The Characteristics Of Target Diagram And ECG Of Frequent Premature Ventricular Contractions In Radiofrequency Ablation

Backgrounds Radiofrequency catheter ablation (RFCA) for ventricular premature contractions (PVC) is mainly guided by pace mapping and activation mapping, or guided by the combination of pace mapping and activation mapping. When pacing at a point of the endocardial, it can be determined as the ablation target if the12-lead (at least11leads)ECG QRS morphology is the same with the VPC morphology. This process is defined as pacing mapping. When ventricular premature beats happened, if local activation time (LAT)of a point in the endocardial is ahead of25ms the surface ECG QRS, it can be determined as the ablation target, and this process is defined as activation mapping. When pacing at bystander position of VPC origin, the pacing VPC morphology is the same as the patients own VPC, but the ablation at bystander position is invalid. LAT mapping is limited by the large variation among patients. There is no fixed standard LAT for ablation. There ia no specific criteria for effective target diagram, resulting in a number of invalid discharges in ineffective targets. It not only aggravate the patient myocardial injury, but also to increase the X-ray exposure time. Therefore, It need to study the characteristics of effective target diagrams for the accurate identification of an effective target to reduce the number of invalid discharge, and reduce the harm to the patient and reduce X exposure time.Objectives The purpose of this study was to investigate the difference between the successful and unsuccessful target electrograms, and the value of unipolar electrogram morphology (QS configuration) with a fast downstroke slope and reversed polarity in bipolar electrograms for predicting a successful ablation site premature ventricular contractions originating in RVOT.Methods Fifty-four consecutive patients undergoing RFCA for idiopathic premature ventricular contractions originating in RVOT were studied. fifty-two successful target electrograms and seventy-nine unsuccessful target electrograms were collected. We studied the sensitivity, specificity, positive predictive value (PPV)and negative predictive value (NPV)of the precence of a fast downstroke slope in unipolar electrogram (QS configuration) and reversed polarity in bipolar electrogram for predicting the successful targetResults (1)Both the difference between successful target electrograms and unsuccessful target electrograms in LAT, and the difference between fast downstroke slope in unipolar electrogram and reversed polarity in bipolar electrogram reach significance.(2)The sensitivity and specificity were54.1%and76.9%when the target electrograms LAT>35ms The PPV and NPV of those target electrgrams for predicting successful target were76.9%and56.9%.The sensitivity and specificity were38.5%and94.4%when the target electrograms LAT>35ms and the unipolar electrogram (QS configuration) had a fast downstroke slope. The PPV and NPV of those target electrgrams for predicting successful target were76.9%and69.5%. The sensitivity and specificity were42.3%and94.9%when the target electrograms LAT>35ms and those bipolar electrogram had reversed polarity.The PPV and NPV of those target electrgrams for predicting successful target were84.6%and71.5%.The sensitivity and specificity were25.0%and96.2%when the target electrograms LAT>35ms, bipolar electrograms had reversed polarity, and the unipolar electrogram had a fast downstroke slope. The PPV and NPV of those target electrgrams for predicting successful target were81.5%and72.4%.Conclusions The differences between successful target electrgrams and unsuccessful target electrgrams in LAT, fast downstroke slope in unipolar electrogram and reversed polarity in bipolar electrogram were significant.(2) Mapping based on LAT>35ms and unipolar electrogram(QS configuration) with a fast downstroke slope, and mapping based on LAT>35ms with reversed polarity in bipolar electrogram showed a higher specificity and PPV for a successful ablation site than mapping based on LAT. Background The electrocardiography (ECG) of PVC originating from either the septal of right ventricular outflow tract (RVOT) or the aortic sinus cusp, especially from the right coronary sinus, are similar, namely left bundle branch block (LBBB)and R wave in lead Ⅱ, Ⅲ and AVF, making it difficult to distinguish the PVC from the two origins.Objectives We sought to investigate the electrocardiographic characteristics of PVC originating from the ASC and RVOT.Methods ECG analysis was performed in12patients with PVC originating from ASC (group B), and ECG of twelve patients ECG with PVC from the septal of RVOT were selected as a control group(group A).Results The indexes of R-wave duration in V1, V2,V3were signficantly lower in group A than that in group B (V1:0.23±0.10vs.0.49±0.28, V2:0.24±0.12vs0.57±0.23, V3:0.46±0.03vs.0.63±0.23, P<0.05respectively). The indexes of R/S-wave amplitude in V1, V2, V3were significantly lower in group A than that in group B((V1:0.10±0.02vs.0.87±0.55, V2:0.21±0.14vs1.13±1.49, V3:1.22±1.01vs2.37±2.27;, P<0.05, respectively).The R-wave precordial transitional position was located in V3or after V3in group A, while in VI or V2in group B. The transitional indexes of V1and V2were were significantly lower in group A than in group B((VI0.25±0.15vs1.30±0.68, V20.31±0.20vs1.71±1.14, p<0.05, respectively).Conclusions PVC originating from the ASC has a similar QRS morphology to that from RVOT. The indexes of R-wave duration, and R/S-wave amplitude in lead V1、V2、V3were significantly different between the two origins. The R wave precordial transitional position and the indexes of R wave transitional zone of V1V2aslo different. Those indexes can be used to distinguish the PVC originating from the two origins.