Fig 2) and a trend toward improved results with bovine pericardium vs Dacron was noted. None of the variables tested on univariate analysis proved significant predictors of restenosis (Table IV). Five-year survival was significantly higher in patients who underwent BPA compared with those who underwent DPA or PC (see Table III, Fig 3). Given that 95% of CEAs from 2003 onward were performed with BPA, we analyzed the effect of treatment date and found no statistical evi-

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5-year restenosis

restenosis (%)

10

BPA DPA PC

5

0 0

10

20

30

40

50

60

months 0-12 months

12-24 months

24-36 months

36-48 months

48-60 months

BPA

330

290

206

142

81

DPA

543

513

461

393

342

PC

194

184

163

139

123

Fig 2. Five-year cumulative restenosis (with numbers at risk). BPA, Bovine pericardial patch angioplasty; DPA, Dacron patch angioplasty; PC, primary closure.

Table IV. Multivariate analysis of 5-year restenosis and survival 5-year restenosis Variable Age Prior stroke Renal failure Statina Arrhythmia Male gender Diabetes mellitus COPD CAD Hypertension Plavixa Dacron patch Beta blockera Smoking Aspirina Bovine patch Indication for CEA Coumadina

5-year survival

P value

Hazard ratio

P value

.15 .12 1.0 .74 1.0 .55 .73 .72 .10 .10 .45 .06 .59 .49 .39 .15 .28 .94

.95 .83 .29 1.3 .71 1.21 .77 .67

⬍.001 ⬍.001 ⬍.001 .004 .004 .05 .02 .02 .91 .76 .60 .43 .39 .36 .34 .21 .18 .11

CAD, Coronary artery disease; CEA, carotid endarterectomy; COPD, chronic obstructive pulmonary disease. a Postoperative.

dence to suggest that temporal bias was a contributing factor in the observed enhanced survival seen. Similarly, to determine if improved cardiovascular risk management with antiplatelet agents, ␤-blockers and statin therapy influenced survival in the BPA cohort, we included the perioperative use of these medications in our regression analysis, the results of which are in Table IV. While patients in the BPA cohort were more likely to be on statin and dual aspirin and Plavix antiplatelet therapy and less likely to be on Coumadin than those in either the DPA or PC subgroups (Table V), only statin therapy proved to be a signif-

icant predictor of enhanced survival on multivariate analysis. Male gender also positively predicted survival, while advanced age, diabetes mellitus, prior stroke, chronic obstructive pulmonary disease, renal failure, and the presence of an arrhythmia negatively influenced survival on multivariate analysis. DISCUSSION At our institution, PC of the arteriotomy during CEA was routinely practiced until 1997. Between 1997 and 2003, closure with DPA became the more commonly performed technique, with 75% of procedures being performed in this manner and 25% being closed primarily. From 2003 onward, 95% of all CEAs have been performed utilizing bovine pericardium. We have been swayed toward use of this patch material by its ready availability, excellent handling characteristics, minimal associated suture hole bleeding, comparative cost, relative resistance to thrombosis, and the ability to insonate directly through the patch. We believe this latter feature confers a clear advantage over prosthetic alternatives and has allowed us to significantly reduce our restenosis rates below those commonly reported.26 Concerns over immunogenicity or infection with bovine spongiform encephalopathy do not appear to be clinically relevant given current preparation techniques.9 While several reports have indicated that bovine pericardium can be used effectively as a carotid patch,15,20-25 there are few comparative studies between bovine pericardium and Dacron patches, and the longer-term risk of associated patch infection or patch degeneration with bovine pericardium remains unclear. The most notable finding in our study was that of the comparatively low rates of postoperative infection and bleeding across each closure strategy, again demonstrating the short-term safety of using bovine pericardium for this indication.29,30 Further, fears of patch degeneration as

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survival (%)

5-year survival 100 90 80 70 60 50

BPA DPA PC 0

10

20

30

40

50

60

months 0-12 months

12-24 months

24-36 months

36-48 months

48-60 months

BPA

332

293

209

144

82

DPA

546

521

469

398

344

PC

200

189

168

145

128

Fig 3. Five-year cumulative survival (with numbers at risk). BPA, Bovine pericardial patch angioplasty; DPA, Dacron patch angioplasty; PC, primary closure.

Table V. Selected cardiovascular medications used perioperatively by patients in each cohort Medication Beta blocker Statin Aspirin and Plavix Coumadin

DPA vs PC (P value)

BPA vs PC (P value)

BPA vs DPA (P value)

61% vs 57% (.34) 49% vs 44% (.22) 3% vs 3% (.64) 3% vs 6% (.03)

72% vs 57% (.001) 72% vs 44% (.001) 13% vs 3% (.001) 0.2% vs 6% (.001)

72% vs 61% (.34) 72% vs 49% (.001) 13% vs 3% (.001) 0.2% vs 3% (.001)

BPA, Bovine pericardial patch angioplasty; DPA, Dacron patch angioplasty; PC, primary closure.

