Endovascular intervention for lower-extremity critical limb ischemia is associated with equivalent or even superior outcomes compared to open bypass. However, chronic exposure to fluoroscopic radiation during interventional procedures and orthopedic strain from protective garments may impact the health of the interventionalist. This report describes the use of the CorPath GRX Robotic System to improve the safety of the interventionalist during percutaneous balloon angioplasty of an occluded posterior tibial artery.
Key words: posterior tibial artery, critical limb ischemia, peripheral artery disease, robotics, percutaneous peripheral vascular intervention
Critical limb ischemia (CLI) of the lower extremities secondary to advanced peripheral artery disease (PAD) is associated with poor wound healing, tissue ulceration, infection, gangrene, limb amputation, and elevated rates of morbidity and mortality.1–3 Amputation rates of the lower limbs due to CLI have been estimated to range from 10% to 40% of patients within 6 months of diagnosis.1,2
Evidence-based guidelines issued by the American Heart Association/American College of Cardiology call for either open surgical or endovascular revascularization to treat CLI, with the goal of preserving a functional foot by healing existing wounds completely and minimizing further tissue loss.4 There is currently insufficient high-quality evidence to definitively support one approach over the other.1,2 However, based on available evidence and clinical experience, an “endovascular first” treatment paradigm may be appropriate,4–7 especially in the setting of specific lesion anatomy and location,5 patient-specific health status, and comorbidities associated with PAD that increase surgical risk, such as cardiovascular disease and diabetes mellitus.4
Accordingly, the use of peripheral vascular interventions such as balloon angioplasty, atherectomy, and stenting for revascularization of the lower extremities has grown markedly in the last 20 years.8 With it, unfortunately, interventionalists’ exposure to occupational hazards such as fluoroscopic radiation and orthopedic injury has also grown. A potential solution for this problem has been the use of robotic-assisted peripheral vascular intervention (PVI), which enables clinicians to perform percutaneous procedures while physically removed from exposure to radiation sources, under more ergonomic working conditions, and without the use of heavy protective clothing.9–12
The CorPath GRX Robotic System (Corindus, Inc), is cleared for use in the United States for percutaneous coronary and for peripheral vascular interventions. This case report describes the use of the robotic system to assist in balloon angioplasty of a total occlusion of the posterior tibial artery in a patient with CLI.
In December 2018, a 78-year-old man presented to our catheterization suite with a non-healing ulcer involving the first digit of the left foot. The patient’s medical history included coronary artery disease, diabetes mellitus, prior cerebrovascular accident, and tobacco abuse, in addition to severe PAD. The patient had a known occlusion of the anterior tibial artery and dorsalis pedis, as well as multiple prior interventions for bilateral lower-extremity CLI. In July 2018, he had undergone intervention in the left posterior tibial artery for the same non-healing ulcer. Healing had improved after that procedure but had eventually stalled, prompting him to visit the clinic. Arterial non-invasive imaging suggested re-occlusion of the posterior tibial artery, in addition to occlusion of the anterior tibial artery.
After a discussion of the potential risks and benefits of various treatment options, the patient gave informed consent for an angiogram and possible endovascular intervention to the left lower extremity with robotic assistance.
The patient was positioned on the procedure table with the tableside arm of the CorPath GRX robotic system in proximity. The bilateral groins and left leg were prepared and draped in sterile fashion. Lidocaine 2% was injected into the left groin region for anesthesia and the patient was sedated with fentanyl and midazolam.
The left femoral artery was accessed in an antegrade fashion under direct visualization using ultrasound guidance, with a 4-French (F),
10 cm stiffened micropuncture catheter (Cook Medical). This sheath was exchanged for a 6F, 55 cm, Flexor Ansel 1 sheath with a Tuohy-Borst Sidearm Adapter (Cook Medical). Standard angiograms of the left lower extremity were performed (Figure 1), revealing patent superficial femoral and popliteal arteries. The tibial-peroneal trunk was patent, as was the peroneal artery. Both the anterior and posterior tibial arteries were occluded, leaving single-vessel runoff to the ankle. Given the plantar location of the ulcer and adhering to the angiosome concept of revascularization, the decision was made to intervene on the chronically occluded posterior tibial artery.
In preparation for the intervention and the use of the Corindus vascular robot, 6000 units of heparin were administered through the sheath with a goal of activated clotting time >270 seconds. The tableside arm of the robotic system was brought into position and secured. A 6F MPA1 guide catheter (Cordis Corporation, a Cardinal Health company) was introduced over the guidewire into the sheath. The MPA1 guide was used as a “support” catheter and advanced into the distal portion of the popliteal artery. The proximal end of the guide catheter was attached to the Y-connector, which was then loaded into the appropriate drive track within the single-use cassette. The cassette serves as the sterile interface between the interventional devices and the robotic drive unit. A .014-inch × 300 cm length Command ES guidewire (Abbott Vascular) was introduced into the guide catheter through the Y-connector. The proximal end of the guidewire was loaded into the appropriate track.
