Author + information
- Received April 13, 2016
- Revision received June 13, 2016
- Accepted June 30, 2016
- Published online October 10, 2016.
- Ehtisham Mahmud, MDa,∗ (, )
- Florian Schmid, MDb,
- Peter Kalmar, MDb,
- Hannes Deutschmann, MDb,
- Franz Hafner, MDc,
- Peter Rief, MDc and
- Marianne Brodmann, MDc
- aDivision of Cardiovascular Medicine, Sulpizio Cardiovascular Center, University of California, San Diego, La Jolla, California
- bDivision of Interventional Radiology, Medical University, Graz, Austria
- cClinical Division of Angiologie, Medical University, Graz, Austria
- ↵∗Reprint requests and correspondence:
Dr. Ehtisham Mahmud, Sulpizio Cardiovascular Center, University of California, San Diego, 9434 Medical Center Drive, La Jolla, California 92037.
Objectives The goal of this study was to evaluate the feasibility and safety of a robotic-assisted platform (CorPath 200, Corindus Vascular Robotics, Waltham, Massachusetts) for treating peripheral artery disease.
Background A robotic-assisted platform for percutaneous coronary intervention is available for treating coronary artery disease.
Methods In this prospective single-arm trial, patients with symptomatic peripheral artery disease (Rutherford class 2 to 5) affecting the femoropoplital artery were enrolled. Endpoints evaluated were: 1) device technical success, defined as successful cannulation of the target vessel with the robotic system; 2) device safety, defined as absence of device related serious adverse event (hospitalization, prolonged hospitalization, life threatening, or resulted in death); and 3) clinical procedural success, defined as <50% residual stenosis without an unplanned switch to manual assistance or device-related serious adverse event in the periprocedural period.
Results The study enrolled 20 subjects (65.5 ± 9.3 years of age; 70% male) with primarily Rutherford class 2 to 3 (90%) symptoms. A total of 29 lesions (lesion length: 33.1 ± 15.5 mm) were treated with the majority (89.7%) being located in the superficial femoral artery. Device technical success, safety and clinical procedural success were all 100% with provisional stenting required in 34.5% of lesions. Fluoroscopy time (7.1 ± 3.2 min) and contrast use (73.3 ± 9.2 ml) compared favorably with studies in similar patient cohorts. There were no adverse events associated with the use of the robotic system.
Conclusions These data demonstrate the feasibility and safety of using a robotic-assisted platform for performing peripheral arterial revascularization.
Since the advent of percutaneous cardiovascular interventions, tremendous advances in adjunctive pharmacotherapy and percutaneous device technology have been made. However, the fundamental technique of manually advancing intravascular devices at the patient’s bedside while wearing heavy lead aprons in relative close proximity to the x-ray radiation source remains largely unchanged. The heavy lead apron worn by cardiovascular interventionalists is associated with orthopedic complications, and concerns also exist for radiation-associated occupational hazards of the profession (1–8). Robotic-assisted peripheral vascular intervention (PVI) can potentially limit the occupational hazards associated with vascular interventions, addressing both the orthopedic and radiation associated risks.
The ability to perform remote controlled robotic percutaneous coronary intervention (PCI) was initially described by Beyar et al. (9) and subsequently, the PRECISE (Percutaneous Robotically Enhanced Coronary Intervention) trial demonstrated the safety and feasibility of robotic-assisted PCI in a large multicenter study consisting of 164 patients (10). We undertook this study to evaluate the feasibility and safety of robotic technology using the CorPath 200 System (Corindus Vascular Robotics, Waltham, Massachusetts) for PVI.
The RAPID (Robotic-Assisted Peripheral Intervention for peripheral arterial Disease) study was a prospective single-arm, single-center, open-label, nonrandomized study of robotic-assisted PVI (NCT02371785). It was approved by the local ethics committee and competent authority, and was carried out in accordance with the Declaration of Helsinki. All patients provided written informed consent. The objectives of the study were to evaluate the feasibility and safety of the CorPath System in performing endovascular intervention of the femoropopliteal artery.
Patients were eligible for enrollment with age ≥18 years and symptomatic peripheral artery disease as evidenced by either the presence of critical limb ischemia or lifestyle-limiting claudication (Rutherford class 2 to 5), and with angiographic stenosis of >50% or occlusion of femoropopliteal arteries. Patients were excluded if the target vessel was previously treated with bypass; the target vessel had angiographic evidence of aneurysm, dissection, perforation, or acute thrombosis; or the culprit lesion was severely calcified requiring artherectomy.
