Cardiovascular Reflex in Response to Supine and Upright Exercise

MH. Al-Shamma MBChB, Yesar; Ph.D,

	Cardiovascular Reflex in Response to Supine and Upright Exercise
KUFA MEDICAL JOURNAL
Article 1, Volume 11, Issue 1, 2008, Pages 89-109
Authors
Yesar MH. Al-Shamma MBChB;
Abstract
This study was carried out on 21 normal healthy male volunteers, aged 20-40 years in order to study cardiovascular reflexes response to postural changes at rest and during exercise by using non-invasive technique. Bicycle ergo-meter for doing exercise, mercury sphygmomanometer for measuring the blood pressure(BP) and Doppler echocardiography for estimating of heart rate(HR), stroke volume(SV), cardiac output(CO), velocity time integral(VTI), ejection time(ET), peak or maximum flow velocity through aortic valve(Vmx) and maximum pressure gradient across aortic valve(PGmx). The results were at rest there are significant increase in HR, diastolic BP, mean BP, peripheral vascular resistance(PVR) and significant decrease in SV, CO, VTI, ET in upright position on comparison with the supine position, while systolic BP, Vmx, PGmx are not significantly different between both positions at rest. During change from rest to exercise all variables significantly changed in both positions except ET during upright exercise which is not significantly decreased. On comparison between supine and upright exercise it was found that there are significantly higher HR, systolic BP, PVR and significantly lower SV, CO, VTI in upright exercise in comparison with supine exercise, while diastolic BP, mean BP, ET, Vmx, PGmx are not significantly different between supine and upright exercise. On comparison between the differences in both positions in response to exercise it was found that there are significantly higher HR, systolic BP, PVR and significantly lower CO, diastolic BP, ET in upright position on comparison with the supine position, while mean BP, VTI, Vmx, PGmx not significantly changed. We concluded that there is inverse relationship between HR and ET and direct relationship between VTI and Vmx.

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