Workflow and Patient Satisfaction in Treating Peripheral Arterial Disease in the Office-Based Setting

Contemporary concepts in health-care reform promote a shift in the provision of care away from hospitals in favor of the more cost-effective and efficient use of outpatient facilities including ambulatory surgery centers and office-based procedure centers particularly in the care of cardiovascular disease. This article reviews the experience of patients and specialists in caring for patients with peripheral arterial disease in an office-based care setting.

Initial experience with the ambulatory management of acute iliofemoral deep vein thrombosis with May-Thurner syndrome with percutaneous mechanical thrombectomy, angioplasty and stenting

OBJECTIVE

Patients undergoing intervention for acute iliofemoral deep vein thrombosis (IFDVT) with May-Thurner syndrome (MTS) typically require inpatient (IP) hospitalization for initial treatment with anticoagulation and management with pharmacomechanical thrombectomy. Direct oral anticoagulants and percutaneous mechanical thrombectomy (PMT) devices offer the opportunity for outpatient (OP) management. We describe our approach with these patients.

METHODS

Patients receiving intervention for acute IFDVT from January 2020 through October 2022 were retrospectively reviewed. Patients undergoing unilateral thrombectomy, venous angioplasty, and stenting for IFDVT with MTS comprised the study population and were divided into two groups: (1) patients admitted to the hospital and treated as IPs and (2) patients who underwent therapy as OPs. The two groups were compared regarding demographics, risk factors, procedural success, complications, and follow-up.

RESULTS

A total of 92 patients were treated for IFDVT with thrombectomy, angioplasty, and stenting of whom 58 comprised the IP group and 34 the OP group. All 92 patients underwent PMT using the Inari ClotTriever (Inari Medical), intravascular ultrasound, angioplasty, and stenting with 100% technical success. Three patients in the IP group required adjuvant thrombolysis. There was no difference in primary patency of the treated IFDVT segment at 12 months between the two groups (IP, 73.5%; OP, 86.7%; P = .21, log-rank test).

CONCLUSIONS

Patients with acute IFDVT and MTS deemed appropriate for thrombectomy and iliac revascularization can be managed with initiation of ambulatory direct oral anticoagulant therapy and subsequent return for ambulatory PMT, angioplasty, and stenting. This approach avoids the expense of IP care and allows for effective use of resources at a time when staffing and supply chain shortages have led to inefficiencies in the provision of IP care for nonemergent conditions.

Hybrid repair of aberrant right subclavian artery using open and endovascular techniques

An aberrant right subclavian artery, the most common anatomic variant of the aortic arch, occurs in 0.5% of the population. Symptoms generally result from compression of the esophagus and/or trachea as the aberrant vessel passes posteriorly in the mediastinum. Treatment includes revascularization of the right subclavian artery from the right common carotid artery using a cervical approach combined with occlusion of the origin of the aberrant vessel from the thoracic aorta. We describe a hybrid treatment approach for a symptomatic aberrant right subclavian artery using cervical revascularization and branched thoracic stent graft coverage of the origin of the aberrant vessel.

Management with right atrium to jugular and brachiocephalic vein bypass for dialysis catheter-related superior vena cava syndrome

Superior vena cava (SVC) syndrome is a spectrum of potentially life-threatening clinical manifestations resulting from either partial or complete obstruction of central venous blood flow. Approximately 70% of cases are caused by malignancy. The primary treatment end point for SVC syndrome is the achievement of long-term patency of the SVC. Malignant SVC syndrome is managed by either radiation therapy, open surgical intervention, or endovascular therapy with angioplasty and stenting. The current report describes an uncommon case of nonmalignant SVC syndrome resulting from complications of hemodialysis catheters that was managed with open revascularization between the right internal jugular and brachiocephalic veins and the right atrium.

Effect of Two Years of Doxycycline Treatment on Infrarenal Aortic Neck Diameter

Objective

Endovascular aneurysm repair (EVAR) is a widely used option for patients with suitable vascular anatomy who have a large infrarenal abdominal aortic aneurysm (AAA). Neck diameter is the primary anatomical determinant of EVAR eligibility and device durability. Doxycycline has been proposed to stabilise the proximal neck after EVAR. This study explored doxycycline mediated aortic neck stabilisation in patients with small AAA, monitored by computed tomography over two years.

Methods

This was a multicentre prospective randomised clinical trial. Subjects from the Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA³CT, NCT01756833) were included in this secondary a priori analysis. Female baseline AAA maximum transverse diameter was between 3.5 and 4.5 cm, and male was between 3.5 and 5.0 cm. Subjects were included if they completed pre-enrolment and two year follow up computed tomography (CT) imaging. Proximal aortic neck diameter was measured at the lowest renal artery, and 5, 10, and 15 mm caudal to this point; mean neck diameter was calculated from these values. Unpaired, two tailed parametric t test analysis with post hoc Bonferroni correction was used to detect differences between neck diameters in subjects treated with placebo vs. doxycycline at baseline and two years.

Results

One hundred and ninety-seven subjects (171 male, 26 female) were included in the analysis. All patients, regardless of treatment arm, demonstrated larger neck diameter caudally, a slight increase in diameter at all anatomical levels over time, and greater growth caudally. There was no statistically significant difference in infrarenal neck diameter between treatment arms at any anatomical level at any time point, nor mean change in neck diameter over two years.

Conclusion

Doxycycline does not demonstrate infrarenal aortic neck growth stabilisation in small AAA followed for two years by thin cut CT imaging using a standardised acquisition protocol and cannot be recommended for mitigation of growth of the aortic neck in patients with untreated small abdominal aortic aneurysms.

Acute Limb Arterial Ischemia Following Iliac Vein Stenting in the Setting of a Frozen Pelvis

The authors report on a young patient with previous radiation to her pelvis who presented with acute limb ischemia following iliac vein stenting believed to be secondary to extrinsic iliac artery compression in the setting of a frozen pelvis. She underwent revascularization and a trans-femoral amputation, ultimately needing a femoral to femoral artery crossover bypass in order to achieve amputation stump healing. This case describes a potential arterial complication of venous stenting in a previously irradiated field.

The Use of Re-Entry Devices Through Pedal Arterial Access in the Management of Chronic Limb-Threatening Ischemia

Infra-inguinal arterial chronic total occlusions remain a challenging scenario for the endovascular practitioner. Retrograde access has quickly become an essential tool in approaching such lesions, increasing the chances of crossing success. When antegrade and retrograde access techniques fail in achieving lesion crossing, re-entry devices have proven to be useful. Their use is however, somewhat limited by the size of the sheaths required to accommodate their passage. As newer and slimmer profiled sheaths become available, the possibilities of interventions available from minimally invasive approaches increases. We present 2 complex arterial revascularization cases that required intravascular ultrasound-based re-entry devices utilizing a pedal retrograde access.

Mycotic infrarenal aortic aneurysm due to mycobacterium after intravesical treatment for bladder cancer

Intravesical instillation of Bacillus Calmette-Guerin, a live-attenuated strain of Mycobacterium bovis, is a common adjuvant therapy for bladder cancer with a low incidence of serious adverse events. The case described herein illustrates a rare complication of intravesical Bacillus Calmette-Guerin instillation that resulted from invasion of the mycobacterium into tissue outside of the bladder lining, also known as microbial dissemination, leading to infection of the aortic wall and development of a mycotic aneurysm, and highlights the therapeutic challenges presented by the aortic pathology in this clinical scenario.

