Indian journal of physiology and pharmacology
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Indian J. Physiol. Pharmacol. · Apr 2005
Correlation between short-term heart rate variability indices and heart rate, blood pressure indices, pressor reactivity to isometric handgrip in healthy young male subjects.
The purpose of the present study was to determine whether readily measured blood pressure (BP) indices and, responses to autonomic reflex tests could be used as surrogates of short-term heart rate variability (HRV), which is an established marker of autonomic regulation of SA node. Therefore, we examined the correlation between short-term HRV and heart rate (HR), BP indices viz. systolic pressure, diastolic pressure, pulse pressure (PP), and rate-pressure product (RPP), during supine rest and head-up tilt in 17 young healthy normotensive subjects, aged 19.8 +/- 1 yr (mean +/- SD). Three classic autonomic indices viz. ⋯ The possible physiologic significance of these and other correlations is discussed in this paper. In conclusion, the presence of a statistically significant correlation between RPP, PP and spectral measures of short-term HRV supports a simplistic approach to autonomic assessment, in that, easily measurable BP indices could be used as surrogates of HRV when it is not feasible to determine HRV indices directly. However, the same have to be tested in healthy subjects belonging to various age groups and in patients with conditions known to be associated with autonomic dysregulation.
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Indian J. Physiol. Pharmacol. · Apr 2005
Comparative StudyRegulation of cardiovascular functions during acute blood loss.
Sudden blood loss of moderate degree causes fall in blood pressure, which is compensated to certain extent by baroreceptor mediated rise in heart rate and vasoconstriction. In case of severe haemorrhage fall in blood pressure is accompanied by bradycardia indicating failure of baroreceptor mediated recovery in blood pressure. In such conditions partial recovery in the blood pressure with time is possible due to mechanisms other than baroreflex. ⋯ There was a recovery in cardiac output and mean arterial pressure with time in both the cases of blood loss. While a rise in heart rate and stroke volume was produced in 20% blood loss however an initial increase in stroke volume alone and later rise in heart rate alone was produced during recovery phase in 35% blood loss. These finding suggest that 20% blood loss is compensated by baroreflex while 35% blood loss is not accompanied by tachycardia so mechanisms other than the baroreflex, like increase in the vagal tone, contribute to the initial recovery in blood pressure and cardiac output.