indicated by a higher pseudoaneurysm rate were not realized across the intermediate follow-up period represented by this series. We do not have a ready explanation for the unexpected finding of improved 30-day stroke and death rates with PC in our study. This result represents an exceptionally low stroke and death rate for both symptomatic and asymptomatic patients in the PC cohort and runs counter to the wealth of accumulated data from multiple randomized controlled trials indicating improved perioperative stroke and death with patching. Consistent with an abundance of prior literature,6,7 however, our study found improved long-term patency with both types of patches compared with PC of the arteriotomy. The observed trend toward improved patency favoring bovine pericardium over Dacron could potentially be explained by our adoption of completion duplex as a standard practice beginning shortly after transitioning to bovine pericardium as our patch of choice.26 Predictors of long-term survival in the entire cohort were similar to those well known to affect mortality in this patient population. However, the enhanced survival seen with bovine patch angioplasty on univariate analysis was an unexpected result, and we remain cautious with regard to drawing any strong conclusions from this finding. While it potentially reflects the now widely known beneficial effects of statin therapy in patients with cardiovascular disease,31,32 it could also reflect a temporal bias undetected by

our statistical efforts; we acknowledge the challenges in completely eliminating such bias in retrospective studies such as ours. The discrepant rate of asymptomatic patients, age, and degree of coronary disease in the BPA cohort is a further recognized limitation of the study and could also bear on the identified survival advantage. Additional limitations include the inherent subjectivity of our definition of neck hematoma and the lack of information on internal carotid artery diameters in those patients undergoing PC. Finally, while the survival analysis methods used in this study should control for the variability in follow-up seen in the different subgroups and account for the uncertainty of censorship, we recognize the inherent limitations of the statistical analysis. In sum, our findings support the use of bovine pericardium as a patch material after carotid endarterectomy and suggest it is safe in the short and intermediate-term for this indication. The authors thank Ms Julie Lombara for her assistance in data management. AUTHOR CONTRIBUTIONS Conception and design: KH, MM Analysis and interpretation: KH, LN, MM Data collection: KH Writing the article: KH, LN, MM

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Critical revision of the article: KH, LN, MM Final approval of the article: KH, LN, MM Statistical analysis: KH, LN, MM Obtained funding: Not applicable Overall responsibility: MM REFERENCES 1. The Asymptomatic Carotid Surgery Trial (ACST) Collaborative Group. Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial. Lancet 2004;363:1491-502. 2. The Asymptomatic Carotid Atherosclerosis Study Group. Endarterectomy for asymptomatic carotid artery stenosis. JAMA 1995;273: 1421-8. 3. Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet 1998;351:1379-87. 4. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. N. Engl. J. Med. 1998;339:1415-25. 5. Imparato AM. The role of patch angioplasty after carotid endarterectomy. J Vasc Surg 1988;7:715-6. 6. Bond R, Rerkasem K, Naylor AR, AbuRahma AF, Rothwell PM. Systematic review of randomized controlled trials of patch angioplasty versus primary closure and different types of patch materials during carotid endarterectomy. J Vasc Surg 2004;40:1126-35. 7. Eikelboom BC, Ackerstaff RG, Hoeneveld H, Ludwig JW, Teeuwen C, Vermeulen FE, et al. Benefits of carotid patching: a randomized study. J Vasc Surg 1988;7:240-7. 8. Rosenthal D, Archie JP Jr, Garcia-Rinaldi R, Seagraves MA, Baird DR, McKinsey JF, et al. Carotid patch angioplasty: immediate and long-term results. J Vasc Surg 1990;12:326-33. 9. Muto A, Nishibe T, Dardik H, Dardik A. Patches for carotid artery endarterectomy: current materials and prospects. J Vasc Surg 2009;50: 206-13. 10. O’Hara PJ, Hertzer NR, Krajewski LP, Beven EG. Saphenous vein patch rupture after carotid endarterectomy. J Vasc Surg 1992;15: 504-9. 11. Archie JP, Green JJ Jr. Saphenous vein rupture pressure, rupture stress and carotid endarterectomy vein patch reconstruction. Surgery 1990; 107:389-96. 12. AbuRahma AF, Hopkins ES, Robinson PA, Deel JT, Agarwal S. Prospective randomized trial of carotid endarterectomy with polytetrafluoroethylene versus collagen-impregnated Dacron (Hemashield) patching: late follow-up. Ann Surg 2003;237:885-92. 13. AbuRahma AF, Hannay RS, Khan JH, Robinson PA, Hudson JK, Davis EA. Prospective randomized study of carotid endarterectomy with polytetrafluoroethylene versus collagen-impregnated Dacron (Hemashield) patching: perioperative (30-day) results. J Vasc Surg 2002; 35:125-30. 14. McCready RA, Siderys H, Pittman JN, Herod GT, Halbrook HG, Fehrenbacher JW, et al. Delayed postoperative bleeding from polytetrafluoroethylene carotid artery patches. J Vasc Surg 1992;15:661-3. 15. Biasi GM, Mingazzini P, Baronio L, Sampaolo A. Processed bovine pericardium as patch angioplasty for carotid endarterectomy: a preliminary report. Cardiovasc Surg 1996;4:848-52.

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Submitted Apr 28, 2010; accepted Oct 1, 2011.