Researsh Of The Clinical Value Of Betaloc In The Intervention For Children’s Frequent Premature Ventricular Contractions

Objective:To explore the clinical value of metoprolol in the intervention forchildren’s frequent premature ventricular contractions(PVCs) by using theeffectiveness of metoprolol for different types of frequent PVCs.Methods:Collected a total of21of children who were diagnosed with frequentPVCs in Children’s Hospital of Chongqing Medical University fromJanuary2012to March2014. All cases were divided into the left ventricleand right ventricle groups based on the QRS morphology on body surfaceelectrocardiogram. On the other hand, all cases were divided into mixed,night and daytime type in accordance with the time of PVCs appeared onthe Holters. All cases were treated with metoprolol1-2mg/(kg d), and2times a day for2weeks and if it was ineffective then withdrawed itwhile if it was effective then continued using for3months beforewithdrawal. Carried out Holter monitoring and echocardiography beforeand after the treatment then compared effective rates and time domain parameters of HRV between or among different groups.Results:1. Relationship between PVCs and HR: All cases were divided intothree groups based on the relationship hourly PVCs on24-hour Holterwith average HR of the same period. P-PVCs meant PVCs increases withthe increase of HR. N-PVCs meant PVCs decrease with the increase ofHR. I-PVCs meant there was no linear correlation between PVCs and HR.2. Relationship between PVCs and autonomic nervous system (ANS):There were15patients (71.4%) showed correlations with SDNN andwere12cases showed positive correlations with RMSSD while3casesshowed negative correlation with RMSSD.There were11cases showedpositive correlation with PNN50while1case showed negativecorrelation with PNN50. In N-PVCs group there were5cases (100%)showed positive correlation with PNN50. But in P-PVCs group there were3cases (27.3%) showed positive correlation with PNN50while6cases(54.5%) showed negative correlation with PNN50。The distribution ofgender, age, whether combined myocarditis，PVCs origin locations,average HR and the percentage of PVCs of total cardiac beats in24hours showed no significant difference while there was a significantdifference on the circadian rhythm among the three groups. All the8casesof daytine type were distributed in P-PVCs, but in the N-PVCs there was1case of night type and the others were mixed type and I-PVCs consisted of5cases of mixed type. The time domain parameters of HRVamong the three groups had no significant difference. But in P-PVCsgroup the time domain parameters SDANN was bigger than that of theN-PVCs, while in N-PVCs group the time domain parameters RMSSDwas higher than that of P-PVCs.3. Metoprolol showed different effectiveness among different PVCsgroups: According to the analysis of relationships between PVCs andHR，there were11cases with in P-PVCs group and9cases were effective,two cases were effective with the efficiency was81.8%.5cases is inN-PVCs group and I-PVCs group, both were2cases were effective and3cases were ineffective with the efficiency was40.0%. The efficiencyP-PVCs group was higher than N-PVCs group and I-PVCs group.4. The role of metoprolol on different type frequent PVCs based onlocalization: According to the analysis of the localization of PVCs, therewere13cases originated in the left ventricle and8cases originated in rightventricle. The distribution of age, gender, etiology, average HR, percentageof the number of PVCs of total stroke in24hours and circadian rhythmbetween the two groups had no significant difference. After usingmetoprolol, PVCs originated in right ventricle showed a higher sensitivityto metoprolol with6(75.0%)cases were effective compared to PVCsoriginated in the left ventricle with7cases (53.8%) were effective.5.The role of metoprolol played on different type frequent PVCs based on circadian rhythm: According to analysis of the circadian rhythmof PVCs, there were8cases of daytime type,12cases of mixed-type and1case of night type. The distribution of age, gender, etiology, average HR,percentage of the number of PVCs of total stroke in24hours andlocalization of PVCs between mixed-type and daytime type groups showedno significant difference. Daytime type showed a higher sensitivity tometoprolol with7cases (87.5%) were effective compared to5cases(41.2%) were effective in mixed type.6. Comparison of time domain parameters of HRV before and afterthe treatment: After the treatment SDNN rised, SDANN decreased andRMSSD increased compared with pre-treatment. But all of the threeparameters domain parameters of HRV above before and after thetreatment showed no significant difference.7. Change of the number of PVCs during the follow-up time: Thereare13cases were effective for the intervention of metoprolol showing thenumber of PVCs on24-hour Holter reduced over50%when comparedto PVCs before the treatment. But excepted for two cases diagnosed withmyocarditis, the number of PVCs of the rest cases showed a gradualincreasing trend with reduction or withdrawal of metoprolol,and partlyrecovered to and even more than the level before treatment.Conclusion:1. For frequent PVCs originating from different locations, metoprolol is more effective for the right ventricle than the left ventricle.2For frequent PVCs with different circadian rhythm, metoprolol ismore effective for daytime type than mixed type.3. Metoprolol show different effects in treating different children’sfrequent PVCs. For the frequent PVCs cases without organic heart diseaseassociate with imbalance of autonomic nerve system function will recurafter treatment and it may disappear until autonomic nerve system functiondeveloped while for frequent PVCs cases with impaired autonomic nervoussystem relate to myocarditis will not recur after withdrawal.