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We report initial experience using Intra-Operative Positioning System (IOPS), a novel endovascular navigation system that does not require contrast or radiation, in the treatment of chronic mesenteric ischemia (CMI). We used IOPS to help treat three of four consecutive CMI patients; technical problems prevented successful use in one. In the cases where IOPS was used effectively, catheterization of the mesenteric artery was accomplished more quickly than for the case in which IOPS was not effective. Our experience shows that IOPS can be safely and effectively used for CMI and may reduce contrast load and radiation.
] but can involve significant time, contrast, and radiation. Among four consecutive CMI cases, three were facilitated by a novel navigation tool. The Intra-Operative Positioning System (IOPS, Centerline Biomedical, Inc., Cleveland, OH, USA) is a 3D-image guidance system for endovascular interventions based on electromagnetic tracking. All cases were done under moderate conscious sedation. All patients consented to publication of case data/images.
An 81-year-old woman presented with weight loss and post-prandial abdominal pain. She had undergone open aortic aneurysm repair. CTA (Figure 1A) revealed a tortuous 4-cm para-visceral aorta, near-total celiac (CA) occlusion, occluded inferior mesenteric artery (IMA), and critical superior mesenteric artery (SMA) stenosis.
An aortic model was created using the preoperative CTA. This model was aligned to the patient with aid of intra-operative cone beam CT generated by the imaging system (Artis Zeego, Siemens Healthcare, Erlangen, Germany). A 6-French, Ansel1 45cm vascular sheath (Cook Medical, Bloomington, IN, USA) was inserted. The IOPS wire was inserted into a SOS catheter (Angiodynamics, Latham, NY, USA) and advanced using the IOPS console images, without fluoroscopy (Figure 1B). The SMA was cannulated in 45 seconds. Cannulation was confirmed by fluoroscopy. Following unsuccessful attempt to seat the catheter in the SMA, wire access was lost. The SMA was accessed again with IOPS after replacing the Ansel1 sheath with a 6-French TourGuide Steerable Sheath (Medtronic, Inc., Minneapolis, MN, USA). Contrast injection confirmed severe stenosis in the proximal SMA (Figure 1C), which was treated with a 6mm x 22mm iCAST Covered Stent (Atrium Medical Corporation, Hudson NH, USA). Completion angiogram (Figure 1D) demonstrated wide patency. Clinical improvement was observed at follow-up.
A 75-year-old female presented with chronic visceral artery disease. She had undergone SMA angioplasty via groin access, but stent placement was unsuccessful due to tracking difficulty. The patient now had recurrent post-prandial abdominal pain and nausea. CTA (Figure 2A) demonstrated recurrent 70% proximal SMA stenosis. Brachial access was planned because of the previous difficulty from the groin.
An aortic model was created using the preoperative CTA and aligned to the patient with the aid of an intra-operative spin CT. The left brachial artery was accessed and, after systemic heparinization, a 6-French 75cm Ansel1 sheath was advanced into the visceral aorta. The IOPS wire was inserted into an MPA catheter, following which the SMA was catheterized without fluoroscopy (Figure 2B). Cannulation was achieved in approximately 60 seconds following initial IOPS imaging. Contrast injection demonstrated 70% ostial stenosis (Figure 2C). The SMA was treated with a 5mm x 22mm iCAST. Angiography showed wide patency (Figure 2D). The sheath was withdrawn into aorta, following which IOPS was used to catheterize the CA, again without fluoroscopy. Angiography showed severe stenosis, deemed unsuitable for endovascular therapy. Symptoms were resolved at early postoperative follow-up.
A 69-year-old female presented with recurrent severe post-prandial abdominal pain. She had known CA and infrarenal aortic occlusion and had previously undergone right axillary bifemoral bypass and SMA stent. CTA showed severe in-stent stenosis (Figure 3A).
