Editor's Choice - Comparison of Renal Outcomes in Patients Treated by Zenith® Fenestrated and Zenith® Abdominal Aortic Aneurysm Stent grafts in US Prospective Pivotal Trials.

OBJECTIVE/BACKGROUND: Fenestrated endovascular repair (FEVAR) has been used to treat complex abdominal aortic aneurysms (AAAs). The risk of renal function deterioration compared with infrarenal endovascular aortic repair (EVAR) has not been determined. METHODS: Patients with preserved renal function (estimated glomerular filtration rate [eGFR] > 45 mL/minute) enrolled in two prospective, non-randomised studies evaluating Zenith fenestrated and AAA stent grafts were matched (1:2) by propensity scores for age, sex, hypertension, diabetes, and pre-operative eGFR. Sixty-seven patients were treated by FEVAR and 134 matched controls treated by EVAR. Mean follow-up was 30 ± 20 months. Outcomes included acute kidney injury (AKI) defined by RIFLE and changes in serum creatinine (sCr), eGFR, and chronic kidney disease (CKD) staging up to 5 years. RESULTS: AKI at 1 month was similar between groups, with > 25% decline in eGFR observed in 5% of FEVAR and 9% of EVAR patients (p = .39). There were no significant differences in > 25% decline in eGFR at 2 years (FEVAR 20% vs. EVAR 20%; p > .99) or 5 years (FEVAR 27% vs. EVAR 50%; p = .50). Progression to stage IV-V CKD was similar at 2 years (FEVAR 2% vs. EVAR 3%; p > .99) and 5 years (FEVAR 7% vs. EVAR 8%; p > .99), with similar sCr and eGFR up to 5 years. During follow-up, there were more renal artery stenosis/occlusions (15/67 [22%] vs. 3/134 [2%]; p < .001) and renal related re-interventions (12/67 [18%] vs. 4/134 [3%]; p < .001) in patients treated by FEVAR. Rate of progression to renal failure requiring dialysis was low and identical in both groups (1.5% vs. 1.5%; p > .99). CONCLUSION: Aortic repair with FEVAR and EVAR was associated with similar rates of renal function deterioration in patients with preserved pre-operative renal function. Renal related re-interventions were higher following FEVAR, although net changes in renal function were similar in both groups.

Aortic Arch Morphology and Aortic Length in Patients with Dissection, Traumatic, and Aneurysmal Disease.

OBJECTIVES: To assess aortic arch morphology and aortic length in patients with dissection, traumatic injury, and aneurysm undergoing TEVAR, and to identify characteristics specific to different pathologies. METHOD: This was a retrospective analysis of the aortic arch morphology and aortic length of dissection, traumatic injury, and aneurysmal patients. Computed tomography imaging was evaluated of 210 patients (49 dissection, 99 traumatic injury, 62 aneurysm) enrolled in three trials that received the conformable GORE TAG thoracic endoprosthesis. The mean age of trauma patients was 43 ± 19.6 years, 57 ± 11.7 years for dissection and 72 ± 9.6 years for aneurysm patients. A standardized protocol was used to measure aortic arch diameter, length, and take-off angle and clockface orientation of branch vessels. Differences in arch anatomy and length were assessed using ANOVA and independent t tests. RESULTS: Of the 210 arches evaluated, 22% had arch vessel common trunk configurations. The aortic diameter and the distance from the left main coronary (LMC) to the left common carotid (LCC) were greater in dissection patients than in trauma or aneurysm patients (p < .001). Aortic diameter in aneurysm patients was greater compared with trauma patients (p < .05). The distances from the branch vessels to the celiac artery (CA) were greater in dissection and aneurysm patients than in trauma patients (p < .001). The take-off angle of the innominate (I), LCCA, and left subclavian (LS) were greater, between 19% and 36%, in trauma patients than in dissection and aneurysm patients (p < .001). Clockface orientation of the arch vessels varies between pathologies. CONCLUSIONS: Arch anatomy has significant morphologic differences when comparing aortic pathologies. Describing these differences in a large sample of patients is beneficial for device designs and patient selection.

Stent-graft use in urgent and emergent AAA management.

