Infrainguinal Vein Grafts Research Articles

Comparing the Benefit of Duplex Ultrasound Surveillance Following Both Infrainguinal Bypass Surgery and Stenting for Femoro-Popliteal Disease

Duplex ultrasound surveillance (DUS) is commonly used following infrainguinal vein bypass. The role of DUS following endovascular revascularisation is as yet unclear. This study focuses on the role of DUS in a contemporary group of patients undergoing infrainguinal bypass or stent insertion. All patients undergoing either an infrainguinal vein graft bypass or stent insertion into the femoro-popliteal segment (November 2014 - January 2017) were identified. Patients were followed up for 2years. Data on entry into DUS, pre-operative characteristics, adjunctive pharmacotherapy and reintervention were collated. The primary outcomes were major lower limb amputation and mortality at 2years post revascularisation. One hundred and thirty-five patients underwent infrainguinal vein bypass and 100 patients underwent stent insertion. 107 patients in the bypass cohort and 58 patients in the stent cohort entered DUS. For the bypass cohort, entering DUS was associated with a lower mortality rate (P = .003) but was not associated with an improvement in amputation rates. The odds ratio of major amputation or mortality was greater in the no surveillance group (4.58, 95% CI: 1.855 - 11.364). In the stent cohort, DUS was not associated with a significant improvement in either major amputation or death (odds ratio 2.13 (95% CI 0.903 - 5.051; P = .081). DUS was associated with improved survival rates in patients undergoing lower limb bypass but had no benefit in those patients undergoing stent insertion. The role of DUS following stent insertion in the femoropopliteal segment needs to be better defined.

Application of Percutaneous Ultrasound Guided Intervention (PUSGI) for Patients with Infra-Inguinal Vein Graft Stenosis

Application of Percutaneous Ultrasound Guided Intervention (PUSGI) for Patients with Infra-Inguinal Vein Graft Stenosis

Validation of randomized controlled trial-derived models for the prediction of postintervention outcomes in chronic limb-threatening ischemia

BackgroundChronic limb-threatening ischemia (CLTI) represents the most severe form of peripheral artery disease and has a large impact on quality of life, morbidity, and mortality. Interventions are aimed at improving tissue perfusion and averting amputation and secondary cardiovascular complications with an optimal risk-benefit ratio. Several prediction models regarding postprocedural outcomes in CLTI patients have been developed on the basis of randomized controlled trials to improve clinical decision-making. We aimed to determine model performance in predicting clinical outcomes in selected CLTI cohorts. MethodsThis study validated the Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL), Finland National Vascular registry (FINNVASC), and Prevention of Infrainguinal Vein Graft Failure (PREVENT III) models in data sets from a peripheral artery disease registry study (Athero-Express) and two randomized controlled trials of CLTI in The Netherlands, Rejuvenating Endothelial Progenitor Cells via Transcutaneous Intra-arterial Supplementation (JUVENTAS) and Percutaneous Transluminal Angioplasty and Drug-eluting Stents for Infrapopliteal Lesions in Critical Limb Ischemia (PADI). Receiver operating characteristic (ROC) curve analysis was used to calculate their predictive capacity. The primary outcome was amputation-free survival (AFS); secondary outcomes were all-cause mortality and amputation at 12 months after intervention. ResultsThe BASIL and PREVENT III models showed predictive values regarding postintervention mortality in the JUVENTAS cohort with an area under the ROC curve (AUC) of 81% and 70%, respectively. Prediction of AFS was poor to fair (AUC, 0.60-0.71) for all models in each population, with the highest predictive value of 71% for the BASIL model in the JUVENTAS population. The FINNVASC model showed the highest predictive value regarding amputation risk in the PADI population with AUC of 78% at 12 months. ConclusionsIn general, all models performed poor to fair in predicting mortality and amputation. Because the BASIL model performed best in predicting AFS, we propose use of the BASIL model to aid in the clinical decision-making process in CLTI. However, improvements in performance have to be made for any of these models to be of real additional value in clinical practice.

