Aortofemoral Bypass Grafting Research Articles

Microbial Pathogenesis of Bacterial Biofilms

Vascular surgical site infection (SSI) is caused by pathogenic bacterial strains whose preferred mode of growth is within a surface biofilm. Bacterial biofilm formation can develop within hours to days in a wound and produces a recalcitrant infectious process especially in the presence of a prosthetic graft. The initial steps of biofilm formation are bacterial adhesion to biologic or inert surgical site structures followed by organism production of exopolysaccaride matrix which encases developing bacteria colonies to produce a protective microenvironment. As the biofilm matures, a dynamic process of organism cell-to-cell signaling occurs with varying growth modes of sessile bacteria within the biofilm and the release of planktonic bacteria with the potential to spread and expand the biofilm-mediated infection. The prevalence of staphyloccocal strains causing vascular SSI is best understood when viewed as a biofilm-mediated infection with virulence factors related to specific cell surface adhesion proteins and bacteria-derived matrix production. Nonhealing surgical sites following lower limb revascularization, the late appearance of prosthetic graft infection caused by Staphylococcus epidermidis, and the development of groin site tracts after aortofemoral bypass grafting are clinical examples of a biofilm-mediated SSI. A mature biofilm within a wound or coating a prosthetic device exhibits resistance to host defenses and selected antibiotics, impairs wound healing, and is a perpetual irritant to that host by inciting a chronic inflammatory process. By understanding the microbial pathogenesis of biofilm formation, strategies to treat and prevent biofilm-mediated infection can be developed and utilized to reduce vascular SSIs.

Patterns and Outcomes of Aortofemoral Bypass Grafting in the Era of Endovascular Interventions

Objectives The aim of the study is to study contemporary presentation patterns and clinical results in patients undergoing aortofemoral bypass (AFB) surgery. Design This was a retrospective comparative study. Material and methods During a 14-year period, 269 consecutive patients (mean age 65 years) underwent AFB. Indications included occlusive disease with severe intermittent claudication (IC) ( n = 86), critical limb ischaemia (CLI, n = 97) and aneurysmo-occlusive disease ( n = 86). Results From 2000–07 on, AFB was performed more frequently for occlusive disease with CLI than for other indications (48% vs. 31% before 2000, P = 0.009) and also in women (51% vs. 32% before 2000, P = 0.003), compared to the period before 2000. Thirty-day mortality was reduced during 2000–2007 to 2.4%, compared with 4.3% during 1993–1999, although this difference was not statistically significant ( P = 0.73). Morbidity did not change substantially over the study period. Predictors of 30-day mortality included indication (CLI = 4.1% vs. claudication = 1.2% ( P = 0.37)) and chronic kidney disease (CKD, serum creatinine > 1.5 mg dl −1) (11.1% vs. 2.9% in normal renal function, P = 0.07), the latter being the single predictor on multivariate analysis (hazard risk 4.2, P = 0.047). Overall 5 and 10-year assisted primary and secondary patency was 95% and 88%, and 99% and 95%, respectively. Survival at 5 and 10 years was 69% and 48%, respectively. Patient age (hazard risk 1.05, P < 0.001), CKD (hazard risk 1.79, P = 0.018) and diabetes (hazard risk 1.56, P = 0.022) were independent predictors of worse long-term survival. Long-term outcome did not change over the course of the study. Conclusions In the contemporary era, AFB is more likely to be performed for CLI and in women than in the past. Despite these changes, perioperative mortality and morbidity remain low and long-term outcome excellent.

