Cath Lab Digest

Results of Pinnacle TIF Tip Sheath Safety and Feasibility Pilot Study

Introduction

Vascular access management (VAM) and its complications (VAC) remain a significant source of clinical and therefore economic costs in the interventional treatment of cardiovascular disease. Even with a trend towards a decreasing incidence of VAC in the last decade, VAC during percutaneous coronary interventions (PCI) have been reported between 0.4 – 27%, depending on the definition of complications.1-5 It is now clear that even with a “minor” complication, there are significant clinical, ischemic and economic VAC costs, with multiple recent reports of increased in-house, 30-day and one-year mortalities and morbidities now associated with VAC during PCI.5-10 Sparse data exists regarding the incidence or costs of VAC during percutaneous peripheral vascular interventions (PVI) but a review of the literature cites an incidence of 3.5% – 32.7%.11-13 Shammas recently reported a 16% VAC incidence in 131 PVI with a death rate (0.8%), limb loss (1.5%), major bleeding (4.6%), urgent revascularization (7.6%) and vascular complications (1.5%).11 Minor complications were not categorized in this report, thus likely underestimating the true clinical impact of VAC. In a just-published report, Dick et al evaluated VAC in 619 consecutive PVI cases and focused on VAC in octogenarians.14 Complication rates were significantly higher in octogenarians compared to patients below 80 years, including the rates of overall complications (18.1% versus 8.5%, p = 0.010), major complications (11.1% versus 1.8%, p < 0.001), all access site complications (12.5% versus 4.9%, p = 0.009), and access site bleeding complications (12.5% versus 2.2%, p < 0.001). By multivariable analysis, octogenarians had a 2.49-fold increased adjusted risk [95% confidence interval (CI) 1.10 to 5.65, p = 0.029] for any postintervention complication and a 10.99-fold increased adjusted risk (95% CI 2.76 to 45.74, p = 0.001) for major complications compared to patients below 80 years.14 It is likely that the potential incidence for VAC during PVI is greater than during PCI due to the complexity of the peripheral vascular patient, including advanced age, hypercoagulability, common femoral artery (CFA) calcification, higher incidence of diabetes and chronic kidney disease, frequent need for re-access and the complexity of the PVI procedure itself.

Background

Interestingly, transfemoral CFA access has remained the preferred percutaneous vascular access entry, with little change in an overall VAM strategy since its original description by Selinger in 1953.15 Over the last decade, multiple vascular closure devices (VCD) have been developed in an attempt to facilitate VAM and final arteriotomy closure without significantly decreasing VAC. VCDs have even created a “new disease” with their own, real-world set of catastrophic VCD complications, including infection, vessel thrombosis, vessel injury, embolization, limb loss and even death (Figure 1). The VCD approach to facilitate VAM has focused on device-orientated manipulation of the already created arteriotomy site. This approach invariably leaves some form of “VCD debris” (suture, anchor, collagen, clip, plug, staple, glue, etc.) at the arteriotomy site and within the arteriotomy tract that may result in significant perivascular scarring. VCD debris potentially has a negative effect on future CFA re-access, and the need for re-access is becoming more common in our cardiovascular patients, especially patients requiring PVI.

Until recently, little attention has been given to VAM regarding vascular access beginning at the skin level. It is now accepted that detailed attention to the bony elements of the groin (head of femur, iliac rim, pelvic rim, etc.) and vascular wall calcifications under fluoroscopy should be given on all “CFA sticks,” which likely will decrease VAC. All “CFA sticks” are performed in this manner in our cath lab. Various Doppler-assisted devices and micropuncture kits are also now available to facilitate more complex CFA accesses. Little attention and few technical advancements have been made in introducer sheath technology despite “difficult groin access” cases becoming more frequent occurrences in all our labs secondary to previous surgical procedures, multiple previous access, older age populations, more frequent, heavily calcified CFAs, more PVI cases, and now a decade of patients harboring a host of VCD debris-scar in their groins and on the CFA wall. It is becoming commonplace, especially for those labs doing high-volume PVI, to encounter patients in which safe and uncomplicated introducer sheath access can be problematic. Access can generally be gained, but often requires multiple extra steps, wires, dilators, sheath exchanges, devices, excessive penetration forces and maneuvers, etc., and exposes the patient and staff to additional fluoroscopy, economic costs and potentially increased VAC. This difficulty in advancing the introducer sheath set into the CFA lumen is invariably secondary to excessive perivascular tissue scarring from the dermis to the intima, and an attempt was made previously with an intraoperative study to subjectively categorize this phenomenon with the description of the perivascular scar score.16

It could be theorized that increased VAC might be associated with the creation of the arteriotomy during the “CFA stick” and with the advancement of the introducer sheath through the subdermal, subcutaneous and perivascular tissues, and vessel wall. It seems intuitive that the creation of a smooth, atraumatic arteriotomy would be better suited for uncomplicated final hemostasis, regardless of the final arteriotomy management or closure (manual compression or VCD). Likewise, it seems a reasonable assumption that a more traumatic tissue tract advancement and arteriotomy site creation would be associated with an increased perivascular and tissue tract bleeding, inflammation, scarring and therefore, VAC.