A case of leiomyosarcoma of the common femoral artery

Leiomyosarcomas are rare malignant tumors of smooth muscle cell origin with those originating from blood vessels accounting for <1%. We report the unusual case of a leiomyosarcoma originating in the wall of the common femoral artery, highlighting the management decisions for vascular tumors and providing a brief literature review for these unusual malignancies.

Hybrid Approach with Angiography and Limited Open Exposure to Treat Type Ia Endoleaks after Endovascular Aortic Aneurysm Repair

BACKGROUND

Type Ia endoleaks after endovascular aortic repair (EVAR) almost always mandate secondary percutaneous reinterventions. Several patients, however, will require conversion to open surgical repair with complete graft explant, which is associated with significant morbidity and mortality. We herein present 3 cases of hybrid surgical repair for type Ia endoleaks, using a limited open exposure for proximal stent graft edge revision to achieve graft preservation and effective aneurysm sac exclusion.

METHODS

Angiography was used to confirm type Ia endoleak in 3 patients (2 males) who had previous EVAR between October 2017 and October 2019. Time to the endoleak after the index EVAR was immediate in 1 patient during repair of a ruptured aneurysm, 2 months in 1 patient and 2 years in 1 patient. The aorta was exposed through a limited transabdominal (n = 1) or retroperitoneal (n = 2) approach and circumferential aortic control was achieved below the renal arteries. A row of interrupted horizontal mattress sutures of 3-0 polypropylene reinforced with Teflon pledgets was placed along the aortic neck circumference. Multi-planar angiography was then repeated to verify the absence of sac filling and successful type Ia endoleak exclusion. Follow-up abdominal duplex was obtained for all 3 patients after discharge to monitor the stent graft and confirm endoleak resolution. Furthermore, there were no instances of acute renal failure.

RESULTS

In the period of review, 77 patients underwent EVAR. In the 3 patients described, we were able to achieve complete aneurysm sac exclusion and stent graft preservation in all cases. Follow-up imaging was available on 2 patients at 4-6 weeks after surgery demonstrating sustained exclusion of the endoleak. Two patients died during follow-up: one from a myocardial infarction 7 weeks after surgery and one from metastatic lung cancer at 8 months after surgery. Follow up duplex imaging at one year on the single survivor demonstrated sac shrinkage and absence of endoleak.

CONCLUSIONS

Type Ia endoleaks represent a significant source of morbidity and mortality after EVAR and typically require repair to avoid aneurysm rupture. Our use of limited proximal revision without explant provides an alternative approach to resolve the endoleaks while reducing the magnitude of physiological stress when compared to an open explant. It represents a feasible option for high-risk patients.

Upper Arm Arteriovenous Grafts are Superior over Forearm Arteriovenous Grafts in Upper Extremity Dialysis Access

BACKGROUND

In this study, we compared the outcomes of forearm arteriovenous grafts (AVGs) and upper arm AVGs in a large, prospectively collected data set, which represents real-world experience with upper extremity prosthetic dialysis access, to determine if there are clinically significant differences in the upper arm and forearm positions.

METHODS

We identified 2,063 patients who received upper extremity AVGs within the Vascular Quality Initiative data set (2010-2018). Axillary to axillary upper arm AVGs were excluded (n = 394) from the analysis. The main outcome measures were primary and secondary patency rates at 12 months. Other outcomes were 6-month wound infection, steal syndrome, and arm swelling. The log-rank test was used to evaluate patency loss using a Kaplan-Meier analysis. Cox proportional hazards models were used to examine adjusted association between locations (forearm and upper arm) and outcomes.

RESULTS

There were 1,160 forearm AVGs and 509 upper arm brachial artery AVGs in the study cohort. Patients with forearm AVGs were more likely to have a body mass index > 30 (45% vs. 38%, P = 0.013), no history of previous access (73% vs. 63%, P < 0.001), and underwent local-regional anesthesia (56% vs. 43%, P < 0.001). The 12-month primary patency (51.5% vs. 62.9%, P < 0.001) and secondary patency (76.4% vs. 89.1%, P < 0.001) were significantly lower for forearm AVGs. Wound infection, steal syndrome, and arm swelling were similar between forearm AVGs and upper arm AVGs at the 6-month follow-up. In multivariable analysis, the primary patency loss (adjusted hazard ratio (aHR) 1.66, 95% confidence interval (CI) 1.33-2.01, P < 0.001) and 12-month secondary patency loss (aHR 2.71, 95% CI 1.84-3.98, P < 0.001) were significantly higher for forearm AVGs at 12 months.

CONCLUSIONS

From this observational study of the Vascular Quality Initiative data set, the primary and secondary patency rates were superior for upper arm brachial artery AVGs compared with forearm AVGs.

Mycotic aneurysm of the distal thoracic aorta after botulinum toxin injection for esophageal dysmotility

Endoscopic injection of botulinum toxin is a common method to treat esophageal dysmotility and achalasia. Patients undergoing this procedure who subsequently present with abdominal or back pain and constitutional symptoms should be evaluated for possible complications of the procedure, including occult esophageal perforation, mediastinitis, and mycotic aneurysm of the thoracic aorta. The case described herein illustrates the importance of serial imaging in a patient with persistent symptoms after botulinum toxin injection to identify and to treat occult aortic inoculation leading to mycotic aneurysm before sepsis and aortic rupture ensue with their attendant morbidity and mortality risks.

Endothelial vascular cell adhesion molecule 1 is a marker for high-risk carotid plaques and target for ultrasound molecular imaging

BACKGROUND

Molecular imaging of carotid plaque vulnerability to atheroembolic events is likely to lead to improvements in selection of patients for carotid endarterectomy (CEA). The aims of this study were to assess the relative value of endothelial inflammatory markers for this application and to develop molecular ultrasound contrast agents for their imaging.

METHODS

Human CEA specimens were obtained prospectively from asymptomatic (30) and symptomatic (30) patients. Plaques were assessed by semiquantitative immunohistochemistry for vascular cell adhesion molecule 1 (VCAM-1), lectin-like oxidized low-density lipoprotein receptor 1, P-selectin, and von Willebrand factor. Established small peptide ligands to each of these targets were then synthesized and covalently conjugated to the surface of lipid-shelled microbubble ultrasound contrast agents, which were then evaluated in a flow chamber for binding kinetics to activated human aortic endothelial cells under variable shear conditions.

RESULTS

Expression of VCAM-1 on the endothelium of CEA specimens from symptomatic patients was 2.4-fold greater than that from asymptomatic patients (P < .01). Expression was not significantly different between groups for P-selectin (P = .43), von Willebrand factor (P = .59), or lectin-like oxidized low-density lipoprotein receptor 1 (P = .99). Although most plaques from asymptomatic patients displayed low VCAM-1 expression, approximately one in five expressed high VCAM-1 similar to plaques from symptomatic patients. In vitro flow chamber experiments demonstrated that VCAM-1-targeted microbubbles bind cells that express VCAM-1, even under high-shear conditions that approximate those found in human carotid arteries, whereas binding efficiency was lower for the other agents.

CONCLUSIONS

VCAM-1 displays significantly higher expression on high-risk (symptomatic) vs low-risk (asymptomatic) carotid plaques. Ultrasound contrast agents bearing ligands for VCAM-1 can sustain high-shear attachment and may be useful for identifying patients in whom more aggressive treatment is warranted.

The Excimer Laser: Science Fiction Fantasy or Practical Tool?