17 URETEROCALICOSTOMY FOR THE TREATMENT OF SELECT CASES OF URETEROPELVIC JUNCTION OBSTRUCTION

INTRODUCTION AND OBJECTIVES: Hydronephrosis can be a serious complication of aortic reconstructive surgery, presenting in early or late postoperative period. The incidence and treatment tactics for this infrequent complication are still debated in literature. Our study tries to answer these questions. METHODS: 450 patients following aortofemoral and aortoiliac reconstruction were included. There were 382 (84.9%) males and 68 (15.1%) females with a median age of 65.7 8.3 years. Patients were investigated preoperatively and at 1 week, 3, 6 and 12 months after vascular surgery. Two urologists performed clinical and ultrasound examination, intravenous pyelograms assessment. Patients with preoperatively diagnosed urological pathology were not included into this study. RESULTS: We revealed unilateral hydronephrosis in 8.0% (36/ 450) of patients. 83.3% (30/36) of them had a history of aortic aneurysm resection with aortofemoral bypass grafting and 16.7% (6/36) underwent aortofemoral bypass only (p 0.05). There were 44.4% (16/36) patients with mild obstruction and 55.6% (20/36) patients with extensive ureteral strictures. The mild asymptomatic obstruction resolved spontaneously following 1 month of observation. Patients with late (6–12 months) obstruction developed ureteral strictures and required for active management. They underwent ureterolysis and ureteral resection with ureteroureterostomy. Four of them developed stricture relapse postoperatively. Intraureteral metallic self-expanding endoprosthesis placement was performed to eliminate the obstruction in 3 cases. One patient with obliteration of ureter underwent subcutaneus nephrovesical bypass. CONCLUSIONS: Ureteral obstruction can be a serious complication of reconstructive aortic surgery. This especially concerns to aneurysms of abdominal aorta and patients with graft complications. Early mild asymptomatic obstruction may resolve spontaneously or require ureteral stenting. Late hydronephrosis may contribute to retroperitoneal fibrosis associated with periureteral inflammatory process and extensive ureteral strictures. Intraureteral metallic self-expanding endoprosthesis or subcutaneus nephrovesical bypass placement can be appropriate in patients with contraindications to open reconstructive surgery.

The learning curve of robot-assisted laparoscopic aortofemoral bypass grafting for aortoiliac occlusive disease

Since the end of the 20th century, robot-assisted surgery has been finding its role among other minimally invasive methods. Vascular surgery seems to be another specialty in which the benefits of this technology can be expected. Our objective was to assess the learning curve of robot-assisted laparoscopic aortofemoral bypass grafting for aortoiliac occlusive disease in a group of 40 patients. Between May 2006 and January 2010, 40 patients (32 men, 8 women), who were a median age of 58 years (range, 48-75 years), underwent 40 robot-assisted laparoscopic aortofemoral reconstructions. Learning curve estimations were used for anastomosis, clamping, and operative time assessment. For conversion rate evaluation, the cumulative summation (CUSUM) technique was used. Statistical analysis comparing the first and second half of our group, and unilateral-to-bilateral reconstructions were performed. We created 21 aortofemoral and 19 aortobifemoral bypasses. The median proximal anastomosis time was 23 minutes (range, 18-50 minutes), median clamping time was 60 minutes (range, 40-95 minutes), and median operative time was 295 minutes (range, 180-475 minutes). The 30-day mortality rate was 0%, and no graft or wound infection or cardiopulmonary or hepatorenal complications were observed. During the median 18-month follow-up (range, 2-48 months), three early graft occlusions occurred (7%). After reoperations, the secondary patency of reconstructions was 100%. Data showed a typical short learning curve for robotic proximal anastomosis creation with anastomosis and clamping time reduction. The operative time learning curve was flat, confirming the procedure's complexity. There were two conversions to open surgery. CUSUM analysis confirmed that an acceptable conversion rate set at 5% was achieved. Comparing the first and second half of our group, all recorded times showed statistically significant improvements. Differences between unilateral and bilateral reconstructions were not statistically significant. Our results show that the success rate of robot-assisted laparoscopic aortofemoral bypass grafting is high and the complication rate is low. Anastomosis creation, one of the main difficulties of laparoscopic bypass grafting, has been overcome using the robotic operating system and its learning curve is short. However, the endoscopic dissection of the aortoiliac segment remains the most difficult part of the operation and should be addressed in further development of the method to reduce the operative times. Long-term results and potential benefits of this minimally invasive method have to be verified by randomized controlled clinical trials.

Robot Assisted Aorto-femoral Bypass

Laparoscopic vascular surgery has not been widely embraced by vascular surgeons because of the specific technical skills needed in performing vascular anastomosis. Robot assisted vascular surgery has shown the possibility to overcome several limitations of laparoscopic vascular surgery in previous studies. We report two cases of robot assisted aortofemoral bypass grafting for aortoiliac occlusive disease. Two male patients, 65 and 62 years old were admitted complaining of disabling claudication. CT angiography revealed total occlusion of left iliac artery and bilateral superficial femoral arteries in one case and concentric stenosis of lower abdominal aorta, severe occlusion of left common iliac artery in the other case. Laparoscopic aortofemoral bypass grafting was performed with a proximal end-to-side anastomosis constructed with robotic arms using Dacron graft. Femoral anastomosis was performed in the conventional method. The aortic clamping times were 80 and 198 minutes and operating times were 435 and 605 minutes, respectively. The patients were discharged uneventfully on postoperative days 20 and 13. Robot assisted vascular surgery is a technically feasible and safe procedure.

