The doctoral dissertation in the field of Applied Physics will be examined at the Faculty of Science, Forestry and Technology, Kuopio campus and online.
What is the topic of your doctoral research? Why is it important to study the topic?
My dissertation focuses on the impacts of obstructive sleep apnea (OSA) on the cardiovascular function. OSA is a highly prevalent disorder estimated to affect nearly one billion people worldwide. Untreated OSA is associated with various adverse long-term health consequences including cardiovascular diseases. OSA is characterized by repeated complete or partial upper airway closures during sleep. These obstructive events can lead to blood oxygen desaturation, large negative intrathoracic pressure swings, and arousals. Evidence indicates that OSA and its related physiological sequelae contributes to the alterations of cardiac electrophysiology and thus, the development of arrhythmias.
My studies aimed to expand the understanding of how OSA and its physiological sequelae alters cardiac electrophysiology and contributes to the possible development of nocturnal cardiovascular events.
What are the key findings or observations of your doctoral research?
The results of my doctoral research presented evidence of OSA contributions to the altered cardiac electrophysiology, specifically ventricular repolarization (VR) phase of cardiac activity. My results presented sleep stage-specific alterations in markers of VR activity in OSA patients.
Furthermore, OSA related oxygen desaturations observed to be associated with significant temporal variations in VR activity, with deeper desaturations and presence of accompanying arousals leading to greater changes. Altered VR activity during desaturations hints at the potential mechanistic pathway of increased risk of arrhythmias and sudden cardiac death in OSA patients. The temporal OSA-induced VR alterations can be more profound in OSA patients with more fragmented sleep and high hypoxic load, highlighting the potential of detailed electrocardiogram analytics for cardiac risk profiling in OSA patients.
What are the key research methods and materials used in your doctoral research?
This doctoral thesis utilized different subsets of a retrospective dataset comprising 917 type I polysomnography (PSG; a comprehensive measurement of multiple physiological functions through bioelectrical signals) recordings of suspected OSA patients. The dataset involves anthropometric and demographic information of the patients along with the history of comorbidities and medication.
PSG recordings were conducted at the Princess Alexandra Hospital (Brisbane, Australia) between 2015 and 2017. PSG recordings involved electrocardiography (ECG) signals measured with a modified lead II configuration. ECG signals segmented and delineated to extract information related to the temporal VR activity.
The doctoral dissertation of Serajeddin Ebrahimian, MSc, entitled Influence of obstructive sleep apnea on cardiac repolarization – Modulatory effects of sleep stages, desaturations, and arousals will be examined at the Faculty of Science, Forestry and Technology, Kuopio campus and online. The opponent will be Associate Professor Frida Sandberg, Lund University, Sweden, and the custos will be Professor Timo Leppänen, University of Eastern Finland. Language of the public defence is English.
For more information, please contact:
Serajeddin Ebrahimian, [email protected], tel. +358 458 092 688
