Infrainguinal Arterial Intervention: Is There a Role for an Atherectomy Device?

Excision of atheromatous plaque is an attractive option for the minimally invasive treatment of peripheral arterial disease. Approved for use in 2003, the SilverHawk Plaque Exicison System (FoxHollow Technologies, Redwood City, CA) is a catheter-based plaque excision device allowing percutaneous removal of atheromatous material. This device represents the most recent generation of atherectomy tools. Overall experience with plaque debulking in the peripheral arteries spans almost two decades, and understanding of the technique continues to evolve. This article reviews the technology, current practices, and data on plaque excision.

Spliced arm vein grafts are a durable conduit for lower extremity bypass

BACKGROUND

Many patients with peripheral vascular disease (PAD) requiring revascularization do not have adequate ipsilateral great saphenous vein (GSV) for constructing a bypass because of intrinsic vein disease or prior harvesting for limb or coronary bypass. Prosthetic conduits have poor long-term patency, especially for distal bypass. With advancing endovascular sophistication, tibial angioplasty may be a good revascularization option, but we hypothesize that using spliced arm vein for distal lower extremity bypass is still a well-tolerated and more durable solution.

METHODS

A retrospective chart review was conducted of all PAD patients undergoing lower extremity bypass or tibial angioplasty for lifestyle-limiting claudication or critical limb ischemia at a single institution over a 7-year period. Statistical analysis was conducted by Kaplan-Meier survival analysis and Cox proportional hazards model. Statistical significance was set at P = 0.05.

RESULTS

From 2005 to 2012, there were 120 patients who underwent infrageniculate revascularization with conduit other than GSV. Over half of the patients (66 patients, 71.2% male, mean age 62 years) underwent bypass operations using arm vein conduit, and 88% of those bypasses were to tibial vessels. Patency was 100% at 1 year and 85% at 2 years. There was no impact on patency or amputation rate based on the source of vein or the number of splices. Forty-three patients underwent tibial angioplasty and patency was 70% at 1 year and 50% at 2 years.

CONCLUSIONS

When GSV is not available, spliced arm vein grafts provide durable lower extremity revascularization with favorable patency and limb preservation rates. Spliced arm vein grafts should be considered over prosthetic grafts and angioplasty alone in patients with distal occlusive disease.

Current insights on the biology and clinical aspects of VEGF regulation

Vascular endothelial growth factor (VEGF) is a key molecule that orchestrates the formation and function of vascular networks. Impaired regulation of angiogenesis is implicated in a number of pathologic states. For instance, neoplasias exhibit uncontrolled angiogenesis, whereas ischemia and states of vascular insufficiency involve reduced VEGF activity. As the role of VEGF has been elucidated in these disease processes, its therapeutic role has been developed. The Food and Drug Administration has approved several anti-VEGF agents for treating colorectal, lung, and kidney cancer. VEGF-inducing agents have also been used experimentally to induce angiogenesis in patients with critical limb ischemia. As more knowledge is gathered about the biology of VEGF and its receptors, there is greater promise for therapeutic modulation of VEGF expression. The purpose of this review is to describe the various therapeutic and biologic factors that regulate the expression of VEGF.

Direct thrombin inhibitors: alternatives to heparin

After more than 70 years of effective clinical use, heparin remains the most common anticoagulant in use and one of the most commonly prescribed drugs to hospitalized patients. However, the biologic variability and immunogenicity limit its utility. With increasing volumes of vascular intervention and an aging population, an increase in the need for anticoagulation can be anticipated. This article reviews current viable options and barriers to the use of heparin.

Analysis of Outcomes Following Failed Endovascular Treatment of Chronic Limb Ischemia

Despite recent studies highlighting the advantages of endoluminal intervention in the management of chronic limb ischemia (CLI), outcomes following failed peripheral angioplasty remain less well described. We present a retrospective analysis of failed transluminal infrainguinal percutaneous arterial angioplasty with or without stenting (PTA/S) in patients with CLI. A database of patients undergoing infrainguinal PTA/S between 2002 and 2005 was maintained. Patients underwent duplex scanning follow-up at 2 weeks, 3 months, and every 6 months after the intervention. Angiograms were reviewed in all cases to assess lesion characteristics. Results were standardized to current Transatlantic Inter-Society Consensus (TASC) criteria. Kaplan-Meier survival analyses were performed to assess time-dependent outcomes. In total, our analysis involved 246 patients who underwent treatment for CLI using PTA/S. Eighteen percent of procedures (n = 46) were considered an intervention failure secondary to restenosis by duplex ultrasound, returning clinical symptoms, a nonhealing foot lesion, or the absence of a prior palpable pulse. Indications for the original procedure in patients whose PTA/S failed were tissue loss in 44%, claudication in 44%, and rest pain in 12%, while TASC lesion grades were A (0%), B (18%), C (18%), and D (64%). Of patients failing PTA/S, 4% failed in the first 30 days, 78% failed between 1 and 18 months, while 18% failed following 18 months, with a mean time to failure of 8.7 months. Also, 82% of PTA/S failures were candidates for a second endovascular procedure, 11% were suitable for only traditional open bypass, and 4% demonstrated progression of disease necessitating amputation. Of patients undergoing a second endovascular procedure, limb salvage rates were 86% at 12-month follow-up and there was a single periprocedural mortality and complication rate of 6.6%. Of patients requiring open surgical bypass after failed PTA/S, 20% (n = 1) required a major amputation and there were no mortalities. Failure of endoluminal therapy for treatment of lower extremity arterial occlusive disease is amenable to subsequent endovascular intervention for limb salvage with limited morbidity and mortality.