Details regarding the CorPath System have been published previously (10); briefly, the system consists of a remote work space and a table side robotic unit (Figure 1). The remote work space consists of a radiation-shielded mobile workstation where a control console with 2 joysticks allows independent manipulation of guidewires and catheters by the seated physician performing PVI. The joysticks on the control console remotely deliver signals through a communication cable to the table side robotic unit, which consists of an articulating arm, robotic drive, and single-use cassette. The articulating arm supports the robotic drive, which houses the cassette. The cassette functions to translate the signals from the joystick manipulations into precise movements of guidewires and rapid exchange catheters.
All procedures in the study were performed with standard techniques by 3 procedural operators using unfractionated heparin as the anticoagulant. Antegrade common femoral artery access was obtained in all subjects following which the cassette was attached to the sheath using a Tuohy borst system (Copilot Bleedback Control Valve, Abbott Vascular, Santa Clara, California) (Figure 2A). Balloon angioplasty of the femoropopliteal vessels was then performed robotically (Figure 2B) with option for provisional stenting for flow-limiting dissections. Commercially available U.S. Food and Drug Administration–approved guidewires (0.014-inch) and rapid exchange balloon catheters (3 to 7 mm diameter; 20 mm length) were used at the discretion of the treating physician. Per protocol, for patients requiring provisional stenting, an over-the-wire self-expanding stent was delivered manually. Provisional stenting was not considered a failure of the robotic system.
The 2 primary endpoints were device technical success and safety. Device technical success was defined as cannulation of the target vessel with the guidewire and dilating angioplasty balloon. The primary safety measure was the absence of device-related serious adverse events during the procedure. These were defined as adverse events related to the use of the robotic device that resulted in hospitalization, prolonged hospitalization, were life threatening, or resulted in death. Additional endpoints included clinical procedural success, fluoroscopy time, subject radiation exposure, contrast volume, procedure time, and adverse events. Clinical procedural success was defined as <50% residual stenosis without an unplanned switch to a manual procedure or device-related serious adverse event in the periprocedural period.
Descriptive statistics (frequency and percentage for categorical variables and number of observations, mean, and standard deviation for continuous variables) were used to present results of the patient, lesion, and procedure characteristics. The peak systolic velocity ratio and percent diameter stenosis were compared before and after robotic PVI using a repeated measures analysis of variance. The revascularization results ankle and toe brachial indices were compared with prerevascularization indices using the Wilcoxon signed-rank test (a nonparametric paired t test).
A total of 20 subjects who met the study inclusion criteria underwent robotic-assisted PVI. Overall, 39 patients were screened for enrollment and 19 were excluded due to not meeting inclusion criteria (n = 12), not consenting for clinical trial participation (n = 5), not consenting to PVI (n = 1), or an inability to obtain common femoral arterial access (n = 1). Study subjects were elderly (65.5 ± 9.3 years of age; 70% male) and primarily Rutherford class 2 (30%) or 3 (60%) (Table 1). Twenty-nine lesions, of which 2 were occlusions, were treated with the majority being in the superficial femoral artery (89.7%). One lesion covered the distal superficial femoral artery and the proximal popliteal artery. Lesions were relatively short (lesion length: 33.1 ± 15.5 mm), with mild vessel tortuosity (93.1%) but with significant calcification (55.2% moderate to severe) (Table 2). High-grade stenosis was relieved (angiographic stenosis: 85.5 ± 11.0% to 7.2 ± 11.1%) with reduction in systolic flow velocity (Table 3). Representative images of treated lesions are shown (Figure 3). Total procedure (sheath in–sheath out) and fluoroscopy times were 45.5 ± 6.2 and 6.8 ± 3.4 min, respectively (Table 4). Technical and clinical procedural success were achieved in 100% of treated lesions and patients, respectively. Ten lesions (34.5%) required provisional stenting and only 3 minor adverse events, all access site hematomas, were reported. No adverse events related to the robotic system were reported.
The more recent Peripheral Academic Research Consortium definition of acute technical success for peripheral revascularization requires a final residual stenosis of <30% after stenting and <50% after balloon angioplasty or atherectomy in the absence of a flow-limiting dissection or residual pressure gradient (11). Using this definition, of the 29 lesions treated, 19 treated with angioplasty all had residual stenosis of <50% (mean 21.2 ± 8.2%; range 8.1% to 38.6%) and 9 of 10 with provisional stenting had residual stenosis of <30% (mean 17.2 ± 9.5%; range 6.5% to 33.1%).
