Dr. Victoria Claydon

Research interests:

Cardiovascular physiology and pathophysiology; altitude physiology; cerebrovascular control; autonomic nervous system; spinal cord injury; syncope.

Cardiovascular Physiology Laboratory: K8512; Telephone 778-782-8560.

Directions

The office and laboratory are located in Shrum Science - K Building on the 8000 level. The laboratory is room K8512 and the office is room L8006. A map showing wheelchair access/elevators is available here. If arriving by taxi, it is best to drop off at the entrance to the Applied Sciences Building. Parking (including wheelchair accessible parking) is available upon request.

Research Themes

My research interests are focused on human cardiovascular control in health and disease. My main research contributions have addressed cardiovascular reflex control in response to: spinal cord injury; chronic hypoxia and hypocapnia due to permanent residence at high altitude; and orthostatic stress.

1. Spinal Cord Injury

   In addition to the well known motor and sensory consequences of spinal cord injury, descending cardiovascular pathways can also be affected. This leads to widespread abnormalities in cardiovascular control. These alterations not only impair function, but can also be life-threatening. Consequently, the leading cause of morbidity and mortality in spinal cord injured individuals is cardiovascular disease. Continuing research in my laboratory, and in conjunction with the International Collaboration On Repair Discoveries (ICORD) and members of the American Spinal Injury Association (ASIA) aims to elucidate the mechanisms underlying cardiovascular dysfunction after spinal cord injury.

   Selected publications:

   • V.E. Claydon and A.V. Krassioukov (2007) Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury. American Journal of Physiology, 294: H668-H678.
   • V.E. Claydon and A.V. Krassioukov (2006) Orthostatic hypotension and autonomic pathways after spinal cord injury. Journal of Neurotrauma, 23: 1713-1725.
   • V.E. Claydon, A.T. Hol, J.J. Eng, A.V. Krassioukov (2006) Cardiovascular responses and post-exercise hypotension after arm cycling exercise in subjects with spinal cord injury. Archives of Physical Medicine and Rehabilitation, 87: 1106-1114.
   • V.E. Claydon, S.L. Elliott, A.W. Sheel, A. Krassioukov (2006) Cardiovascular responses to vibrostimulation for sperm retrieval in men with spinal cord injury. Journal of Spinal Cord Medicine, 29: 207-216.
   • V.E. Claydon, J.D. Steeves, A.V. Krassioukov (2006) Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology. Spinal Cord, 44: 341-351.

2. Altitude Physiology

   Ongoing work in my laboratory and in conjunction with the Environmental Physiology Unit (EPU) at Simon Fraser University involves characterising the various patterns of cardiovascular and cerebrovascular adaptation that occur in response to permanent residence at high altitude. These evaluations have involved numerous field studies of different high altitude dwelling populations in the Peruvian Andes, in the Ethiopian Highlands, and in the Himalayas. The chronic hypoxia and hypocapnia that is an inescapable consequence of high altitude living has profound effects upon the cardiovascular system. Lifelong exposure to high altitude leads to various adaptations affecting haemodynamics, cardiovascular control and cerebrovascular reactivity. The pattern of these adaptations varies in different high altitude populations, and not all high altitude residents adapt well to the environment in which they live. These studies have important implications for the millions of people who live and work at high altitude, and potentially to the study of hypoxic disease in the clinic at sea level.

   Selected publications:

   • V.E. Claydon, G. Gulli, M. Slessarev, O. Appenzeller, G. Zenebe, A. Gebremedhin, R. Hainsworth (2007) Cerebrovascular responses to hypoxia and hypocapnia in Ethiopian high altitude dwellers. Stroke, 39: 336-342.
   • G. Gulli, V.E. Claydon, M. Slessarev, G. Zenebe, A. Gebremedhin, M. Rivera-Ch, O. Appenzeller, R. Hainsworth (2007) Autonomic regulation during orthostatic stress in highlanders: comparison with sea-level residents. Experimental Physiology, 92: 427-435.
   • J.P. Moore, V.E. Claydon, L.J. Norcliffe, M.C. Rivera-Ch, F. Leon-Velarde, O. Appenzeller, R. Hainsworth (2006) Carotid baroreflex regulation of vascular resistance in high altitude Andean natives with and without chronic mountain sickness. Experimental Physiology, 91: 907-913.
   • V.E. Claydon, L.J. Norcliffe, J.P. Moore, M. Rivera-Ch, F. Leon-Velarde, O. Appenzeller, R. Hainsworth (2005)Cardiovascular responses to orthostatic stress in healthy altitude dwellers, and altitude residents with chronic mountain sickness. Experimental Physiology, 90: 103-110.
   • V.E. Claydon, L.J. Norcliffe, J.P. Moore, M. Rivera-Ch, F. Leon-Velarde, O. Appenzeller, R. Hainsworth (2004) Orthostatic tolerance and blood volumes in Andean high altitude dwellers. Experimental Physiology, 89: 565-571.

3. Syncope

   Syncope, or fainting, is a significant cause of morbidity for those affected, and greatly impacts upon quality of life; many sufferers sustain injury or are unable to work or drive due to their frequent episodes of loss of consciousness. The precise mechanisms underlying syncopal attacks are, however, poorly understood. Research in my laboratory aims to elucidate those mechanisms, and to aid in the treatment of syncopal and presyncopal (near-fainting) attacks.

   Selected publications:

   • V.E. Claydon, C. Schroeder, L.J. Norcliffe, J. Jordan, R. Hainsworth (2006) Water drinking improves orthostatic tolerance in patients with posturally related syncope. Clinical Science, 110: 343-352.
   • V.E. Claydon and R Hainsworth (2005) Increased postural sway in control subjects with poor orthostatic tolerance. Journal of the American College of Cardiology, 46: 1309-1313.
   • V. E. Claydon and R. Hainsworth (2004) Salt supplementation improves orthostatic cerebral and peripheral vascular control in patients with syncope. Hypertension, 43: 1-5.
   • V. E. Claydon and R. Hainsworth (2003) Cerebral autoregulation during orthostatic stress in healthy controls and in patients with posturally related syncope. Clinical Autonomic Research, 13: 321-329.
   • C. Schroeder, V.E. Bush, L.J. Norcliffe, F.C. Luft, J. Tank, J. Jordan, R. Hainsworth (2002) Water drinking acutely improves orthostatic tolerance in healthy subjects. Circulation, 106: 2806-2811.

   For a full listing of publications, see PubMed.

Potential graduate students or post-doctoral fellows interested in the research in my laboratory should contact me directly: 778-782-8513 or victoria_claydon@sfu.ca. Additional information concerning graduate studies and opportunities in the laboratory can be found on the department of Biomedical Physiology and Kinesiology Graduate Studies web page.

Available Graduate Student Positions

Funding:

Research in my laboratory is funded by the following agencies: