Analysis Of The Premature Ventricular Contractions Originated From Outflow Tract Through ECG

Objective:To evaluate and conclude 12-lead electrocardiographic (ECG) characteristics of premature ventricular contractions (PVCs) originating from the ventricular outflow trcat.Methods:A retrospective analysis was made in 32 cases of PVCs patients originating from ventricular outflow tract who underwent successful catheter ablation, and calculated the specificity and sensitivities of various criteria for diagnosing PVCs of different ventricular outflow trcat originating sites based on the QRS pattern and amplitude.Results:There were 22 patients originating from right ventricular outflow trcat (RVOT), including septal region 16 cases, free wall 6 cases; Originated from left ventricular outflow trcat (LVOT) patients 10 cases, including the left coronary cusp 3 cases, right coronary cusp 1 case, between the two 3 cases, and the infravalvular endocardial region of the aortic valve 3 cases.(1) 15 patients of 22 originated from RVOT translated at V4-V6 and the specificity and sensitivity of the standard that R/S transition at V4-V6 determined PVCs originating from RVOT was 100% and 63.6%, respectively; Similarly, the standard of R/S transition at VI-V2 to determine PVCs originating from LVOT was with the specificity of 95.4%, the sensitivity of 70%.(2) There were 10 patients who translated at lead V3,and the V2 transition ratio, R-wave amplitude and duration were significantly larger for LVOT-PVCs compared with RVOT-PVCs(P<0.05). ECG that met the standard of "the indexes of the R-wave amplitude>30% and duration>50%, and the V2 transition ratio>1 " was defined as LVOT-PVCs origined and with the specificity of 71.4%, sensitivity of 100%, positive predict value 60.0%, negative predict value 100%. (3)Analysis the patients originating from septal and free wall, and found the QRS pattern in leads Ⅰ,Ⅱ, Ⅲ,AVF and QRS duration in leads Ⅱ were significantly different. Besides, for anterior RVOT-PVCs, QRS in lead Ⅰ manifested as QS, rs, qr or rsr’ and QS (AVL) larger than QS(AVR); for posterior RVOT-PVCs, QRS in lead 1 manifested as R or rR and QS(AVR) larger than QS(AVL); PVCs originated from superior part of RVOT, the QS(AVL)/QS(AVR) ratio was>1, R wave amplitude was higher in leads Ⅱ,Ⅲ,AVF than inferior part and the upper, the taller "r" wave was observed in lead V1/V2(P<0.05). (4) The R-wave amplitude in lead Ⅱ,Ⅲ,AVF of PVCs originated from the aortic sinus cusp was higher than PVCs originated from the infravalvular endocardial region of the aortic valve, and the clear s wave in lead V1 or V2 and absent s wave in lead V5 or V6 could be observed, by contrast, for PVCs originated from the infravalvular endocardial region of the aortic valve, high amplitude R wave in lead V1-V6 and an s wave in both lead V5 and V6 or only in lead V6 could be seen.(p<0.05) (5) Compared with LVOT-RCC originated, QRS of LVOT-LCC manifested as rs,rS,QS in lead Ⅰ,AVL, and the precordial R wave transition (R/S>1) no later than V2, besides, for RCC originated, QS(AVL)/QS(AVR) ratio was>1 and R Ⅲ/R Ⅱ ratio was significantly greater than RCC pacemaps.(P<0.05)Conclusion:Most of LVOT translated at lead V1-V2 and RVOT-PVCs translated at lead V4-V6; for patients translated at lead V3, the V2 transition ratio, index of R/S amplitude and R-wave duration could be calculated to evaluate LVOT or RVOT origined; besides, ECG characteristics of RVOT-PVCs originated from different positions including septal region and free wall, anterior and posterior, superior and inferior were all not the same. LVOT-PVCs originated from the aortic sinus cusp and infravalvular endocardial region of the aortic valve could be identified by R-wave amplitude in lead Ⅱ,Ⅲ,AVF and an s wave in lead V1,V2 or V5,V6; and there were evidently difference on the ECG characteristics between RCC and LCC of aortic sinus originated. All in all,12-leads surface ECG had a significant meaning on identifying the origin of outflow tract PVCs.