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Original Contribution
Clinical Experience with a Circumferential Clip-Based Vascular Closure Device in Diagnostic Catheterization
October 2005
Approximately 7 million angiograms and interventional procedures are performed worldwide each year, and the incidence of these procedures continues to rise, particularly in developing countries. The vast majority of these procedures are performed utilizing access via the femoral artery.1,2 Traditionally, manual compression has been utilized to achieve closure of the arteriotomy despite the close observation, prolonged immobilization and bedrest that are required for this method. In the past decade, a variety of closure devices has been developed to facilitate access site management and to increase patient comfort. Although a number of new devices has been introduced in the last several years, there remain concerns about the safety, efficacy and ease-of-use with these closure devices.3–8
Preferably, mechanical closure of the arteriotomy would involve complete capture of the vascular opening and primary apposition of the tissue to achieve a safe, secure closure. A new clip-based extravascular closure device was developed to address this need and the need for an expedited procedure that minimizes subject discomfort and potential skin contamination. The StarClose™ Vascular Closure System (Abbott Vascular Devices, Redwood City, California), which features an innovative nitinol clip, was designed to achieve rapid hemostasis while promoting the primary healing process. When deployed, the clip provides 360° extravascular tissue apposition for rapid healing and immediate hemostasis. An additional characteristic of the StarClose system is the potential for physicians to close the artery through the existing procedural sheath. Elimination of the exchange steps may minimize the exposure of the wound and clip to potential skin contamination. The Clip CLosure In Percutaneous Procedures (CLIP) Trial was initiated to study the StarClose device in patients undergoing catheterization procedures.
Methods
Study design. The CLIP study is a prospective, randomized, multicenter trial utilizing a noninferiority design to compare the rate of major vascular complications and time-to-hemostasis using the StarClose system to manual compression. Based on a comparative study reported by Gerckens et al.9 involving a similar patient population, the margin to establish noninferiority was set at 6%. For study planning purposes, the expected rate of major vascular complications in each study arm was assumed to be 2.5%, requiring a minimum sample size of 189 subjects. Patients were enrolled at 17 clinical centers following approval of the investigational plan and informed consent form by each site’s institutional review board (IRB). All patients signed an informed consent prior to participating in the trial.
An initial roll-in phase was conducted in order for the investigators to become familiar with the device, after which patients were randomized to either treatment or control at a 2:1 ratio. Patients were also analyzed within their own specific treatment group (diagnostic or interventional).
Inclusion criteria were: an arterial puncture in an appropriate vessel, suitability as a candidate for vascular surgery and the ability to complete the required clinical follow-up. Patients with uncontrolled hypertension, clinically severe peripheral vascular disease (including calcification at the arteriotomy), obesity (BMI > 35), or a history of bleeding diathesis were excluded from participation in the trial.
Study procedures: Pre-closure femoral angiography was performed in all subjects to document puncture of the common femoral artery which was required to be at least 6 mm in diameter. Immediately following the index procedure, intravenous heparin was discontinued. In the diagnostic arm of the study, activated clotting times (ACTs) were not required for patients who did not receive anticoagulation during their index procedure, while patients who did receive intravenous heparin were required to achieve an ACT Device use. Four clicks cue the operator to the sequence of steps for device use (Figure 4). The hub of the Introducer Sheath is modified to allow insertion of the Clip Applier. When the primary procedure is completed, the catheter is removed and the sheath is left in place. The Clip Applier is attached to the Introducer Sheath and the clip is then advanced down the inside of the sheath (Click #1). The Vessel Locator Button is depressed (Click #2). The device is apposed against the arteriotomy with gentle traction, then an atraumatic “no-tension” position is assumed with device stabilization. A Thumb Advancer slides forward, splitting the sheath as the clip is advanced to the arteriotomy (Click #3). While maintaining neutral tension or pressing down slightly, the Trigger Button is depressed (Click #4), deploying the clip. Subsequently, the Clip Applier and Introducer Sheath are withdrawn. The nitinol clip provides a secure extravascular closure that does not invade the vessel lumen (Figures 5 and 6).
Study endpoints. The primary safety endpoint of the study was the incidence of major vascular complications, defined as a composite of vascular injury requiring repair, new ipsilateral distal ischemia requiring revascularization, access site nerve injury requiring intervention, access-site bleeding requiring transfusion, and access-site infection requiring intravenous antibiotics or a prolonged hospital stay. The primary efficacy endpoint was the time-to-hemostasis, defined as the elapsed time between sheath removal and first observed hemostasis. Secondary efficacy endpoints included device success, procedure success,time-to-ambulation, and the time to when the patient was eligible to be discharged from the facility. Time-to-ambulation was defined as the time from sheath removal to the time when the patient stands and walks 20 feet without re-bleeding. Time-to-dischargeability was defined as time from the removal of the sheath to the time when the subject could be medically discharged based solely on assessment of the access site (diagnostic subset endpoint only). Device success was defined as attainment of hemostasis using the StarClose system alone or with adjunctive compression of 5 minutes, and freedom from major vascular complications. Procedural success at discharge was defined as attainment of final hemostasis using any method and freedom from major vascular complications. Procedure time was defined as time from initiation of sheath exchange to clip deployment.