Analysis of anatomic factors and age in patients undergoing carotid angioplasty and stenting

Recent data suggest that patient age >80 years may be associated with increased risk of periprocedural complications from carotid angioplasty and stenting (CAS). In this study, we analyzed anatomic risk factors in patients undergoing CAS based on age >80 or <80 years. Our hypothesis was that patients >80 would have more challenging anatomy. Between February 2003 and August 2004, 82 patients underwent CAS. Images for 57 lesions were available for review. Eighteen patients were > or =80 years old and 39 were <80. Cerebral protection devices, including EPI Filterwire, Percusurge, Accunet, and Angioguard, were used in all but two cases; and self-expanding stents (Wallstent, NexStent, Acculink, Precise) were placed in all. Arterial anatomic characteristics were assigned a score based on complexity and associated procedural risk. Characteristics evaluated using angiographic images were aortic arch elongation classification, arch calcification, common carotid/innominate stenosis, common carotid tortuosity, internal carotid tortuosity, index lesion length, index lesion calcification, and index lesion stenosis. Statistical analysis was performed using Fisher's exact test. CAS was successfully completed in 98% of cases. The two patients in whom we could not perform CAS were 79 and 83 years old. The anatomic characteristics that were statistically significantly more complex/severe in patients > or =80 were arch calcification (p = 0.045), common carotid/innominate stenosis (p = 0.023), common carotid tortuosity (p = 0.049), and internal carotid tortuosity (p = 0.032). There was no statistically significant difference in arch elongation classification, lesion length, lesion calcification, or stenosis severity (p = nonsignificant). Overall, patients > or =80 years had an increased incidence of complex anatomic risk factors compared to younger patients (p < 0.001). Cerebrovascular accident without residual deficits occurred in two patients; both were >80 years old. Complex arterial anatomy is more often present in patients >80 years and may explain the increased complication rates associated with CAS. Pre- or intraoperative consideration of these characteristics may help provide better risk assessment in candidates for CAS.

Argatroban for anticoagulation during cardiopulmonary bypass in an infant

Heparin induced thrombocytopenia (HIT) is a rare, but potentially life-threatening complication of heparin therapy. In patients with HIT, alternative means of anticoagulation are necessary. The authors present an infant with HIT who required anticoagulation during cardiopulmonary bypass for tricuspid valve excision in the treatment of bacterial endocarditis. The direct thrombin inhibitor, argatroban, was successfully used. Previous reports regarding the use of argatroban and other nonheparin anticoagulants for anticoagulation are reviewed and suggestions regarding argatroban dosing in infants are presented.

Heparin-induced thrombocytopenia in the pediatric intensive care unit population

OBJECTIVES

To report the occurrence of heparin-induced thrombocytopenia (HIT), discuss its pathophysiology, and outline an approach to management in the pediatric intensive care unit (ICU) patient.

DESIGN

Retrospective case reports.

SETTING

Pediatric ICU in a tertiary-care center.

PATIENTS AND RESULTS

Two pediatric ICU patients (2 and 6 mos of age) who developed HIT in the pediatric ICU. One was receiving heparin as a flush solution through a central line and the other had full heparinization during cardiopulmonary bypass. Both had received heparin during their neonatal course and developed thrombocytopenia; however, HIT was not considered as a possible diagnosis. HIT was diagnosed using a heparin-induced platelet aggregation study. The thrombocytopenia resolved with the cessation of heparin administration. One of the patients developed a deep vein thrombosis around a femoral venous catheter.

CONCLUSION

Although well described in the adult literature, there have been a limited number of reports of HIT in pediatric-aged patients. Given its potential for morbidity, HIT should be considered in the differential diagnosis of thrombocytopenia in the pediatric ICU patient.

Pharmacomechanical thrombectomy for treatment of symptomatic lower extremity deep venous thrombosis: Safety and feasibility study

PURPOSE

The current standard of care for deep venous thromboembolism (DVT) is anticoagulation; however, this treatment method does not rapidly relieve clot burden or clinical symptoms. We describe a rapid and effective method of thrombus removal, with simultaneous percutaneous mechanical thrombectomy (PMT) and thrombolysis.

METHODS

Over 26 months 20 patients (22 men, 2 women; mean age, 52 +/- 6 years [range, 38-79 years]) with extensive lower extremity DVT were treated with PMT with the AngioJet thrombectomy device in combination with lytic agent (urokinase, tissue plasminogen activator, or reteplase) added to the infusion. Three patients underwent treatment twice, because of recurrent DVT. The primary end point was angiographic evidence of restoration of venous patency at completion of the procedure. Complications, recurrent ipsilateral DVT, and improvement in clinical symptoms were evaluated.

RESULTS

Complete thrombus removal was obtained in 15 procedures (65%), and partial resolution in the remaining 8 procedures (35%). Inciting occlusive lesions responsible for acute DVT were revealed in 14 patients (61%), and angioplasty with or without stenting was performed when necessary. In the 8 procedures with partial resolution additional catheter-directed thrombolysis was carried out on average for 5.7 hours, with further thrombus reduction. Overall, immediate (<24 hours) improvement in clinical symptoms was noted in 17 patients (74%). There were no complications related to either PMT or the short duration of lytic agent infusion. At average follow-up of 10.2 +/- 0.3 months (range, 3-26 months), 3 patients had recurrent ipsilateral DVT, and underwent repeat treatment.

CONCLUSIONS

Addition of lytic agent to PMT facilitates thrombus extraction, decreases overall interventional treatment time, and improves patient outcomes. In addition, definitive management of underlying anatomic lesions can be performed in the same setting. Further outcome measures are necessary to study the long-term efficacy of this treatment method on preservation of valve function, reduction of chronic venous insufficiency, and improved quality of life.