Comparison Of The Electrocardiographic Criteria In Location Diagnosis Of Outflow Tract Ventricular Arrhythmias

Objective: The purpose of this study is to investigate the characteristics of electrocardiogram of ventricular arrhythmia in the outflow tract,and to verify and evaluate various identification criteria of outflow tract origin ventricular arrhythmia in recent years,and select valuable indicators as the location diagnosis basis of body surface electrocardiogram for ventricular arrhythmias,so as to provide reference for clinical practice.Methods: We collected a total of 37 cases in cardiovascular medicine of Affiliated Hospital Zunyi Medical College on January 1,2013 to August 30,2017,which all underwent successful radiofrequency catheter ablation or intracardiac electrophysiological examination of ventricular arrhythmia(including ventricular premature contractions and ventricular tachycardia).According to the inclusion and exclusion criteria,30 cases have been screened out(including 23 cases of right ventricular outflow tract origin and 7 cases of left ventricular outflow tract origin).We measured and calculated the parameters of chest lead transitional zone,transitional zone index,V2 transition ratio,R-wave duration index,R/S-wave amplitude index,V2S/V3 R index,maximum deflection time(TMD),maximum deflection index(MDI),pseudo-delta wave(PdW),intrinsicoid deflection time(IDT)and shortest RS complex(SRS),and used statistical methods to analyze the differences between the identification indexes and the intracardiac electrophysiological mapping results or the successful radiofrequency ablation point,and to calculate the sensitivity,specificity,positive predictive value and negative predictive value of each index.Results: The general characteristics of body surface electrocardiogram in outflow tract ventricular arrhythmias: ventricular arrhythmias originating from LVOT and RVOT usually show inferior electrical axis(R wave of inferior wall leads is positive and high)with negative QS complexes in leads aVR and aVL.If the origin is from the RVOT,the ECG will typically display a left bundle branch block(LBBB)and R wave transition at lead V3 or greater,while LVOT origin will display a right bundle branch block(RBBB)or LBBB with R wave transition leads at V3 or earlier.The gender composition ratio and age composition between the group of RVOT and the group of LVOT have no significant differences,four indicators of QRS duration,PdW,TMD,MDI between the two groups have no statistical significance,ten indicators of chest lead transitional zone,transitional zone index,V2 transition ratio,R-wave duration,R-wave duration index,R-wave amplitude,R/S-wave amplitude index,V2S/V3 R index,IDT and SRS between the two groups are statistically significant.Comparison of the criteria and the results of successful radiofrequency ablation or cardiac electrophysiology mapping showed that the R/S-wave amplitude index(cutoff value of 0.30)and V2 transition ratio(cutoff value of 0.50)have statistical significance.Both of them in distinguish ventricular arrhythmia of the origin from RVOT have low sensitivity,respectively 65.22% and 56.52%.While,the seven criteria of chest lead transitional zone,transitional zone index,V2 transition ratio(cutoff value of 0.60),R-wave duration index(cutoff value of 0.50),R-wave duration index(cutoff value of 0.51),R/S-wave amplitude index(cutoff value of 0.34),V2S/V3 R index have no statistical difference.The highest sensitivity is the R-wave duration index,which is 100%.Secondly,the sensitivity of the transitional zone index is 95.65%.When the R-wave duration index cutoff value is 0.50,the sensitivity was 91.30%.The chest lead transitional zone and V2S/V3 R index sensitivity are the same,both are 86.96%.When the R/S-wave amplitude index cutoff value is 0.34,the sensitivity is 82.61%.The sensitivity of V2 transition ratio(cutoff value of 0.60)is the lowest,which is 69.57%.In summary,the sensitivity from high to low: R-wave duration index(cutoff value of 0.51)> transitional zone index > R-wave duration index(cutoff value of 0.50)> chest lead transitional zone = V2S/V3 R index > R/S-wave amplitude index(cutoff value of 0.34)> V2 transition ratio(cutoff value of 0.60)> R/S-wave amplitude index(cutoff value of 0.30)> V2 transition ratio(cutoff value of 0.50).The specificity of transitional zone index is the lowest,which is 71.43%.The specificity of the other eight criteria are the same,all of them are 85.71%.The positive predictive value and negative predictive value of the R-wave duration index(cutoff value of 0.51)are the highest,respectively 95.83% and 100%.When the R-wave duration index is combined with transitional zone index to distinguish ventricular arrhythmia of the origin from RVOT,the sensitivity is high and the specificity is decreased.When combined with other indicators,the specificity is constant and the sensitivity decreases.Conclusion: We can predict the origin of ventricular arrhythmias by analyzing the characteristics of the body surface electrocardiogram and the measurement and calculation of the related parameters.Regardless of patients' cardiac transposition,respiratory influence,thoracic shape and other individual differences,when the R-wave duration index cutoff value is 0.51,its sensitivity,positive predictive value and negative predictive value are the highest and specificity is not lower than other identification criteria on distinguish ventricular arrhythmia of the origin from RVOT,and the accuracy of diagnosis is the highest.The R-wave duration index have the greatest significance in distinguishing ventricular arrhythmia of the origin from RVOT,which is better than the other indicators.When it is combined with transitional zone index,the sensitivity is still high and the specificity is decreased.When combined with other criteria,the specificity is constant and the sensitivity decreases.