The Method Of Distinguishing Left Ventricular Outflow Tract Arrhythmia Origin From Right Ventricular Outflow Tract Arrhythmia Origin By Surface Electrocardiogram Characteristics

Objectives: To develop a method of distinguishing ventricular arrhythmiaorigin from left ventricular outflow tract (LVOT) or right ventricularoutflow tract (RVOT) by surface electrocardiogram (ECG) characteristics.Methods: ECG characteristics were analyzed in208consecutive patientswith ventricular outflow tract arrhythmia (OTA) referred to GeneralHospital of Shenyang Military Command between May2000and March2011. OTA included ventricular tachycardia (VT) and premature ventricualrcontraction (PVC) which originated from LVOT or RVOT.Electrophysiologic study and successful radiofrequency catheter ablationwas performed in every patient, and the origin of OTA was the target site ofsuccessful ablation. In some patients, the origin of OTA was furtherconfirmed by coronary artery angiogram or ventricular angiography. ECGcharacteristics were analyzed in all patients by measuring R-and S-waveamplitude in leads V1to V6, observing precordial R/S transition lead,calculating V2transition ratio when R/S transition lead was in V3.According to above ECG characteristics, OTA origin was judged fromLVOT or RVOT by a presetting protocol. The effectiveness of thispresetting protocol was evaluated.Results: There were208patients (76male and132female, mean age43.6±13.8years) with OTA included in this study, and none of them had organic heart disease. VT with or without the same morphologic PVC asmain clincal manifestation was showed in21patients (21/208,10.1%), andfrequent PVC was present in the other187patients (187/208,89.9%). Thenumber of patients with OTA originating from the septum of RVOT, thefreewall of RVOT and above the pulmonary valve were149,29and6respectively. The number of patients with OTA originating from LCC, RCC,NCC, LCC and RCC continuity, below aortic valve and left fibrous trigonewas12,2,2,2,5and4respectively. There were18cases with OTAmorphology of R/S transition before lead V2, and the OTA origin waslocated at LVOT in17patients. The criteria of R/S transition before lead V2for judgment of OTA origin from LVOT was with the specificity of99.5%,sensitivity of63.0%, positive predictive value of94.4%, and negativepredictive value of94.7%. There were112cases with OTA morphology ofR/S transition after lead V4, and OTA origins were from RVOT in all thesepatients. The criteria of R/S transition after lead V4for prediction of OTAorigin from RVOT was with the specificity of100%, sensitivity of61.9%,positive predictive value of100%, and negative predictive value of28.1%.There were78cases with OTA morphology of R/S transition in lead V3, andthe OTA origins were located at LVOT in10patients, at RVOT in68patients. V2transition ratio of LVOT origin OTA was larger than that ofRVOT origin OTA (1.32±0.26vs0.52±0.20, P＜0.05). In patients with OTAmorphology of R/S transition in lead V3, the criteria of V2transition ratiogreater than1.0for the judgment of OTA origin from LVOT was with thespecificity of94.1%, the sensitivity of80.0%, the positive predictive valueof66.7%and the negative predictive value of96.7.%respectively. However,the criteria of V2transition ratio greater than0.6for the judgment of OTAorigin from LVOT was with the specificity of66.2%, the sensitivity of100%, the positive predictive value of30.3%, and the negative predictivevalue100%, respectively. In these78cases with OTA morphology of R/Stransition in lead V3, there were22patients with SR morphology of R/Stransition in lead V2, and OTA was originated from RVOT in all these22patients. The criteria of OTA morphology of R/S transition in lead V3andSR morphology of R/S transition in lead V2for the judgment of OTA origin from RVOT was with the specificity of100%, sensitivity of32.4%, positivepredictive value of100%, and negative predictive value of17.9%.Conclusions: The specificities of the criteria of identifying the origin ofOTA from LVOT by R/S transition before lead V2, and the criteria ofidentifying the origin of OTA from RVOT by R/S transition after lead V4were both high. The specificity of the criteria of the origin judgement ofOTA from RVOT by OTA morphology of R/S transition in lead V3and SRmorphology of R/S transition in lead V2was100%. In patients with bothOTA and SR R/S wave transition in lead V3, V2transition ratio played animportant role in identifying the origin of OTA. V2transition ratio≥1.0asa criteria for predicting OTA origin from LVOT was more accuracy than V2transition ratio≥0.6as a criteria. The protocol used in this study ofdistinguishing LVOT origin from RVOT origin by ECG characteristics had agreat clinical utility and accuracy.