This is the first study to demonstrate the feasibility and safety of a robotic-assisted PVI platform for femoropopliteal vessels using the CorPath System. In 20 patients with 29 treated lesions, device technical success and clinical procedural success were achieved in all patients. Using the more contemporary Peripheral Academic Research Consortium definition, acute technical success was achieved in 96.6% and no adverse clinical events related to the robotic platform were observed. In addition, the rate of provisional stenting (34.5%) was comparable with published results (18.0% to 64.3%) for manually performed PTA procedures of the lower extremities (12,13).
Although, operator radiation exposure was not assessed in the current trial, robotic-assisted PVI did not result in increased procedure time or fluoroscopy time compared with historical controls (14–17). The mean total procedure time of 39.1 ± 15.8 min is comparable with the 60 to 83 min reported for a randomized trial comparing uncoated balloons to drug-eluting balloons (14) and 41 min for stents (15). Similarly, fluoroscopy time in this study (7.1 ± 3.2 min) compares favorably with the mean of 13 to 15 min reported in studies in similar patient cohorts (16,17). However, future studies should focus on comparing these outcomes with an appropriately matched control group undergoing manual PVI. Importantly, using the CorPath System for PVI, the operator can perform the procedure in a seated position in a radiation-shielded cockpit, being protected from radiation and limiting the potential for orthopedic injuries.
In PCI, using the CorPath robotic-assisted system, a high degree of procedural success is expected with reduction in longitudinal geographical miss when compared with manual PCI procedures (18). Geographic miss has also been described in manually performed peripheral balloon angioplasty with incidence as high as 28.6% (19). It is likely that a robotic-assisted PVI system could facilitate more precise lesion measurement (20) and accurate device selection (21), reducing longitudinal geographical miss in PVI procedures. However, additional studies are required to provide definitive evidence.
Although the purpose of the current study was to validate the concept of safe remotely controlled robotic-assisted PVI, future iterations of the platform require that the majority or entirety of the PVI procedure after initial vascular access be performed robotically. In contemporary practice, the use of atherectomy devices for calcified lesions, use of reentry devices for chronic total occlusion, and delivery of drug-coated balloons and self-expanding stents is performed over 0.018- to 0.035-inch guidewires and delivered over the wire. To expand the application of robotic technology in these patients, an iterative advance in the technology and future studies focusing on evaluating robotic-assisted PVI outcomes in more complex patients and lesions are required. It is likely that a hybrid approach of manual and robotic-assisted PVI could still result in substantive operator benefits with the current generation platform.
Previously, another robotic vascular system (Hansen Medical, Mountain View, California) was reported to be successful for the treatment of iliac and femoropoliteal vessels (22). However, the Hansen system requires the use of a proprietary catheter and has not gained widespread use. Furthermore, though there are no direct comparisons, the CorPath System use in the current study was associated with lower procedure time (45.5 ± 6.2 min vs. 82 ± 30 min) and fluoroscopy time (7.1 ± 3.2 min vs. 26 ± 14 min) as compared with the Hansen system. The Hansen system has, however, been very successfully used in electrophysiology to guide ablation procedures. Uniformly, these advanced robotic technologies improve physician ergonomics, reduce operator radiation exposure, and have the potential to improve procedural accuracy.
This study represents a single high-volume tertiary care center experience and the results need to be replicated by multiple users to show the general applicability of these findings. Further, this study was limited by a small sample size and enrolled patients with relatively short lesions; the robotic system was also limited to commercially available rapid exchange balloon catheters. Because this study was conducted for U.S. Food and Drug Administration submission, only U.S. Food and Drug Administration–approved devices were used. Therefore, provisional stenting, if required, was performed manually. Evaluation of the robotic system for both drug-coated balloons and stenting for longer, more complex and calcified lesions is required.
This study demonstrates the feasibility and safety of a robotic-assisted platform for PVIs. Technical and clinical procedural success was obtained in all 20 patients and no device-related periprocedural adverse events were reported.
WHAT IS KNOWN? Occupational hazards associated with the field of interventional cardiovascular medicine include both risks associated with radiation exposure and orthopedic injuries due to heavy lead aprons and ergonomically challenging operator position.
WHAT IS NEW? Remote robotic-assisted PVI of the femoropopliteal vessels is feasible and can be performed safely.
WHAT IS NEXT? Future studies are required to study robotic-assisted PVI in a heterogeneous, contemporary patient population with complex peripheral artery disease.
Funding for the study provided by Corindus Vascular Robotics; independent data review and statistical analysis.
Dr. Mahmud has received research grant and consulting support from Corindus. The other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- percutaneous coronary intervention
- peripheral vascular intervention
- Received April 13, 2016.
- Revision received June 13, 2016.
- Accepted June 30, 2016.
- American College of Cardiology Foundation
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