Efficacy of Balloon Angioplasty for Infrainguinal Vein Graft Stenosis

Vein graft stenosis is a critical complication of lower-limb bypass surgery. For vein graft stenosis, balloon angioplasty has been performed instead of surgical revision in recent years. We therefore investigated the effectiveness of the balloon angioplasty for vein graft stenosis. We conducted a retrospective analysis of prospectively collected data for 115 vein graft stenoses performed via balloon angioplasty from August 2011 to January 2018. The rate of freedom from reintervention after balloon angioplasty was 54.3%, 44.4%, and 38.0% at 1, 2, and 3years, respectively. The rate of freedom from graft occlusion after balloon angioplasty was 79.9%, 71.9%, and 61.3% at 1, 2, and 3years, respectively. Predictors of freedom from graft occlusion after balloon angioplasty by a multivariate analysis were a single treated lesion (hazard ratio [HR]: 0.38; 95% confidence interval [CI]: 0.17-0.85; P=0.0189), balloon angioplasty within 90days after bypass surgery (HR: 3.59; 95% CI: 1.56-8.07; P=0.0033), and using a cutting balloon (HR: 0.42; 95% CI: 0.17-0.97; P=0.0426). The freedom from graft occlusion rate after balloon angioplasty remained relatively high. Furthermore, better results can be expected in single treated lesions and cases of balloon angioplasty occurring 90days after bypass surgery or in which a cutting balloon was used. Balloon angioplasty for lower-limb bypass graft stenosis was shown to be a useful treatment.

Validation of a Decision Tree to Streamline Infrainguinal Vein Graft Surveillance

Duplex ultrasound (DU)-based graft surveillance remains controversial. The aim of this study was to assess the ability of a recently proposed decision tree in identifying high-risk grafts which would benefit from DU-based surveillance. Consecutive patients undergoing infrainguinal vein graft bypass from January 2008 to December 2015 were identified from the National Vascular registry and enrolled in a duplex surveillance program. An early postoperative DU was performed at a median of 6weeks (range: 4-9 weeks). Grafts were classified into high risk or low risk based on the findings of the earliest postoperative scan and 4 established risk factors for graft failure (diabetes, smoking, infragenicular distal anastomosis, and revision bypass surgery) using a classification and regression tree (CRT). The accuracy of the CRT model was evaluated using area under receiver operator characteristic (AROC) curve. About 278 vein graft bypasses were performed; 29 grafts had occluded by the first surveillance visit; 249 vein grafts were entered into surveillance. Sixty-four (23%) developed critical stenosis. Overall 30-month primary patency, primary-assisted patency, and secondary patency rates were 71.2%, 77.2%, and 80.1%, respectively. AROC for prediction of graft stenosis or occlusion was 83% (95% confidence interval [CI]: 78-87%). The sensitivity and specificity of the CRT model for prediction of graft stenosis or occlusion were 95% (95% CI: 88-98%) and 52.2% (95% CI: 45-60%). A prediction model based on commonly recorded clinical variables and early postoperative DU scan is accurate at identifying grafts which are at high risk of failure. These high-risk grafts may benefit from DU-based surveillance.

Stenting as a bail-out option after failed percutaneous transluminal angioplasty in infrainguinal vein bypass grafts.

To study the safety and efficacy of bare and covered stents in infrainguinal vein grafts after failure of PTA for treating graft stenoses. An analysis of a prospective database of all patients who underwent stenting of infrainguinal vein bypass grafts at this institution between 1 January 2008 and 31 December 2012 was carried out. The main outcome considered was primary patency, which was reported at 1, 6 and 12 months. A total of 18 patients with a mean age of 73 years (range: 56 to 86) were included. The indications for stent placement were significant recoil (7, 39%), graft rupture (6, 33%), residual vein cusps (3, 17%) and aneurysmal degeneration (2, 11%). There was a high overall technical success rate of 94% (17/18) and arrest of haemorrhage was achieved in all cases of graft rupture. The primary patency at 1, 6 and 12 months was 89%, 71% and 59%, respectively. The use of bare and covered stents in infrainguinal vein grafts appears safe and effective. They are an excellent bail-out option for the treatment of graft rupture and give acceptable short-term results.

