A novel Ventricular map of Electrograms DUration as a Method to identify areas of slow conduction for ventricular tachycardia ablation: The VEDUM pilot study.

BACKGROUND: Bipolar electrogram (EGM) duration is indicative of local activation property and, if prolonged, is useful to discover areas of slow conduction favoring arrhythmias. OBJECTIVE: The present study aimed to create a map of EGM duration during the ventricular tachycardia (VT) (Ventricular Electrograms DUration as a Method map [VEDUM map]) to verify if the slowest activation area is crucial for reentry and could represent a suitable target for rapid VT interruption during ablation. METHODS: Prospectively 30 patients were enrolled for this study. Twenty-one patients were selected, and 24 VT maps with complete circuit delineation (>90% tachycardia cycle length) were analyzed. Activation and VEDUM maps during VT as well as voltage maps during sinus rhythm were created. RESULTS: Twenty-two of 24 VTs (88%) were interrupted during the first radiofrequency delivery (mean time 7.3 ± 5.4 seconds; range 3-25 seconds) at the area with the longest EGM duration (212 ± 47 ms; range 113-330 ms). The mean percentage of the cycle length of VT covered by the EGM with the longest duration was 58% ± 12%. In 9 patients (37%), the longest EGM was located at the isthmus entrance, at the exit in 7 maps (30%), and the mid-isthmuses in 8 maps (33%). In 6 patients (25%), the EGM covered the full diastolic phase. The mean isthmus width was 28 ± 11 mm (range 16-48 mm; median 25 mm). CONCLUSION: A VEDUM map is highly accurate in defining a conductive vulnerable zone of the VT circuit. The longest EGM duration within the isthmus is highly predictive of rapid VT termination at the first radiofrequency delivery even in the case of large isthmuses.

Complete Electroanatomic Imaging of the Diastolic Pathway Is Associated With Improved Freedom From Ventricular Tachycardia Recurrence.

BACKGROUND: The development of multielectrode mapping catheters has expanded the spectrum of mappable ventricular tachycardias (VTs). Full diastolic pathway recording has been associated with a high rate of VT termination during radiofrequency ablation as well as noninducibility at study end. However, the role of diastolic pathway mapping on VT recurrence has yet to be clearly elucidated. We aimed to explore the role of complete diastolic pathway activation mapping on VT recurrence. METHODS: Eighty-five consecutive patients who underwent VT ablation guided by high-density mapping were enrolled. During activation mapping, the presence of electrical activity in all segments of diastole defined the evidence of having had recorded the whole diastolic interval. Patients were categorized as having recorded the full diastolic pathway, partial diastolic pathway, or no diastolic pathway map performed. Recurrences of VT were defined as appropriate implantable cardioverter defibrillator therapies or on the basis of ECG-documented arrhythmia. RESULTS: Eighty-five patients were included. Complete recording of the diastolic pathway was achieved in 36/85 (42.4%) patients. Partial recording of the diastolic pathway of the clinical VT was achieved in 24/85 (28.2%) patients. No recording of the diastolic pathway of the clinical VT was feasible in 25/85 patients (29.4%). At a mean of 12.8 months, freedom from VT recurrence was 67% in the overall cohort. At a mean of 12.8 months, freedom from VT recurrence was 88%, 50%, and 55% in patients who had full diastolic activity recorded, partial diastolic activity recorded, or underwent substrate modification, respectively; the observed differences were statistically significant (P=0.02). CONCLUSIONS: Mapping of the entire diastolic pathway was associated with a higher freedom from VT recurrence as compared with partial diastolic pathway recording and substrate modification. The use of multielectrode mapping catheters in recording diastolic activity may help predict those VTs employing intramural circuits and further optimize ablation strategies.

Grid Mapping Catheter for Ventricular Tachycardia Ablation.

