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KOÇ UNIVERSITY

GRADUATE SCHOOL OF SCIENCES & ENGINEERING

BIOMEDICAL SCIENCE & ENGINEERING

PhD THESIS DEFENSE BY CAGLAR OZTURK

 

Title: Development of a Novel Centrifugal Left Ventricular Assist Device and the First In Vivo Study: Istanbul Heart VAD

 

Speaker: Çağlar Öztürk

 

Time: April 19, 2018, 14:00

 

Place: Manufacturing and Automation Research Center (MARC), ENG B203

Koç University

Rumeli Feneri Yolu

Sariyer, Istanbul

Thesis Committee Members:

Prof. Dr. İsmail Lazoğlu (Advisor, Koç University)

Assoc. Prof. Dr. Kerem Pekkan (Koç University)

Prof. Dr. Deniz Süha Küçükaksu (Bahçeşehir University)

Asst. Prof. Dr. Özlem Yalçın (Koç University)

Prof. Dr. Nurcan Arat (İstanbul Bilim University)

Abstract:

Heart failure (HF) is a life-threatening disease that affects the structure and functions of the heart. The possible solutions for HF condition are mainly limited to the heart transplantation and mechanical circulatory support systems. Due to the shortage of available donor hearts, left ventricular assist devices (LVADs) have been used as a common treatment for HF patients as a bridge to transplant, bridge to recovery or destination therapy. LVADs have been a promising option for the survival of patients. However, high importing costs limit the use of VAD for every heart patient. Therefore, this study aims to develop a novel centrifugal blood pump for the HF patients who are not eligible for cardiac transplants to access a low cost, high-quality device.

Computational fluid dynamics (CFD) analysis has been used during the design to accurately predict hydraulic performance and flow field within the blood pump. Virtual design of the pump is constructed for CFD optimizations. A number of impeller/volute configurations were established in the design. CFD-based design optimization method has been developed, involving hydraulic performance, efficiency, and hemolysis. Shear stress and exposure time, are considered as main factors to the hemolytic performance of blood pumps. CFD analysis reveals regions of high shear and stagnation zones that could damage the red blood cells (RBC) and affect the hydraulic performance of the pump. This comprehensive CFD analysis of the pump performance and hemocompatibility provide a path for pump optimizations. The presented method can also be utilized as an efficient CFD tool for new pump designs or multi-objective optimization.

Experimental evaluation of the prototype was performed to validate the computational results. An in vitro blood test of the final prototype has been conducted with hemolysis test rig. The in vitro test result demonstrates satisfying performance regarding the hemolysis index, pHb generation, hematocrit level, etc. in the range of clinically available LVADs.

In vivo device evaluation is vital for the validation of device performance before human clinical trials. The porcine animal model was selected in this study for initial acute evaluation. Three pigs weighing 77–92 kg have been used to assess the anatomical fitting and blood-handling characteristics during the acute experiments up to 6 hours. The study demonstrated appropriate circulatory support, and flow characteristics. Further acute in vivo studies are in progress for short-term evaluation.

 

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