Development of a Decision Tree to Streamline Infrainguinal Vein Graft Surveillance

Duplex ultrasound (DU) remains the gold standard for identification and grading of infrainguinal vein graft stenosis. However, DU-based graft surveillance remains controversial. The aim of this study was to develop a decision tree to identify high-risk grafts which would benefit from DU-based surveillance. Consecutive patients undergoing infrainguinal vein graft bypass were enrolled in a DU surveillance program. An early postoperative DU was performed at a median of 6weeks (range 4-9). Based on the findings of this scan and 4 established risk factors for graft failure (diabetes, smoking, infragenicular distal anastomosis, revision bypass surgery), a classification and regression tree (CART) was created to stratify grafts into grafts which are at high and low risk of developing severe stenosis or occlusion. The accuracy of the CART model was evaluated using area under receiver operator characteristic curve (ROC). Of 796 vein graft bypasses performed (760 patients), 64 grafts were occluded by the first surveillance visit and 732 vein grafts were entered into surveillance program. The CART model stratified 299 grafts (40.8%) as low-risk and 433 (59.2%) as high-risk grafts. One hundred twenty-six (17.2%) developed critical vein graft stenosis. Overall, 30-month primary patency, primary-assisted and secondary patency rates were 76.2%, 83.6%, and 85.3%, respectively. The area under ROC curve for the CART model was 0.88 (95% confidence interval 0.81-0.94). Primary graft patency rates were higher in low-risk versus high-risk grafts (log rank 186, P<0.0001). Amputation rates were significantly higher in the high-risk grafts compared with low-risk ones (log rank 118, P<0.0001). A clinical decision rule based on readily available clinical data and the findings of significant flow abnormalities on an early postoperative DU scan successfully identifies grafts at high risk of failure and will contribute to safely improving the efficacy of infrainguinal vein graft surveillance services.

Infrainguinal Vein Graft Stenoses: Long-Term Outcomes of Graft Angioplasty

Graft angioplasty combines the durability and ability of surgical bypasses to treat long arterial occlusions with the minimally invasive nature of endovascular procedures. The purpose of this study was to evaluate the efficacy of single and repeated graft angioplasty in revising failing infrainguinal vein bypass grafts and to determine predictors of medium- and long-term freedom from revision after graft angioplasty. This was a retrospective analysis from a prospectively maintained database. Consecutive endovascular revisions of graft-threatening lesions identified by duplex ultrasound surveillance were reviewed from 2003 to 2010. Patients were followed up until death, major amputation, or the end of follow-up, with the data last updated on January 1, 2013. 178 graft angioplasty procedures performed in 114 bypass grafts in 103 limbs from 98 patients were studied. At 5 years, freedom from revision was 22.6%, graft survival was 45.8%, amputation-free survival was 57.9%, and patient survival was 64.9%. Analysis of repeated angioplasties found no evidence that effectiveness diminishes significantly with the number of previous angioplasties performed (p=.892). Higher Rutherford Grade of ischemia and longer time interval from index surgery to first angioplasty were significant positive predictors of medium- and long-term patency. Percutaneous transluminal angioplasty of infrainguinal vein grafts is safe and effective in the treatment of failing grafts identified by duplex surveillance. Graft angioplasties do not lose effectiveness when repeated and have shown cumulative benefit in prolonging graft survival. Treatment of claudicants and time interval from graft implantation of more than 6monthsat the time of first angioplasty are positive predictors of at least medium-term patency after graft angioplasty.

Validation of the Wound, Ischemia, foot Infection (WIfI) classification system in nondiabetic patients treated by endovascular means for critical limb ischemia