Nearly 20 years ago, in vitro experiments left no doubt about the fact that laser light can ablate atherosclerotic plaque. The initial enthusiastic results with the technology, particularly in coronary arteries, were followed by reports showing unacceptably high restenosis and complication rates. These poor results were due to the premature application of an underdeveloped technology, a lack of understanding of laser/tissue interaction, and the use of incorrect lasing techniques. Consequently, and without discrimination, all lasers were banned from the catheterization laboratories for nearly a decade. Technological enhancements of the excimer laser, combined with refined catheter lasing techniques, resulted in greater debulking of atherosclerotic material in long superficial femoral artery occlusions. These results triggered the application of the excimer laser technique as an atherectomy tool in more complex lesions below the knee. The multicenter Laser Atherectomy for Critical Ischemia study clearly demonstrated that the excimer laser technology resulted in limb salvage rates >90% in patients with critical limb ischemia (CLI). Furthermore, new clinical results indicate that the excimer laser is very effective in dissolving thrombotic obstructions, redirecting this technology to the coronary field.

The results of the excimer laser in CLI validate the role of the cool laser in treating complex peripheral vascular disease. The results suggest a larger indication for this technology and support a more aggressive use of these interventional techniques in the treatment of this large patient cohort. However, all lasers are not equally effective in debulking atherosclerotic material. Only the athermic process associated with the excimer laser produces a safe and effective endovascular ablation of obstructive atherosclerotic and/or thrombotic material. The appropriate and safe utilization of the equipment and lasing techniques, combined with correct indications and patient selection, will contribute to the successful application of laser-assisted atherectomy in complex peripheral and coronary artery obstructive disease. Unfortunately, little consistent scientific data has been generated to convince the interventional community of the usefulness of excimer laser ablation.

Predicting arteriovenous fistula maturation with intraoperative blood flow measurements

OBJECTIVE

To establish the criteria for intraoperative blood flow measurements taken at the time of autologous arteriovenous fistula (AVF) construction to predict future access maturation and thereby avoid waiting periods for futile fistulas to declare themselves.

METHODS

From April 2006 through to March 2007 consecutive patients undergoing native AVF construction at one institution underwent intraoperative measurements of blood flow using transit-time ultrasound technology. No action was taken based upon the flow measurement at the time of surgery. Patients were followed and data collected comprising demographics and AVF maturation. A fistula was considered mature when it was successfully accessed for hemodialysis (HD) at least three times. Statistical analysis was performed including receiver operating characteristics (ROC), ANOVA, and Chi square using the JMP software package.

RESULTS

During the 12-month period, 70 autologous AVFs were created including 41 antecubital brachiocephalic, 21 radiocephalic, and 8 basilic vein transpositions in 35 females and 33 males with a mean age of 58+/-1.7 (mean+/-SEM). The group included 37 Hispanic, 17 Native American, 10 Caucasian, 3 African American and 1 Asian patient. The etiology of renal failure comprised 53 diabetics, 13 hypertensives, 1 polycystic kidney disease and 1 congenital abnormality. Complete follow-up was available in 69/70 AVFs in 67 patients. Patients were excluded from analysis if they had not yet started dialysis (n=12), stopped or died (n=4) before their fistula was accessed. Patients whose AVFs were patent, but required a secondary procedure to achieve a functional access were considered non-functional. There was a significant difference between the maximal intraoperative flow rates between functional and non-functional AVFs (573.6+/-103 mL/min vs. 216.8+/-35.8 mL/min; p<0.05). There was no difference between groups in regard to age, gender, race or etiology of renal failure. ROC analysis suggested a threshold value of 140 mL/min for radiocephalic and 308 mL/min for brachiocephalic AVFs to predict maturation to a functional access.

CONCLUSION

Intraoperative blood flow measurements obtained at the time of autologous AVF construction can identify fistulas that are unlikely to mature; and therefore, that require immediate revision or abandonment which will ultimately expedite the establishment of a useful access in the HD patient. This is the first study to establish the minimal flow values uniquely needed for both radial artery and brachial artery AVFs to expect primary maturation to a functional access.

Endovascular Treatment of a Thoracic Aortic Pseudoaneurysm After Previous Open Repair

The use of endovascular stents to treat descending thoracic aortic pathologies is emerging as a less invasive therapy to treat high-risk patients. This case report describes the presentation of a patient with a pulsatile mass on her back. The patient's computed tomographic scan revealed the mass to be an extension of a large psuedoaneurysm from the site of a previous repair of her thoracic aorta for a dissecting aneurysm several years earlier. The psuedoaneurysm was successfully treated with an endovascular stent and the patient was discharged home on postoperative day 5.

Results of PREVENT III: A multicenter, randomized trial of edifoligide for the prevention of vein graft failure in lower extremity bypass surgery

OBJECTIVE

The PREVENT III study was a prospective, randomized, double-blinded, multicenter phase III trial of a novel molecular therapy (edifoligide; E2F decoy) for the prevention of vein graft failure in patients undergoing infrainguinal revascularization for critical limb ischemia (CLI).

METHODS

From November 2001 through October 2003, 1404 patients with CLI were randomized to a single intraoperative ex vivo vein graft treatment with edifoligide or placebo. After surgery, patients underwent graft surveillance by duplex ultrasonography and were followed up for index graft and limb end points to 1 year. A blinded Clinical Events Classification committee reviewed all index graft end points. The primary study end point was the time to nontechnical index graft reintervention or major amputation due to index graft failure. Secondary end points included all-cause graft failure, clinically significant graft stenosis (>70% by angiography or severe stenosis by ultrasonography), amputation/reintervention-free survival, and nontechnical primary graft patency. Event rates were based on Kaplan-Meier estimates. Time-to-event end points were compared by using the log-rank test.

RESULTS

Demographics, comorbidities, and procedural details reflected a population with CLI and diffuse atherosclerosis. Tissue loss was the presenting symptom in 75% of patients. High-risk conduits were used in 24% of cases, including an alternative vein in 20% (15% spliced vein and 5% non-great saphenous vein) and 6% less than 3 mm in diameter; 14% of the cases were reoperative bypass grafts. Most (65%) grafts were placed to infrapopliteal targets. Perioperative (30-day) mortality occurred in 2.7% of patients. Major morbidity included myocardial infarction in 4.7% and early graft occlusion in 5.2% of patients. Ex vivo treatment with edifoligide was well tolerated. There was no significant difference between the treatment groups in the primary or secondary trial end points, primary graft patency, or limb salvage. A statistically significant improvement was observed in secondary graft patency (estimated Kaplan-Meier rates were 83% edifoligide and 78% placebo; P = .016) within 1 year. The reduction in secondary patency events was manifest within 30 days of surgery (the relative risk for a 30-day event for edifoligide was 0.45; 95% confidence interval, 0.27-0.76; P = .005). For the overall cohort at 1 year, the estimated Kaplan-Meier rate for survival was 84%, that for primary patency was 61%, that for primary assisted patency was 77%, that for secondary patency was 80%, and that for limb salvage was 88%.

CONCLUSIONS

In this prospective, randomized, placebo-controlled clinical trial, ex vivo treatment of lower extremity vein grafts with edifoligide did not confer protection from reintervention for graft failure.

