Preprocedural Discrimination of Posteroseptal Accessory Pathways Ablated from the Right Endocardium from Those Requiring a Left-sided or Epicardial Coronary Venous Approach

The success of radiofrequency catheter ablation of the accessory pathway (AP) depends on the accurate localisation of the bypass tract. In that respect, posteroseptal or inferior paraseptal APs often pose a diagnostic challenge because of the complex anatomy at the crux of the four cardiac chambers. Considering the differences in procedure risks and success rate depending on the need for a left-sided approach or a coronary sinus ablation, an accurate anticipation of the precise location of inferior paraseptal APs is critical to inform the consent process and guide the initial mapping strategy. Here, the preprocedural clues to discriminate APs that can be ablated from the right atrium, from those requiring a left-sided or epicardial coronary venous approach, are reviewed. Both manifest and concealed APs will be considered and, following the diagnostic process made by the operator before interpretation of the intra-cardiac signals, each of the following aspects will be addressed: clinical context and initial probability; and 12-lead ECG analysis during baseline ECG with manifest AP, maximal preexcitation, and orthodromic reciprocating tachycardia

Morphological Study of Intracardiac Signals as a New Tool to Track the Efficiency of Stepwise Ablation of Persistent Atrial Fibrillation

Intracardiac organization indices such as atrial fibrillation (AF) cycle length (AFCL) have been used to track the efficiency of stepwise catheter ablation (step-CA) of longstanding persistent AF, however with limited success. The morphology of AF activation waves reflects the underlying activation patterns. Its temporal evolution is a local organization indicator that could be potentially used for tracking the efficiency of step-CA. We report a new method for characterizing the structure of the temporal evolution of activation wave morphology. Using recurrence plots, novel organization indices are proposed. By computing their relative evolution during the first step of ablation vs baseline, we found that these new parameters are superior to AFCL to track the effect of step-CA “en route” to AF termination

Contribution of Left and Right Atrial Appendage Activities to ECG Fibrillation Waves

It was recently shown that atrial fibrillation (AF) waves on chest lead V1 adequately reflect right atrial appendage (RAA) activity during long standing persistent AF (pers-AF). The contribution of the left atrial (LA) activity to chest leads AF waves, however, remains unknown. Our study is aimed at evaluating the respective contribution of the RA and LA depolarization to ECG chest leads AF waves during pers-AF. Methods: Catheters (CAT) were introduced in 10 consecutive patients (60±5 y, AF duration 22±14 m) prior to ablation: 1) a quadripolar CAT in the RAA, 2) a decapolar CAT in the coronary sinus (CS) and 3) a duodecapolar CAT in the LA appendage (LAA). Local activation times were extracted from bipolar recordings using sliding windows. Chest lead V6 was placed in the back (V6b). Mean AF cycle length (AFCL) of leads V1 to V6b were computed as the inverse of the dominant frequency of ECG spectra after QRST cancellation, and compared to intracardiac RAA, LAA and CS AFCL using Pearson’s correlation coefficient. Results: The figure shows that the correlation between RAA and chest leads AFCL was maximal for V1 and progressively dropped till V5, with a moderate rise for V6b. LAA AFCL showed the opposite pattern with the highest correlation in V6B and the lowest one in V2. The correlation of CS AFCL was similar to the LAA one, but of lower magnitude. Conclusion: Our preliminary results suggest that the respective contribution of RAA and LAA activities can be estimated using a modified surface ECG. Whether this technique has the potential to guide ablation of LA and RA drivers in pers-AF needs further validation

Adaptive harmonic frequency schemes of atrial ECG reveal divergent patterns of organization during catheter ablation of persistent atrial fibrillation

Introduction: We hypothesized that organization indices based on the analysis of atrial ECG harmonic components may help identify patients (pts) with persistent AF (pAF) unresponsive to pulmonary vein isolation (PVI) and left atrial (LA) ablation. Using adaptive harmonic frequency tracking schemes, we computed on the atrial ECG: 1) the variance of the phase difference (aPD) between the dominant frequency (DF) and the 1st harmonic (H1), and 2) the organization index (AOI) defined as the ratio of the power of the DF and H1 over the total power of the unprocessed atrial signal as measures of AF regularity. Methods: In 34 consecutive pts (61±7 y, pAF duration: 19±11 m), PVI and LA ablation were performed until AF termination. 40-sec ECG time series devoid of QRST were recorded at baseline (BL), after PVI (end_PVI) and at the end of LA ablation (end_ABL). APD and AOI were estimated on leads V1 and V6b (placed on the pts back). Results: pAF was terminated within the LA in 68% (23/34 LT - left terminated) of the pts, while 32% (11/34 NLT - not left terminated) did not. The figure shows that: 1) LT pts displayed higher AOI values at BL indicative of greater atrial ECG organization that increased significantly (p<0.05 for V1 and V6b) during LA ablation as opposed to NLT pts, and 2) NLT pts displayed higher APD values at BL indicative of greater atrial ECG disorganization that decreased during LA ablation, but did not reach LT pts values. Conclusion: Estimation of the level of organization of atrial ECG based on adaptive harmonic schemes appears as promising tools for the measure of pAF complexity and prediction of procedural outcome