Numerical Simulation of Thrombus Aspiration in Two Realistic Models of Catheter Tips

Abstract

Thrombus aspiration catheters are devices used to remove a blood clot from a vessel, usually prior to angioplasty or stent implantation. However, in vitro results showed that the use of different commercial devices could produce very different thrombus removals, suggesting a primary dependence on the distal tip configuration of the catheter. A computational methodology based on realistic catheter tip modeling was developed to investigate the factors affecting the thrombus suction. Two different designs were considered, either with a single central lumen or a combination of central and side holes. First, steady-state aspiration of distilled water from a reservoir was simulated and compared with experimental tests. Subsequently, the aspiration of a totally occlusive thrombus, modeled as a high viscous fluid, was simulated solving a complex two-phase (blood and thrombus) problem. In particular, the benefit of additional openings was investigated. Good matching between the steady-state experimental and numerically simulated hydraulic behaviors allowed a validation of the numerical models. Numerical results of thrombus aspiration showed that the catheter with central and side holes had a worse performance if compared with the single central lumen catheter. Indeed, the inlets in contact with both blood and thrombus preferentially aspirate blood due to its much lower viscosity. This effect hindered the aspiration of thrombus. The amount of aspirated thrombus highly depends on the complex, two-phase fluid dynamics occurring across the catheter tips. Results suggested that location of additional holes is crucial in the catheter aspiration performance.

Possible Benefits of Catheters With Lateral Holes in Coronary Thrombus Aspiration: A Computational Study for Different Clot Viscosities and Vacuum Pressures

“…The relative position of clot and catheter tip is important with regard to the presence of lateral holes, as it was previously demonstrated that holes far from the clot preferentially aspirate blood and may hinder the percutaneous treatment (10). In the current study, a gap (1 mm) existed between the tip and the clot mass, whereas in previous studies done by Pennati et al (10), the catheter tip was immersed within the blood clot.…”

“…In the current study we adopt a two-phase flow approach, similar to that of Pennati et al (10) but using more sophisticated modeling: (i) non-Newtonian behavior was adopted for both blood and clot, based on experimental measurements on porcine blood clots; (ii) a surface tension was introduced to more realistically represent clot rheological behavior; and (iii) an image-based geometry was used for the coronary arteries.…”

Blood Clot Simulation Model by Using the Bond‐Graph Technique

“…Concerning the “ R union ” value, Pennati et al [20] considers some useful parameters. In that work, values of the viscosity of the blood appear for the clot that they use in their model; taking into account the viscosity of the clot, we can assume that R union = 0.035 kg/m·s.…”

Removing vascular obstructions: a challenge, yet an opportunity for interventional microdevices

“…A low-pressure region can be created near the occlusion by means of a catheter connected to an external sucking device. This is at the basis of aspiration strategies, which can only be used for thrombi; it has been also numerically modeled by a twophase flow approach (Pennati et al 2010). Alternatively, pressure can be locally lowered by increasing the liquid speed, as described by the well-known Bernoulli theorem, best applied when viscosity plays a minor role (Landau and Lifshitz 1987).…”