The Society for Vascular Surgery Lower Extremity Guidelines Committee developed the Wound, Ischemia, foot Infection (WIfI) a classification system to predict the amputation risk in patients with critical limb ischemia (CLI). A number of published studies have already evaluated its prognostic value. However, most of the included patients were diabetic, and the validation was done independent of the revascularization procedure. This single-center study evaluated the prognostic value of WIfI stages in nondiabetic patients treated by endovascular means. A retrospective analysis was performed of prospectively collected data of nondiabetic patients treated by endovascular means between January 2013 and September 2014. All patients were classified according to their wound status, ischemia index, and extent of foot infection to four classes: very low risk, low risk, moderate risk, and high risk. Comorbidities and vascular lesions for each group were analyzed. The prognostic value of WIfI was analyzed based on the amputation-free survival, overall survival rate, and freedom from amputation at 12months. Data from 302 CLI patients treated in the study period were reviewed. A total of 219 patients (73%) underwent an endovascular intervention, and among them, 126 nondiabetic patients (58%) were enrolled in this study. Most patients were classified as low risk (33%), and the prevalence of very low-risk, moderate-risk, and very high-risk patients was 23%, 23%, and 21%, respectively. The modified Edifoligide for the Prevention of Infrainguinal Vein Graft Failure (PREVENT III) scorewas statistically significantly higher in the high-risk group (5.2± 2.4) than in the very low-risk, low-risk, and moderate-risk groups (4.3± 2.5, 3.5± 2.3, 4.5± 2.2, respectively; P= .048). One major amputation (1%) was performed during the hospital stay in a high-risk patient. Mean follow-up was 14± 8months. The amputation-free survival at 12months was 87%, 81%, 81%, and 62%, in the very low-risk, low-risk, moderate risk, and very high-risk groups, respectively (P= .106). The difference was statistically significant between the very low-risk and high-risk groups (hazard ratio, 3.4; 95% confidence interval, 1.1-10.3; P= .029). A similar trend was also observed for 1-year survival between the very low-risk and the high-risk groups (87%, 84%, 81%, 65%; P= .166). The amputation rate during the follow-up time was 0%, 2% (n= 6), 3% (n= 5), and 12% (n= 9) for the very low-risk, low-risk, moderate-risk, and very high-risk groups, respectively (P= .033). The WIfI classification system predicted the amputation risk and survival in this highly selected group of nondiabetic CLI patients treated by endovascular means, with a statistically significant difference between very low-risk and high-risk patients already at 1year.

Objective performance goals after endovascular intervention for critical limb ischemia

During the last decade, primary endoluminal therapy for critical limb ischemia (CLI), assessed as rest pain and tissue loss of the lower extremity, has significantly increased. Reporting of patient-centered outcomes using the new Society for Vascular Surgery objective performance goals (OPGs) has been limited. This study examined the OPGs for infrainguinal endovascular management of CLI. A prospective database of patients undergoing endovascular treatment of the lower extremity for CLI between 2000 and 2011 was queried. Evaluated were clinical efficacy (absence of recurrent symptoms, maintenance of ambulation and absence of major amputation), amputation-free survival (survival without major amputation), and freedom from major adverse limb events (MALEs; above-ankle amputation of the index limb or major reintervention - new bypass graft, jump/interposition graft revision). A total of 728 patients (60% male; age, 68 ± 14 years) underwent lower extremity interventions for CLI (66% tissue loss); of these, 39% had superficial femoral artery and tibial interventions. Diabetes mellitus was present in 71%, hyperlipidemia in 64%, and chronic renal insufficiency in 37%. Technical success was 96%. The overall rate at 30 days of major adverse cardiovascular events (MACEs) was 3% and MALEs was 12%. At 5 years, clinical efficacy was (mean ± standard error of the mean) 42% ± 5%, amputation-free survival was 41% ± 7%, and freedom from MALEs was 51% ± 4%. Clinical efficacy was significantly different in those presenting with rest pain and tissue loss and in the anatomic high-risk group compared with the clinical high-risk group, and both were worse compared with the group without clinical or high-risk criteria. Endoluminal therapy for CLI is associated with early low MACE rates but high MALE rates. When the key outcome of amputation free survival is considered, predictors of a better outcome were absence of current smoking, a lower modified Edifoligide for the Prevention of Infrainguinal Vein Graft Failure (PREVENT III) amputation risk score, better preoperative ambulation status, lower MACEs, and discharge disposition to home. The presence of tissue loss and anatomic risk factors negatively affect outcomes. Longer-term outcomes after endovascular intervention for CLI remain relatively poor, with <40% success in objective performance outcomes at 5 years.

Vein graft aneurysms following popliteal aneurysm repair are more common than we think.

