Electrocardiographic Features And Catheter Ablation Of Exacerbation Of Ventricular Arrhythmias

Part I:Multiple Intercostal Electrocardiogram Recording Allow More Accurate Localization for Outflow Tract Ventricular Arrhythmia.Background:Outflow Tract Ventricular Arrhythmia (OT-VA, including Premature Ventricular complexes and Ventricular tachycardia) is the most common type of idiopathic ventricular arrhythmia. Differentiating the origin of OT-VA is essential for procedure planning, assessing the procedure outcome of ablation and preventing possible complications. Electrocardiogram (ECG) serves as an important tool for differentiating the origin of OT-VA. QRS morphology of the regular 12 leads ECG recording are most commonly used as the tool for differentiating the origin. Multiple intercostal recordings were supposed to get a more comprehensive view of the depolarization vector of the OT-VA, which may help to identify the OT-VA origin more accurately.Objective:To investigate a more accurate electrocardiogram (ECG) criterion for differentiating between left and right OT-VA origins.Methods:OT-VA with a left bundle branch block pattern and inferior axis QRS morphology in consecutive series of 47 patients was enrolled, in which catheter ablation was sucessful in the right ventricular OT (RVOT; n=37) or in aortic coronary cusp (ACC; n=10). ECG from superior and inferior precordial leads were taken together with the routine 12-lead ECG before procedure. The ECG during the OT-VA and during sinus beats were analyzed. Transition ratio, transition zone (TZ) index, R/S amplitude index, and R-wave duration index were measured in the regular, superior, and inferior precordial leads. The combined TZ index was defined as the combination of TZ index in three intercostal precordial leads.Results:The combined TZ index, TZ index inferior was significantly smaller (P< 0.05). The area under the curve for the combined TZ index by a receiver operating characteristic analysis was 0.974, which was significantly larger than other parameters. A cutoff value≤0.25 predicted an ACC origin with 94% sensitivity and 100% specificity. This advantage of the parameter over others also held true for a subanalysis of OT-VAs with a lead V3 precordial transition or TZ index=0.Conclusions:The combined TZ index was superior to other ECG criteria to differentiate left from right OT-VA origins.Part Ⅱ:The Value of Frequency Domain Analysis in Predicting Late Recurrence after Catheter Ablation for Ventricular Arrhythmia from the Aortic Root.Background:Outflow tract ventricular arrhythmias (OT-VAs) with different origin may have different outcome in response to catheter ablation. Ventricular arrhythmias with Aortic root origin (AR-VAs) is associated with poorer outcome in response to ablation. The reason for acute successful ablation but late recurrence was undetermined. Insufficient damage to the ventricular foci of the aortic root is one of the possible reasons. We speculated that ventricular electrogram was the combination of the near-field and far-field electrogram, in which the high frequency fragmented electrogram was the near-field electrogram. Fourier analysis was design to transform the time-domain signal to the frequency-domain signal. By using this we can quantify the change of high frequency signal in response to ablation.Objective:This study was aimed to quantify the changes of near-field activation in response to ablation for AR-VAs by Fourier analysis and to assess its relationship with late ablation outcome.Methods:Fifty-six consecutive patients who underwent acutely successful ablation for AR-VAs were analyzed. Ventricular electrograms acquired before and after ablation at VAs origin were subjected to spectrum analysis. Frequencies of 50-200 Hz and 0-50 Hz were set as the high-frequency component (HFC) and low-frequency component (LFC), respectively. The ratio of the area under the curve of the HFC to that of 0-200 Hz was defined as the HFC integral ratio (HFCIR). The change in the HFCIR in response to ablation was defined as HFCIR pre-post. VAs with the same morphology after an acute successful procedure were defined as late recurrence.results:VAs recurred in 17 patients. HFCIR pre-post was significantly higher in patients without recurrence (no recurrence vs. recurrence:6.6±7.3% vs.-2.8±2.8%, p=0.002). Multivariate analysis indicated that HFCIR pre-post was the only predictor of VAs late recurrence (Odds Ratio=0.291 [95% CI:0.121-0.700], p=0.006). A cutoff value for HFCIR pre-post of 1.0% differentiated two groups (sensitiviry=84.6%, specificity=100%). Higher HFCIR pre-post was correlated with shorter VAs termination time (correlation coefficient=-0.399, p=0.009) and larger impedance drop (correlation coefficient=0.798, p＜0.001).Conclusions:Spectrum analysis can help to quantify the change of near field activation in response to ablation and help to assess the endpoint of VAs ablation.