Ten Years Experience of Treating Aorto-Femoral Bypass Graft Infection with Venous Allografts

Objective: The aim of the present study was to analyze our results of treating synthetic vascular graft infection in the aorto-femoral segment with venous allografts. Patients and methods: During 1997–2006 we treated 11 male patients with venous allografts for aorto-femoral segment prosthetic graft infection. Patients were followed postoperatively with patency assessment based on Doppler ultrasonography. Results: The mean interval between the implantation of the synthetic vascular graft and the appearance of infection was 43 ± 29 months (range 5 months–10 years). Overall primary patency of the venous allograft was 100%, 88% and 66% at 1, 6 and 36 months, respectively. Secondary patency rates of the venous allograft were 94% and 73% after 5 and 8 years, respectively. Overall survival rate was 100%, 64%, 46% and 27% after one month, 3, 5 and 8 years, respectively. Limb salvage rate was 100%, 94% and 73% after 1 month, 5 and 8 years, respectively. Conclusions: The use of in situ venous allograft for the treatment of synthetic graft infection in the aorto-femoral segment has led to favourable short- and long-term results.

Ten Years Experience of Treating Aorto-Femoral Bypass Graft Infection with Venous Allografts

ObjectiveThe aim of the present study was to analyze our results of treating synthetic vascular graft infection in the aorto-femoral segment with venous allografts. Patients and methodsDuring 1997–2006 we treated 11 male patients with venous allografts for aorto-femoral segment prosthetic graft infection. Patients were followed postoperatively with patency assessment based on Doppler ultrasonography. ResultsThe mean interval between the implantation of the synthetic vascular graft and the appearance of infection was 43±29 months (range 5 months–10 years). Overall primary patency of the venous allograft was 100%, 88% and 66% at 1, 6 and 36 months, respectively. Secondary patency rates of the venous allograft were 94% and 73% after 5 and 8 years, respectively. Overall survival rate was 100%, 64%, 46% and 27% after one month, 3, 5 and 8 years, respectively. Limb salvage rate was 100%, 94% and 73% after 1 month, 5 and 8 years, respectively. ConclusionsThe use of in situ venous allograft for the treatment of synthetic graft infection in the aorto-femoral segment has led to favourable short- and long-term results.

Long-Term Follow-Up After Endovascular Treatment of Acute Aortic Emergencies

To investigate the long-term outcome and efficacy of emergency treatment of acute aortic diseases with endovascular stent-grafts. From September 1995 to April 2007, 37 patients (21 men, 16 women; age 53.9 +/- 19.2 years, range 18-85 years) with acute complications of diseases of the descending thoracic aorta were treated by endovascular stent-grafts: traumatic aortic ruptures (n = 9), aortobronchial fistulas due to penetrating ulcer or hematothorax (n = 6), acute type B dissections with aortic wall hematoma, penetration, or ischemia (n = 13), and symptomatic aneurysm of the thoracic aorta (n = 9) with pain, penetration, or rupture. Diagnosis was confirmed by contrast-enhanced CT. Multiplanar reformations were used for measurement of the landing zones of the stent-grafts. Stent-grafts were inserted via femoral or iliac cut-down. Two procedures required aortofemoral bypass grafting prior to stent-grafting due to extensive arteriosclerotic stenosis of the iliac arteries. In this case the bypass graft was used for introduction of the stent-graft. A total of 46 stent-grafts were implanted: Vanguard/Stentor (n = 4), Talent (n = 31), and Valiant (n = 11). Stent-graft extension was necessary in 7 cases. In 3 cases primary graft extension was done during the initial procedure (in 1 case due to distal migration of the graft during stent release, in 2 cases due to the total length of the aortic aneurysm). In 4 cases secondary graft extensions were performed--for new aortic ulcers at the proximal stent struts (after 5 days) and distal to the graft (after 8 months) and recurrent aortobronchial fistulas 5 months and 9 years after the initial procedure--resulting in a total of 41 endovascular procedures. The 30-day mortality rate was 8% (3 of 37) and the overall follow-up was 29.9 +/- 36.6 months (range 0-139 months). All patients with traumatic ruptures demonstrated an immediate sealing of bleeding. Patients with aortobronchial fistulas also demonstrated a satisfactory follow-up despite the necessity for reintervention and graft extension in 3 of 6 cases (50%). Two patients with type B dissection died due to mesenteric ischemia despite sufficient mesenteric blood flow being restored (but too late). Two suffered from neurologic complications, 1 from paraplegia and 1 from cerebral ischemia (probably embolic), 1 from penetrating ulcer, and 1 from persistent ischemia of the kidney. Five of 9 (56%) patients with symptomatic thoracic aneurysm demonstrated endoleaks during follow-up and there was an increase in the aneurysm in 1. Endovascular treatment is safe and effective for emergency treatment of life-threatening acute thoracic aortic syndromes. Results are encouraging, particularly for traumatic aortic ruptures. However, regular follow-up is mandatory, particularly in the other pathologies, to identify late complications of the stent-graft and to perform appropriate additional corrections as required.