True infrainguinal vein graft aneurysms are reported infrequently in the literature. We sought to identify the true incidence of these graft aneurysms after popliteal aneurysm repair and identify factors which may increase the risk of such aneurysms developing. Using a prospectively compiled database, we identified patients who underwent a popliteal aneurysm repair between January 1996 and January 2011 at a single district general hospital. Patients were routinely followed up in a graft surveillance programme. Out of 45 patients requiring repair of a popliteal aneurysm over a 15-year period, four (8.8%) patients developed aneurysmal graft disease. Of the patients who developed graft aneurysms, all had aneurysmal disease at other sites compared with 18 (45.0%) patients who did not develop graft aneurysms. Patients with graft aneurysms had a mean of 1.60 aneurysms elsewhere compared to 0.58 in patients with non-aneurysmal grafts (P = 0.005). True vein graft aneurysms occur in a significant number of patients following popliteal aneurysm repair. Our data would suggest this to be more likely in patients who have aneurysms elsewhere and therefore a predisposition to aneurysmal disease. It may be appropriate for patients with aneurysms at other sites to undergo more prolonged post-operative graft surveillance.

Percutaneous transluminal angioplasty of infrainguinal vein graft stenosis is not a negative predictor for long-term patency

To investigate whether maintenance percutaneous transluminal angioplasty (PTA) for significant stenosis after infrainguinal bypass grafting affects long-term patency of the bypass grafts in comparison to those not needing intervention. The cohort includes 141 consecutive patients with 157 infrainguinal vein grafts performed from January 1996 to December 2005. Grafts occluded within three months after operation were excluded. Revascularisations needing maintenance PTA for significant stenoses of graft or adjacent in- or outflow vessels (intervention group, n = 39) were compared to those not needing intervention during follow up (non-intervention group, n = 118). Primary end point was bypass occlusion. Secondary end points were major amputation or death. Long-term patency in the intervention and non-intervention groups was estimated using Kaplan-Meier curves and compared using the Tarone-Ware test. In the intervention group, primary assisted patency rate after 36 and 60 months was 94.1 % and 89.4 %, respectively, whereas in the non-intervention group patency rate was 92.5 % and 91.0 %, respectively (p = 0.644). Comparing the intervention group to the non-intervention group, 1 versus 2 major amputations (p = 0.642) and 14 versus 40 deaths (p = 0.233) occurred. Occurrence of graft stenosis did not decrease long-term patency rate when treated by PTA in comparison to grafts not needing maintenance PTA.

A cost-effectiveness analysis of infrainguinal bypass in the absence of great saphenous vein conduit

Good-quality great saphenous vein (GSV) is the preferred conduit for infrainguinal surgical revascularizations, but it is not available in all patients. We sought to identify the alternative conduit that would maximize cost-effectiveness in the context of infrapopliteal bypass for critical limb ischemia and nonhealing foot wounds. A Markov model was used to create a detailed simulation of 10-year outcomes in a hypothetical Edifoligide for the Prevention of Infrainguinal Vein Graft Failure (PREVENT) III-type patient cohort undergoing infrainguinal bypass for nonhealing foot wounds. The following management options were evaluated: (1) conservative therapy (local wound care, amputation as needed); (2) primary amputation; (3) bypass with autologous alternative vein (AAV), including arm or lesser saphenous vein; (4) bypass with GSV<3 mm in diameter; (5) bypass with polytetrafluoroethylene (PTFE); (6)cryopreserved venous allograft; and (7) cryopreserved arterial allograft. Estimates of 10-year total costs were incorporated into the model. Cost-effectiveness was measured in terms of incremental United States dollars per additional year of ambulation. Bypass with AAV had the highest effectiveness as measured in median years of ambulation. After primary amputation, bypass with PTFE had the lowest total costs. With incremental cost-effectiveness ratios of $5325 and $21,228, bypass with PTFE or AAV appeared to be cost-effective alternatives to conservative therapy for nonhealing ischemic wounds. Primary amputation, GSV<3 mm, and allograft options were dominated (ie, more costly and less effective). Primary amputation was weakly dominated. Bypass with PTFE or AAV appears to be a cost-effective option for the management of critical limb ischemia and nonhealing foot wounds when good-quality GSV is not available.

