ORCID Identifier(s)

0000-0001-7638-1864

Graduation Semester and Year

2020

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Kinesiology

Department

Kinesiology

First Advisor

Michael D Nelson

Abstract

Cardiology has long focused on the hearts ability to generate forward pressure and ejection of blood from the left ventricle to supply the systemic circulation with oxygen and nutrients. The ability and capacity of the left ventricle to fill with blood prior to systolic ejection is equally important and, until recently, has been largely under studied. The coordination of passive elastic recoil and active relaxation allows the left ventricle to fill with blood in early diastole through generation of the transmitral pressure gradient. Therefore, dysregulation of the molecular and cellular mechanisms governing these two processes could lead to diastolic dysfunction. While invasive assessment of left ventricular isovolumic pressure decay remains the gold-standard approach for measuring diastolic function, echocardiography and magnetic resonance imaging (MRI) are often used in place of this invasive approach, as non-invasive surrogates. Despite the relative successes of both techniques however, the majority of work in this area has been limited to evaluation of diastolic function under resting conditions, challenging the interpretation of results, particularly in subclinical disease. To address this limitation, diastolic stress testing— often with a cycle ergometer— has emerged as a complementary approach, unmasking diastolic dysfunction otherwise hidden at rest. However, cycle-based stress testing is limited by both movement and respiratory artifact, orthopedic limitations, and resource availability. Accordingly, this dissertation, focused on the development and application of an alternative diastolic stress testing approach, using isometric handgrip exercise, which addresses each of the aforementioned limitations. First, we showed that isometric handgrip echocardiography could discriminate between normal and abnormal diastolic function. Then, given the popularity of using cycle exercise to perform diastolic stress testing, we directly compared isometric handgrip with cycle exercise, demonstrating good agreement between both approaches. With these positive results, we then incorporated isometric handgrip into a single-center prospective clinical trial to define specific mechanisms of diastolic dysfunction in women with ischemia but no coronary artery disease; a population at increased risk of developing heart failure with preserved ejection fraction. Together, the work performed herein, supports the use of isometric handgrip as a robust diastolic discriminator. Unlike cycle exercise, which is currently advocated by the American Society of Echocardiogaphy and European Association of Cardiovascular Imaging, isometric handgrip is easy to perform, requires fewer resources, and can easily be adopted into both echocardiography and MRI-based exams/studies.

Keywords

Diastolic stress testing, Diastolic, Isometric handgrip

Disciplines

Kinesiology | Life Sciences

Comments

Degree granted by The University of Texas at Arlington

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Kinesiology Commons

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