The use of stent grafts in the treatment of ruptured aortic aneurysm, abdominal (AAA) may reduce mortality associated with this process through its dramatic alteration of the surgical technique employed. Advantages of endovascular repair include the ability to perform the procedure under local anesthesia, decreased physiologic stress of avoiding a laparotomy and avoiding collateral damage during open repair. Criticisms of this technique include additional preoperative time spent obtaining appropriate imaging, the necessity for specialized products and personnel required to perform the procedure, and late complications such as abdominal compartment syndrome. Current data regarding a survival advantage appear favorable but flawed, highlighting the need for prospective randomized trial. Three trials are currently underway with the largest, the IMPROVE trial, the most likely to yield definitive evidence.

Computational mechanics of Nitinol stent grafts.

A finite element analysis of tubular, diamond-shaped stent grafts under representative cyclic loading conditions for abdominal aortic aneurysm (AAA) repair is presented. Commercial software was employed to study the mechanical behavior and fatigue performance of different materials found in commercially available stent-graft systems. Specifically, the effects of crimping, deployment, and cyclic pressure loading on stent-graft fatigue life, radial force, and wall compliances were simulated and analyzed for two types of realistic but different Nitinol materials (NITI-1 and NITI-2) and grafts (expanded polytetrafluoroethylene-ePTFE and polyethylene therephthalate-PET). The results show that NITI-1 stent has a better crimping performance than NITI-2. Under representative cyclic pressure loading, both NITI-1 and NITI-2 sealing stents are located in the safe zone of the fatigue-life diagram; however, the fatigue resistance of an NITI-1 stent is better than that of an NITI-2 stent. It was found that the two types of sealing stents do not damage a healthy neck artery. In the aneurysm section, the NITI-1&ePTFE, NITI-1&PET, and NITI-2&PET combinations were free of fatigue fracture when subjected to conditions of radial stress between 50 and 150mmHg. In contrast, the safety factor for the NITI-2&ePFTE combination was only 0.67, which is not acceptable for proper AAA stent-graft design. In summary, a Nitinol stent with PET graft may greatly improve fatigue life, while its compliance is much lower than the NITI-ePTFE combination.

Surgical bypass procedures to facilitate endovascular repair of aortic arch pathology.

Thoracic aortic aneurysms and other thoracic aortic lesions may become life-threatening conditions if they remain untreated. Conventional open surgical reconstruction with placement of an interposition graft is regarded as a definitive form of treatment, but is associated with considerable operative morbidity and mortality. Thoracic aortic lesions involving the aortic arch require more complex surgical interventions necessitating cardiopulmonary bypass, and hypothermic circulatory arrest. Outcomes from this form of treatment have a reported early stroke and death rate of up to 25%. Thoracic endovascular aortic repair is a less invasive alternative for the treatment of many thoracic aortic lesions. The application of a thoracic endoprosthesis may be limited by the extent of involvement of the proximal thoracic aorta as coverage of arch vessel ostia may be necessary to obtain adequate proximal endograft fixation and aneurysm exclusion. In an effort to overcome proximal landing zone limitations imposed by arch vessel involvement, hybrid surgical-endovascular reconstructive and debranching bypass procedures have been performed to create a proximal landing zone of adequate length. Although these adjunctive techniques incorporate invasive surgical procedures, it is believed that minimizing the procedural invasiveness, by avoiding aortic cross-clamping and/or hypothermic circulatory arrest, morbidity and mortality outcomes can be improved especially in high-risk patients. Several surgical approaches and techniques have been described for various levels of aortic arch involvement with encouraging early and mid-term results, although the long-term durability of these hybrid surgical-endovascular procedures remains to be defined.

Thoracic endovascular aortic repair of traumatic injuries involving the descending thoracic aorta.

Acute traumatic thoracic aortic transection is a devastating injury that often occurs in the context of multiple associated traumatic injuries. Patients who survive the initial trauma and present to the hospital experience progressive hospital mortality and remain at risk for rupture of the contained injury. Conventional open surgical repair is regarded as a definitive form of treatment with long-term durability. Unfortunately, the stress subjected upon the multitrauma patient during the operative intervention is believed to contribute to considerable operative morbidity and mortality. Despite advancements in the management and treatment of this condition, hospital and operative mortality remains high. Thoracic endovascular aortic repair (TEVAR) has emerged as a viable alterative to conventional open repair for the treatment of these injuries. This less invasive form of therapy allows for a rapid stabilization of the aortic disruption without subjecting the patient to the physiologic stress of a major operative intervention. This may potentially translate into reductions in associated operative mortality and morbidity for this condition. This review highlights some of the anatomic and technical considerations regarding endovascular repair of traumatic thoracic aortic injuries, and reviews reported outcomes.

