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Autonomic Nervous System in the Patients with Coronary Artery Diseases during Hyperbaric Oxygenation Therapy.
Stepanov Andrey, MD; Stepanova Svetlana, MD.
Central Clinical Hospital N5
Department of Blood Purification and Hyperbaric Oxygenation Therapy
Material and Methods
Introductions: Hyperbaric oxygenation therapy (HBOT) is inhalation of pure oxygen at grate then 1 atm absolute pressure. Prior trials detected benefits from HBOT for patients with coronary artery diseases (CAD). But not all is known about the influence of HBOT on autonomic nervous system (ANS). Heart rate variability (HRV) is a proven tool for examining the ANS.
Objectives: The aim of this study was to assess the changes in ANS during HBOT by using the HRV.
Material and Method: The first group of 6 patients with CAD were pressurized up to 1,5 atm absolute pressure (aap) and remained at this pressure for 40 minutes. In the control groupe these 6 patients stayed in HBOT chamber under 1,0 aap in 21-40% oxygen instead sessions 1 and 7. The HRV was recorded using "Cardiolab 2000" system during sessions 2, 6 and 10. Patients were examined before HBOT and on the first and 40th minute under 1,5 aap. TP, LF, HF, and LF/HF ratio were analysed for the frequency domain measures.
Results: In the first group we observed significant increase (p<0,05) of TP by 97%, LF by 56%, HF by 97%, LF/HF ratio decreased by 1,76 (p<0,05). There were no significant changes in the control group.
Discussion: The analysis of indexes of HRV during a HBOT session showed significant increase of parasympathetic activity and total variability in the first group compared with control group.
Conclusion: HRV might be helpful in monitoring during session of HBOT and it can reflect the effect for patients with CAD. HBOT can improve prognosis in patients with CAD.
Introduction: Hyperbaric oxygenation therapy (HBOT) is inhalation of pure oxygen at great then 1 atm absolute pressure. Prior trials detected benefits from HBOT for patients with coronary artery diseases (CAD)  and acute myocardial infarction . HBOT increases plasma concentration of dissolved oxygen, and this effect may normalize or even increase oxygen tension to hyperoxic levels in ischemic tissue . HBOT is a useful modality for treatment of diseases in which tissue oxygen availability is decreased. HBOT reduces the ischemic effects of coronary artery occlusion in animal and clinical studies . But a little is known about the influence of HBOT on autonomic nervous system (ANS). The changes in ANS have a high relation with cardiac function and mortality [9, 10, 11, 13]. The heart rate variability (HRV) as the one of potential prognostic value of markers of autonomic activity has gained progressive popularity [6,7]. Now HRV is a proven tool for examining the ANS .
Objectives: The aim of this study was to assess the changes in ANS in patients with CAD during HBOT by using the technique of HRV.
Material and Methods: The studys patients received HBOT as adjunctive therapy of CAD and they were drawn from the Cardiology Department of Central Clinical Hospital N5, Kharkov. They were 4 men and two women, mean age 52± 10 year. All of the patients were in sinus rhythm; none had history of acute myocardial infarction. The study began in September 1998 and it is still in progress. This is a preliminary report. The first group included 6 patients with CAD (stable angina pectoris IIII class NYHA) and receiving usual treatment.
Patient were pressurized during 15-20 minute period up to 1,5 atmosphere absolute pressure (aap) and remained at this pressure for 40 minutes and then depressurized during 15 minute period to normal atmosphere pressure. Total time of HBOT was 70 - 80 minutes. In the control group these 6 patients stayed in HBOT chamber under 1,0 aap in the 21- 40% oxygens atmosphere instead first, 7th and 11th HBOT sessions during 70 - 80 minutes. We used monoplace chamber "OKA-MT" with 1m3 volume inside. Monitoring of electrocardiogram (ECG), noninvasive blood pressure (before and after HBOT in supine position) was performed during HBOT sessions. Every patient received 10 HBOT sessions in the same time every day.
HRV was calculated in general agreement with the standards of measurement proposed by Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology . The HRV was recorded using computer based electrocardiograph system "Cardiolab 2000" during sessions 2, 6 and 10 before HBOT, on the first minute under the 1,5 aap and on 40th minute under 1,5 aap. In the control group the HRV was recorded before HBOT, on 15 and 55 minutes of the sessions 1, 7 and 11.
HRV was analyzed on 5-minute period of stable ECG recording for the frequency domain measures with the use of fast Fourier transform. We measured the total power (TP) of the R R interval (0 0.5 Hz). The frequency ranges were subdivided into 0.03 0.15 Hz as a low frequency component (LF) and 0.15 0.5 Hz as a high frequency (HF) one. TP, LF, HF was expressed in absolute values (ms2). We measured also the LF/HF ratio and LF and HF in normalized units (LFn, HFn respectively calculated as a percentage of TP of the R R interval, from which the power of any component with a frequency of less than 0.03 Hz was removed) . The results are given as mean ± standard deviation (SD). A p-value <0.05 was considered significant.
Results: Table 1 shows the mean values and SD of HRV measurement for the study group before and during HBOT. There were no significant changes in the control group. On the first minute under 1,5 aap we observed significant increase of TP by 99,3% (p=0.006), LF by 138% (p=0.022), HF by 67.6% (p=0.01). Increase of LFn by 0.8% (p=0.26) and decrease of HFn by 1.4% (p=0.32) and LF/HF ratio by 34,8% (p=0,176) was not significant. The changes on the 40th minute under 1,5 aap were significant in all values compared with values before HBOT. We observed significant increase of TP by 153,3% (p=0.001), LF by 155% (p=0.03), HF by 252% (p=0.003), HFn by 39.6% (p=0.003), and decrease of LFn by 25.9% (p=0.004) and LF/HF ratio by 61.1% (p=0,004).
Discussion: As confirmed by other investigator, we found HRV to be reduced in patient with CAD and with the signs of increased sympathetic activity . It has been hypothesized that influences can make impairment of HRV may predict acute myocardial infarction and sudden cardiac death. This is the first study to record changes in frequency domain measures of HRV during HBOT. The analysis of HRV during a HBOT session showed significant changes. We observed significant increase of TP and it components LF and HF. But if analyze LF/HF as marker of sympathovagal balance and LFn and HFn we could noted the increasing of parasympathetic activity more significant than decreasing of sympathetic activity. From this point of view the use of HBOT for patient with CAD is useful modality as adjunctive increasing of parasympathetic activity. The studies of influence of HBOT on organism is not finished and well understanding the changes in ANS will help in management the patient that received HBOT for a long time (it was reported about more than 200 sessions for one patient). In some patients that were not included in this study we observed decreasing the TP and increasing the LF/HF ratio and it was close correlated with problems during the sessions such as claustrophobia, the signs of hypersensitive to oxygen etc. The positive HRV changes were more expressed at patients with more successful results in treatment. In Figure 1 and Figure 2 we presented the changes in HRV before and during HBOT.
Conclusions: Our preliminary results showed that measurement of HRV was helpful in monitoring during the sessions of HBOT and reflected the effects in the treatment of patients with CAD. Adjunctive HBOT can improve prognosis in patients with CAD. Based on values of HRV it will be possible in the future to modulate the protocols of HBOT. Of course it need to explore the influence of other treatment protocols of HBOT on ANS and in particularly how long changes we detected last. In Figure 1 and 2 showed changes in Very LF component that reflected another ways to change HRV, but it will be another report.
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