Arnab Chanda

Abstract

The Left Ventricle (LV) can be considered to be a near-conical fibrous Flexible Matrix Composite (FMC) structure in which the myocardial fibers contract by a maximum of 15% in length while pumping to cause an approximately 50% overall volume contraction. The Pumping Potential (PP), defined as the relative volume reduction due to an input stroke, of a simple conical structure was estimated numerically to be approximately 1-2. However, the actual PP of the near-conical LV structure is in the range of 3.3-4. And the question crops up: what is the cause of such a high PP of the LV? To investigate this, the LV is modeled physically and using the finite element software ANSYS. The modeling is based on a recent concept of Helical Ventricular Myocardial Band (HVMB), according to which the heart is made of a single band called the HVMB, which twists and loops to form the heart. Multiple goat hearts are dissected and unfolded into the HVMB. The shape of the band as well as the crude fiber orientation in its outermost (epicardium) and innermost (endocardium) layers are observed. The trace of the band together with the two-layer fiber orientation is recorded, and a Matlab program is written to numerically twist and loop the band into a simple and practical near conical two layer LV like FMC model. Polyurethane (Matrix material) and shape memory alloys (as actuating fibers) are used to physically construct the model. The experimental and analytical investigations yielded a reasonably high PP in the range of 2.5-2.8. Moreover, the twist phenomenon and wall thickening effects, which have been previously pointed out in literature to contribute to the high PP of the LV, were observed clearly in the simulations.

Library of Congress Subject Headings

Blood--Circulation, Artificial; Heart, Artificial; Heart--Left ventricle; Hemodynamics

Publication Date

2-7-2014

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Hany Ghoneim

Comments

Physical copy available from RIT's Wallace Library at QP110.A7 C42 2014

Campus

RIT – Main Campus

Plan Codes

MECE-MS

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