The Comprehensive Risk Assessment for Bypass (CRAB) facilitates efficient perioperative risk assessment for patients with critical limb ischemia

Specific perioperative risk assessment models have been developed for bariatric, pancreatic, and colorectal surgery. A similar instrument, specific for patients with critical limb ischemia (CLI), could improve patient-centered clinical decision making. We describe a novel tool to predict 30-day major morbidity and mortality (M&M) after bypass surgery for CLI. Data for 4985 individuals from the 2007 to 2009 National Surgical Quality Improvement Program were used to develop and internally validate the model. Outcome measures included mortality, major morbidity, and a composite end point (M&M). M&M included mortality and the most severe postoperative morbidities that were highly associated with death (eg, sepsis and major cardiopulmonary complications). More than 30 preoperative factors were tested for association with 30-day mortality, major morbidity, and M&M. Significant predictors in multivariate models were assigned integer values (points), which were added to calculate a patient's Comprehensive Risk Assessment For Bypass (CRAB) score. Performance was assessed (C-index) across all outcome measures and compared with other general tools (American Society of Anesthesiologists class, Surgical Risk Scale) and existing CLI-specific survival prediction models (Finnvasc score, Edifoligide for the Prevention of Infrainguinal Vein Graft Failure [PREVENT III] score) on a distinct validation sample (n = 1620). In the derivation data set (n = 3275), the 30-day mortality rate was 2.9%. The rate of any major morbidity was 19.1%. The composite end point M&M occurred in 10.1%. Significant predictors of M&M by multivariate analysis included age >75 years, prior amputation or revascularization, tissue loss, dialysis dependence, severe cardiac disease, emergency operation, and functional dependence. Applied to a distinct validation sample of 1620 patients, higher CRAB scores were significantly associated with higher rates of mortality, all major morbidities, and M&M (P < .0001). Comparison with other models by assessment of area under the receiver-operating characteristic curve revealed the CRAB was a more accurate predictor of mortality, all major morbidity, and M&M. The CRAB is a CLI-specific, risk assessment instrument derived from multi-institutional American College of Surgeons-National Surgical Quality Improvement Program surgical outcomes data that out-performs existing prognostic risk indices in the prediction of clinically significant adverse events after bypass surgery. Use of the CRAB as a risk assessment tool provides an evidence basis for patient-centered clinical decision making and may have a role in identifying patients at higher risk for surgical revascularization in whom an endovascular approach is preferable.

Protective constriction of coronary vein grafts with knitted nitinol

Different flow patterns and shear forces were shown to cause significantly more luminal narrowing and neointimal tissue proliferation in coronary than in infrainguinal vein grafts. As constrictive external mesh support of vein grafts led to the complete suppression of intimal hyperplasia (IH) in infrainguinal grafts, we investigated whether mesh constriction is equally effective in the coronary position. Eighteen senescent Chacma baboons (28.8 ± 3.6 kg) received aorto-coronary bypass grafts to the left anterior descending artery (LAD). Three groups of saphenous vein grafts were compared: untreated controls (CO); fibrin sealant-sprayed controls (CO + FS) and nitinol mesh-constricted grafts (ME + FS). Meshes consisted of pulse-compliant, knitted nitinol (eight needles; 50 μm wire thickness; 3.4 mm resting inner diameter, ID) spray attached to the vein grafts with FS. After 180 days of implantation, luminal dimensions and IH were analysed using post-explant angiography and macroscopic and histological image analysis. At implantation, the calibre mismatch between control grafts and the LAD expressed as cross-sectional quotient (Qc) was pronounced [Qc = 0.21 ± 0.07 (CO) and 0.18 ± 0.05 (CO + FS)]. Mesh constriction resulted in a 29 ± 7% reduction of the outer diameter of the vein grafts from 5.23 ± 0.51 to 3.68 ± 0 mm, significantly reducing the calibre discrepancy to a Qc of 0.41 ± 0.17 (P < 0.02). After 6 months of implantation, explant angiography showed distinct luminal irregularities in control grafts (ID difference between widest and narrowest segment 74 ± 45%), while diameter variations were mild in mesh-constricted grafts. In all control grafts, thick neointimal tissue was present [600 ± 63 μm (CO); 627 ± 204 μm (CO + FS)] as opposed to thin, eccentric layers of 249 ± 83 μm in mesh-constricted grafts (ME + FS; P < 0.002). The total wall thickness had increased by 363 ± 39% (P < 0.00001) in CO and 312 ± 61% (P < 0.00001) in CO + FS vs 82 ± 61% in ME + FS (P < 0.007). In a senescent non-human primate model for coronary artery bypass grafts, constrictive, external mesh support of saphenous veins with knitted nitinol prevented focal, irregular graft narrowing and suppressed neointimal tissue proliferation by a factor of 2.5. The lower degree of suppression of IH compared with previous infrainguinal grafts coincided with a lesser reduction of calibre mismatch in the coronary grafts.

