Shawn M. Gage

Multi-center experience of 164 consecutive Hemodialysis Reliable Outflow [HeRO] graft implants for hemodialysis treatment.

OBJECTIVE To report a multi-center experience with the novel Hemodialysis Reliable Outflow (HeRO) vascular access graft. MATERIALS AND METHODS Four centers conducted a retrospective review of end stage renal disease patients who received the HeRO device from implant to last available follow-up. Data is available on 164 patients with an accumulated 2092.1 HeRO implant months. RESULTS At 6 months, HeRO primary and secondary patency is 60% and 90.8%, respectively and at 12 months, 48.8% and 90.8%, respectively. At 24 months, HeRO had a primary patency of 42.9% and secondary patency was 86.7%. Interventions to maintain or re-establish patency have been required in 71.3% of patients (117/164) resulting in an intervention rate of 1.5/year. Access related infections have been reported in 4.3% patients resulting in a rate of 0.14/1000 implant days. CONCLUSIONS In our experience the HeRO device has performed comparably to standard AVGs and has proven superior to TDCs in terms of patency, intervention, and infection rates when compared to the peer-reviewed literature. As an alternative to catheter dependence as a means for hemodialysis access, this graft could reduce the morbidity and mortality associated with TDCs and have a profound impact on the costs associated with catheter related infections and interventions.

Analysis of Infection Risk following Covered Stent Exclusion of Pseudoaneurysms in Prosthetic Arteriovenous Hemodialysis Access Grafts

PURPOSE To determine whether exclusion of pseudoaneurysms with the use of a covered stent in prosthetic arteriovenous (AV) hemodialysis access grafts impacts the incidence of eventual AV graft infection. MATERIALS AND METHODS Review of an interventional radiology database for prosthetic AV graft interventions involving stent deployment anywhere within the AV graft circuit revealed 235 interventions in 174 patients between November 2004 and December 2008. Incidence of AV graft infection was analyzed based on stent type (bare metal vs covered), location, and indication for stent deployment on a per-stent, per-procedure, and per-graft basis. RESULTS A total of 16.3% of the stent-implanted AV grafts were eventually surgically excised as a result of graft infection. Covered stents used to treat an intragraft pseudoaneurysm were more commonly associated with subsequent graft infection compared with bare or covered stents deployed within the graft for other reasons: 42.1% versus 18.2% (P = .011). Stents deployed in an intragraft location were also associated with a higher incidence of graft infection compared with those deployed at the venous anastomosis or outflow vein: 26.9% versus 6.9% (P < .001). No significant difference was identified in infection rates between bare and covered stents. CONCLUSIONS Covered stent exclusion of intragraft pseudoaneurysms demonstrated a significant correlation with eventual prosthetic AV graft infection.

Use of autologous blood-derived endothelial progenitor cells at point-of-care to protect against implant thrombosis in a large animal model.

Titanium (Ti) is commonly utilized in many cardiovascular devices, e.g. as a component of Nitinol stents, intra- and extracorporeal mechanical circulatory assist devices, but is associated with the risk of thromboemboli formation. We propose to solve this problem by lining the Ti blood-contacting surfaces with autologous peripheral blood-derived late outgrowth endothelial progenitor cells (EPCs) after having previously demonstrated that these EPCs adhere to and grow on Ti under physiological shear stresses and functionally adapt to their environment under flow conditions ex vivo. Autologous fluorescently-labeled porcine EPCs were seeded at the point-of-care in the operating room onto Ti tubes for 30 min and implanted into the pro-thrombotic environment of the inferior vena cava of swine (n = 8). After 3 days, Ti tubes were explanted, disassembled, and the blood-contacting surface was imaged. A blinded analysis found all 4 cell-seeded implants to be free of clot, whereas 4 controls without EPCs were either entirely occluded or partially thrombosed. Pre-labeled EPCs had spread and were present on all 4 cell-seeded implants while no endothelial cells were observed on control implants. These results suggest that late outgrowth autologous EPCs represent a promising source of lining Ti implants to reduce thrombosis in vivo.

Percutaneous interventions on the hemodialysis reliable outflow vascular access device.

PURPOSE To determine the outcomes of percutaneous interventions for prolonging the patency of the Hemodialysis Reliable Outflow (HeRO) device. MATERIALS AND METHODS Between January 2007 and August 2011, 73 percutaneous interventions were performed on 26 HeRO devices in 25 patients. The graft was implanted in the upper arm with the outflow catheter tip in the superior vena cava or right atrium. Procedural reports, angiographic images, and clinical notes were retrospectively reviewed. The primary and secondary patency rates after intervention were calculated using the Kaplan-Meier method. RESULTS The mean time from HeRO implantation to initial dysfunction or thrombosis was 171 days. In 60 (82%) procedures, the HeRO device was thrombosed. An intragraft stenosis was the most common lesion identified (59%; n = 43) followed by an arterial anastomosis stenosis identified in 18% (n = 13). In 22% (n = 16) of procedures in which the HeRO device was thrombosed, an underlying cause was not identified after thrombectomy. The 3-, 6-, and 12-month primary patency rates after intervention were 47%, 37%, and 26% for first-time interventions. The secondary patency rates were 80%, 70%, and 64%. The only complication was pulmonary embolism resulting in death 2 days after HeRO thrombectomy. CONCLUSIONS Percutaneous interventions on thrombosed and failing HeRO devices yielded acceptable primary and secondary patency rates after intervention in these patients with few, if any, alternatives for hemodialysis access.