Few recent advancements have been made with introducer sheath technology, especially regarding the transition zone between the wire and introducer sheath tip and the dilator. In a “difficult to access” or “scarred groin,” it is believed that excessive resistance to sheath set penetration can occur at this transition zone, resulting in a failure to gain vessel access due to several sheath set failures, including kinking, sheath fish-mouthing or sheath peeling. Terumo Interventional Systems (Somerset, NJ) has developed the Pinnacle Total Integrated Fit (TIF) Tip™ introducer sheath system, designed to bend and flex without gapping, kinking or producing sharp crimps, to potentially facilitate vascular access and minimize potential trauma (Figure 2A-B). TIF technology was developed with a unique manufacturing process that creates a super-fine tapered edge and super-smooth transition from dilator-to-sheath and guidewire-to-dilator (Figure 2C). The dilator taper is more gradual and much smoother than traditional sheaths (Figure 2 D-E). The dilator outer diameter (OD) and sheath tip inner diameter (ID) are perfectly rounded, with tighter tolerances eliminating any gaps or irregularities at the sheath tip (Figure 2F). The dilator lumen is perfectly rounded at the tip with an improved transition to the wire, facilitating optimal wire placement through the entire dilator-sheath assembly (Figure 2F).

In bench-top tests, the Pinnacle TIF Tip required up to 24% less penetration force in vascular entry than traditional sheaths. Additionally, the TIF Tip sheath flexed beyond 45° without kinking or collapsing, whereas all other traditional sheaths consistently kinked at 45°. It was hypothesized that these sheath characteristics may facilitate vascular access, resulting in easier, safer introducer sheath access with the potential for less VAC. The Terumo Pinnacle TIF Tip Set Study was a 3-month pilot safety and feasibility experience utilizing the TIF sheath in a high-volume cath lab that primarily performs complex PVI.

Methods

The Pinnacle TIF Tip sheath pilot study was a 3-month (February – May 2008), prospective, non-randomized, single-center clinical experience conducted at Southwest Medical Center (Lafayette, LA), a high-volume tertiary referral facility for complex PVI, especially critical limb ischemia (CLI) and limb salvage. Prospective and retrospective data was collected and recorded according to HIPAA standards by a trained clinical research nurse and audited by a monitoring coordinator. Study endpoints included completion of a subjective sheath performance characteristic matrix of the TIF sheath, overall access site complications at hospital discharge and any access site-related blood loss. Multiple additional periprocedural variables were collected, including: previous use of access site, sheath sizes, specific procedure performed, bleeding upon sheath removal, sheath-induced complications, type of closure system/device used and each operator’s subjective categorization of each “groin stick” into normal-mild, moderate or severe scarring at the access site. This subjective categorization was based on the intraoperative perivascular scar score that has been published previously.16

A subjective sheath performance matrix was created to subjectively assess each case by asking the operator to grade a series of 11 sheath performance characteristics. On each data collection form, the operator was asked to provide a subjective evaluation of the TIF sheath relative to the 11 performance characteristics, based on a grading scale of 5 through 1, with 5 representing “excellent performance” and 1 representing “failure to achieve access” (Table 1).

The following sheath performance characteristics and definitions were included in the matrix:

1. Durability – the ability of the sheath to withstand all peri-procedural device exchanges.

2. Fish-mouthing – uneven ovaling of the distal opening of the sheath, resulting when the sheath slips back off the dilator due to penetration resistance or sheath transition mismatch.

3. Kinking – any buckling or bending of the wire, sheath or dilator shaft during advancement over the wire.

4. Peeling – the sheath folding over itself, bunching on top of the dilator (accordination of the sheath).

5. Stiffness – the support and stoutness of the shafts of both the sheath and dilator.

6. Tractability – the ability of the sheath to follow the wire through the skin and in the vessel, and not buckle or kink.

7. Visualization – ability to visualize the system under fluoroscopy.

8. Resistance – amount of pressure required to advance the sheath set through the tissues to gain vascular access. Wire/dilator/ sheath kinking or fish-mouthing may be associated with increased resistance. Extreme insertion forces (penetration force) may be associated with vessel wall (including intimal) trauma and arteriotomy site injury or widening.

9. Penetration force – the subjective measure of pressure required to insert the sheath and dilator into the vessel (Scale of 1 = easy to 5 = unable to access).

10. Tactile feel – the tactile sensation felt by the operator as the sheath set is advanced over the wire and through the tissues. This includes pushability, force, stiffness, traceability, resistance and friction to movement, and tells the operator that the distal end of the system is advancing properly through the tissues and into the vessel.