The BASIL survival prediction model in patients with peripheral arterial disease undergoing revascularization in a university hospital setting and comparison with the FINNVASC and modified PREVENT scores

Critical limb ischemia carries a significant risk of morbidity and mortality. The development of scores to predict risk can aid clinical decision making. The Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial investigators developed a model to predict death, which has not been previously validated. Data were collected in a prospectively maintained database on all patients who underwent angioplasty or arterial bypass for peripheral artery disease in a university hospital between January 2008 and June 2010. The main outcome measures were all-cause mortality and amputation-free survival at 3, 6, 12, and 24 months after the index intervention. The BASIL survival predictor, Finland National Vascular (FINNVASC) registry, and Edifoligide for the Prevention of Infrainguinal Vein Graft Failure (PREVENT) models were applied and receiver-operating characteristic (ROC) curve analysis was used to evaluate their predictive power. Data on 342 patients were collected. Patients with isolated iliac disease or claudication were excluded. The 6-, 12-, and 24-month all-cause mortality rates were 11.6%, 17.9%, and 26.8%, respectively. The area under the ROC curve (95% confidence interval) using the BASIL score to predict mortality at 6, 12, and 24 months was 0.700 (0.60-0.80; P<.001), 0.651 (0.56-0.74; P<.003), and 0.681 (0.59-0.74; P<.001), respectively. ROC curve analysis indicated that the performance of the BASIL score in this cohort was comparable to other validated predictive scores. The BASIL survival prediction model can moderately predict short-term and medium-term mortality in patients with limb ischemia and may be a useful adjunct to decision making in everyday clinical practice.

Abstract 116: Enhanced Systemic Inflammation Results in Loss of Vein Graft Lumen and Augments Adaptation to Increased Wall Shear

Introduction: Unlike animal models which are highly reproducible, human vascular remodeling demonstrates marked heterogeneity both within and between patients. Studying human vein grafts (VG), we hypothesize that the local wall shear stress (WSS), modulated by the systemic inflammatory milieu, dictates vascular adaptation and preservation (or loss) of VG lumen. Methods: Following infrainguinal VG placement, 33 patients were evaluated with ultrasound duplex, CT scanning and computational fluid dynamic modeling (at 1 week (1w), 1 month (1m), and 6 months (6m) post-op) to determine the WSS and cross-sectional area at 1 mm intervals along the entire VG. Plasma samples were collected (pre-op, 2 hours, 1 day, 1 week, 1 month) and analyzed for 28 pro- and anti-inflammatory cytokines and chemokines. Results: Regions of reduced shear (&lt; 5 dynes/cm 2 ) demonstrated a loss of VG lumen area in the 1w-1m (-6.5% ± 3.2%) and 1m-6m (-8.2% ± 4.8%) timeframe; elevated shear areas (&gt; 50 dynes/cm 2 ) led to an expansion in lumen area (1w-1m: 27% ± 8%; 1m-6m: 36% ± 14%). Patients with pre- and early post-op elevations in the pro-inflammatory cytokines IL-12, -13, -15 demonstrated enhanced loss of VG lumen between 1 w and 1m ( A ). Increased levels of IL-1b, -2, -3, -4, -6 at 1 month were associated with late reductions in VG lumen area ( B ). In contrast, early elevations in MMP-9, E-selectin, and VCAM-1 were accompanied by enhanced outward remodeling, most prominently in high shear regions ( C , p&lt;0.05). Conclusions: Human VG remodeling are highly responsive to the local WSS, and specific cytokines patterns appear to modulate this process in both early and late vein graft remodeling. Using this information, therapeutic manipulation of the peri-operative inflammatory state may be used to improve VG survival.

