Effects of Cone-Shaped Bend Inlet Cannulas of an Axial Blood Pump on Thrombus Formation: An Experiment and Simulation Study

Abstract

BackgroundCannula shape and connection style influence the risk of thrombus formation in the blood pump by varying the blood flow characteristics inside the pump. Inlet cannulas should be designed based on the need for anatomical fit and reducing the risk of thrombus generation in the blood pump. The effects on thrombus formation of the cone-shaped bend inlet cannulas of axial blood pumps should be studied.Material/MethodsThe cannulas were designed as cone-shaped, with 1 bent section connecting 2 straight sections. Both the silicone tube and novel cone-shaped cannula were simulated for comparison. The flow fields of a blood pump with inlet cannula were simulated by computational fluid dynamics (CFD) at flows of 2.0, 2.5, and 3.0 liters per minute (lpm), with pump rotational speeds of 7500, 8000, and 8500 rpm, respectively. Then, 6 two-dimensional (2D) particle image velocimetry (PIV) tests were conducted and the velocity distributions were analyzed.ResultsA low-velocity region was located inside the pump entrance when a soft silicone tube was used. At 8500 rpm and 3.0 lpm working condition, the minimum velocity inside the pump with cone-shaped cannulas was 2.5×10−1 m/s. The cone-shaped cannulas eliminated the low-velocity region inside the pump. Both CFD and PIV results showed that the low-velocity region did not spread to the entrance of the blood pump within the flow range from 2.0 lpm to 7.0 lpm.ConclusionsThe designed cone-shaped bent cannulas can eliminate the low-velocity region inside the blood pump and reduce the risk of thrombus formation in the blood pump.

Interaction between microorganisms and dental material surfaces: general concepts and research progress

“…As a well-known example of a Sharklet surface ( Figure 4 ), a shark’s skin is always smooth and clean because it is composed of millions of tiny tooth-like dermal denticles with a regular arrangement that forms a micron-scale structure, making it difficult for the adhesion process [ 62 ]. Compared with the flat surface of the same material, many micron and nanometer topographic patterns with different sizes and shapes can inhibit biofilm formation, including concave-convex squares, round and parallel channels of polydimethylsiloxane (PDMS) [ 63 ], cone patterns of silicone resin [ 64 ], ridge patterns on polydimethylsiloxane [ 65 ], strain-induced wrinkles on polydimethylsiloxane [ 66 ], and round poles on polystyrene [ 67 ]. Some well-defined nanostructures induce superhydrophobicity and reduce biological contamination [ 68 ].…”

Analysis of rotary ventricular assist devices using CFD technique—A Review

“…A smooth and effective simulation of the flow problem in the solver needs a lot of manipulations during mesh generation. Some of the meshing software is dedicated to the meshing of turbomachines, which have the ability to generate meshes (O-grid) near the blade region of the blood pumps for computing flow variables (136,137). Generally, an H-grid mesh is generated between two blades.…”

“…The inlet cannulas of the axial blood pump are mostly not affected by high shear rate or by flow separation (98). However, the cannulas flow fields of the axial blood pump are closely related to the thrombus property (125,136).…”

“…Some of the meshing software is dedicated to the meshing of turbomachines, which have the ability to generate meshes (O-grid) near the blade region of the blood pumps for computing flow variables. 130,131 Generally, an H-grid mesh is generated between two blades. The mesh size is generally kept very small near the blade because of high gradients, while it is generally kept reasonably coarse between the blades to manage memory requirements during the computational process.…”

“…95 However, the cannulas flow fields of the axial blood pump are closely related to the thrombus property. 120,130 In light of the current situation, hemolysis models can be broadly classified in two aspects:…”