Using the joystick controls located on the remote radiation-shielded workstation, the guidewire was advanced through the MPA1 guide, without a support catheter, under fluoroscopic guidance. The occlusion of the middle posterior tibial artery was navigated using the wire alone, staying in the true lumen. The lesion was successively dilated, first using a 2 × 120 mm ADVANCE 14LP low-profile balloon dilatation catheter (170 cm length) (Cook Medical) and then a 2.5 × 200 mm ADVANCE 14LP balloon catheter. Balloons were inflated to nominal pressure, with an inflation time of 5 minutes. A post-procedural angiogram confirmed successful intervention, with a patent left posterior tibial artery and residual stenosis of approximately 15% (Figures 1-2). At the end of the procedure, all devices were removed, and arterial closure was achieved by using a 6F/7F MynxGrip closure device (Cordis Corporation, a Cardinal Health company). There were no complications. The total fluoroscopy time and dose were 30.8 minutes and 76 mGy, respectively. The contrast volume was 55 mL of iodixanol. At the end of the procedure, the patient had a palpable posterior tibial pulse. He recovered uneventfully in the post-procedure care unit and was discharged home the same day on aspirin and clopidogrel, in addition to his statin and blood pressure medications. Noninvasive testing, which included arterial duplex testing 4 weeks post procedure, showed that the treated vessel was patent. Improved wound healing was noted at 30-day follow-up.
While both open surgical bypass and endovascular PVI techniques appear to be effective for improving outcomes in patients with PAD, there remains a lack of comparative data to prove the superiority of one technique over the other, particularly for specific regions of the lower extremities, such as below the knee.1,2,5,7 Therefore, much of the current clinical decision-making in this area is still informed by physician experience, preferences, and institutional practices. Interestingly, Hicks and colleagues recently published the results of an analysis of data from the 2008–2014 Vascular Quality Initiative, specifically comparing infrageniculate lower-extremity open bypass versus PVI in 2566 patients with CLI.5 They found that one-year primary patency was significantly worse after bypass compared to PVI (73% vs 81%; P<.001), whereas one-year major amputation (14% vs 12%; P=.18) and mortality (4% vs 6%; P=.15) were similar. These results suggested that PVI was a viable treatment approach for arterial occlusions occurring below the knee.
Infrapopliteal interventions for patients with CLI are challenging and complex. This difficulty is often attributed to long chronic occlusions and heavy calcification. A successful procedure hinges on the ability to recanalize the vessel, and if one can stay within the true lumen, the intervention becomes much more manageable. The specific impetus behind this report was to evaluate the ease of use of the robotic system for a tibial intervention, despite some of the limitations the current model imposes, such as lack of dedicated equipment (sheaths, support catheters, etc), and monorail system. Normally, we would not consider wiring a tibial chronic total occlusion without an over-the-wire support catheter, or with a wire alone for that matter. However, for this case we desired to see how the robotic system would respond. I was frankly impressed by its ability to rotate the wire and “peck” at the cap simultaneously. Ultimately, we found the implementation of the robotic controls for a tibial chronic total occlusion to be smooth and without a significant increase in procedural time. The ability to wire the occlusion without either a support catheter or manual contact with the guidewire was also impressive.
Furthermore, of particular interest was that the wiring and angioplasty procedures were easily performed with the operator seated comfortably at the radiation-shielded workstation, without the use of a leaded apron.
For those contemplating potential use of this system, it is important to note that the CorPath GRX System is not universally compatible with all available guidewires and catheters. The user should consult the operator’s manual for compatible device information prior to conducting any case with the system.
The robotic system served as a useful addition to the PVI procedure, and facilitated balloon angioplasty within a totally occluded posterior tibial artery.
Jeanne McAdara, PhD, provided professional assistance with manuscript preparation, which was funded by Corindus, Inc.
Disclosure: Dr. Phillips discloses that he is part of the Speakers Bureau, and/or a Consultant, and/or part of an Advisory Board with the following companies: Cook Medical, Medtronic, Boston Scientific, and Janssen.
Corindus, Inc. provided funds for professional medical writing. The medical writer worked under the direction of the author.
Manuscript submitted June 10, 2019; accepted July 2, 2019.
Address for correspondence: John A Phillips, MD; Medical Director, Endovascular Medicine, Riverside Methodist Hospital, OhioHealth Heart & Vascular Physicians; 3705 Olentangy River Road, Suite 100, Columbus, Ohio 43214; 614-738-5143. Email: John.Phillips2@ohiohealth.com
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