| Background and ObjectivesAs the "gold standard" in the diagnosis of arrhythmia, Electrocardiogram(ECG)also plays a considerable role in the diagnosis of myocardial infarction,atrioventricular hypertrophy,etc. With the rapid development of science andtechnology, digital electrocardiograph has emerged, which has progressivelydeveloped from previous vibrating wire type circuits, electronic tube circuits andtransistor circuits to present digital signal acquisition and processing systems.As electrocardiograph was upgraded, its parameters including frequencyresponse have been gradually upgraded as well.Frequency response range ofelectrocardiogram machine refers to the amplitude allowed range inner electricalsignals can replay the range of frequencies, it determines the range of usefulinformation.Over the past few years, there have been increasingly more studies ondeep relationships between electrocardiography and diseases such as congenital heartdefects, coronary heart disease, acute healed myocardial infarction and diabetes as theprevalence rate of such diseases increased, whereas there have been relatively fewer studies concerning parameter setting for digital electrocardiograph and associationsbetween waveform output and clinical practices.According to QRS waves among ECG waveforms, it may be observed that mostof ECG diagnosis information of the adults are below100Hz,and the max frequencywould be250Hz among pediatric QRS waves, In order to ensure the accuracy ofdiagnosis of ECG waveform by direct stroke electrocardiogram machine, AHAsuggested that the high frequency response up to100Hz in1975. With deepeningunderstanding of ECG signal frequency, ANSI/AAMI advise that at least150Hz highfrequency response had applied to all routine12-lead electrocardiogram in1991, andemphasized the proposal in2001that the maximum frequency response is at least150Hz. In Europe, CES group also suggests that150Hz for the upper limit of the highfrequency response.A study in the Netherlands, bandwidth cap should be250Hz inchildren,150Hz in adolescents in2001. Electrocardiogram machine brand and modelnumber used by the different parts of the different levels of hospitals is uneven atpresent, the frequency response range is also different, still use old electrocardiogrammachine parts of hospitals.Choose the children and adults as the main research object in this article,analysis impacts of different range of frequency response upon children’s and adults’waveforms, while a comparison of the influence on the ECG waveform was madebetween children and adults,explore the frequency response range more suitable forthe children and in order to ensure the precision of ECG waveform acquisition inchildren. In hope that numerous ECG workers could know about the importance ofthe influences of range of frequency response on ECG waveforms. Meanwhile,hospitals were expected to facilitate the upgrading of electrocardiographs andeliminate obsolete electrocardiographs with comparatively lower upper limit offrequency response. Furthermore, electrocardiographs were suggested to be employedin standard manners to improve the accuracy for acquiring ECG waveforms.Respondents and Methods1Respondents: there were two groups of respondents:①83respondents wereselected from227children from an elementary school of Zhengzhou, whose ageranged from5to6. Selection criteria: great efforts were made to eliminate factors that might affect ECG results by inquiring their basic information and performingphysical examinations. Then, the children whose ECG results were shown to benormal were selected as respondents.②98healthy examinees were selected fromstudents who took part in ECG examination in the2ndAffiliated Hospital ofZhengzhou University, whose age was within the range of20to45. Selection criteria:students with normal ECG results were selected, while students whoseelectrocardiography was greatly interfered and ECG results were abnormal wereeliminated.2Research methods: respondents’ basic information was collected. Eli250synchronous electrograph made by American Mortara was utilized. After acquisition,three electrocardiograms within the same period were output within three ranges offrequency responses(0.05~40Hz,0.05~150Hz,0.05~300Hz). These electrocardiogramswere observed and measured respectively after the three ECG amplifier100timesrespectively, Meanwhile, data were respectively collected from theseelectrocardiograms and leads V5were selected for all of them. Additionally, a groupof R wave with the highest amplitude was universally selected to measure amplitudeof P wave, amplitude of q wave,amplitude of R wave, amplitude of QRS wave(amplitude of Q wave+amplitude of R wave+amplitude of S wave), amplitude of Twave and ST-segment deviation. The measurements were expressed with mv. Besides,the notch and smoothness on the baseline were observed, All electrocardiograms wereacquired by the researcher and professional ECG team. The measurement andobservation results were collected.3Grouping method: groups were divided according to range of frequencyresponse (Group1:0.05Hz~40Hz; Group2:0.05Hz~150Hz; Group3:0.05Hz~300Hz) and age (Children Group:5-6years old; Adult Group:20-45yearsold) to analyze impacts of different ranges of frequency response upon ECGwaveforms of children and adults.4Statistical analysis: collected data were sorted out through Excel andstatistically analyzed by SPSS17.0(statistical software). The measurement dataconformed to normal distribution and were indicated by x±S, and differences amonggroups were compared by analysis of variance. To make pairwise comparisons of means among three groups of samples, Bonferroni method was applied.Use the twoindependent samples t test to analysis difference of the ECG waveform effect by therange of frequency response between the children and adults, inspection levelα=0.05.Results1Children’s waveforms differed within different range of frequency response.Higher frequency response limit, P wave,q wave, R wave,QRS wave and T waveamplitude is increased, Concerning comparisons among three groups, the differencesof amplitude were found to be statistically significant. As to pairwise comparisonsamong three groups, Group1had significant statistical differences from Group2andGroup3, whereas differences between Group2and Group3were observed to presentno statistical significance.2Waveforms were different within different range of frequency response foradults. Higher frequency response limit, P wave,q wave, R wave,QRS wave and Twave amplitude is increased, Concerning comparisons among three groups.Aftercomparing three groups, it was found that there were significant statistical differences.Concerning pairwise comparisons among three groups, differences were found to bestatistically significant between Group1and Group2, Group2and Group3, whereasno significant statistical differences were observed between Group2and Group3.3Low range of frequency response (40Hz), when the baseline is smooth; Athigh range of frequency response (150Hz and300Hz), baseline is relatively coarse;Three kinds of range of frequency response of ST segment deviation are no change.4The difference was statistically significant between the influence of ECGwaveform when electrocardiogram machine set different frequency response range ofchildren and impact on adult ECG waveform,40~150Hz QRS complex amplitudevariation within the scope of children less than adults,150~300Hz QRS complexamplitude variation within the scope of children than adults.Conclusions1Different frequency response range of electrocardiogram machinecouldaffect on P wave, q wave,R wave, the QRS wave, T wave amplitude andbaseline smoothness.2150~300Hz’s influence on children’s ECG waveform is more obvious than in adults of ECG waveform,That there should have a higher frequency between therange of frequency response in children QRS complex,A higher value of frequencyresponse may better reflect children’s ECG characteristics more truly when thefrequency response of the electrocardiograph is within the upper limit of300Hz, but italso increased the introduction of interference wave; In order to improve the accuracyof the ECG waveforms collected, also speculated that children use the maximumfrequency of electrocardiogram machine for at least250Hz according to the resultsof the Dutch study, comprehensive consideration. |
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