title: Gender differences of heart rate variability in healthy volunteers.
abstract: OBJECTIVE
  To identify the basic values of heart rate variability in Pakistani population and to verify our hypothesis that there are gender differences in cardiovascular autonomic modulation.
  
  
  METHODS
  The descriptive cross sectional study based on convenience probability sampling was conducted at Armed Forces Institute of Cardiology/National Institute of Heart Diseases (AFIC/NIHD) Pakistan. The duration of the study was from December 2009 to July 2010. It involved 24-hour holter monitoring of 45 healthy individuals using holter electrocardiography (ECG) recorder. Heart rate variability was analysed in time (SDNN, SDANN, SDNNi, rMSSD, pNN50) and frequency domains (power, VLF, LF, and HF).
  
  
  RESULTS
  The time domain indices; SDNN (male = 140 +/- 36ms vs. females = 122 +/- 33ms; p = 0.09), SDANN (male = 123 +/- 34ms vs. females = 111 +/- 34ms; P = 0.23), SDNNi (male = 64 +/- 19ms vs. females = 52 +/- 14ms; P = 0.03), and pNN50 (male = 14 +/- l0ms vs. females = 12 +/- 7ms; P = 0.43) were decreased in female volunteers when compared with males. Comparison of frequency domain indices; Total power (male = 4041 +/- 3150ms(2) vs. females = 2750 +/- 1439ms(2); P = 0.07), VLF (male = 2912 +/- 2675ms(2) vs. females = 1843 +/- 928ms(2); P = 0.06), LF (male = 788 +/- 397ms(2) vs. females = 556 +/- 346ms(2); P = 0.04) and HF (male = 318 +/- 251ms(2) vs. females = 312 +/- 277ms(2): P = 0.94) amongst males and females showed attenuated heart rate variability in females. Of all the observed values, SDNNi and LF were found significantly (p < 0.05) decreased in women.
  
  
  CONCLUSIONS
  In healthy population, heart rate variability is low in women than men. It reflects sympathetic dominance in women in our population.
authors: Department of Physiology, Federal Medical and Dental College, Quaid-e-Azam University, Islamabad. drshemailasaleem@gmail.com
authors: Shemaila
authors: S
authors: Saleem
authors: Muhammad Mazhar
authors: MM
authors: Hussain
authors: Syed Muhammad Imran
authors: SM
authors: Majeed
authors: Muhammad Alamgir
authors: MA
authors: Khan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010154:Pakistan; D012016:Reference Values; D012737:Sex Factors