| Objective: Premature ventricular contractions(PVCs)is one of the most common arrhythmias,and symptomatic outflow tract PVCs are more suitable for the treatment of radiofrequency catheter ablation in patients with frequent seizures or poorly controlled drug effects because of its unique anatomical characteristics,focal point of origin and the availability of intracardiac catheter.Recent studies showed that characteristics of PVCs circadian rhythm are different,Some mostly occurred during the daytime,some in the night,and some occurred during the whole day.The mechanism that the same PVCs exhibit different clinical manifestations is still unclear.However,autonomic mechanisms behind these different relationships have been rarely reported.this study assumed that different Circadian rhythm characteristics of the outflow tract PVCs are associated with the regulation of autonomic nerves,aimed to investigate the characteristic of heart rate viability(HRV)changes in patients with different circadian rhythm of outflow tract frequent PVCs,and compared with normal people,to evaluate the correlation of outflow tract PVCs and autonomic nervous function,and to select the appropriate treatment strategy for patients with different circadian rhythm of PVCs.Method:44 patients diagnosed OT-PVCs from November 2014 to November 2015 at the 1st affiliated hospital of Dalian Medical University have been recruited into the study,and were divided into group A(PVCs load mainly in daytime),group B(PVCs load mainly in nighttime)and group C(balanced load during the day and night)based on their different PVCs load during day(8:00am to 8:00pm)and night(8:00pm to next 4 day 8:00am).Balanced load was defined as less than 10%(including 10%)of the difference in the number of PVCs between day and night.71 subjects without any known diseases served as control and their baseline data,HRV parameters and hourly tend of SDNN were compared among groups.Results:1.The comparison of each groups and subgroups about age,gender,history of high blood pressure,mean heart rate and LVEF,are without the statistical significance(P > 0.05).Group C was significantly higher than group A and B in total PVCs load of 24 hours(P=0.006).2.Each HRV parameters(SDNN,SDNN,PNN50,LF,HF)in PVCs group was significantly higher than control group(P <0.05).There were no significant differences of HRV parameters among the subgroups,while there showed a certain statistical trend that each HRV parameters(except for LF / HF)in group C are the highest among 4 groups,and the control group was just the opposite(the lowest).3.There were statistical differences among 4 groups in each hour of SDNN lever(P <0.05).From 24 hours SDNN trend chart,SDNN in control group tends to be stable during the day and night,and exhibited the lowest level among 4 groups.SDNN in group C had wide fluctuations,but overall showed higher levels than any other group during 24 hours.SDNN in group A were significantly higher than control group on the whole day,the overall trend was consistent with group C,but had less fluctuations.SDNN in group B had a small range of fluctuation in the daytime,the trend was close to control group,while the levels were significantly higher than control group during the night.Conclusion:1.group A(PVCs load mainly in daytime)may be sympathetically mediated,their autonomic nervous system activity in both day and night were increased comparing with normal people.Group B(PVCs load mainly in nighttime)may be parasympathetic mediated,which was no difference in autonomic nervous system activity during the daytime,but will increase significantly at night comparing with normal people.2.Different characteristics of circadian rhythm and the related autonomic mechanisms should be taken into consideration when treating idiopathic PVCs. |
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