Statistical analysis. Data were presented as mean standard deviation unless otherwise noted. Differences between the experimental groups were noted by the two-tailed students t-test, Chi square, and the exact Mann-Whitney rank test where appropriate. p-values Subject enrollment. A total of 596 subjects were enrolled in the trial, 208 of these in the diagnostic arm, which is the focus of this report.
Subject population. Two-hundred eight subjects were enrolled into the diagnostic subset of this study. The mean age of the subjects was 61.7 ± 11.8 years and the percentage of males was 66.8% (139/208) (Table 1). There were no differences in demographic features between the StarClose and manual compression patients. Twenty-eight subjects (13%) were on intravenous heparin at the time of diagnostic catheterization.
Device efficacy. Procedural success using the clip was 100% (136/136) and 100% (72/72) for manual compression (Table 2). Device success was 94.1% (127/135); one subject had a data point missing, therefore time-to-hemostasis could not be calculated. Lack of device success was attributed to 1 case of device malfunction (the nylon tube to pusher body failed), while the remainder were attributed to 4 cases of time-to-hemostasis > 5 minutes (even though in all cases hemostasis was achieved without sequalae), 2 operator technique issues (e.g., excessive tension when retracting the device, inability to advance the tube set), and 1 case that was aborted. Re-bleeding occurred in 2 (0.9%) of the 136 clipped subjects; in both cases additional compression (Device Safety: There were no major vascular complications noted in the StarClose group over the 30-day follow-up (Table 4). The upper limit of the one-sided confidence interval of the difference was less than stated in the null hypothesis, i.e., the major vascular complication rate ascribed to the StarClose system was not greater than observed with manual compression plus the delta (6%). As a result of these findings, the claim of noninferiority is substantiated (Table 4). Overall, minor vascular complications occurred in 2.2% (3/136) of the StarClose subjects and in 1.4% (1/72) manual compression subjects (p = 1.00). One subject in each group had a hematoma > 6 cm in diameter and 2 StarClose subjects had transient access site-related nerve injury as defined by the protocol, which resolved prior to the 30-day follow-up evaluation. The nerve injury cases were identified based upon complaints of pain localized to the access site. No neurotomal or radicular pain pattern was noted, and there were no sensory deficits noted. No intervention or treatment was administered (Table 4).
Discussion
Currently approved vascular closure systems are typically collagen plug or suture-based devices.9–11 Suture-based technologies were initially developed to approach the arteriotomy as a vascular surgeon would — with a mechanical closure forcing apposition of tissue to achieve safe and effective closure.12–20 In an analogous strategy to the “surgical” method, several newer technologies are approaching the problem of vascular closure following catheterization using staples and clips for mechanical closure.21 Clips and staples have a history of providing safe and effective vascular repair and effective wound healing.22–24 The StarClose Vascular Closure System takes this paradigm to the femoral artery and utilizes a small (0.008 inch in thickness and diameter of 4 mm nitinol) clip to provide “extravascular” closure to the arteriotomy.
The current randomized study focused on the StarClose system in diagnostic catheterization subjects. Compared to standard manual compression, StarClose substantially reduced time-to-hemostasis, time-to-ambulation and time-to-dischargeability. Procedural and device success rates were high. The device is simply and rapidly applied with procedural times consistently less than 30 seconds. The device appeared to be safe with no major vascular complications noted and a low number of minor vascular complications, which were no different than the control.
The lack of vascular complications is likely to be related to the technology working above the artery — the clip closes on top of the artery without disrupting the arterial flow. This extravascular approach closes by apposing the tissue at and above the arteriotomy site, leaving nothing8 in the arterial lumen. The extravascular closure aspect of the StarClose device provides no luminal obstruction post-closure. The lack of any blood exposure to the foreign implant also may reduce thrombotic risk. Groin site infections, a potentially devastating complication of groin closure, were not noted in this study. The ability to close through the sheath minimizes exposure of the arteriotomy to a guidewire exchange and delivers the clip without any exposure to the blood field or skin flora, helping to minimize the probability of infection.
The safety and efficacy of the StarClose system is favorable in comparison to currently available devices.
Conclusions
The clinical results of this study concluded that the StarClose Vascular Closure System is noninferior to standard compression with respect to the primary safety endpoint of closing arteriotomies in patients who undergo percutaneous diagnostic procedures.
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