Linear Short-Term Heart Rate Variability Parameters of Subjects Tobacco Cigarette Smokers and Subjects Nonsmokers in Preoperative Period

BACKGROUND Variations of heart cycles reflect complex dynamic cardiocirculatory regulatory systems in humans. Exposure to tobacco from cigarettes has been shown to elicit specific alterations of heart rate variability parameters leading to predominance of sympathetic and decreasing parameters of parasympathetic measures of cardiac autonomic nervous system tone. AIM The aim of the trial was assessing differences of linear parameters of heart rate variability in subjects with habit of consuming of cigarettes tobacco in regard to subjects who are not consumers of tobacco. METHODS Patients of ASA II class with border-line arterial hypertension planned for elective abdominal surgery were included in the clinical trial. Twenty-two subjects were allocated to group I, with history of smoking twenty or more cigarettes per day for five or more years, and twenty-three subjects nonsmokers were allocated to group II. Recordings of electrocardiogram were done by Holter device and later on short- term heart rate variability (five minutes periods) were analyzed. Parameters of time domain analysis (SDNN-standard deviation of NN intervals, mean RR interval, mean heart rate) and frequency domain measures (low frequency (LF), high frequency (HF), and LF/HF ratio) were analyzed. RESULTS Baseline measures of mean NN intervals and standard deviation of normal to normal interval (SDNN) were slightly lower in subjects consumers of nicotine by cigarette tobacco smoking in regard to nonsmokers but without significant difference (640+-15ms vs 675+-8ms, p<0.1;45,1+-3,4 ms vs 51,4+ 3,7ms, p<0.08, respectively). Values of frequency domain measures (LF, HF and LF/HF ratio) have shown variations between two groups, but no significant difference was found.