Fluid-structure interaction analyses of stented abdominal aortic aneurysms.

Rupture of abdominal aortic aneurysms (AAAs) alone is the thirteenth leading cause of death in the United States. Thus, reliable AAA-rupture risk prediction is an important advancement. If repair becomes necessary, the minimally invasive technique of inserting a stent-graft (SG), commonly referred to as endovascular aneurysm repair (EVAR), is a viable option in many cases. However, postoperative complications, such as endoleaks and/or SG migration, may occur. Computational fluid-structure interaction simulations provide physical insight into the hemodynamics coupled with multi-wall mechanics' function as an assessment tool for optimal SG placement and improved device design.

Overexpression of the focal adhesion kinase (p125FAK) in the vascular smooth muscle cells of intimal hyperplasia.

PURPOSE: The migration and proliferation of vascular smooth muscle cells (VSMCs) are important events in the development of intimal hyperplasia (IH). The focal adhesion kinase (FAK) gene encodes a protein tyrosine kinase (p125FAK) involved in signal transduction pathways used in cell adhesion, motility, and proliferation. Because alterations in these cellular processes are thought to occur in VSMCs during IH, we studied FAK expression in healthy arteries and veins in comparison with that in pathologic vessels containing IH. METHODS: To determine p125FAK expression at the cellular level, we developed a monoclonal antibody that specifically detected FAK in formalin-fixed, paraffin-embedded tissue sections (5 microm) and analyzed the levels of FAK expression in human arteries and veins. Specificity of monoclonal antibody 4.47 was demonstrated by means of immunofluorescence microscopy showing FAK-specific staining at focal adhesions of healthy human vascular smooth muscle cells (AoSMCs). By using immunohistochemistry techniques, we analyzed the expression of p125FAK in 25 adult human vascular tissue samples from individual patients, which contained a histologically confirmed healthy artery, vein, or IH. RESULTS: FAK expression in healthy and pathologic human vascular tissue was localized predominantly within VSMC cytoplasm. In healthy human artery and vein, borderline FAK expression was detected in the media of seven of 17 vessels and undetectable in the remainder of specimens. However, in vessels containing IH, FAK was overexpressed in the pathologic VSMC populations at moderate-to-strong levels in eight of eight specimens. The levels of FAK expression were directly correlated with structures containing IH, and the results of FAK staining intensity and the percentage of positive cells in these samples were significantly increased compared with normal vascular tissue levels (P <.05, Student t test). CONCLUSION: These results provide the first evidence that FAK is overexpressed in VSMCs involved in IH and suggest that FAK upregulation may be part of a mechanism for migration and proliferation of VSMCs during this process. Furthermore, the dramatic upregulation of FAK in IH and the relative lack of expression in healthy vessels suggest that FAK may be a rational target for controlling IH.

Distal thoracic aorta as inflow for the treatment of chronic mesenteric ischemia.

PURPOSE: Mesenteric revascularization for chronic mesenteric ischemia (CMI) traditionally involves antegrade or retrograde bypass graft originating from the supraceliac or infrarenal aorta. The distal thoracic aorta (DTA) may provide a better inflow source than the abdominal aorta. The purpose of this study was to evaluate the results with the DTA used as inflow for the surgical treatment of CMI. METHODS: All patients undergoing mesenteric revascularization for CMI with grafts originating from the DTA were identified from 1990 to 1999. A ninth interspace thoracoretroperitoneal incision was used for exposure, and distal aortic flow was maintained by use of a partial occlusion clamp. RESULTS: Eighteen consecutive patients with CMI underwent mesenteric bypass grafting with the DTA used as inflow. All patients were admitted with chronic abdominal pain or weight loss, with two (12%) requiring urgent revascularization because of acute exacerbation of chronic symptoms. Fourteen (78%) patients had both celiac and superior mesenteric artery bypass grafts placed, and three (17%) patients had superior mesenteric artery grafts alone. There was one (6%) perioperative death and three (17%) major complications. There was no kidney failure, mesenteric infarction, or spinal cord ischemia. The life-table survival rate was 89%, 89%, and 76% at 1, 3, and 5 years, respectively. All 18 patients remained symptom free and required no additional procedures to assist patency. There was no evidence of graft stenosis or occlusion (100% patency) for those grafts evaluated objectively during the mean follow-up of 34.8 months (range, 1-97 months). CONCLUSIONS: Antegrade mesenteric revascularization with the DTA used as inflow is associated with low morbidity and mortality rates. Furthermore, it provides excellent midterm patency and survival results and should be considered as a primary approach for reconstruction of patients with CMI.

