The normal variations in heart rate and QRS complex of healthy individuals in different age groups

Mahendrappa SK, Sathyanarayana TB


Background:Electrocardiography is the only practical method of recording the electrical behavior of the heart. It is often an independent marker of myocardial disease and occasionally the only indication of the pathologic process. Therefore the present study has been undertaken to find out the degree of normal variations in healthy individuals in different age groups.

Methods:This study was conducted after the institutional ethical clearance and informed written consent from all the subjects belongs to age group of 18 to 40 years of either sex. All the ECG was taken in resting and supine position using BPL CARDIART 308 machine. The body weight, the QRS duration, QRS axis, P wave duration, P wave voltage, P wave axis in the frontal plane, QTc interval, T wave voltage and QRS-T angle was calculated. The values are expressed as mean and the percentile was calculated in each parameters.

Results:The weight ranges from 56.37 ± 6.53 kg. QRS duration ranged from 0.04 to 0.12 seconds mean of 0.064 seconds. QRS voltage in V6 varied from 0.30 to 2.1 mv with a mean of 1.14 mv. The QTc interval was 0.31 to 0.47 seconds mean was 0.39 seconds.  QRS-T angle varied from 0° to 70° with a mean of 30.9°.

Conclusion:The study provides the frequency distribution and other statistical data when applied to all components of ECG which are commonly assessed during investigations of healthy young individuals. Having knowledge of these normal variants will be helpful in arriving at correct diagnosis.



Electrocardiogram, QRS duration, QRS axis, QRS voltage, QTc interval, T wave voltage

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