The Novel Angiolink Staple-mediated Vascular Closure Device

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Despite the recent introduction of vascular closure device (VCD) technology, vascular access site complications remain the leading source of morbidity and costs after the approximately eight/eight and a half million percutaneous catheter-based procedures performed annually worldwide. VCD trials consistently demonstrate increased patient satisfaction, early ambulation, and decreased hospital resource utilization as compared with manual compression (MC). Unfortunately, these reports have not consistently demonstrated decreased complication rates, and current VCD technology has even created a new category of complications and treatments primarily involving infection and arterial thrombosis.

In 1953, Seldinger classically reported the original description of percutaneous femoral artery access and, in so doing, first reported vascular access hemostasis (VAH). Since then, significant technological advances in the field of catheter-based cardiovascular therapy have rendered most early percutaneous technology obsolete. It is remarkable that, 50 years later, the gold standard of VAH remains MC, performed almost exactly as Seldinger originally described, ÔÇ£20-30 minutes hand-held pressure after catheter removal followed by overnight bed rest.ÔÇØThis gold standard remained largely unchallenged over the next four decades, until the widespread adoption of percutaneous cardiovascular interventions. These procedures require larger sheaths and more potent anticoagulation, therefore increasing the clinical potential for complication.

The Problem Exposed

Femoral artery access complications (FAC) remain a significant source of mortality and are the leading cause of morbidity and costs after percutaneous coronary intervention (PCI). Remarkably, no standardization exists with regard to reporting 'majorÔÇÖ and/or 'minorÔÇÖ FAC rates, which vary widely from 0.4% to 27% depending upon the definition of complications. Most reports site only 'majorÔÇÖ FACs requiring surgery, and it is highly likely that many FACs go unreported or are accepted as 'part of the territoryÔÇÖ. Duffin et al. were among the first to identify FACs as a major problem noting a 14% bleeding rate with PCI. In a randomized trial comparing MC with AngioSeal (St Jude Medical, St Paul, MN),Kussmall et al. reported a 27% overall ÔÇ£any complicationÔÇØ rate in the MC group with heparin. In 2001, Danges et al. compared MC (N=4,596) with VCDs (N=497) after PCI and reported higher ÔÇ£overall complicationÔÇØ rates with VCDs versus MC (21.4% versus 12.1%, respectively), again confirming significant ÔÇ£overall complicationsÔÇØ with MC and identifying that current VCD use may increase complications.

Pracyk et al. cited a 64% overall FAC rate with MC when patients were thoroughly scrutinized by physical examination and duplex ultrasound. A review of the literature reveals sparse data on MC with regard to a hemostatic mechanism, healing or scarring of the arteriotomy site, short- or long-term femoral artery (FA) clinical sequale, systemic effects of a groin hematoma, or a consensus recommendation on the safety, risks, and timing of FA re-entry. After 50 years of truly remarkable cardiovascular technological achievements, it seems reasonable to ask the questions 'why?ÔÇÖ and 'should MC still be the gold standard?ÔÇÖ

F - Clinical and Economic Costs

Aguirre et al. found FAC increased the length of patient stay to an average of 3.5 days compared with <2 days in an uncomplicated PCI. Moscucci et al. has suggested that FAC may indirectly increase ischemic complications after PCI when they reported the incidence of death and myocardial infarction (MI) among patients with FAC as 2.4% and 13% respectively, versus 0.2% and 3.0% in 4,090 PCI patients without FAC (P <0.0001). Extrapolating financial costs to FAC is difficult, but in tracking blood transfusions after PCI, Lauer et al. has estimated a single unit of blood transfusion during PCI to add an additional US$8,000 to the overall cost of that hospitalization. The Replace-2 study has now shown increased 30-day and one-year mortalities in PCI patients who experience a bleeding complication and increased morbidities (myocardial infarctions, need for repeat PCI, etc.).

Limitations of Current VCD

Currently, it is estimated that only 20% to 25% of all catheter-based procedures performed worldwide utilize a VCD for access site hemostasis.