Contemporary Management of Postcatheterization Pseudoaneurysms

A pseudoaneurysm (PSA) is a contained rupture; there is a disruption in all 3 layers of the arterial wall (Figure 1). PSAs may occur under 4 circumstances: (1) after catheterization (Figure 2); (2) at the site of native artery and synthetic graft anastomosis (eg, aortofemoral bypass graft); (3) trauma; and (4) infection (eg, mycotic PSA) (Figure 3). This review will focus on PSAs that occur after cardiac and peripheral endovascular procedures. PSAs occur when an arterial puncture site does not adequately seal. Pulsatile blood tracks into the perivascular space and is contained by the perivascular structures, which then take on the appearance of a sac. Hematoma and the surrounding tissue form the wall of the PSA. Figure 1. Artist’s rendition of a postcatheterization PSA with proper placement of the needle for thrombin injection. There is a disruption in all 3 layers of the arterial wall. In essence, this represents a contained rupture. Figure 2. Arteriogram that demonstrates an axillary artery PSA after a diagnostic arteriographic procedure. Note the disruption in the vessel wall (white arrow) and the larger PSA sac (black arrow). Figure 3. Ultrasound of a spontaneous PSA in the left brachial artery. Note the absence of a tract. The PSA chamber is directly connected to the brachial artery. This type of PSA must be treated surgically. This patient had infective endocarditis. Postcatheterization PSA is one of the most common vascular complications of cardiac and peripheral angiographic procedures. The incidence of PSA after diagnostic catheterization ranges from 0.05% to 2%.1 When coronary or peripheral intervention is performed, the incidence increases to 2% to 6%. In 1 series where diagnostic ultrasound was performed on 536 consecutive patients who underwent catheterization, the incidence of PSA was 7.7%, with 83% of the PSAs associated with interventional procedures.2 Despite a low …

Major Groin Complications Following the Use of Synthetic Grafts

The ideal results of vascular reconstructive surgery include an uncomplicated operation, symptomatic relief, prompt wound healing, rapid return to pre-operative functional status without long term functional consequences. Long term complications are often not emphasized. This study describes false femoral aneurysms (FFA) and infection following use of synthetic graft in the groin. All patients under the care of one surgeon, undergoing synthetic graft insertion involving the groin between January 1988 and December 2005 were included. Some 489 patients were included (745 at risk groins). A total of 34 patients developed either FFA or infection, involving 39 groins (5.2%). There were 18 FFA, presenting a median of four years after the original operation. FFA was more common following aortofemoral bypass grafts than femorofemoral or femorodistal bypasses (P=0.0084). Repair with interposition grafting was carried out in 17 cases. There was one death postoperatively. The remainder remained satisfactory at a median follow up of 60 months. Median time from original operation to 21 groin infections presenting was 12 months. Infection was commonest after femorofemoral cross over grafts P=0.023. Four major amputations were carried out. Debridement and sartorius transposition was useful in about half of the cases treated. Serious groin complications occur in about 5% of cases following use of a synthetic graft. This can result in significant morbidity long after the original operation has been carried out. Patients need to be made aware of this when obtaining informed consent.