BACKGROUND: A new grid mapping catheter (GMC)-allowing for bipolar recordings of the electrograms in each orthogonal direction-became available. The aim of the current study is to evaluate the utility of the GMC in creating substrate and ventricular tachycardia (VT) activation maps during VT ablation procedures. METHODS: From December 2017 to July 2018, 41 consecutive patients undergoing a VT ablation procedure using a GMC were studied. During the substrate mapping, 3 different maps were created using the 3 GMC bipolar configurations (along the spline, across the spline, HD wave solution); the low voltage area and late potential areas were compared. In case of inducible VTs, the GMC was used to create the VT activation maps focusing on the diastolic interval. The relation between diastolic activities during VT and substrate abnormality during sinus rhythm was also investigated. RESULTS: The median low-voltage area drawn by the HD wave configuration was 28.9 cm2, 13% and 15% smaller than the low-voltage areas identified by the along and across configuration, respectively (33.1 and 33.9 cm2; P<0.0001). The late potential areas obtained with the 3 GMC configuration did not differ (P>0.05). VT activation mappings using the GMC were performed in 40 VTs, visualizing the full diastolic pathway in 22 (55%) of them. While the latest late potential areas were included in VT diastolic pathway in 17 VTs, the other 6 VTs showed mismatching of them. Identifying the full diastolic pathway led to a higher ongoing VT termination rate during the ablation than in case of partial recordings (88% versus 45%; P=0.03); furthermore, in the former situation, the noninducibility of the targeted VTs was achieved in all cases. CONCLUSIONS: The GMC is a useful tool for performing substrate and VT activation mappings during the VT ablation procedure, precisely identifying the low-voltage areas and quickly visualizing the diastolic pathways.

Fast and safe mapping of ventricular tachycardia in patient with left ventricular assist device.

The characterization of the pathological substrate and/or mapping of the clinical ventricular tachycardia in patients with left ventricular assist device may represent a challenge, due to the risk of entrapment of the intracardiac catheter into the inflow cannula. Hereby, we present the technique of a fast and safe mapping using a 20-poles catheter which allowed the identification of the critical isthmus during ventricular tachycardia.

Left atrial model reconstruction in atrial fibrillation ablation: reliability of new mapping and complex impedance systems.

AIMS: The effectiveness of atrial fibrillation (AF) ablation relies on detailed knowledge of the anatomy of the left atrium (LA) and pulmonary veins (PVs). It is common to combine computed tomography/magnetic resonance (CT/MR) with imaging by electroanatomical (EA) mapping systems. The aim of this study was to evaluate the accuracy of LA anatomical reconstruction by 'One Model' and 'VeriSense' tools (Ensite Velocity 3.0, St Jude Medical), compared with CT/MR imaging. METHODS AND RESULTS: Seventy-two patients with AF underwent pre-procedural imaging (97% CT-scan, 3% MR imaging) and transcatheter ablation of PVs. Operators were blinded to CT/MR imaging. Electrical Coupling Index (ECI) was used to recognize venous structures when the circular catheter could not. The LA 'One Model' map was obtained without complications; all 124 main left PVs and 144 main right PVs were detected. Nine of 9 intermediate right PVs and 30 of 30 early branches were detected, whereas 1 of the 27 early branches on the right inferior PVs was missed. Comparison between LA intervein distances measured on the roof (RO) and the posterior wall (PW) showed a high correspondence between the EA model and CT/MR imaging (RO CT/MR imaging vs. EA: 32 ± 7 vs. 32 ± 7 mm; PW CT/MR imaging vs. EA: 36 ± 6 vs. 36 ± 7 mm). The EA model yielded slightly larger PV ostia diameters, owing to the distortion caused by catheter pressure. CONCLUSIONS: Recent 3D mapping tools allow outstanding anatomical rendering and are key in complex ablation procedure set-up. This study shows that 3D anatomical reconstruction of LA, PVs, and their variable branches is not only safe and fast but also accurate and reliable.