Strategies for predicting and treating access induced ischemic steal syndrome

Access induced ischemia is an uncommon but devastating complication for patients maintained on hemodialysis. A number of clinical risk factors have been identified to select patients at risk. Intraoperative measurement of the digital-brachial index may further distinguish at-risk patients when the DBI is <0.45. Once clinically significant steal has developed, surgical strategies to treat this problem should ideally reverse the ischemia while maintaining uninterrupted access for hemodialysis. To date, the distal revascularization-interval ligation or DRIL procedure has been the most consistently successful tactic in achieving these dual objectives. A number of alternative strategies have recently been proposed and will be discussed.

Advances in endovascular techniques to treat failing and failed hemodialysis access

During the decade since JEVT was inaugurated, we have witnessed the growing application of endovascular techniques for arteriovenous (AV) access in parallel with the evolution of endovascular therapy for arterial pathology. To date, few if any technologies have compared with balloon angioplasty for treating venous anastomotic stenosis, the most common cause of access failure. Only one device, which incorporates the principles of access graft design and self-expanding stent technology, has been uniquely conceived for this pathology. The encapsulated polytetrafluoroethylene stent-graft has achieved reasonable preliminary results, but randomized data is forthcoming. Technology to clear the clot from a thrombosed graft continues to evolve, but will never be as cost-effective as simple balloon thrombectomy. However, the pressure placed on providers to perform all percutaneous interventions and move away from open techniques continues to fuel interest in this component of treatment. Finally, the pursuit of a completely percutaneous AV access continues. As with endovascular procedures in general, whether or not the procedure is cost-effective or time-consuming seems to take a back seat to the all-percutaneous approach that so many seem to converge upon. Moreover, as most autogenous fistulas and AV grafts can be created with minimal incisions under local anesthesia, the pursuit of a completely percutaneous access system seems more like an academic exercise than a practical application of technology. We must try and avoid the tendency to "minimize invasiveness" with technology that is maximally intensive (and expensive), such as limiting ourselves to only percutaneous methods. Given the increasing pressure to have an all autogenous access program, current techniques that apply well in prosthetic grafts will need to be modified to accommodate the different biology of a native fistula. Clearly, the enlarging end-stage renal disease population will continue to provide endovascular specialists with clinically challenging problems requiring new and revolutionary technology.

Distal revascularization-interval ligation: a durable and effective treatment for ischemic steal syndrome after hemodialysis access

PURPOSE

The treatment of hemodialysis access-induced ischemic steal syndrome is challenging. Despite promising early results with the distal revascularization-interval ligation (DRIL) procedure, the operation has not been widely adopted because of concerns about its complexity and long-term efficacy. The purpose of this report was to determine the efficacy and durability of the DRIL procedure in relieving hand ischemia and in maintaining access patency in the setting of hemodialysis access-induced ischemia.

METHODS

A retrospective review was performed of all patients who underwent the DRIL procedure for access-induced ischemia. Demographic information was compiled, as were data regarding access and bypass patency, limb salvage, and patient survival. Arteriovenous access and brachial artery bypass patency rates were determined with life-table methods.

RESULTS

Between 1995 and 2001, we performed 55 DRIL procedures in 52 patients (35 women and 17 men; mean age, 60.8 years; range, 30 to 86 years). The indications for surgery were ischemic pain in 27 patients, tissue loss in 20 patients, loss of neurologic function in four patients, and pain on hemodialysis in one patient. Most patients (92%) had diabetes. The mean interval from access placement to DRIL was 7.4 months (range, 1 to 84 months). The mean follow-up interval was 16 months (range, 1 to 67 months). The brachial artery bypass primary patency rate was 80% at 4 years, and the arteriovenous access primary patency rate was 83% at 1 year. Forty-seven of 52 patients (90%) had substantial or complete relief of ischemic hand symptoms, and 15 of 20 patients with digital ischemic lesions have healed completely.

CONCLUSION

DRIL is a durable and effective procedure that reliably accomplishes the twin goals in the treatment of angioaccess-induced ischemia: persistent relief of hand ischemia and continued access patency.

Institutional economic losses associated with AAA repair are independent of technique

PURPOSE

To investigate the perception of significant economic loss associated with endovascular abdominal aortic aneurysm (AAA) repair by comparing economic variables for the open and endovascular techniques.

METHODS

In a 1-year period, 20 consecutive patients (19 men; mean age 73.3 years, range 62-89) were treated for uncomplicated infrarenal AAAs using conventional open repair in 11 and endovascular repair (EVR) in 9. For the open repair, standard techniques were employed, including transperitoneal and retroperitoneal exposures; in EVR, both the AneuRx and Ancure systems were utilized. Length of stay and institutional costs were carefully tracked and compared.

RESULTS

The patients were similar with regard to comorbidities, but the endograft patients were older (p=0.02) Length of stay was significantly lower in the EVR group (1.9 +/- 0.9 days) compared with the open group (8.4 +/- 4.5 days, p=0.0004). However, total mean treatment costs (open: $17,576 +/- $11,025 and EVR: $20,247 +/- $5003; p=0.51) and subsequent losses (open: -$3949 +/- $7095 and EVR: -$7572 +/- $4488; p=0.20) were not significantly different between the groups. CONCLUSIONS; The costs associated with the care of AAA patients are independent of the technique used for repair. The economic loss associated with treatment is directly related to inadequate reimbursement on the part of Medicare and other carriers.

Abdominal aortic healing associated with a thin-walled Dacron-covered endovascular graft in a canine model

PURPOSE

To characterize the healing response associated with an experimental endovascular graft (EVG) by examining the lumen of the prosthesis and the native vessel wall responses after implantation in a canine model.

METHODS

An endovascular graft (EVG) constructed of hookless self-expanding nitinol springs covered by an ultrathin Dacron fabric was placed in the abdominal aorta of 8 dogs following femoral artery catheterization. After 12 weeks, specimens were subjected to histological and immunocytochemical testing to quantitatively and qualitatively analyze the cellular makeup of the luminal and abluminal tissues.

RESULTS

Gross examination revealed a glistening, thrombus-free luminal surface on all prostheses, which was confirmed by scanning electron microscopy. The EVGs were well incorporated into the aortic wall, leaving a concentric, smooth flow surface. Immunocytochemistry verified the presence of von Willebrand factor-positive endothelial cells on the luminal surface and alpha-smooth muscle cell actin-positive smooth muscle and/or fibroblast cells in the subendothelial space. A sparse inflammatory response and a paucity of proliferating nuclear cell antigen-positive cells were noted within the neomedial lining adjacent to the graft material. In addition, a rich vaso vasorum-like plexus of microvessels was evident within the neomedial tissue. The native vessel wall upon which the EVG impinged was largely unaffected. CONCLUSIONS; These data demonstrate that placement of an experimental EVG in the canine abdominal aorta elicits a healing response that is distinct from interpositional vascular grafts. Results from this study have particular relevance to the proximal and distal anastomotic neck regions.

Impact of nonpenetrating clips on intimal hyperplasia of vascular anastomoses

Non-penetrating, arcuate-legged titanium clips create an interrupted, non-penetrated, yet compliant vascular anastomoses that is associated with significantly reduced anastomotic neointimal hyperplasia. Recent experimental and clinical studies provide evidence that the non-suture alternative changes the biology of vessel-to-vessel and graft-to-vessel connections that reduces the stimulus for hyperplasia at a number of critical points in the response to injury schema. The compliant, "blood-tight" characteristics of clipped vascular reconstructions are associated with no endothelial injury or intraluminal foreign body, minimal platelet aggregation and laminal flow. Clinical applications including vascular access, femoropopliteal bypass, and closure of carotid endarterectomies are remarkable for the absence of restenosis and preserved anastomotic patency.