Percutaneous Staple Technology

Surgical metal staple technology has revolutionized traditional general, vascular, and cardiothoracic surgery for several decades and has proven safe, biocompatible, and cost-effective. The Vascular Closure System (EVS) closure device (Angiolink Corporation) was specifically designed with the goal of being the ideal VCD by addressing the limitations of current VCDs utilizing well-known surgical and endovascular concepts, including biocompatibility, sterility, simplicity, and the 'anatomic purse-string effectÔÇÖ to achieve immediate, safe, secure, and cost-effective extraluminal femoral arteriotomy closure.

The Angiolink Staple

Device Description

The device consists of three components:

  1. A low profile, 3mm biocompatible titanium staple designed for deployment 1mm above the vessel adventitia, and four staple legs, each with a distal 'pledget-flareÔÇÖ designed to gather an 'autogeneous tissue pledgetÔÇÖ of femoral sheath, adventitia, and media for an autogeneous extraluminal closure.
  2. A simple one-piece 'three-stepÔÇÖ introducer assembly containing an introducer, a dilator with a blood-marking lumen positioned 7mm from the distal tip, and two small 'stabilization filamentsÔÇÖ designed to transiently deploy intraluminally maximizing vessel wall stabilization for staple deployment.
  3. A trigger-activated staple deployment device. The staple and stapler utilize a unique proprietary deployment cycle design that allows initial staple expansion and advancement to gather autogeneous tissue prior to final staple closure, achieving an 'anatomic purse-stringÔÇÖ.

Deployment Technique

The arterial sheath is removed and the dilator and introducer are introduced over a 0.035ÔÇØ guidewire through the overlying tissues until brisk bleeding is noted from the distal dilator port marking the depth of the arterial lumen. The guidewire is removed and the 'three-stepÔÇÖ introducer maneuver is performed, stabilizing the anterior vessel wall. The dilator is then removed and the staple device is advanced through the introducer until the stapler reaches the level of the stabilized anterior vessel wall, where the system locks itself in place, which can be noted by an audible 'clickÔÇÖ. The staple, still housed sterile in the deployment device, is now located 1-2mm above the adventitia. As the trigger is activated, the staple deployment cycle is performed, the stabilization filaments are retracted, and the introducer is removed all in the same final movement, having deployed the completely sterile staple to the arteriotomy site.

Achieving the 'Ideal VCDÔÇÖ

Titanium has become the most common human metal implant material because of its superior properties of strength and pliability, biocompatibility and inertness, and cost-effectiveness when compared with stainless steel, making it ideal for the intricate Angiolink staple design. Permanent braided sutures, collagen plugs, and other absorbable procoagulants used with current VCD are non-inert, highly reactive, and may be an etiologic factor in infection and arterial thrombosis.

The one-piece introducer assembly system has been designed for simplicity, uses cost-effective materials, and has a short learning curve. The staple remains sterile within the stapler 'housingÔÇÖ and introducer until final deployment inside the body at the extraluminal vessel wall - much like the sterile deployment of a stent, therefore avoiding operator or skin contamination. The entire system is designed for single-operator use and, with experience, the total operator closure time should be less than 60 seconds.

The 'purse-string sutureÔÇÖ closure concept is a well-known surgical technique used to close large arteriotomies in large vessels, with the most notable being decannulation of large-bore cannulas from the ascending aorta during cardiac surgical procedures. The technique utilizes pledgets to gather only vessel adventitia and media at the arteriotomy edges, allowing for tissue approximation when the cannula is removed and the suture is tied. This results in immediate, secure, totally extraluminal vessel closure in the anticoagulated patient with pulsatile aortic blood flow. This extraluminal closure is accomplished without luminal narrowing and, therefore, this device theoretically could be utilized in any vessel regardless of 'stickÔÇÖ location, size or anticoagulation status and could allow almost immediate ambulation.

The Angiolink Trial

The Angiolink pivotal safety and efficacy study and 30-day follow-up was completed in the first quarter of 2004 and will be presented in September 2004 at the TCT. This multicenter, prospective, randomized trial was challenged by the US Food and Drug Administration (FDA) with higher standards than previous VCD trials by requiring >50% coronary and peripheral interventions, therefore larger sheaths (7-8Fr) in heavily anticoagulated patients.Ôûá

This article is continued, with references and graphics, in the Reference Section on the website supporting this business briefing (www.touchbriefings.com).