Comparison Of Mason-likar Lead And Standard ECG On The Location Value Of Premature Ventricular Contraction Originated From Ventricular Out-flow Tract

Objectives: Electrocardiogram is a method has important clinical significance on the location value of premature ventricular contraction(PVC), which can effectively improve the efficiency of catheter ablation. The position of Mason-Likar lead is the electrode placement of the conventional 24-hour dynamic electrocardiogram, it is also the electrode placement of radiofrequency ablation. The aim of the study is to compare Mason-Likar lead with standard electrocardiogram(ECG) on the location value of PVC originated from outflow tract.Methods: From May 2014 to December 2015, 70 consecutive subjects with outflow tract PVC were recruited in the Second Hospital of Hebei Medical University, who have successfully achieved radiofrequency ablation. These 70 patients all took Mason-Likar lead and standard ECG before the radiofrequency ablation, The QRS complex pattern of I, aVL, II, III and aVF lead, existence of a notch in inferior wall leads, the QRS complex pattern of V1, V5 and V6 lead, the R wave duration index, R/S amplitude ratio in lead V1 and V2, precordial QRS complex transition and the transitional zone index were analysed carefully. Then the ablation target spot were predicted, respectively.Inclusion criteria: 1 Patients who had clinical symptoms caused by PVC, such as chest congestion, palpitations, short of breath, insomnia, inefficiency of drug treatment or intolerance of drug therapy. 2 The amount of PVC more than 10% of total daily heart beats or more than ten thousands every 24 hours, no matter people have clinical symptoms or not. 3 Patients with numerous PVC except of heart amplification caused by pathologic heart disease(consider as arrhythmia induced cardiomyopathy). Exclusion criteria: 1 PVC caused by reversible etiological factors, including acute myocardial infarction, acute myocarditis, untreated hyperthyroroidism and heart or thoracic surgery history. 2 Patients with infectious diseases, malignant tumor, autoimmune disease and severe hepatic and renal dysfunction. 3 Patients with sinus node dysfunction and pacemaker implantation.Every subject took cardiac ultrasound before RFCA, to rule out pathologic heart disease. Complete 24-hour dynamic electrocardiogram and preoperative examination(routine blood examination, coagulation convention, blood type), to make sure there was no operation contraindication. An informed consent was signed before operation, then RFCA would be performed with Carto 3 three-dimensional mapping and the ablation target spot would be clear. Sustained electrocardiographic monitoring for 24 hours after the operation.Statistical methods: SPSS17.0 statistical software was used in the data analysis, the measurement data was expressed as mean±standard deviation;the enumeration data was tested by the chi-square test, and P<0.05 was considered as statistically significant.Results: There had a difference between Mason-Likar lead and standard ECG on the QRS complex pattern of I lead, which the former could be positive and negative two-way even negative while the QRS complex could be positive with standard lead(P=0.00), there was no statistical significance on the location value of the QRS complex pattern of I lead on PVC(46 cases) originated from anterior or posterior septum of RVOT and from left or right coronary cusp(P=0.36). No statistical differences showed on the QRS complex pattern of aVL lead and inferior wall leads between these two methods(P>0.05), there was no statistical significance on whether existed a notch in inferior wall leads(P>0.05). Also there was no difference on the precordial QRS complex of V1(P>0.05), no statistical difference existed on the location value of the R wave duration index and R/S amplitude ratio in lead V1 and V2 on PVC(50 cases) originated from RVOT and LCC between Mason-Likar lead and Standard ECG(P=0.508). Compared with standard ECG, precordial QRS complex of V3 transition was earlier by Mason-Likar lead ECG(P=0.016), but there was no difference on the location value of precordial V3 lead on PVC originated from RVOT or LVOT between Mason-Likar lead and Standard ECG(P=0.453), there was no statistical difference on the transitional zone index between these two methods(P=0.063). There had no difference between Mason-Likar lead and standard ECG on the precordial QRS complex of V5 and V6(P>0.05). In brief, there was no statistical difference between two methods on the location value of ouf-flow tract PVC(P=0.092).Conclusions: It was always indicated the ablation target at the posterior out-flow tract when the QRS complex pattern of I lead was positive, in contrast, when the QRS complex pattern of I lead was positive and negative two-way even negative means the ablation target at anterior out-flow tract. There had a difference on the QRS complex pattern of I lead between Mason-Likar lead and standard ECG, but there was no statistical significance on the location value of the QRS complex pattern of I lead of PVC originated from anterior or posterior septum of RVOT and left or right coronary cusp. Precordial QRS complex of V3 transition was earlier by Mason-Likar lead ECG, but there was no difference on the location value of precordial V3 lead on PVC originated from RVOT or LVOT between two methods. In conclusion, Mason-Likar system has same location value on ouf-flow tract PVC as standard ECG.