Improved patency of infrainguinal polytetrafluoroethylene bypass grafts using a distal Taylor vein patch

OBJECTIVE

The purpose of this study was to evaluate graft patency and limb salvage rates for infrainguinal polytetrafluoroethylene (PTFE) bypass grafts using distal anastomotic Taylor vein patch in patients lacking suitable vein conduit.

METHODS

We reviewed 44 patients who underwent infrainguinal bypass between January 1996 and August 2000 using 6-mm PTFE and a distal Taylor vein patch. Postoperative oral anticoagulation was administered to 80% of patients. Graft patency was confirmed during follow-up with serial graft duplex scanning.

RESULTS

Operative indications were rest pain, nonhealing ulcer, or gangrene in 76% of patients, 43% of whom had undergone previous ipsilateral leg bypass. Distal anastomotic sites were the below-knee popliteal (29%) and tibial-peroneal arteries (67%). At 1 month, 1 year, and 2 years, respectively, the primary patencies (SE <10%) were 86%, 71%, and 71%; limb salvage rates were 95%, 75%, and 66%; and mortality rates were 5%, 20%, and 20%.

CONCLUSIONS

These early results with PTFE and distal Taylor vein patch are promising, and markedly superior to previous reports of PTFE without anastomotic modification. Further long-term follow-up will be necessary to determine the 3- to 5-year durability of such reconstructions.

Impact of secondary procedures in autogenous arteriovenous fistula maturation and maintenance

PURPOSE

The purpose of this study was to evaluate the impact of secondary procedures to facilitate maturation of autogenous arteriovenous (AV) fistulas and optimize their use for hemodialysis access.

METHODS

The records of patients undergoing new autogenous AV fistulas were reviewed. Analyses of fistula maturation, subsequent interventions, access function, and patency were performed.

RESULTS

From July 1998 through June 2000, 362 new AV access fistulas and grafts were constructed in 310 patients. In this cohort, 170 autogenous fistulas (55%) were placed in 163 patients. Fistula types included 115 antecubital brachiocephalic fistulas (Kaufmann) (68%), 47 radiocephalic fistulas (Brescia-Cimino) (28%), and 8 basilic vein transposition fistulas (4%). Secondary procedures were required in nine cases (5%) for failure to mature (4 Brescia-Cimino, 5 Kaufmann) and included 3 vein patches, 3 interposition vein grafts, 1 transposition to a more proximal artery, 1 branch ligation, and 1 balloon angioplasty of the subclavian artery; they occurred at 4.4 +/- 2.1 months (mean +/- SD). Additional procedures were needed to revise patent but failing fistulas in six cases (3.5%; 3 Brescia-Cimino, 3 Kaufmann) and included 5 transpositions to a more proximal artery and 1 vein patch; they occurred at 12.3 +/- 5.6 months (P =.002 compared with immature fistulas). For this series of autogenous fistulas, a functional access was achieved in 129 of 143 patients (90%) for whom follow-up was available. Twelve-month actuarial primary patency for autogenous fistulas was 78% compared with 49% for prosthetic grafts placed in the same period (P =.001, log-rank).

CONCLUSIONS

In the current series, a 10% improvement in accomplishing or maintaining a functional autogenous access was achieved through secondary procedures applied to autogenous fistulas that either fail to mature or develop functional deterioration. Aggressive assessment of immature or failing autogenous AV fistulas for correctable lesions should be included in any hemodialysis practice to optimize their use and exploit the superiority of the native fistula.

Intimal growth and neovascularization in human stenotic vein grafts

BACKGROUND

Myointimal thickening and microvessel ingrowth are commonly observed in vein graft stenosis, which complicates a third of infrainguinal bypass procedures. But a direct correlation between these two features has not been established. Our purpose was to analyze the relationship between neovascularity and intimal thickness in human vein grafts.

STUDY DESIGN

Twenty-two explant stenotic vein grafts (STVG), 8 nonstenotic arterialized vein grafts (AVG), and 20 age-matched control greater saphenous veins (CGSV) were analyzed histologically and compared morphologically by light microscopy. Digitized computer image analysis was used to measure intimal thickness and quantitate microvessel ingrowth. Immunolocalization of endothelial cells around the lumen and in microvessels was determined using antibodies to factor VIII and to endothelial nitric oxide synthase (eNOS), respectively.

RESULTS

Focal areas of endothelial disruption and thrombus deposition were present in 23% (5 of 22) of stenotic vein grafts. The neointima of STVG grafts was two- and fourfold thicker than that of AVG and CGSV, respectively (p < 0.0001). Microvessels were most frequently observed in the adventitia and media of STVG and increased in number with increasing intimal thickness (p < 0.001 by ANOVA).

CONCLUSIONS

A fourfold increased neointimal thickness in critically stenotic vein grafts is associated with increased medial and adventitial neovascularization. Remodeling alone with doubling of the intimal thickness in nonstenotic arterialized vein grafts does not appear to be associated with enhancement of the graft microvasculature. More specific observations using an experimental model may allow us to further define the role of angiogenesis in vein graft stenosis and to determine the therapeutic implications of such observations.

Distal revascularization-interval ligation for maintenance of dialysis access and restoration of distal perfusion in ischemic steal syndrome

Ischemic steal syndrome after hemodialysis access challenges the clinician to reconcile the dichotomy of maintenance of access patency and restoration of distal limb perfusion. Results from traditional procedures directed toward increasing the resistance in the fistula (eg, banding, lengthening) have yielded unreliable results and frequently eventuate in fistula thrombosis. The recently described technique of distal revascularization, interval ligation (DRIL) provides a more physiological approach. Based on several recent series, application of the technique has provided excellent resolution of ischemic symptoms and superior preservation of fistula patency.

Comparison of carotid endarterectomy using primary closure, patch closure, and eversion techniques

BACKGROUND

This study was undertaken to evaluate the role of eversion endarterectomy in the management of extracranial carotid occlusive disease.

METHODS

A retrospective review was performed of all patients undergoing carotid endarterectomy between July 1994 and July 1998. After reviewing the records, patients were assigned to one of three groups: eversion (ECEA); open with primary closure (CEA); or open with patch closure (CEAP). Statistical comparisons were made.

RESULTS

The 190 index cases comprised 33 ECEA (17%), 15 CEA (8%), and 142 CEAP (75%). Both ECEA and CEA were more likely to be done on males versus females compared with CEAP (P = 0.01). For the entire 190 cases, stroke occurred in 1 patient (0.5%); and myocardial infarction in 2 patients (1%), resulting in death in both. Two patients (1.4%) in the CEAP group have undergone redo surgery at 8 and 24 months.

CONCLUSIONS

This study demonstrates that eversion endarterectomy achieves early results similar to open endarterectomy with and without patch closure.

Anastomotic tissue response associated with expanded polytetrafluoroethylene access grafts constructed by using nonpenetrating clips

PURPOSE

The gross, light microscopic, and scanning microscopic appearance of arterial and venous anastomoses in expanded polytetrafluoroethylene (ePTFE) access grafts constructed with nonpenetrating clips were compared with that of those constructed with polypropylene suture. We hypothesized that clip-constructed anastomoses would provide controlled approximation of native vessel intimal and medial components with the ePTFE grafts. We further hypothesized that anastomotic healing with clips would involve primarily an intimal cellular response, as compared with suture-constructed anastomoses in which cells within the media and adventitia walls participate.

