Development and Hydrodynamic Evaluation of a Novel Inflow Cannula in a Mechanical Circulatory Support System for Bridge to Decision

Numerical investigation of the effects of cannula geometry on hydraulic blood flow to prevent the risk of thrombosis

Despite significant advances in left ventricular assist devices and the cannula, unfavorable events leading to the death of patients, including bleeding, infection, neurological disorders, hemolysis, and thrombosis, are still being reported. Local parameters of blood flow, including static flow, vorticity and critical values of shear stress on the wall of ventricle and cannula, increase the risk of thrombosis. Therefore, the analysis of blood flow domains inside the ventricle and cannula is necessary to investigate the probability of forming thrombosis in the cannula of left ventricular assist devices. In this study, blood flow is investigated in a Medtronic DLP 16F clinical cannula by using computational fluid dynamics through three-dimensional modeling of the left ventricle and cannula based on real geometry. Apart from the fact that blood is considered non-Newtonian fluid, the effect of heart movement in the left ventricle is also applied. In this research, blood flow in the cannula has been examined and some problems resulting from the use of the cannulas have been investigated. The results indicate that changing the geometry of input holes, such as their number and size, on the tip of the cannula, alter the probability of forming thrombosis and the standard mode shows a better performance.

Effect of inflow cannula side-hole number on drainage flow characteristics: flow dynamic analysis using numerical simulation

Background:

Venous drainage in cardiopulmonary bypass is a very important factor for safe cardiac surgery. However, the ideal shape of venous drainage cannula has not been determined. In the present study, we evaluated the effect of side-hole number under fixed total area and venous drainage flow to elucidate the effect of increasing the side-hole numbers.

Method:

Computed simulation of venous drainage was performed. Cannulas were divided into six models: an end-hole model (EH) and models containing four (4SH), six (6SH), eight (8SH), 10 (10SH) or 12 side-holes (12SH). Total orifice area of the side-holes was fixed to 120 mm2 on each side-hole cannula. The end-hole orifice area was 36.3 mm2. The total area of the side-holes was kept constant when the number of side-holes was increased.

Result:

The mean venous drainage flow rate of the EH, 4SH, 6SH, 8SH, 10SH and 12SH was 2.57, 2.52, 2.51, 2.50, 2.49, 2.41 L/min, respectively. The mean flow rate decreased in accordance with the increased number of side-holes.

Conclusion:

We speculate that flow separation at the most proximal site of the side-hole induces stagnation of flow and induces energy loss. This flow separation may hamper the main stream from the end-hole inlet, which is most effective with low shear stress. The EH cannula was associated with the best flow rate and flow profile. However, by increasing side-hole numbers, flow separation occurs on each side-hole, resulting in more energy loss than the EH cannula and flow rate reduction.

Artificial organs 2011: a year in review

In this Editor's Review, articles published in 2011 are organized by category and briefly summarized. As the official journal of The International Federation for Artificial Organs, The International Faculty for Artificial Organs, and the International Society for Rotary Blood Pumps, Artificial Organs continues in the original mission of its founders "to foster communications in the field of artificial organs on an international level."Artificial Organs continues to publish developments and clinical applications of artificial organ technologies in this broad and expanding field of organ replacement, recovery, and regeneration from all over the world. We take this time also to express our gratitude to our authors for offering their work to this journal. We offer our very special thanks to our reviewers who give so generously of time and expertise to review, critique, and especially provide meaningful suggestions to the author's work whether eventually accepted or rejected. Without these excellent and dedicated reviewers, the quality expected from such a journal would not be possible. We also express our special thanks to our Publisher, Wiley-Blackwell, for their expert attention and support in the production and marketing of Artificial Organs. In this Editor's Review, that historically has been widely well-received by our readership, we aim to provide a brief reflection of the currently available worldwide knowledge that is intended to advance and better human life while providing insight for continued application of technologies and methods of organ replacement, recovery, and regeneration. We look forward to recording further advances in the coming years.