Hydraulic analysis of the functional properties of saline-jet aspiration thrombectomy catheters

The purpose of this paper is to clarify the functional properties of a saline-jet aspiration thrombectomy catheter based on hydraulics. This catheter, developed by the authors, aspirates intravascular thrombi by means of the effect of a high-speed jet. We have derived the relationships between Qs, Qa and Pn, where Qs is the water supply rate, Qa is the water aspiration rate and Pn is the negative pressure created in the distal lumen of the catheter. The relationships are represented by simple equations using c₁ and c₂, where c₁ and c₂ are coefficients proper to the catheter. We have obtained c₁ and c₂ experimentally for three types of catheter with different distal shapes. Two practical conclusions are derived from this study. First, making a short taper at the distal end increases the negative pressure created and is advantageous for thrombus aspiration. Second, making the diameter of the inner tube and nozzle smaller is essential for improving the aspiration ability of the catheter.