Paraprosthetic fistula in a patient presenting with fever and lumbar pain

A 59-year-old woman presented to our emergency department with 10 days of fever and lumbar pain radiating to the right leg. She had undergone a right aortofemoral bypass graft (Dacron, 7 mm; Gold Knitted Microvel Double Velour Vascular Graft, Boston Scientific/Medi-Tech, Wayne, NJ) 8 months previously and was on warfarin therapy for atrial fibrillation and mitral stenosis. There was no history of GI bleeding. She was febrile (39°C), with normal blood pressure (110/70 mm Hg) and pulse (77 beats/min).

Robotically Assisted Aorto-Femoral Bypass Grafting: Lessons Learned From Our Initial Experience

Robotically Assisted Aorto-Femoral Bypass Grafting: Lessons Learned From Our Initial Experience

Aortofemoral bypass and the role of concomitant femorodistal reconstruction.

A consecutive series of 200 patients having aortofemoral bypass grafts were studied in order to determine the effect of femoropopliteal occlusive disease on the results and the role of concomitant femorodistal bypass. Bifurcated aortic grafts were used in 177 patients and unilateral aortofemoral grafts in 23 giving 377 limbs for study. Of the 377 limbs, 184 (49 per cent) had minimal femoropopliteal disease (Group 1), 24 (6.4 per cent) had a femoropopliteal stenosis (Group 2) and 169 (44.6 per cent) had complete femoropopliteal occlusion (Group 3). In Group 3 aortofemoral bypass was carried out alone in 106 cases (Group 3a): in the other 63 cases femorodistal bypass was carried out at the same time as aortoiliac reconstruction (Group 3b). The cumulative patency at 5 years for all aortofemoral grafts together was 91 per cent. However, that for grafts in Group 3a was only 65 per cent compared with 98 per cent for Groups 1 and 3b and 94 per cent for Group 2. The cumulative patency rate for grafts in Group 3a was significantly lower than for all other groups (P less than 0.001). The operative mortality for those patients who had concomitant aortofemoral and femorodistal grafts (Group 3b) did not differ significantly from that of any of the other groups (P greater than 0.1). Of the cases in Group 3a, 21 (26 per cent) required femoropopliteal reconstruction at a later date. The results indicate that in the presence of combined aortoiliac and femoropopliteal occlusive disease concomitant reconstruction of both arterial segments yields significantly better results than aortoiliac bypass alone.

'Circumflex' arterial bypass for ischaemia of the lower limbs--another imitation of natural collaterals.

Abstract Occasionally revascularization of the lower limb by direct aortofemoral or iliofemoral bypass graft is impracticable because of sepsis in the femoral triangle. In such cases the femoral triangle has been circumvented by using an alternative route via the obturator foramen for the bypass. It is pointed out that this obturator bypass is simply an imitation of natural collaterals (obturator and medial femoral circumflex arteries), but that it has certain limitations. Another alternative pathway is described and named the ‚circumflex’︁ bypass because it is an imitation of the circumflex collaterals (deep circumflex iliac and lateral femoral circumflex arteries). This bypass has been used successfully in 2 patients-from the common iliac to the superficial femoral in the first, and from the axillary to the superficial femoral in the second.

Aortoiliac and aortofemoral bypass grafting are widely used operative treatment modalities of aortic reconstruction for both aortic occlusive disease and aneurysms of abdominal aorta. Graft occlusion,

Aortoiliac and aortofemoral bypass grafting are widely used operative treatment modalities of aortic reconstruction for both aortic occlusive disease and aneurysms of abdominal aorta. Graft occlusion,

Potential Benefits of Laparoscopic Aorto-Bifemoral Bypass Surgery

Background : This series aims to prove the positive impact of laparoscopic approach in aortofemoral bypass grafting.Methods : It concerns a retrospective non randomized study comparing 58 consecutive patients treated with laparoscopic procedure (n = 30) and with a standard open procedure (n = 28) in a single center. The different operating times, the complications and the follow-up of these two groups are comparedResults : The demographics and angiographic data of the two groups were comparable. Operating time was longer in the laparoscopic group. However, we noticed a significant shorter hospitalisation stay (p < 0.0001) after the laparoscopic procedure with a mean 5.1 days. There was no significant difference of morbidity.Conclusion : We suggest that the trans-peritoneal approach is the best way in laparoscopic procedure in term of exposure and ergonomics. Laparoscopic aortofemoral bypass grafting is feasible, safe and effective. Shortening of operating time is observed as surgeon’as experience grows.

