RESUMEN
Aims: To construct normal values of Valsalva ratio for heart rate responses during Valsalva maneuver (VM) and arterial pulse amplitude ratio as reference values for different age groups, and to investigate the effect of aging alone , without , the presence of risk factors, on autonomic nervous system. This is a case control study, performed in Marjan teaching hospital, in Hilla city, from February 2012 to June 2012. Methodology: 40 subjects were included in this study, all were healthy males, group 1 (G1) mean age 28.3±9.7 years, group 2 (G2) mean age 48.4±7.1 years. Strips of lead II of ECG were recorded during performance of VM for calculation R-R intervals and measurement of blood pressure during phase I and phase II by mercury sphygmomanometer. Calculation of Valsalva ratio for heart rate and arterial pulse amplitude ratio for both groups were done. Results: The systolic and diastolic blood pressures of G2 were significantly higher than values of systolic and diastolic blood pressures of G1 at phase I and phase II of VM (P=0.05). Pulse pressure for the two groups at phase I (G1:51±11, G2: 53±13mmHg) and phase II (G1:41±5, G2:41±3.99) of VM were not significant (P>0.05). Valsalva ratio for G1 was (1.5±0.3) and for G2 was (1.39±0.29), pulse amplitude ratio for G1 was (0.80±0.19) and for G2 was (0.77±0.19). There were no significant differences between the two groups (P>0.05). All values were expressed as mean±SD. Conclusions: The results showed that the autonomic nervous system is intact in the older group. The aging process, without the presence of risk factors, does not affect the autonomic nervous system.