METHODS

Femoral artery to femoral vein arteriovenous (AV) grafts were constructed in five dogs using 4-mm internal diameter ePTFE graft material. Each animal received one AV graft with anastomoses constructed by using polypropylene sutures in one leg and one AV graft with anastomoses constructed with Vascular Closure System clips in the contralateral leg. Animals were given aspirin for the duration of the study, and grafts were explanted at 5 weeks. At the time of explantation, graft segments were grossly evaluated and then underwent light and scanning electron microscopic analysis.

RESULTS

At the time of explantation, all access grafts were patent. Joining the ePTFE grafts to the native vessels with clips resulted in minimal vessel wall damage. The lumenal contours of the discontinuous approximation were smooth and without gross endothelial disruption. These observations are in contrast to the lumenal compromise and endothelial disturbance associated with the sutured anastomoses. Furthermore, hemostasis was achieved immediately in the clipped grafts, decreasing the incidence of perianastomic hematoma. Finally, cellular reconstitution occurred at the anastomotic cleft in both the sutured and the clipped junctions. The neointima exhibited an endothelial cell lining on the lumenal surface and the presence of alpha-smooth muscle cell actin positive cells within the subendothelial layer.

CONCLUSION

Vascular Closure System clips are a viable alternative to suture for the approximation of ePTFE AV access grafts to native blood vessels. The use of the clips resulted in a more streamlined anastomosis, with decreased vessel wall damage, immediate hemostasis, and a trend toward shorter procedure times.

Characterization of cellular density and determination of neointimal extracellular matrix constituents in human lower extremity vein graft stenoses

Arterial restenosis has been attributed to a hyperproliferative smooth muscle cell response. Paradoxically, studies of human coronary atherectomy and vein graft stenotic lesions have demonstrated a relatively low nuclear proliferative rate with the majority of the neointimal mass consisting of extracellular matrix. The purpose of the present study was to characterize the cellular density and determine the relative composition of the extracellular matrix protein constituents in stenotic, human lower extremity vein-bypass graft lesions.

METHODS

Duplex surveillance of 148 consecutive infrainguinal bypass grafts identified 17 patients with 22 preocclusive autogenous vein graft stenoses (mean graft age 7 months). Morphological analyses of these stenotic lesions were compared with excised samples of 20 greater saphenous vein segments taken at the time of graft implantation from matched control patients. Intimal and medial areas were compared and cell density was determined with fluorescent nuclear (Bisbenzimide) staining. Differential light microscopy with pentachrome staining was performed to determine the relative percent composition of intimal matrix constituents by stereological morphometric (point-count) techniques.

RESULTS

The intimal areas for control and stenotic vein segments were 1.64 x 10(6) microm2 and 3.85 x 10(6) microm2, P < 0.0001, whereas the intimal nuclear densities (cells/unit volume) were 1.42 x 10(3) and 1.70 x 10(3) cells/microm2, P = 0.03. respectively. The corresponding medial area and medial nuclear densities were 5.01 x 10(6) microm2, 3.31 x 10(6) microm2; P = 0.08, and 2.27 x 10(3), 3.29 x 10(3); P = 0.001, for control and stenotic specimens, respectively. The intima:media area ratios were much greater, whereas the intimal and medial cell densities were only slightly greater in the stenotic compared with control veins. The relative composition of intimal extracellular matrix proteins of stenotic vein graft segments consisted of 21% cellular (fibrous) material, 33% collagen, and 46% glycosaminoglycan ground substance.

CONCLUSION

The intimal lesions responsible for lower extremity vein graft stenosis are more hypertrophic than hyperplastic. Therapies aimed at preventing arterial and vein graft restenosis may thus need to inhibit matrix biosynthetic processes in addition to cellular proliferation.

Inflammation and neovascularization associated with clinically used vascular prosthetic materials

This study was designed to evaluate and compare healing characteristics, specifically neovascularization and inflammation, of polymeric vascular graft materials commonly used in clinical applications. Our hypotheses were (i) polymeric materials used in vascular graft manufacture stimulate chronic inflammation and (ii) inflammation and neovascularization of polymeric materials are related. Impra and Gore-Tex ePTFE, Meadox weavenit and woven Dacron, Hemashield microvel and woven Dacron, and Golaski microknit Dacron were implanted as 6-mm diameter disks within rat subcutaneous and adipose tissue. Following 5 weeks of implantation samples were evaluated by histological and immunocytochemical analysis. Sections were stained using hematoxylin and eosin or reacted with ED1 antibody and GS1 lectin to quantify inflammation and neovascularization. respectively. The extent of inflammation and neovascularization were influenced by both tissue site of implantation and polymer characteristics. For subcutaneous implants, inflammation was graded as follows: Meadox weavenit > Hemashield woven > Meadox woven > Gore-Tex ePTFE > Hemashield microvel > ImpraePTFE > Golaski microknit, while only the Golaski microknit neovascularized. Inflammation was graded as follows for adipose implants: Hemashield woven > Hemashield microvel > Meadox weavenit > Meadox woven > Gore-Tex ePTFE > Golaski microknit > Imnpra ePTFE, while the following order of neovascularization was observed: Impra ePTFE > Gore-Tex ePTFE > Golaski microknit. The degree of inflammation following biomnaterial implantation has a profound effect on implant neovascularization. These data suggest an inverse relationship exists between inflammation and neovascularization.

Vein patching reduces neointimal thickening associated with prosthetic graft implantation

PURPOSE

Modified anastomotic techniques utilizing autogenous vein-cuffs or patches have been devised with the hope of improving prosthetic graft patency. The mechanisms of the presumed improvement in patched anastomoses have never been elucidated and remain speculative. We characterized the healing response of the Taylor vein patch in prosthetic arteriovenous fistulae in a canine model of intimal hyperplasia.

METHODS

Six adult dogs underwent placement of bilateral (6 patched, 6 control) 4-mm diameter expanded polytetrafluoroethylene loop femoral artery-vein fistulae. Serial duplex ultrasound examinations confirmed graft patency until explant at 6 weeks. Differential light microscopy with computerized image analysis was performed on serial 5-microm sections. Intimal thickness through the venous anastomosis and outflow veins of Taylor patch and control (nonpatched) grafts were compared. Cell type-specific immunocytochemical antibody stains for smooth muscle cells (alpha SMC actin) and endothelial cells (von Willebrand factor) were performed.

RESULTS

Eleven of 12 grafts remained patent for 6 weeks, 1 control graft thrombosed. Mean duplex-derived peak systolic velocities of patched (96 cm/sec) and control (108 cm/sec) grafts were similar. Microscopy revealed more intimal pannus anastomotic suture line ingrowth in controls (mean thickness = 178 microm) than Taylor patched grafts (mean 147 microm, p = 0.0002). Significantly less intimal thickening was present in the outflow vein of patched (mean thickness = 90 microm) versus control grafts (mean 195 microm, P <0.0001). The intima maintained a single cell layer of vWF + endothelial cells, while the majority of the cells comprising the lesion expressed alpha SMC actin.

CONCLUSION

Perianastomotic pannus is primarily composed of intimal smooth muscle cells. Neointimal thickening is significantly reduced in prosthetic arteriovenous fistulae created with the Taylor vein patch in a canine model. Reduction in perianastomotic intimal thickening may explain the reported clinical improvement in prosthetic bypass graft patency when modified with vein patch techniques.

Treatment of patients with venous thromboembolism and malignant disease: should vena cava filter placement be routine?