The right brachial artery was accessed. A 6-French sheath was advanced into the abdominal aorta. The original plan was to use IOPS, but upon review of the IOPS display, the guidewire position did not match the expected location, possibly due to overlay mismatch caused by shifting of the trackpad (Figure 3B). Conventional techniques were used instead. After multiple attempts using fluoroscopy, the severely stenosed stent was accessed and then a catheter advanced (Figure 3C). This cannulation took approximately 7 minutes. The lesion was successfully treated using a covered stent.
A 64-year-old male presented with abdominal pain and weight loss. CTA demonstrated severe CA and SMA disease (Figure 4A).
An aortic model was created using the preoperative CTA and aligned to the patient using an intra-operative cone beam CT. A SOS catheter was advanced into the aorta. With the IOPS wire and without fluoroscopy, the SMA was cannulated without difficulty (Figure 4B) in approximately 90 seconds, but there was difficulty advancing the catheter, consistent with a severe stenosis. Wire access was given up and the sheath switched to a 6- French, 45cm TourGuide. The SMA was easily re-cannulated using IOPS. Contrast imaging demonstrated 80% stenosis (Figure 4C). With appropriate shaping, the TourGuide was advanced. The lesion was treated with a 6mm x 22mm iCAST. Arteriography demonstrated a widely patent stent with good flow into the celiac distribution (Figure 4D).
Endovascular CMI treatment is often challenging and can cause embolic complications. Prolonged procedure time, combined with steep oblique views, can lead to high radiation.
Advances in imaging such as IOPS offer opportunity to enhance cannulation while reducing fluoroscopic times. This early experience suggests that IOPS’ real-time navigation may improve outcomes by reducing procedural times with better visualization and control. Among the 4 consecutive cases in this report, IOPS facilitated rapid catheterization (range 45-90 seconds) of the target artery in 3 cases without fluoroscopy or contrast. In the case of IOPS registration error, traditional fluoroscopy and contrast were employed, with SMA cannulation time of 7 minutes.
IOPS (Figure 5) provides 3D electromagnetic navigation of interventional devices as an adjunct to fluoroscopy. Image guidance is provided using 3D maps of the vasculature, generated from thin-slice contrast-enhanced preoperative CTA. The CT scan should be within 180 days, and the vascular morphology must not have changed significantly. Physicians and technicians must be trained prior to using IOPS. Centerline Biomedical provided thirty-minute hands-on training with a phantom and provided support during the procedures.
The ultra-high-definition display provides up to four simultaneous maps and depicts the tips of the tracked catheters and guidewires. The viewing angle and magnification of each map can be independently customized. A cut-planes mode permits visualization from an angle inside the aorta. Electromagnetic sensors, embedded within the devices and not exposed to the circulation, permit real-time tracking. The catheter hubs have cables which connect to a tableside interface. The guidewire has a connector at the proximal end for this purpose (Figure 5).
The workflow is like that of fluoroscopic fusion, with the addition of an electromagnetic field generator, attached under the table without tools and largely hollow. Currently, the generator is contraindicated for patients with pacemakers, implanted defibrillators, or high-density metallic implants.
At procedure start, a self-adhesive sterile fiducial tracking pad is attached to the patient's lumbar region, and the angiography system is used to perform a non-contrast cone-beam CT scan. The cone-beam CT volume is then loaded on the IOPS cart and manually aligned with the preoperative CT volume. This work can be done in parallel with gaining vascular access, with minimal effect on procedure time.
During interventions, the IOPS devices can be visualized with on-screen image guidance. The console is operated by a technician under physician instruction. IOPS guidewires and catheters can be used together or combined with off-the-shelf 0.035" catheters and guidewires as needed. The technology has been used by our group and others for visceral and renal cannulation during complex aortic aneurysm procedures.
These cases demonstrate that percutaneous mesenteric revascularization for CMI with the aid of IOPS can be safely accomplished even in cases with high grade lesions and vessel occlusions. The use of this technology can help to make mesenteric revascularization easier with fewer procedural complications.
Chronic mesenteric ischemia: critical review and guidelines for management.
Ann Vasc Surg.2013; 27 ([PubMed] [Google Scholar]): 113-122