Initial multicenter experience with a new high-density coloring module: impact for complex atrial arrhythmias interpretation.

BACKGROUND: High-density automated mapping of complex atrial tachycardias (ATs) requires accurate assessment of activation maps. A new local activation display module (HD coloring, Biosense Webster®) provides higher map resolution, a better delineation of potential block reducing color interpolation, and a new propagation display. We evaluated the accuracy of a dedicated local activation display compared with standard algorithm. METHODS: High-density maps from 10 AT were collected with a multipolar catheter and were displayed with standard activation or HD coloring. Six expert operators retrospectively analyzed activation maps and were asked to define (1) the tachycardia mechanism, (2) ablation target, and (3) level of difficulty to interpret those maps. RESULTS: Using HD coloring, operators were able to reach a correct diagnosis in 93% vs. 63%, p < 0.05 compared to standard activation maps. Time to diagnosis was shorter 1.9 ± 1.0 min vs. 3.9 ± 2.1 min, p < 0.05. Confidence level would have allowed ablation without necessity for entrainment maneuvers in 87% vs. 53%, p < 0.05. Operators would have needed to remap or proceed with multiple entrainments in 3% vs. 13% of cases, p < 0.05. Finally, ablation strategy was more accurately identified in 97% vs. 67%, p < 0.05. CONCLUSION: Activation mapping with the new HD coloring module allowed a more accurate, reliable, and faster interpretation of complex ATs mechanisms compared to standard activation maps.

Elimination of the negative component of the unipolar electrogram as a local procedural endpoint during paroxysmal atrial fibrillation catheter ablation using contact-force sensing: the UNIFORCE study.

PURPOSE: Elimination of the negative component of the unipolar atrial electrogram is a reliable indicator of the creation of a transmural lesion. Contact-force (CF) sensing technology has the potential to increase the durability of pulmonary vein isolation (PVI). In the present multicenter study, we assessed the 2-year sinus rhythm (SR) maintenance rate in patients with paroxysmal atrial fibrillation (PAF) after PVI guided by these two approaches. METHODS: Two hundred fifteen consecutive PAF patients (62.1 ± 10.1 years, 65 women) were prospectively enrolled. All patients underwent PVI under CARTO guidance according to a systematic contiguous "point-by-point" approach, using radiofrequency energy, and a CF externally irrigated ablation catheter with the goal of at least 10g (ideally 20g) of force. The ablation endpoint of each individual lesion was elimination of the negative component of the unipolar atrial signal. The procedural endpoint was PVI with bidirectional block. RESULTS: All PVs were successfully isolated. After 30 min of waiting time, 35 patients (16%) had PV reconnection and in all of them, the PVs were re-isolated. Two years after a single ablation procedure, 187 patients (87%) remained arrhythmia free, without anti-arrhythmic drugs. Of the 28 patients presenting with AF recurrence, 25 had PV reconnection and underwent repeat PVI while in the remaining 3 patients, all four PVs were isolated and extra-PV triggers were identified. There were six groin hematomas and one transient ischemic attack. CONCLUSIONS: Unipolar atrial signal analysis combined with CF sensing ensures a robust 2-year SR maintenance rate in the treatment of PAF. Clinical trial registration-URL: http://www.clinicaltrials.gov . Unique identifier: NCT02520960.

Ventricular fibrillation induced by spontaneous hypothermia in a patient with early repolarization syndrome.

INTRODUCTION: The early repolarization (ER) pattern on ECG was originally described in the context of hypothermia. CASE SUMMARY: We present the case of a 34-year-old male with cardiac arrest in the context of spontaneous hypothalamic mediated thermal dysregulation after intracranial hemorrhage. Ventricular fibrillation with a marked ER pattern recurred with therapeutic hypothermia. Spontaneous hypothermia due to hypothalamic dysregulation was observed to enhance the amplitude of the ER pattern and was contemporaneous with recurrent ventricular fibrillation during follow-up. CONCLUSIONS: Hypothermia is an important trigger of VF in the setting of early repolarization syndrome, and warrants assessment as an environmental trigger of spontaneous events.

Voltage-guided ablation technique for cavotricuspid isthmus-dependent atrial flutter: refining the continuous line.

Ablation of the cavotricuspid isthmus has become first-line therapy for "isthmus-dependent" atrial flutter. The goal of ablation is to produce bidirectional cavotricuspid isthmus block. Traditionally, this has been obtained by creation of a complete ablation line across the isthmus from the ventricular end to the inferior vena cava. This article describes an alternative method used in our laboratory. There is substantial evidence that conduction across the isthmus occurs preferentially over discrete separate bundles of tissue. Consequently, voltage-guided ablation targeting only these bundles with large amplitude atrial electrograms results in a highly efficient alternate method for the interruption of conduction across the cavotricuspid isthmus. Understanding the bundle structure of conduction over the isthmus facilitates more flexible approaches to its ablation and targeting maximum voltages in our hands has resulted in reduction of ablation time and fewer recurrences.

Tachycardia induction with ventricular extrastimuli differentiates atypical atrioventricular nodal reentrant tachycardia from orthodromic reciprocating tachycardia.

BACKGROUND: Differentiating atypical atrioventricular nodal reentrant tachycardia (AVNRT) from septal orthodromic reentrant tachycardia (ORT(Septal)) is challenging in nonsustained tachycardia. When sustained, the postpacing interval minus tachycardia cycle length following entrainment (PPI(Entrainment) - TCL) and stimulation to atrial interval minus ventriculoatrial interval (Stim-A(Entrainment) - VA) are utilized. OBJECTIVE: We hypothesized that the first tachycardia cycle after tachycardia induction with right ventricular apical extrastimulation would yield comparable information to entrainment, precluding the need for sustained tachycardia. METHODS: Twenty-four patients with AVNRT (age 47 ± 18 years), 19 with ORT(Septal) (age 42 ± 17 years), and 15 with ORT over a left lateral accessory pathway (ORT(Left)) (age 41 ± 16 years) were included. The ventricular extrastimulus to atrial depolarization at tachycardia initiation (Stim-A(Initiation)) and tachycardia VA interval were measured to establish the Stim-A(Initiation) minus VA interval (Stim-A(Initiation) - VA). The ventricular extrastimulus to the subsequent right ventricular apical depolarization (postpacing interval at initiation, PPI(Initiation)) was utilized to obtain the PPI(Initiation) minus TCL (PPI(Initiation) - TCL). The AH interval associated with the PPI(Initiation) minus the AH in tachycardia was utilized to establish a corrected PPI(Initiation) minus TCL (cPPI(Initiation) - TCL). RESULTS: The intervals after tachycardia initiation were longer for AVNRT than for ORT: mean PPI(Initiation) - TCL (193 ± 44 vs 91 ± 73; P <.001), cPPI(Initiation) - TCL (174 ± 44 ms vs 88 ± 50 ms; P <.001), and Stim-A(Initiation) - VA (161 ± 45 ms vs 69 ± 53 ms; P <.001). The correlation coefficient for Stim-A(Initiation) minus VA against Stim-A(Entrainment) minus VA was 0.79 and for cPPI(Initiation) minus TCL against PPI(Entrainment) minus TCL was 0.71. cPPI(Initiation) minus TCL <115 ms or Stim-A(Initiation) - VA <85 ms was observed only in ORT. The converse was observed in AVNRT but also in ORT(Septal) over decremental accessory pathways and ORT(Left). CONCLUSION: Stim-A(Initiation) - VA < 85 ms or cPPI(Initiation) - TCL < 115 ms excludes AVNRT.