Safety steps for a non-fluoroscopic approach in right-sided electrophysiology procedures: A point of view.

BACKGROUND: Electro-anatomic 3D mapping systems enable the fluoroscopy (FL) exposure to be reduced. In right-heart supraventricular tachycardia (SVT) procedures, FL could potentially be avoided. Our aim was to discuss some steps focusing on safety. METHODS AND RESULTS: The patient cohort comprised 70 consecutive SVT patients who underwent electrophysiologic (EP) catheterization. FL was routinely avoided in all cases (54.2% males, age 57.2 ±â€¯13.3 years): 51 ablations and 19 EP study procedures. The Carto®3 (Biosense Webster) mapping system was used in 17/70 cases (24.3%), and the EnSite Precision™ (Abbott) system in the remaining 53/70 (75.7%). The mean procedure time was 94.1 ±â€¯33.2 min; no FL was used. No major complications occurred. Acute procedural success was achieved in all 51 patients who underwent ablation. Over 3-month follow-up, arrhythmia recurred in 1 patient. There were no significant differences in procedural times between the two mapping systems, except for the time dedicated to the full geometry creation, which was longer for the EnSite Precision™ system: 10 min (8.5-15 IQR) vs 8 min (5-10 IQR) for the Carto® system (p < 0.001) mainly due to the sub-diaphragmatic navigation. The following procedural steps were considered critical in order to safely avoid FL use: "loop" advancing of catheters, the use of a fixed intracardiac reference, His signal landmark centered maps and the careful acquisition of sub-diaphragmatic extracardiac geometry. CONCLUSIONS: A routine zero X-ray approach by means of electro-anatomic 3D mapping systems is safe and effective in right-atrium procedures. Some ad-hoc discussed procedural steps may enhance safety.

Prospective Evaluation of Lesion Index-Guided Pulmonary Vein Isolation Technique in Patients with Paroxysmal Atrial Fibrillation: 1-year Follow-Up.

INTRODUCTION: Pulmonary vein isolation (PVI) using contact force (CF) sensing ablation catheters currently relies on CF and force-time integral (FTI) guidelines. Such measurement of lesion effectiveness still lacks information on current delivery to the tissue, influenced by system impedance and power. Lesion Index (LSI) is a multi-parametric index incorporating CF and radiofrequency current data across time. We aimed to prospectively assess the efficacy of an LSI-guided approach to PVI in patients with paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: The study prospectively enrolled 28 consecutive patients with PAF undergoing PVI with a CF sensing catheter (TactiCathTM, Abbott). LSI-guided ablation target was adapted according to the mean regional thickness of pulmonary vein antra (PVA): LSI range 5.5-6 was pursued in the anterior and septal portions of PVA, 5-5.5 elsewhere. Data from 32 consecutive PAF patients who underwent PVI ablation with a non-CF guided approach (NCF-group) were retrospectively collected for comparison of procedural and clinical outcome.AF-free survival rate at follow-up (17±6 months) was higher for LSI-guided group than NCF-group (89.3% vs 65.6%, p=0.037), with no increase in periprocedural complication rate (no tamponades or other major adverse events reported). Among 1126 lesions with LSI within target range (5-6), average CF was >10g and <30g for 976 lesions (86.7%). Moreover, 1015 lesions (90.1%) had FTI>400gs, but with wide distribution: 30.2% within 400-500gs, 30.0% within 501-600gs, 29.9% over 600gs. CONCLUSION: In this first prospective study, LSI-guided PVI improved clinical outcome without any increase in complication rate when compared with standard, non-LSI-guided approach.

In Vitro Validation of the Lesion Size Index to Predict Lesion Width and Depth After Irrigated Radiofrequency Ablation in a Porcine Model.

OBJECTIVES: In an in vitro model, the authors tested the hypotheses that: 1) lesion dimensions correlate with lesion size index (LSI); and 2) LSI could predict lesion dimensions better than power, contact force (CF), and force-time integral (FTI). BACKGROUND: When performing radiofrequency (RF) catheter ablation for cardiac arrhythmias, reliable predictors of lesion quality are lacking. The LSI is a multiparametric index incorporating time, power, CF, and impedance recorded during ablation. METHODS: RF lesions were created on porcine myocardial slabs by using an open-tip irrigated catheter capable of real-time monitoring of catheter-tissue CF. Initially, 3 power settings of 20, 25, and 30 W were used with a fixed CF of 10 g. A fixed power of 20 W was then set with a CF of 20 and 30 g, thereby yielding a total of 5 ablation groups. In each group, LSI values of 5, 6, 7, and 8 were targeted. Sixty RF lesions were created by using 20 ablation protocols (3 lesions for each protocol). RESULTS: Lesion width and depth were not correlated with power or CF, but the results significantly correlated with FTI (p < 0.01) and LSI (p < 0.0001). Four steam pops occurred with power set at 30 W; no pops were noted with 20 or 25 W even when high LSI values were targeted. CONCLUSIONS: In this in vitro model, FTI and LSI predicted RF lesion dimensions, whereas power and CF did not. The LSI predictive value was higher than that of FTI. Steam pops occurred only using high ablation power levels, regardless of the targeted LSI.

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.

Development of artificial neural network-based algorithms for the classification of bileaflet mechanical heart valve sounds.

OBJECTIVES: As is true for all mechanical prostheses, bileaflet heart valves are prone to thrombus formation; reduced hemodynamic performance and embolic events can occur as a result. Prosthetic valve thrombosis affects the power spectra calculated from the phonocardiographic signals corresponding to prosthetic closing events. Artificial neural network-based classifiers are proposed for automatically and noninvasively assessing valve functionality and detecting thrombotic formations. Further studies will be directed toward an enlarging data set, extending the investigated frequency range, and applying the presented approach to other bileaflet mechanical valves. METHODS: Data were acquired for the normofunctioning St. Jude Regent valve mounted in the aortic position of a Sheffield Pulse Duplicator. Different pulsatile flow conditions were reproduced, changing heart rate and stroke volume. The case of a thrombus completely blocking 1 leaflet was also investigated. Power spectra were calculated from the phonocardiographic signals and used to train artificial neural networks of different topologies; neural networks were then tested with the spectra acquired in vivo from 33 patients, all recipients of the St. Jude Regent valve in the aortic position. RESULTS: The proposed classifier showed 100% correct classification in vitro and 97% when applied to in vivo data: 31 spectra were assigned to the right class, 1 received a false positive classification, and 1 was "not classifiable." CONCLUSION: Early malfunction detection is necessary to prevent thrombotic events in bileaflet mechanical heart valves. Following further clinical validation with an extended patient database, artificial neural network-based classifiers could be embedded in a portable device able to detect valvular thrombosis at early stages of formation: this would help clinicians make valvular dysfunction diagnoses before the appearance of critical symptoms.