Presentation Title

Alterations in Longitudinal Motion of the Intima-media Complex During the Respiratory Cycle and in Response to Sympathetic Activation in Humans

Format of Presentation

Poster to be presented Friday March 31, 2017

Abstract

Ultrasound imaging of the arteries that supply blood to the head and brain expand and retract as blood pressure changes with every beat of the heart. This radial movement is often used to describe the stiffness of blood vessels. Recent movements of the inner portions, known as the intima media complex, of these arteries have been measured. This longitudinal movement of the intima-media complex may be a useful non-invasive diagnostic tool for predicting cardiovascular disease risk. However, to our knowledge little research has quantified the basic physiological processes that contribute to these movements and their importance relative to one another. In the present study, we induced activation of the sympathetic nervous system (fight or flight reflex) and altered respiratory rates to examine how these processes impact this novel longitudinal movement. Ultrasound was used to record video clips of the longitudinal movements under each condition in 12 apparently healthy people (n=10 males and 2 females). Sympathetic activation through either a cold pressor test or a muscle chemoreflex had no impact upon longitudinal movement compared to rest (p=0.52 and p=0.23, respectively). However, we did observe substantial respiration related effects on the longitudinal movement of the intima-media complex (p=0.007). These findings suggest that the bulk of the longitudinal movement is respiratory related, inferring that the carotid arteries are tethered to pulmonary structures that contribute substantially to this motion. Altering respiratory mechanics may be a potent method to accentuate this motion and improve mechanics between the layers of the arteries.

Department

Biological Sciences

Faculty Advisor

Mark Rakobowchuk

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Alterations in Longitudinal Motion of the Intima-media Complex During the Respiratory Cycle and in Response to Sympathetic Activation in Humans

Ultrasound imaging of the arteries that supply blood to the head and brain expand and retract as blood pressure changes with every beat of the heart. This radial movement is often used to describe the stiffness of blood vessels. Recent movements of the inner portions, known as the intima media complex, of these arteries have been measured. This longitudinal movement of the intima-media complex may be a useful non-invasive diagnostic tool for predicting cardiovascular disease risk. However, to our knowledge little research has quantified the basic physiological processes that contribute to these movements and their importance relative to one another. In the present study, we induced activation of the sympathetic nervous system (fight or flight reflex) and altered respiratory rates to examine how these processes impact this novel longitudinal movement. Ultrasound was used to record video clips of the longitudinal movements under each condition in 12 apparently healthy people (n=10 males and 2 females). Sympathetic activation through either a cold pressor test or a muscle chemoreflex had no impact upon longitudinal movement compared to rest (p=0.52 and p=0.23, respectively). However, we did observe substantial respiration related effects on the longitudinal movement of the intima-media complex (p=0.007). These findings suggest that the bulk of the longitudinal movement is respiratory related, inferring that the carotid arteries are tethered to pulmonary structures that contribute substantially to this motion. Altering respiratory mechanics may be a potent method to accentuate this motion and improve mechanics between the layers of the arteries.