Sural artery pseudoaneurysms after knee arthroscopy: treatment with transcatheter embolization.

Vascular injury of the popliteal artery or its branches after knee arthroscopy is a rare but potentially devastating complication. We report two cases of sural artery branch pseudoaneurysms resulting from knee arthroscopy. Both patients were successfully treated with transcatheter embolization of the pseudoaneurysms. the diagnosis and treatment options of this unusual injury are discussed.

The value of air plethysmography in predicting clinical outcome after surgical treatment of chronic venous insufficiency.

PURPOSE: The role of air plethysmography (APG) as a predictor of clinical outcome after surgery in venous disease is yet to be defined. The purpose of this study was to investigate the value of APG in predicting clinical outcome after venous surgery for chronic venous insufficiency (CVI). METHODS: Seventy-three extremities in 71 patients with Class 3 through 6 CVI were assessed preoperatively with CEAP (c linical, e tiologic, a natomic, p athophysiologic) criteria, standing reflux duplex ultrasound scan, and APG with measurements of preoperative venous filling index (VFI), venous volumes, ejection fraction, and residual volume fraction. After surgical treatment of the affected limbs, repeat APG studies were obtained within 6 weeks. Established venous reporting standards were used for follow-up to calculate clinical symptom scores (CSSs) in each patient. RESULTS: Superficial venous reflux occurred alone in 24 limbs or in conjunction with perforator incompetence in 26 limbs. Deep and superficial reflux, with or without perforator incompetence, was found in 16 limbs, and seven limbs had isolated deep insufficiency. Follow-up was available in 60 of 71 patients (mean period, 44.3 months). Postoperative APG demonstrated significant hemodynamic changes after surgery as measured with VFI, venous volumes, ejection fraction, and residual volume fraction. Mean CSSs decreased from 7.35 +/- 0.56 preoperatively to 1.79 +/- 0.32 at late follow-up after surgery (P <.001). With the use of logistic regression, the parameter correlating most closely with clinical outcome was the VFI. A normal postoperative VFI (

Prospective screening for postoperative deep venous thrombosis in patients undergoing infrainguinal revascularization.

PURPOSE: The incidence of deep venous thrombosis (DVT) in patients undergoing infrainguinal bypass graft procedures has not been well documented, and the need for routine prophylaxis remains controversial. The purpose of this study was to prospectively evaluate the risk of postoperative DVT complicating infrainguinal revascularization. METHODS: Seventy-four patients undergoing infrainguinal bypass graft procedures during a 12-month period were prospectively screened for DVT. Bilateral lower extremity venous duplex scan imaging was performed preoperatively and within 1 week and 6 weeks, postoperatively. Routine DVT prophylaxis was not used, with anticoagulation reserved for specific indications. RESULTS: Of the 74 patients screened, three patients (4.1%) had DVT identified on preoperative venous duplex scan imaging and were excluded from the study. Of the remaining 71 patients enrolled, only two patients (2.8%) had postoperative DVT. Postoperative DVT was ipsilateral to the bypass graft extremity in both patients, with involvement of the peroneal vein in one patient and the femoral vein in the other. Although routine prophylaxis was not used, 18 of these patients (25%) were anticoagulated for other indications, with DVT occurring in one patient (5.6%). Of the remaining 53 patients who did not receive postoperative anticoagulation, only one patient (1.8%) had DVT. CONCLUSIONS: According to this prospective study, the risk of postoperative DVT in patients undergoing infrainguinal revascularization is low. Routine prophylaxis is not recommended, with postoperative anticoagulation reserved for specific indications.

