Date of Award

6-2012

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Mechanical Engineering

First Advisor

Ronald Bucinell

Language

English

Keywords

hypertension, response, in vivo, deformations, imaging

Abstract

Hypertension, a major cardiovascular disease, is one of the most prevalent and death causing disease worldwide. In the US, over 70 million adults have high blood pressure, that is, 1 in 3. A prolonged state of hypertension cause damages to the brain cells, the kidneys and can lead to a stroke. This research studies the biomechanical response of amphibian hearts in vivo when in hypertensive. A normotensive state is used as the control. Hypertension is induced by injecting a saline fluid directly into the heart ventricle using a syringe. The response of the heart is characterized by monitoring surface deformation fields using the speckle image photogrammetry technique. This is a non-contact optical full field strain technique that uses the ARAMIS photogrammetry software to monitor surface deformations over the entire three dimensional heart over several heart beats. The ARAMIS software is connected to two high speed cameras capable of taking more than 500 frames per second at full field. This technique was successfully used before to characterize myocardial infarction on amphibian hearts. The internal ventricle pressure is measured using a catheter pressure transducer located in the heart. The pressure inside the heart is directly related to the stress on the heart walls which are made of myocardia. During hypertension, the ventricle fluid volume is increased leading to the heart muscles contracting more forcefully. Preliminary results verified this concept with an increase in the deformations of the ventricle from a normotensive state to a hypertensive state. The results obtained showed a displacement increase of 0.18 mm corresponding to 12%. Major strains increased by 6%. The study also investigated whether the ventricle contraction mechanism is a sphere chamber model or a peristaltic tube model. The collected data supports the sphere chamber model. However, more experimentation is required to make these conclusions concrete.

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