Tissue-engineered vascular grafts: autologous off-the-shelf vascular access?

Dialysis grafts have provided reliable access for millions of patients in need of renal replacement therapy. However, regardless of the material used for artificial dialysis grafts their mean patency remains generally poor and infection rates are greater than native arteriovenous fistulas. The need for superior alternatives to conventional synthetic materials used for vascular access has been an area of investigation for more than 25 years and recently there has been a great deal of progress in the field of tissue-engineered vascular grafts. Many of these technologies are either commercially available or are now entering early phases of clinical trials. This review briefly covers the history, potential advantages, and disadvantages of these technologies, which are likely to create an impact in the field of vascular access surgery.

Arteriovenous Fistulae for Haemodialysis: A Systematic Review and Meta-analysis of Efficacy and Safety Outcomes

BACKGROUND Arteriovenous fistulae are the currently recommended gold standard vascular access modality for haemodialysis because of their prolonged patency, improved durability, and low risk of infection for those that mature. However, notable disadvantages are observed in terms of protracted maturation time, associated high rates of catheter use, and substantial abandonment rates. The aim of this study was to quantitatively summarize the outcomes of fistula patency, infection, maturation, and abandonment published in the scientific literature. METHODS This was a systematic review and meta-analyses of studies evaluating fistula outcomes. Literature searches were conducted in multiple databases to identify observational and interventional studies of mean fistula patency rates at 1 year, infection risk, maturation time, and abandonment. Digitisation software was used to simulate individual patient level data from Kaplan-Meier survival plots. RESULTS Over 8000 studies were reviewed, and from these, 318 studies were included comprising 62,712 accesses. For fistulas the primary unassisted, primary assisted, and secondary patency rates at one year were 64%, 73% and 79% respectively, however not all fistulas reported as patent could be confirmed as being clinically useful for dialysis (i.e. functional patency). For fistulas that were reported as mature, mean time to maturation was 3.5 months, however only 26% of created fistulas were reported as mature at 6 months and 21% of fistulas were abandoned without use. Overall risk of infection in fistula patients was 4.1% and the overall rate per 100 access days was 0.018. CONCLUSIONS Reported fistula patency rates may overstate their potential clinical utility when time to maturation, maturation rate, abandonment and infection are considered. Protracted maturation times, abandonment and infection all have a significant impact on evaluating the clinical utility of fistula creation. A rigorous and consistent set of outcomes definitions for hemodialysis access are necessary to clarify factors contributing to fistula success and the clinical consequence of fistula failure.

Salvaging Vascular Access and Treatment of Severe Limb Edema: Case Reports on the Novel Use of the Hemodialysis Reliable Outflow Vascular Access Device

We report two cases in which patients on chronic hemodialysis presented with morbid unilateral edema of the upper extremity and chest on the side of a currently functioning arteriovenous access. Both patients were known to the vascular surgery service and had previously undergone multiple attempts to create and maintain vascular access. Both severe and disabling edema and the need to maintain dialysis access were of significant concern. These patients were taken to the operating room to address both issues. Upper extremity venography with central venous runoff revealed central vein stenosis and/or occlusion resistant to angioplasty and stenting. Ultimately, these two patients received the Hemodialysis Reliable Outflow vascular access device. The experiences in this study demonstrate the novel use of a relatively new vascular access device for salvage of a malfunctioning arteriovenous fistula or graft as well as treatment of symptoms and complications resulting from long standing vascular access.

Bioengineered hemodialysis access grafts

There is a need for bioengineered therapies to improve the overall health of the growing and aging world population. Patients with renal failure have a life-long requirement for a durable form of hemodialysis vascular access. In this article, we review the history of tissue engineering as it pertains to bioengineered grafts and vessels for hemodialysis access. Over the years, various strategies have been utilized to develop ideal, humanized vessels for vascular replacement such as fixation of animal or human vessels, cell seeding of synthetic materials, and the synthesis of completely autologous or allogeneic bioengineered vessels. Tissue engineering technologies from two companies have progressed to reach phase 2 and phase 3 clinical trials, but the prospect of newer strategies on the horizon may offer improved manufacturing efficiency, a greater variety of conduit size and length, and reduce the cost to produce.

Hemodialysis Reliable Outflow device impingement in the subclavian position: a case report

Purpose The purpose of this study is to report a case of Hemodialysis Reliable Outflow (HeRO) device malfunction in the subclavian position secondary to costoclavicular impingement. Methods and Results The electronic medical record was reviewed for the patient in question and pertinent imaging was collected and photographs were taken with the patients consent. The patient presented with signs of outflow obstruction after a period of HeRO venous outflow component function. The outflow component was found to be crushed between the first rib and the clavicle at the costoclavicular junction. Conclusions This case suggests that costoclavicular impingement should be considered as a mode of outflow failure with the HeRO outflow component in the subclavian position. Other central venous access points should be considered first, and the central veins accessed through the lower extremities are possible alternatives if this failure mode was to arise. First rib resection would also be a viable strategy to relieve impingement at this site.

The Hemodialysis Reliable Outflow (HeRO) Graft

In this chapter, the patient population, selection, and strategic planning around the use of the HeRO graft, as well as the technical considerations, potential pitfalls, complications, and outcomes associated with the device, are discussed.