PURPOSE

It has been proposed that inferior vena cava filter placement should be the initial treatment of deep venous thrombosis (DVT) or pulmonary embolus (PE) in patients with coexisting malignant disease. We have chosen instead to selectively place filters only in patients with either a contraindication to anticoagulation therapy or a subsequent complication from anticoagulation therapy. The treatment efficacy and mortality rates in patients with concomitant malignant disease and venous thromboembolism using this approach was determined.

METHODS

We retrospectively reviewed all patients at our institution with malignant disease in whom venous thromboembolism developed between August 1991 through August 1996 and identified 166 patients with PE (n = 8), DVT (n = 147), and DVT/PE (n = 11). Of these patients, 138 (83.1%) were initially treated with anticoagulation therapy, and 28 (16.9%) had primary filter placement because of contraindications to anticoagulation therapy (10 for intracranial tumors, 11 for recent or upcoming operations, 6 for recent hemorrhage, and 1 for a malignant bloody pericardial effusion).

RESULTS

Thirty-two (23%) of the 138 patients who initially underwent anticoagulation therapy subsequently required a filter for the following reasons: bleeding (n = 15, 10.9%); recurrent thromboembolism (n = 6, 4.3%); heparin-induced thrombocytopenia (n = 1, 0.7%); and perceived high risk for bleeding with continued anticoagulation therapy (n = 11, 8%). Both bleeding and recurrent thromboembolism developed in 1 patient. Sixty patients (36%) received filters. No major technical complications occurred from filter placement. Major recurrent thromboembolic complications developed in 10 patients: DVT (n = 6, 10%), PE (n = 2, 3.3%), inferior vena cava thrombosis and phlegmasia cerulea dolens (n = 1, 1.7%), superior vena cava thrombosis (n = 1, 1.7%). Venous gangrene developed in 1 patient with DVT. The 1-year actuarial survival rates for patients treated with filter and anticoagulation therapy were 35% and 38%, respectively (P = NS).

CONCLUSION

In summary, our experience suggests that 64% of patients with malignant disease and venous thromboembolism are effectively treated with anticoagulation alone; 17% require primary filter placement for standard indications, and an additional 19% require subsequent filter placement because of complications (primarily bleeding) or failure of anticoagulation therapy. Although technical complications of filter placement are low, serious life-threatening or limb-threatening thromboembolic complications developed in 17% of patients. Survival was poor in all patients, regardless of treatment. These data support a conservative approach of routine anticoagulation therapy with selective filter placement.

Healing response associated with balloon-dilated ePTFE

Deployment of endovascular grafts composed of a metallic stent surrounded by expanded polytetrafluoroethylene (ePTFE) stretches the polymer beyond its original dimensions, altering the structural characteristics of the ePTFE. We hypothesized this structural modification would alter the healing response associated with the implant. In this study, 4 mm i.d. of ePTFE (30 microns internodal distance) vascular grafts were balloon dilated using angioplasty balloons having final diameters of 6 (1.5X), 8 (2X), 10 (2.5X), 12 (3X), and 18 (4.5X) mm. Following balloon dilatation of the ePTFE, a circular punch (6 mm in diameter) was used to prepare polymer samples for implantation. The ePTFE circular patches were implanted within subcutaneous tissue and epididymal fat pads of male Sprague-Dawley rats. After 5 weeks, the implants were removed and analyzed for fibrous capsule formation, inflammation, and neovascularization associated with the material. Histological analysis revealed the formation of fibrous capsules only with control subcutaneous implants. The inflammatory response associated with subcutaneously implanted ePTFE was decreased significantly following balloon dilatation to at least 2.5 times the original diameter of the graft. In contrast, ePTFE implanted within adipose tissue demonstrated a significantly greater inflammatory response following balloon dilatation when compared to control implants. Only ePTFE balloons dilated to 6 mm and implanted within adipose tissue demonstrated neovascularization to any extent. These data suggest the structural modifications incurred by ePTFE following balloon dilatation dramatically affect the inflammatory response associated with an implant. Therefore, polymeric materials used for endovascular graft technology require designs that consider changes in polymer healing inherent to device design.

A regional pedal ischemia scoring system for decision analysis in patients with heel ulceration

PURPOSE

The objective of this study was to evaluate patients undergoing operative debridement for heel ulceration and to categorize pedal perfusion and its influence on therapeutic alternatives.

METHODS

Patients with heel ulceration were stratified by arteriography and graded I (patent posterior tibial, PT), II (occluded PT/reconstituted from peroneal), III (PT reconstituted from dorsal pedal), IV (no PT reconstitution but visible heel tributaries), and V (avascular heel).

RESULTS

From May 1992 through January 1997, 23 patients underwent operative treatment for 25 heel ulcers. The heel ischemia score stratified patients into two groups: 1, revascularization/debridement (71% grades I to III, 29% grade IV, 0% grade V); and 2, free tissue transfer with or without revascularization (100% grades IV, V). Cumulative functional limb salvage was 91% (BP), 60% (BP + TT), and 81% (TT) at 24 months (P = 0.15 log rank).

CONCLUSION

The heel ischemia score may direct treatment of heel ulceration by identifying patients who will need vascularized tissue transfer early in their treatment regimen.

Stent versus endovascular graft healing characteristics in the porcine iliac artery

PURPOSE

To evaluate the healing characteristics of stents versus endovascular grafts in the porcine iliac artery.

MATERIALS AND METHODS

A total of 20 iliac arteries in 10 domestic swine were used to evaluate the healing characteristics of stents versus endovascular grafts. Each animal received one stent and one endovascular graft in opposite iliac arteries. The endovascular grafts were constructed with use of 6 cm of expanded polytetrafluoroethylene (ePTFE) (3 mm inner diameter, 30 microm internodal distance) and Palmaz stents (P204 or P188) secured at each end of the graft. A solitary Palmaz stent (P308 or P294) was used on the opposite side. The devices were explanted at 1, 5, and 12 weeks.

RESULTS

One of three endovascular grafts and two of three stents were patent at 1 week. Two of three endovascular grafts and all three stents were patent at 5 weeks. All three endovascular grafts and stents were patent at 12 weeks. Gross examination, histologic, and scanning electron microscopy demonstrated differences in the healing response of the two devices. A marked abluminal inflammatory response to the graft material was observed. This resulted in neovascularization of the tissue along the abluminal surface of the graft. In addition, marked neointimal thickening at the unsupported section of the endovascular graft resulted in significant luminal narrowing.

CONCLUSION

The porcine model may be used for evaluating the healing characteristics of endovascular grafts. Intravascular placement of ePTFE prosthetic graft material dramatically alters the healing of this type of graft material. The graft material did not prevent the formation of a progressively thickening neointima.

Free tissue transfer to extend the limits of limb salvage for lower extremity tissue loss

BACKGROUND

The extent of tissue loss amenable to primary healing after revascularization is unknown. Salvage of limbs with large soft-tissue defects with exposed tendon, joint, or bone lies beyond the limits of conventional techniques. We report our results using free tissue transfer as an adjunct to lower extremity vascular reconstruction in patients with complex ischemic or infected wounds.

METHODS

Retrospective chart review of patient and wound characteristics.