Robotically Assisted Aorto-femoral Bypass Grafting: Lessons Learned from our Initial Experience

Objective. The da Vinci™ Surgical System (Intuitive Surgical Inc., Sunnyvale, CA) is a computer-enhanced telemanipulator that may help to overcome some limitations of traditional laparoscopic instruments. This prospective study was performed to assess the safety and feasibility of robotically assisted aorto-femoral bypass grafting (AF). Methods. Five patients undergoing elective AF were enrolled in this study. In three patients, a laparotomy of 6 cm was first performed, the aorta being exposed using an Omnitract° retractor. In two patients, aortic dissection was performed with laparoscopy, with the patient in a modified right lateral decubitus position. In all patients, the proximal anastomosis was attempted with the da Vinci™ system by a remote surgeon. The role of the assistant at the patient's side was limited to exposure, haemostasis and maintaining traction on the running sutures performed by the robot. Six weeks after the operation, all patients underwent a duplex scan of the graft. Results. Mean operative time was 188 min. Robotically assisted aortic anastomoses were successfully completed in four out of five patients. In these four patients, adequate blood flow was observed within the graft with no need for conversion for haemostasis. In the fifth patient, despite an adequate laparoscopic aortic dissection, the anastomosis was impossible to perform due to external conflicts between the robotic arms. A conversion using conventional suture was successfully performed. No robot-related complications were noted. Six weeks after the operation, the duplex scans demonstrated a graft patency of 100%. Conclusion. Robotically assisted anastomoses are possible by their unique ability to combine conventional laparoscopic surgery with stereoscopic 3D magnification and ultra-precise suturing techniques due to the flexibility of the robotic-wristed instruments using different motion scaling of surgeon hand movements. In addition, prior training in laparoscopic aortic surgery is not necessary for surgeons to obtain the level required for suturing. Further clinical trials are needed to explore the clinical potential and value of robotically assisted AF.

Emergency endovascular treatment of acute aortic diseases

To investigate the safety and efficacy of emergency treatment of acute aortic diseases with endovascular stent grafts. In 11 patients (median age 55 years, range 18 - 85) with acute complications of descending aortic diseases endovascular emergency treatment was performed: traumatic aortic rupture (n = 4), penetrating ulcer with aortobronchial fistula or hematothorax (n = 4), acute type B dissection (n = 2, one with penetration, one with subacute mesenteric ischemia), and symptomatic aneurysm of the thoracic aorta (n = 1) with pain and diameter progression. 15 stent grafts were implanted (Talent n = 11, Vanguard/Stentor n = 4). Stent extension was necessary in 4 cases. In 2 cases graft extension was done during the first procedure (due to distal migration and due to the total length of the aortic aneurysm). In 2 cases graft extension was performed 5 days (due to a new aortic ulcer at the proximal stent struts) and 5 months after the initial procedure (recurrent aortobronchial fistula due to aneurysm progression). 14 of 15 implantations required general anesthesia, one symptomatic thoracic aneurysm was performed in local anesthesia and sedation. 14 of 15 graft procedures were performed using the femoral or iliac approach. One procedure required aortofemoral bypass grafting due to extensive arteriosclerotic stenosis and the stent graft was inserted via the bypass graft. The orifice of the subclavian artery was crossed with bare stent struts in 4 cases without neurological complications. Median follow-up is 27 months (range 6 to 72 months). In traumatic aortic ruptures, immediate sealing of bleeding was achieved and follow-up is inconspicuous at a maximum of 72 months. In cases of aortobronchial fistulas, follow-up is satisfactory (maximum 72 months) despite the necessity for reintervention and graft extension. In one acute type B dissection retrograde dissection of the aortic arch occurred during stent release with stable disease during follow-up without neurological complications. In one type B dissection with mesenteric ischemia the mesenteric blood flow was restored. A second look operation confirmed pulsatile flow in the mesenteric trunk but a total necrosis of the small intestine and the patient consequently died. Endovascular treatment is safe and effective for emergency treatment of life-threatening complications in selected acute aortic syndromes. Mid-term results are encouraging, however, regular follow-up is mandatory to recognize late complications of the stent graft.

