Effect of smoking and exposure cigarette smoke on cardiac autonomic function of healthy young adults

Smoking is the one of the main factor in the risk of cardiovascular disease, stroke, sudden death, heart attack, peripheral vascular diseases, aortic sudden death and aortic aneurysm. In addition to cigarette smoking, exposure to cigarette smoke also leads to the occurrence of cardiovascular diseases. Heart rate variability (HRV) that is defined as cyclic changes over time in the sinus rateis used as a measure and indicator for cardiac autonomic tone since it provides information about sympathetic-parasympathetic balance. Heart rate turbulence (HRT) is defined as the physiological changes in the ventricular premature beats after the sinus rate and is considered as an indicator of the baroreflex sensitivity. European Society of Cardiology accepted HRT as a good indicator of vagal activity and independent and powerful indicator for total mortality. In this study, it was aimed to evaluate the changes in HRV and HRT that are the indicators of cardiac autonomic functions in young adults who are either active smokers or passive smoker. In this study, 18-24 years old patients who applied to outpatient cardiology service were selected and allocated into two groups. Group 1 consist of active smokers who has no obvious disease history and group 2 consist of passive smokers who have been exposed to cigarette smoke at least two hours in a day. Group 3, the control group, is made up from patients who have same selection criteria as above groups and consists of non-smokers who have not been exposed to cigarette smoke. Selected individuals were informed and informed consent was signed. Dependence of patients was evaluated with Fagerstrom Test for Nicotine Dependence. Patients and healthy subjects were directed to the cardiology outpatient clinic by cardiology assistant or specialist who performs the cardiological examination and record the patient's ECG, EKO and then the values of HRT and HRV of the subjects were evaluated after taking record of rhythm holter for 24 hours. According to the 24-hour Holter recordings of mean heart rate; no differences have been found between group 1 and group 2, nevertheless, these values in group 3 were found lower than from the other two groups in terms of statistical significance. (Group 1: 82.25 ± 7.87 beats / min; Group 2: 81.87 ± 6:45 beats / min; Group 3: 71.47 ± 23.5 beats/ min, p <0.001). No difference has been found between group 1 and 2 in terms of total ventricular additional beat (VES) according to values obtained from 24 hours holter recordings, nevertheless, in group 3 this value has been found lower from the other 2 groups in terms of statistical significance. Group 1: 12.21 ± 6.23 beat/day; Group 2: 19.87 ± 3.45 beat/day; Group 3 was 5.34 ± 2. beat/day, p <0.001). Statistically significant difference was found in value of Total Onset (TO) and Turbulance Slope (TS) that were calculated from the analysis of 24 hours holter recordings of all groups (p <0.01). In the analysis of HRT; there were 21 cases in group 1, ten cases in group 2 and two cases in group 3 which have the OT value bigger than zero per cent (>0%) that is accepted as a pathologic value (p<0.05). Similarly, the number cases that include the accepted pathological value of TS "<2.5 ms / RRI that observed from the three groups were as follows: 21 cases in group 1, 8 cases in group 2 and 1 case in group 3 (p<0.05). It has been shown that the value of HRV and HRT in cigarette smokers and in passive smokers, are high enough that can cause cardiovascular risk.