Achievable aspiration flow rates with large balloon guide catheters during carotid artery stenting

Abstract

Background: Emergency carotid artery stenting (CAS) is a frequent endovascular procedure, especially in combination with intracranial thrombectomy. Balloon guide catheters are frequently used in these procedures. Our aim was to determine if mechanical aspiration through the working lumen of a balloon occlusion catheter during the steps of a carotid stenting procedure achieve flow rates that may lead to internal carotid artery (ICA) flow reversal which consecutively may prevent distal embolism.

Methods: Aspiration experiments were conducted using a commercially available aspiration pump. Aspiration flow rates/min with 6 different types of carotid stents inserted into a balloon guide catheter were measured. Measurements were repeated three times with increasing pressure in the phantom. To determine if the achieved aspiration flow rates were similar to physiologic values, flow rates in the ICA and external carotid artery (ECA) in 10 healthy volunteers were measured using 4D-flow MRI.

Results: Aspiration flow rates ranged from 25 to 82 mL/min depending on the stent model. The pressure in the phantom had a significant influence on the aspiration volume. Mean blood flow volumes in volunteers were 210 mL/min in the ICA and 101 mL/min in the ECA.

Conclusions: Based on the results of this study, flow reversal in the ICA during common carotid artery occlusion is most likely achieved with the smallest diameter stent sheath and the stent model with the shortest outer stent sheath maximum diameter. This implies that embolic protection during emergency CAS through aspiration is most effective with these models.

Keywords: Balloon catheter; Blood flow; Stent; Stroke.

Fig. 1

Structure of the fluid-container phantom. The air-tight container allowed aspiration under different pressures to mimic different common cartid artery-stump-pressures. The pressure in the container was controlled via a sphyngomanometer and was adjusted manually during aspiration

Fig. 2

Aspiration volume flow rates at a pressure of 50 mmHg (y-axis, mL = Milliliters) plotted vs remaining axial surface area of the guide catheter working lumen after the stent catheter was introduced (x-axis, mm² = Millimeters square). Plotted are aspiration rates with all undeployed stents and the stent catheter shafts of the models where size information was available within the working lumen of the guide catheter (Abbreviations: Acc: Acculink, Prec 7/10: Precise 7 mm/10 mm, Prot: Protégé. The numbers in brackets show the volumetric aspiration rates). The graph depicts a nearly linear relation of flow rates and luminal surface area, which shows that laminar flow is not present