Study of heart rate variability changes in smokers

Background: Heart rate variability (HRV) is an objective and sensitive measure of integrated physiological functioning reflective of heart rhythm responsivity to internal and external demands. Reduced HRV is associated with vulnerability to stress, while increased HRV is associated with a favorable treatment response and recovery from various medical and/or psychiatric conditions. Cigarette smoking has been shown to adversely affect heart rate variability (HRV), suggesting dysregulation of cardiac autonomic function. Objectives: To determine the frequency and time domain measures of heart rate variability in smokers and thereby assessing the cardio vascular status. Materials and methods: 50 smokers and 50 normal male subjects between the age group of 20-50 years were selected. Computerized ECG system with Niviqure Software was used for the study. Frequency domain measures such as very low frequency, high frequency and LF/HF ratio and time domain measures such as mean RR intervals, mean HR, SDNN, RMSSD, were assessed to observe both sympathetic and parasympathetic nerve function status. Statistical analysis was done by Student’s unpaired t-test will be used to compare different parameters between study and control groups. Results: Frequency domain parameters like low frequency and LF/HF ratio were significantly (< 0.001) higher and HF was reduced, Time domain parameters like SDNN, RMSSD, PNN 50% and mean RR were reduced significantly in smokers compared to normal. Conclusion: Impaired cardiac autonomic nerve function characterized by sympathetic over activity and reduced vagal activity were found in the absence of any cardiac disease in smokers.