RESULTS

From January 1992 to June 1996, 585 procedures were performed in 544 patients, including 27 free flaps in 26 patients: 17 free flaps combined with distal bypass (7 staged, 10 simultaneous) and 10 isolated free flaps. Flap donor sites included radial forearm (8), latissimus dorsi (7), rectus abdominus (9), and scapula (3). Surgical indications included extensive ischemic/neurotrophic ulcers, and nonhealing vein graft harvest incision or transmetatarsal amputation site. Mean area of tissue loss was 70 cm2, mean ulcer duration was 5 months, and 92% of patients had exposed tendon, joint, or bone. During a mean follow-up of 14 months, 2 patients died of cardiopulmonary disease and 3 flaps failed, resulting in below-knee amputation. Six flaps were revised for graft stenosis (1), venous thrombosis (1), or flap edge necrosis (4). Limb salvage rate was 70% at 24 months by life-table analysis. Functional ambulation was achieved in 21 of 24 (88%) patients, including 7 of 8 with diabetes, end-stage renal disease, and heel ulcers.

CONCLUSION

In select ambulatory patients with large soft-tissue defects and exposed deep structures, functional limb salvage is obtainable in more than 80% of patients. For lesions not amenable to vascular reconstruction with conventional methods of wound coverage, free tissue transfer extends the limits of limb salvage and is a viable alternative to amputation.

Salvage of femoropedal bypass graft complicated by interval gangrene and vein graft blowout using a flow-through radial forearm fasciocutaneous free flap

We report the case of a 71-year-old man who had interval gangrene of his calf with subsequent vein graft blowout 3 months after undergoing a femoral-to-dorsalis pedis saphenous vein bypass grafting procedure. To provide wound coverage, restore vascular continuity, and preserve functional ambulation, a flow-through radial forearm fasciocutaneous free flap was interposed between cut ends of the bypass graft. Venous drainage of the flap was from the cephalic vein to the popliteal vein. At 1 month after the operation, the patient had complete wound healing and began to ambulate. At 11 months an asymptomatic high-grade stenosis in the distal radial artery segment of the reconstruction was successfully treated with percutaneous angioplasty. After 22 months of follow-up there have been no further complications, and the patient continues to have full, functional ambulation. The radial forearm flow-through free flap allows single-stage restoration of bypass graft continuity and coverage of extensive, complex tissue defects. This technique represents a novel approach to this difficult problem and provides a viable alternative to major limb amputation.

Effects of balloon dilatation on ePTFE structural characteristics

The search for less invasive treatments for cardiovascular disease has lead to the development of endovascular stent grafts, metallic and alloy stents surrounded by prosthetic vascular graft material. Introduced intravascularly, the deployment of stent grafts requires balloon dilatation of the device which results in expansion of the stent along with the vascular graft material. We hypothesized that balloon dilatation of stent grafts would alter the physical structure of the prosthetic graft material. In this study, noncompliant angioplasty balloons were used to dilate expanded polytetrafluoroethylene (ePTFE), a material commonly used for endovascular stent-graft technology. The maximal outer diameter (inflated balloon within the lumen) and the recoiled outer diameter (balloon removed) of two types of ePTFE, 3-mm inside diameter (i.d.) thin wall (30-micron internodal distance) and 4-mm i.d. standard wall (30-micron internodal distance), were measured to compare material recoil. Following balloon dilatation, ePTFE samples were prepared for scanning electron microscopic examination and the following parameters were measured: wall thickness, internodal distance, nodal width, interfiber distance, and fiber width. Following primary dilatation, both types of ePTFE recoiled approximately 20% regardless of inflated balloon diameter. However, following eight repetitive balloon dilatations, recoil decreased to approximately 10%. Scanning electron microscopic analysis revealed variations in internodal distance and significant decreases in wall thickness, nodal thickness, and interfiber distance. Fiber width was significantly decreased following dilatation of 3 mm, but not 4 mm ePTFE. Our data support our initial hypothesis that balloon dilatation alters the structure of ePTFE.

Distal revascularization-interval ligation for limb salvage and maintenance of dialysis access in ischemic steal syndrome

PURPOSE

Traditional options for treating ischemic steal syndrome related to a functioning dialysis access graft or fistula include banding or ligation. Unfortunately, these techniques usually result in inconsistent limb salvage, loss of a functional access, or both. We report our experience with an alternative method of limb revascularization that eliminates steal while maintaining continuous dialysis access.

METHODS

Patients who had critical limb ischemia and functioning arteriovenous fistulae (AVF) underwent color-flow duplex scanning, digital photoplethysmography, and arteriography. Arterial ligation distal to the AVF origin eliminated the steal physiologic mechanism while arterial bypass grafting from above to below the AVF revascularized the extremity (distal revascularization-interval ligation [DRIL] procedure).

RESULTS

From March 1994 through December 1996, 21 patients with functioning extremity AVFs presented with critical ischemia and steal syndrome. Eleven patients had chronic ischemia with rest pain, paresthesias, or ulcerations related to nine native fistulae (six brachiocephalic, two basilic vein transpositions, one radiocephalic) and two prosthetic bridge grafts (one upper arm, one lower extremity). Acute ischemia developed in 10 patients related to three native fistulae (two brachiocephalic, one radiocephalic) and seven prosthetic bridge grafts (three forearm, three lower extremity, one upper arm). All 21 patients were treated with the DRIL technique. Three of these patients required treatment for ischemia at the time of AVF construction. Nineteen of 21 bypass procedures were performed with autogenous vein, including nine brachial-brachial, three brachial-radial, two radial-radial, two brachial-ulnar, one popliteal-popliteal, one femoral-popliteal, and one femoral-peroneal. Polytetrafluoroethylene grafts were used for one external iliac-popliteal bypass graft and one axillary-brachial bypass graft. Limb salvage and maintenance of a functional fistula were achieved in 100% and 94%, respectively, at 18 months by life-table analysis.

CONCLUSION

The DRIL technique reliably restores antegrade flow to the ischemic limb, eliminates the potential pathway for the steal physiologic mechanism, and maintains continuous dialysis access in these difficult patients.

Identification of predictors for lower extremity vein graft stenosis

BACKGROUND

The cause of intrinsic vein graft stenosis, which develops in at least 20% of infrainguinal autogenous bypass grafts during the intermediate follow-up interval, is unknown. We performed standard duplex surveillance of all lower extremity bypass grafts and evaluated the potential of comorbid patient risk factors that might predict development of vein graft flow disturbance or high-grade graft stenosis.

METHODS

Patients with at least 6 months of postoperative duplex surveillance were identified through our vascular registry. The association of clinical and hemodynamic profiles of graft performance were compared with specific patient risk factors, including demographics, cigarette smoking, antihypertensive medical therapy, type and quality of conduit, degree of ischemia, bypass run-off, and presence of infection, using stepwise logistic regression analysis.

RESULTS

Ninety-three patients (55 male, 38 female; mean age 69) underwent 100 infrainguinal bypasses. Twenty-six high-grade graft stenoses (>70%) were identified in 26 patients during follow-up (mean 21 months) by graft-flow peak systolic velocity (PSV) >300 cm/sec on more than one duplex examination, and were electively revised. Graft flow disturbances (180 cm/sec >PSV <300 cm/sec) were identified in an additional 13 grafts (6 regressed, 7 observed). The need for graft revision was associated with an early graft flow disturbance (P = 0.02), or drop in ankle-brachial index >0.15 (P = 0.03), and the use of an alternative conduit in 13 of 100 grafts (P = 0.04). Only smoking was associated with the development of a duplex detected graft flow disturbance during follow up (P = 0.03).

CONCLUSION

Grafts with early flow disturbances warrant close duplex surveillance to identify graft-threatening stenosis. Risk factors that may predict future lower extremity bypass graft stenosis are smoking and the use of alternative bypass conduits.