Electromagnetically Navigated In Situ Fenestration of Aortic Stent Grafts: Pilot Animal Study of a Novel Fenestrated EVAR Approach.

PURPOSE: Assess electromagnetically guided in situ fenestration of juxtarenal aortic stent grafts in an in vivo model. METHODS: Using a newly developed electromagnetic guidance system together with a modified, electromagnetically guidable catheter with steerable tip, an electromagnetically trackable guidewire and a custom in situ fenestrateable stent graft, a series of seven animal experiments was performed. In a swine model, stent grafts were placed juxtarenally, covering the renal arteries. Subsequently, the perfusion of the renal arteries was restored using electromagnetically guided in situ fenestration of the graft at the renal ostia followed by covered stent placement. Intervention times and technical success were assessed. RESULTS: The individual components were successfully combined for the animal experiments. Thirteen of fourteen fenestration experiments in seven animals were successful in restoring perfusion through in situ fenestration. Fenestration (catheter introduction-guidewire placement in renal artery across graft) could be achieved in on average 10.5 ± 9.2 min, and subsequent covered stent placement (guidewire placement-covered stent placement) took on average 32.7 ± 17.5 min. No significant differences between left and right side reperfusion times could be detected. Reperfusion in <30 min was achieved in 3/14 attempts. CONCLUSION: Electromagnetically navigated in situ aortic fenestration for juxtarenal aortic stent grafts was feasible in a healthy animal model. Identified remaining challenges were: shortening the procedure to avoid long warm ischemia times, using an aortic aneurysm animal model, and improving the stability of the stent graft material.

Feasibility of electromagnetically guided transjugular intrahepatic portosystemic shunt procedure.

OBJECTIVES: To develop an electromagnetic navigation technology for transjugular intrahepatic portosystemic shunt (TIPS) creation and translate it from phantom to an in-vivo large animal setting. MATERIAL AND METHODS: A custom-designed device for TIPS creation consisting of a stylet within a 5 French catheter as well as a software prototype were developed that allow real-time tip tracking of both stylet and catheter using an electromagnetic tracking system. Feasibility of navigated TIPSS creation was tested in a phantom by two interventional radiologists (A/B) followed by in-vivo testing evaluation in eight domestic pigs. Procedure duration and number of attempts needed for puncture of the portal vein were recorded. RESULTS: In the phantom setting, intervention time to gain access to the portal vein (PV) was 144 ± 67 s (A) and 122 ± 51 s (B), respectively. In the in-vivo trials, TIPS could be successfully completed in five out of eight animals. Mean time for the complete TIPS was 245 ± 205 minutes with a notable learning curve towards the last animal. CONCLUSIONS: TIPS creation with the use of electromagnetic tracking technology proved to be feasible in-vitro as well as in-vivo. The system may be useful to facilitate challenging TIPSS procedures.

Technical concepts for vascular electromagnetic navigated interventions: aortic in situ fenestration and transjugular intrahepatic porto-systemic shunts.

This work presents concepts for complex endovascular procedures using electromagnetic navigation technology (EMT). Navigation software interfacing a standard commercially available navigation system was developed, featuring registration, electromagnetic field distortion correction, breathing motion detection and gating, and state-of-the-art 3D imaging post processing. Protocols for endovascularly placed, in-situ fenestrated abdominal aortic stent grafts and an EMT guided transjugular intrahepatic portosystemic shunt (TIPSS) creation have been designed. A dedicated set of interventional devices was developed for each of the procedures: For aortic in-situ fenestration a combination of high-porosity stentgrafts, steerable catheters and electromagnetically navigated guidewires was used, for TIPSS a dual-navigated (sheath and stylet) TIPSS-device was designed and manufactured. The developed devices underwent phantom testing, in preparation for animal experiments to prove the feasibility of the approach. Once established, these systems could aid in performing these challenging interventional radiology procedures, exploiting the unique characteristics of electromagnetic navigation and solving multiple of the problems associated with these interventions being performed under X-ray fluoroscopy, such as lacking real-time 3D information or extensive exposure to ionizing radiation.