Infrainguinal arterial reconstructions in patients with aortoiliac occlusive disease: The influence of iliac stenting

Objective: Iliac artery angioplasty (IAA) is an effective adjunct when combined with infrainguinal arterial reconstructions (IARs) in appropriate patients with multilevel occlusive disease. However, the effect of iliac artery stenting (IAS) on the outcome of patients undergoing distal bypass procedures is not defined. The purpose of this study was to estimate the influence of previous IAS for iliac occlusive disease on the outcome of IARs, compared with those after IAA alone or aortofemoral bypass grafting procedures (AFBs). Methods: During a 5-year period (1995-2000), 105 patients with previous intervention for iliac occlusive disease underwent 120 IARs. The criteria prepared by the Ad Hoc Committee on Reporting Standards (Society for Vascular Surgery/International Society for Cardiovascular Surgery) were followed to define the variables. The TransAtlantic Inter-Society Consensus classification was used to characterize the type of iliac lesions. Univariate (Kaplan-Meier) and multivariate analyses (Cox proportional hazards model) were used to determine the association between preoperative variables and cumulative primary patency. Results: Forty-five IARs were performed in patients with an earlier IAS repair, 33 in patients with an earlier IAA repair, and 42 in patients with an earlier AFB repair. There were not significant differences between patients in the IAS and IAA groups, except for a more frequent use of polytetrafluoroethylene grafts for IARs in the IAS group (40% vs 15%; χ2 test, P =.03). The 5-year primary patency rate for IARs was 68% in the IAS group, 46% in the IAA group, and 61% in the AFB group. Univariate analyses revealed that primary patency rates for IARs in patients with previous IAS were significantly higher than those in the IAA group (Kaplan-Meier, log-rank test, P =.02). Previous IAA repair was associated with a two-fold increased risk of IAR graft failure (relative risk, 2.2; 95% CI, 1.1-4.8; P =.04). Conclusions: IARs in patients with previous IAS have significantly improved graft patency, compared with those in patients with previous IAA alone. Such graft patency for IAR after IAS is similar to that obtained after AFB repair. (J Vasc Surg 2001;34:971-8.)

Remodeling and suppression of intimal hyperplasia of vascular grafts with a distal arteriovenous fistula in a rat model

Purpose: The purpose of this study was to evaluate the effects of a distal arteriovenous fistula (dAVF) on the morphologic changes occurring in arterial bypass grafts by the use of a novel experimental model. Methods: Aortofemoral bypass grafts with or without dAVFs were constructed in 36 Sprague-Dawley rats with a microsurgical technique. The bypass graft material consisted of deendothelialized autogenous tail artery (length, 25 mm; inside diameter, 0.5 mm). In 18 rats, dAVFs were constructed at the distal anastomosis. After 6 weeks, flow rates and shear stress were determined, and grafts were then harvested. Luminal, intimal, and medial cross-sectional areas were measured with computer imaging. Desmin, α–smooth muscle actin, and von Willebrand factor (vWF) were identified with immunohistochemistry. Endothelialization was evaluated with SEM. Results: All bypass grafts remained patent at the time of graft harvest. Grafts with dAVFs showed increased flow rates (11.5 ± 0.6 mL/min) compared with grafts without dAVFs (2.1 ± 0.3 mL/min; P <.01). Shear stress was also increased in the dAVF group (340.9 ± 23.4 dyne/cm2 vs 113.7 ± 12.5 dyne/cm2; P <.01), with a corresponding suppression of intimal hyperplasia (0.059 ± 0.011 mm2 for dAVF grafts vs 0.225 ± 0.009 mm2 for non-dAVF grafts; P <.01). Staining for vWF was found in both the reendothelialized flow surface and the neointimal extracellular matrix. Remodeling of the grafts was characterized by a 50% increased luminal area, 70% decreased intimal area, and a 25% decreased medial area when a dAVF was constructed. Conclusion: A small animal experimental model of an arterial bypass graft can enable the evaluation of a variety of factors that influence graft patency. Increased blood flow velocity and shear stress induced by a dAVF are associated with a decrease in intimal and medial areas, which may reflect changes in cell proliferation, apoptosis, migration, or matrix deposition. Deposition of vWF was also found both in the endothelium and throughout the hyperplastic intima. These findings suggest that the hemodynamic and morphologic changes associated with dAVF may potentiate graft patency and function. (J Vasc Surg 2001;34:701-6.)