Quantifying the influence of isometric leg exercise on leg, liver, spleen and if feasible heart volume during modelled orthostatic stress. After this study, the next step will involve taking similar experiments to one of the three upright MRI…
ID
Source
Brief title
Condition
- Other condition
Synonym
Health condition
circulatie fysiologie
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
Volumes of legs, liver, spleen and heart during stages of LBNP with and without
isometric leg exercise.
Secondary outcome
n.a.
Background summary
Muscle tension in the lower body promotes venous return and tensing of leg
muscles increases orthostatic tolerance and can be used to abort an impending
vasovagal faint. It's generally accepted that the underlysing mechanism is an
increase in thoracic blood volume.
The contribution of muscle tensing to the circulation has been poorly
quantified. Earlier studies looked at changes in leg volume during orthostatic
stress using traditional plethysmographic methods. CT and MRI have been used
for determining changes in leg volume during prolonged supine rest but never
have they been used to examine the intracorporal volume shifts, nor during
exercise.
Study objective
Quantifying the influence of isometric leg exercise on leg, liver, spleen and
if feasible heart volume during modelled orthostatic stress. After this study,
the next step will involve taking similar experiments to one of the three
upright MRI scanners available in Europe.
Study design
Eight healthy volunteers will be subjected to an incrementing LBNP challenge
while positioned in an MRI scanner. LBNP is a widely accepted model for
orthostatic stress. During rest and during isometric leg exercise
(retro-flexion in the hip with straightened legs) a scan is made of the legs,
abdomen and thorax. Simultaneously blood pressure is continuously
non-invasively measured with Finapres. Via pulse wave analysis changes in
cardiac output are determined. Cerebral oxygenation is measured by
nera-infrared spectroscopy and cerebral blood flow velocity by trans cranial
echo-doppler. Off-line changes in leg, liver, spleen and (possibly) heart
volume will be related to changes in cardiac output.
Study burden and risks
Risks: pre-syncope complaints during (final stage, 50 tor)LBNP
Meibergdreef 9
1105AZ Amsterdam
Nederland
Meibergdreef 9
1105AZ Amsterdam
Nederland
Listed location countries
Age
Inclusion criteria
healthy normotensive individuals (age 20-35 yr, BMI 20-25, height 160-190 cm)
Exclusion criteria
-use of any medication that interferes with cardiovascular regulation.
-(suspected) pregnancy or desire to become pregnant in the period of the study
-(suspected) cardiovascular disease
-presence of any circumstance that is likely to interfere with normal orthostatic tolerance and/or the use of LBNP and/or MR-Imaging
-wish not to be informed about significant irregularities from MRI;Students and employees of the AMC can not take part in study.
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
| Register | ID |
|---|---|
| CCMO | NL11627.018.06 |