UBC Theses and Dissertations
Cardiac consequences and effects of exercise interventions following spinal cord injury in humans Balthazaar, Shane James Timothy
Individuals with chronic motor-complete spinal cord injury experience reduced cardiac function compared to non-injured individuals. Findings of cardiac deconditioning are not uncommon in this unique population and contribute to the increased risk of developing cardiovascular disease. In addition, disruption of descending autonomic pathways can cause abnormalities in cardiac function due to an intact parasympathetic (vagal) control and decreased sympathetic activity. The lack of research assessing cardiac outcomes during the first year following spinal cord injury limits the knowledge of time course changes and effective clinical therapies. Further investigation using different modalities of exercise as a therapeutic strategy are warranted, as the benefits of aerobic exercise to mitigate health complications associated with spinal cord injury have been well documented. In this thesis, I initially used a cross-sectional design assessing echocardiographic measures for left ventricular structure, systolic function, diastolic function, and mechanics, in individuals with sub-acute (i.e., three months) and chronic (i.e., > one year) cervical spinal cord injury to a non-injured control group. The results showed no differences between the non-injured group and the sub-acute group, though there was a decline in left ventricular indices for the chronic group. Upon further investigation of cardiac consequences, Holter monitoring showed the occurrences of arrhythmias up to six months post-injury in individuals with cervical and thoracic spinal cord injury. Next, echocardiography was used in a longitudinal design to track the changes in left ventricular structure, function, and mechanics within a six-month period for individuals with cervical and thoracolumbar injuries. The results show changes in left ventricular volumes and function occur only months after cervical injury. Finally, to explore cardiac rehabilitation through exercise strategies for this population, echocardiography was used to show that arm cycle ergometry may be more beneficial than body weight supported treadmill training for individuals with cervical or high-thoracic spinal cord injury to improve cardiac mechanics. Overall, the work presented in this thesis explored clinically relevant data that 1) increases our understanding of cardiac function in the months following a spinal cord injury and 2) investigates the efficacy of therapeutic exercise interventions to mitigate the long-term cardiac consequences of spinal cord injury.
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