Use of endovascular stents for the treatment of abdominal aortic aneurysm.

The conventional open surgical repair of abdominal aortic aneurysms is a well-established and durable procedure. However, as with all other major abdominal surgical operations, there are associated morbidities. Both mortality and morbidity increase significantly with advanced patient age and associated comorbid conditions. Endovascular aortic stent-grafts offer a significantly less invasive alternative to conventional open-surgical repair. Patients previously considered unsuitable for open repair can often receive treatment for aneurysms with endovascular techniques. The US Food and Drug Administration has recently approved two endovascular stent-graft devices for use within the United States.

Healing rates and cost efficacy of outpatient compression treatment for leg ulcers associated with venous insufficiency.

OBJECTIVE: Although newer techniques to promote the healing of leg ulcers associated with chronic venous insufficiency are promising, improved healing rates and cost effectiveness are unproven. We prospectively followed a series of patients who underwent treatment with outpatient compression for venous stasis ulcers without adjuvant techniques to determine healing rates and costs of treatment. METHODS: Two hundred fifty-two patients with clinical or duplex scan evidence of chronic venous insufficiency and active leg ulcers underwent treatment with ambulatory compression techniques. The patients were prospectively followed with wound measurements at 1-week to 2-week intervals, and the factors that were associated with delayed healing were determined. RESULTS: Of all the ulcers, 57% were healed at 10 weeks of treatment and 75% were healed at 16 weeks. Ultimately, 96% of the ulcers healed, and only 1 major amputation was necessitated (0.4%). Initial ulcer size and moderate arterial insufficiency (ankle brachial index, 0.5 to 0.8; n = 34) were factors that were independently associated with delayed healing (P <.01). Patient age, ulcer duration before treatment, and morbid obesity did not significantly affect healing times. The cost of 10 weeks of outpatient treatment with compression techniques ranged from $1444 to $2711. CONCLUSION: The treatment of venous stasis ulcers with compression techniques results in reliable, cost-effective healing in most patients. Current adjuvant techniques may prove to be useful but are likely to be cost effective only in a minority of cases, particularly in patients with large initial ulcer size or arterial insufficiency.

Descending thoracic aorta to iliofemoral artery bypass grafting: a role for primary revascularization for aortoiliac occlusive disease?

PURPOSE: Bypass grafts that originate from the descending thoracic aorta to the iliac or femoral arteries are well described but are not commonly used as primary procedures, and the long-term results remain unknown. A 15-year experience with 50 descending thoracic aorta to iliofemoral artery bypass grafts for aortoiliac occlusive disease is the basis of this report. METHODS: From January 1983 to December 1997, patients who underwent bypass grafting procedures from the descending thoracic aorta to the iliac or femoral arteries were identified. Surgical indications, morbidity and mortality rates, primary and secondary patency rates, limb salvage rates, and survival rates were determined. RESULTS: Fifty descending thoracic aorta to iliofemoral artery bypass grafting procedures were performed 24 (48%) for severe claudication, 22 (44%) for rest pain, and 4 (8%) for ischemic ulceration. A primary procedure was performed in 31 patients (62%) for complete occlusion (21 patients) and severe atherosclerotic disease (10 patients) of the infrarenal aorta. The indications for 19 secondary revascularizations (38%) were prior aortic or extra-anatomic graft failure in 17 cases and aortic graft infection in 2 cases. The follow-up periods ranged from 1 to 150 months (mean, 39 months). The cumulative life-table 5-year primary patency, secondary patency, limb salvage, and survival rates were 79%, 84%, 93%, and 67%, respectively. An improved patency trend was observed for patients who underwent operation for severe claudication as compared with limb-threatening ischemia (92% and 69%; P =.07). However, there was no difference between primary and secondary operations in primary patency rates (81% and 79%; P = NS) or survival rates (72% and 62%; P = NS). CONCLUSION: Descending thoracic aorta to iliofemoral artery bypass grafting has excellent overall long-term results. These results support its more liberal use for primary revascularization, especially for patients with severe atherosclerotic disease or complete occlusion of the infrarenal aorta.

