Purpose: We experimentally assessed the pitfalls of distal balloon protection systems to learn technique tips for safe procedures.
Materials and methods: Silicone carotid artery models were connected to a circulatory system to simulate carotid bifurcation. A distal balloon protection device, PercuSurge GuardWire Plus (PSGWP, Medtronic Vascular) was navigated to the internal carotid artery (ICA) and inflated to occlude ICA flow temporarily. A debris aspiration catheter (Thrombuster, Kaneka Medics) was navigated just proximal to the PSGWP coaxially to introduce and diffuse particulate debris (200-500 micro meter in diameter) in the ICA stump. After debris in the stump was aspirated, the PSGWP was deflated. We recorded all the processes of our simulation experiments on a digital video and observed the movements of debris during these experiments.
Exp 1) We simulated the movements of debris in the ICA stump when the PSGWP balloon was gradually deflated to produce a gap between the balloon and vessel wall, simulating accidental movement of the PSGWP balloon during the procedure. Exp 2) To assess the optimal placement of the tip of aspiration catheter, the debris in the ICA stump was aspirated from 3 different sites (from just below the GuardWire balloon, from 5 cm below it, and at the ICA orifice). Exp 3) To assess the capacity of the aspiration catheters (7F, 6F Thrombusters (Kaneka Medics), 5.4F Export catheter (Medtronic Vascular), we compared the time to aspirate 20 cc of normal saline.
Results: Exp 1) When the gap appeared between PSGWP balloon and silicone tube, simulated debris began to concentrate just below the balloon. Then, some debris migrated distally from the gap, and other debris crowded in the gap so that it was impossible to aspirate and migrated. Exp 2) Debris aspiration was most effective from immediately below the PSGWP, and the aspiration ability declined as the distance between the balloon and aspiration catheter became longer. Exp 3) The aspiration time for 20 cc of normal saline is 8.4+/-0.2 sec, 12.8+/-0.5 sec, 13.3+/-0.1 sec. in case of 7F Thrombuster, 5.4F Export catheter, 6F Thrombuster, respectively.
Conclusion: Our simulation studies show that when the PSGWP was moved accidentally during CAS procedures, or when the aspiration catheter was not delivered all the way to the PSGWP balloon, distal embolization might still occur, even when care is taken. So to protect the distal embolism, the PSGWP balloon should be fully dilated and fixed to the arterial wall during procedures, and the aspiration catheter should be navigated just proximal to the PSGWP balloon.
