The effect of ablation settings on lesion characteristics with DiamondTemp ablation system: An ex vivo experiment.

Introduction: Creating large lesion in ablations using the DiamondTemp (DTA) ablation system may reduce the frequency of arrhythmia recurrence and allow the treatment of ventricular arrhythmias. Therefore, this study aimed to investigate whether power, application time, contact force (CF), and contact angle affect lesion formation in the ventricles. Methods: Ablations were delivered to porcine myocardial preps to evaluate the lesion characteristics. Ablations were conducted with a maximum power of 50 W, target temperature of 58°C, CF of 10, 20, or 30 g, and contact angle between the catheter tip and tissue. The ablation durations were 15, 30, 60 s, 15 s × 2, or 30 s × 2. Results: Steam pops occurred only in cases with perpendicular contact. The lesion depth was larger in all settings in the perpendicular orientation than in the parallel orientation. The temperatures were lower in all settings in the perpendicular orientation than in the parallel orientation. The lesions became larger as CF increased with perpendicular contact and duration of ≥30 s. The longer application time resulted in larger surface area, depth, and volume of the lesion. Lesion depth was greater with single application of 30 and 60 s than with 15 s × 2 and 30 s × 2, respectively. Conclusion: It is important to perform a single prolonged application as much as possible to create deeper lesions. Parallel contact with the tissue should be maintained to take advantage of the temperature sensor's capabilities to avoid pop phenomenon.

Novel simultaneous mapping technique to treat multifocal atrial tachycardia.

Although a high-resolution three-dimensional mapping system has made it possible to treat complicated atrial tachyarrhythmia (AT), there remain cases that are difficult to diagnose and treat. However, when multiple different ATs alternately appear, mapping and diagnosis of those are more difficult. Parallel mapping module is well known as a good option to simultaneously map two or more different ATs when they alternately appear. When performing parallel mapping of two different ATs, one bipolar signal of the reference catheter is used as a timing reference and a cycle length filter is used for differentiating AT1, AT2, and others, including sinus rhythm, fusion beats, or catheter-induced premature atrial complex. Therefore, it has some limitations for differentiating multifocal ATs. We present a case wherein multifocal ATs were successfully eliminated by combining parallel mapping module and dual-chamber intra-cardiac pattern matching technique that we have previously reported. Learning objective: ▪Parallel mapping is a useful tool when two or more tachycardias alternately occur; however, it has some limitations.▪Dual-chamber intra-cardiac pattern matching technique, which combines right atrial and coronary sinus potentials, provides better discrimination than coronary sinus reference alone.▪By combining parallel mapping and dual-chamber intra-cardiac pattern matching, two or more atrial tachycardias could be automatically and simultaneously mapped.

Optimal treatment of biatrial tachycardia diagnosed by one-chamber mapping within an ultrahigh-resolution mapping system.

Biatrial tachycardia (BiAT) is a rare arrhythmia, and identification of the re-entry circuit is often complicated. By creating an activation map of the right atrium, left atrium, and coronary sinus as a single chamber, the LUMIPOINT module of the Rhythmia mapping system (Boston Scientific, Marlborough, MA, USA) can be used in real time to make an accurate diagnosis. Ablation of the Bachmann bundle is a feasible way to terminate BiAT, but might cause interatrial conduction delay and electrical isolation of the left atrial appendage. Chemical ablation into the vein of Marshall might be the more beneficial treatment, avoiding any potential interatrial conduction delay.