Efficacy of color flow duplex imaging for proximal upper extremity venous outflow obstruction in hemodialysis patients.

PURPOSE: The efficacy of color flow duplex imaging (CFDI) in detecting proximal upper extremity venous outflow obstruction in hemodialysis patients was compared with that of traditional contrast venography. METHODS: From 1993 through 1997, all hemodialysis patients who were evaluated for upper extremity venous outflow obstruction of the axillary, subclavian, or brachiocephalic veins with both CFDI and venography were identified. Medical history, hemodialysis access procedures, and indications for imaging were reviewed. The diagnostic accuracy of CFDI was compared with that of venography for proximal venous outflow obstruction, including focal stricture, partial obstruction, or complete occlusion. RESULTS: Sixty upper extremities in 42 hemodialysis patients were imaged with both CFDI and venography. Previous ipsilateral intravenous dialysis catheters had been present in 33 (55%) of the extremities imaged; current catheters were present in 16 (27%) of the extremities imaged; and 28 (67%) of the extremities imaged had a current ipsilateral arteriovenous (AV) shunt. Five (8%) of the 60 duplex scans were nondiagnostic because of artifact from intravenous dialysis catheters (3) or incomplete visualization of the subclavian or brachiocephalic veins (2) and were excluded from further analysis. In the remaining 55 duplex scans, proximal venous outflow obstruction was found in 18 (33%), compared with 21 (38%) identified by means of venography (P = not significant [NS]). Overall sensitivity, specificity, positive predictive value, and negative predictive value for CFDI were 81%, 97%, 94%, and 89%, respectively. CONCLUSION: CFDI is a reliable means of detecting proximal upper extremity venous outflow obstruction and should replace contrast venography as the initial imaging study in hemodialysis patients.

The role of air plethysmography in the diagnosis of chronic venous insufficiency.

PURPOSE: The role of air plethysmography (APG) in the diagnosis of venous disease is not well defined. We conducted this study to investigate the value of APG in the diagnosis of chronic venous insufficiency and to determine its correlation with the clinical severity of disease and the anatomic distribution of reflux. METHODS: We studied 186 lower extremities with duplex scanning and venography and measured the venous volume, venous filling index (VFI), ejection fraction, and residual volume fraction with APG. Limbs were categorized according to the Society for Vascular Surgery and International Society for Cardiovascular Surgery classification of clinical severity of disease and according to the anatomic distribution of valvular incompetence. RESULTS: Sixty-one limbs had no evidence of disease (class 0), 60 limbs had mild disease (classes 1, 2, and 3), and 65 limbs had severe disease (classes 4, 5, and 6). According to the results of duplex scanning and venography, there was no evidence of reflux in 56 limbs. Isolated superficial venous reflux occurred in 52 limbs, and perforator reflux, alone or in conjunction with superficial reflux, occurred in 30. Deep reflux, with or without superficial reflux, was found in 25 limbs. Deep and perforator reflux, with or without superficial reflux, was found in 19 limbs. The VFI had a sensitivity of 80% and 99% positive predictive value for any type of reflux. The VFI was significantly different between groups of limbs with different clinical severities of disease or different types of reflux. The incidence of deep or perforator reflux in limbs with a normal VFI value was 7%, and it was 82% in limbs with a VFI of more than 5. Among 86 limbs with VFI values not corrected with use of a thigh tourniquet, 28% did not have evidence of deep or perforator reflux, and among 15 limbs with VFI values corrected with the use of a tourniquet, 33% had perforator reflux, deep reflux, or both. All APG parameters had low positive predictive values for severe disease or ulceration. The ejection fraction and residual volume fraction did not influence the clinical severity of disease, did not discriminate between types of reflux, and in combination with the VFI did not improve the predictive value of APG. CONCLUSIONS: The VFI measured by APG is an excellent predictor of venous reflux, provides an estimate of the clinical severity of disease, and at high levels predicts deep reflux, perforator reflux, or both. Correction of an abnormal VFI with a thigh tourniquet is an unreliable predictor of the absence of deep or perforator incompetence. The predictive value of APG for severe disease or ulceration is poor. The ejection fraction and residual volume fraction, individually or in combination with the VFI, add little to the diagnostic value of APG, and their routine performance may not be clinically justified.