B. Marmie1, C. Sanderfer1, J. Fuchs1, A. Kamenskiy1, P. Aylward1, M. Tommeraasen1, J. MacTaggart1 1University Of Nebraska Medical Center,Surgery,Omaha, NE, USA
Introduction: Fluoroscopy-free endovascular device navigation is receiving increased attention due to its potential to control noncompressible hemorrhage in pre-hospital settings. Many strategies have been proposed to calculate catheter and wire lengths to reach specific aortic zones without the aid of fluoroscopy. It remains unclear whether certain anatomical characteristics that are particularly prevalent in older subjects, such as wide bifurcation angles or vessel tortuosity, will prevent safe fluoroscopy-free device navigation. Our goal was to test the ability to blindly navigate guidewires to aortic occlusion zones through simulated patient-specific aortic anatomies.
Methods: A total of n=86 trauma patient CTAs (5-93 years old, average age 53±2 years) were used to build 3D models of the aorta and its branches using Mimics software. The models were exported into a Mentice VIST G5 simulator using the Case-IT capability. The physical guidewire was represented in the simulator as either a 0.035” J-curve guidewire [JCW] or a 0.035” 35° angle tip hydrophilic guidewire [ATHW]. An electric automatic wire-feeding mechanism was used to advance a physical guidewire at a constant rate into the simulator for a total of six trials performed in each anatomy with each guidewire for a total of 1442 guidewire passages. Final locations of the guidewire tip were recorded and percentage of unsuccessful attempts to advance the guidewire from the femoral access site to the aortic target zone was calculated.
Results: Overall 88% of simulations ended with the guidewire in the target aortic zone. Overall frequency of misplacement increased with age for both wires (p=0.04 for JCW and p=0.04 for ATHW respectively, see Figure). In subjects <50 years there were no differences in misplacements between the wires (p=0.21), but in subjects >50 years, ATHW had statistically more misplacements than the JCW (p=0.04). The most common misplacement locations were ipsilateral internal iliac and contralateral common iliac arteries. No misplacements were observed in 20-29-year-old anatomies for either of the guidewires.
Discussion: Aging is associated with increased guidewire misplacement during simulated fluoroscopy-free endovascular navigation. With anatomies older than age 50, misplacements become more common, particularly when using the ATHW wire, likely due to increased vessel tortuosity and widening of the aortoiliac bifurcation with age. Though results need to be confirmed in vivo, fluoroscopy-free endovascular navigation may be feasible in subjects younger than 50 years (<5% misplacements), but the risk of aberrant vessel catheterization more than doubles in older subjects. This risk might be reduced through device design and proper device selection.