Remodeling leads to distinctly more intimal hyperplasia in coronary than in infrainguinal vein grafts

Flow patterns and shear forces in native coronary arteries are more protective against neointimal hyperplasia than those in femoral arteries. Yet, the caliber mismatch with their target arteries makes coronary artery bypass grafts more likely to encounter intimal hyperplasia than their infrainguinal counterparts due to the resultant slow flow velocity and decreased wall stress. To allow a site-specific, flow-related comparison of remodeling behavior, saphenous vein bypass grafts were simultaneously implanted in femoral and coronary positions. Saphenous vein grafts were concomitantly implanted as coronary and femoral bypass grafts using a senescent nonhuman primate model. Duplex ultrasound-based blood flow velocity profiles and vein graft and target artery dimensions were correlated with dimensional and histomorphologic graft remodeling in large, senescent Chacma baboons (n = 8; 28.1 ± 4.9 kg) during a 24-week period. At implantation, the cross-sectional quotient (Q(c)) between target arteries and vein grafts was 0.62 ± 0.10 for femoral grafts vs 0.17 ± 0.06 for coronary grafts, resulting in a dimensional graft-to-artery mismatch 3.6 times higher (P < .0001) in coronary grafts. Together with different velocity profiles, these site-specific dimensional discrepancies resulted in a 57.9% ± 19.4% lower maximum flow velocity (P = .0048), 48.1% ± 23.6% lower maximal cycling wall shear stress (P = .012), and 62.2% ± 21.2% lower mean velocity (P = .007) in coronary grafts. After 24 weeks, the luminal diameter of all coronary grafts had contracted by 63%, from an inner diameter of 4.49 ± 0.60 to 1.68 ± 0.63 mm (P < .0001; subintimal diameter: -41.5%; P = .002), whereas 57% of the femoral interposition grafts had dilated by 31%, from 4.21 ± 0.25 to 5.53 ± 1.30 mm (P = .020). Neointimal tissue was 2.3 times thicker in coronary than in femoral grafts (561 ± 73 vs 240 ± 149 μm; P = .001). Overall, the luminal area of coronary grafts was an average of 4.1 times smaller than that of femoral grafts. Although coronary and infrainguinal bypass surgery uses saphenous veins as conduits, they undergo significantly different remodeling processes in these two anatomic positions.

Long-term Outcomes of Low-dose Catheter-directed Thrombolytic Therapy: A 5-year Single-center Experience

To determine immediate and long-term outcomes following catheter-directed intraarterial thrombolysis of occluded native arteries and infrainguinal vein grafts by using low-dose tissue-type plasminogen activator (tPA) in patients with lower limb ischemia. One hundred eleven intraarterial thrombolysis procedures were performed in 96 patients during the 2-year study period. Patient records were available for retrospective review in 85 thrombolytic procedures performed in 74 (77%) of the 96 patients. Forty-one native vessels (four iliac, 24 superficial/common femoral, and 13 popliteal/below-knee vessels), six iliac stents, and 38 infrainguinal vein grafts were treated by using a low-dose (0.5 mg/h recombinant tPA) catheter-directed thrombolytic regimen. Procedural success was based on angiographic and clinical outcomes, and the need for further reconstructive surgery or amputation was documented. Intraarterial thrombolysis was successful in 76%, was partially successful in 11%, and failed in 13%. Adjunctive angioplasty was performed in 33 of 55 patients (60%) with successful lysis, and immediate reconstructive surgery was required in five patients. There was one episode of puncture site bleeding and one gastrointestinal hemorrhage but no procedure-related deaths at 30 days. After a median follow-up of 6.5 years, 30 of the 55 patients (55%) who underwent successful thrombolysis required no further surgical intervention; however, further surgery was required in 45% of patients after a mean interval of 301 days (range, 2-1,344 days), including 10 (18%) amputations (six major and four minor). Low-dose intraarterial thrombolysis is safe and effective, delaying and dramatically reducing the need for surgical intervention in lower limb ischemia due to native vessel or infrainguinal graft occlusion.

Pharmacotherapy to Improve Outcomes in Infrainguinal Bypass Graft Surgery: A Review of Current Treatment Strategies

A total of 12,000 infrainguinal bypass grafts are performed annually in the United Kingdom, with outcomes suboptimal: 20% of above-knee vein grafts require intervention by 3 years. Transatlantic Inter-Society Consensus (TASC) guidelines exist on pharmacological management of peripheral vascular disease patients, however, little is recommended regarding optimum pharmacological management following revascularization to improve graft patency. The current recommendation is that all patients are on an antiplatelet agent following bypass grafting, the only intervention with significant evidence supporting use. This article will review pharmacological strategies aimed at improving the survival of infrainguinal vein grafts and the current evidence base for their use.