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Aims Catheter ablation strategies for treatment of cardiac arrhythmias are quite successful when targeting spatially constrained substrates. Complex, dynamic, and spatially varying substrates, however, pose a significant challenge for ablation, which delivers spatially fixed lesions. We describe tissue excitation using concepts of surface topology which provides a framework for addressing this challenge. The aim of this study was to test the efficacy of mechanism-based ablation strategies in the setting of complex dynamic substrates. Methods and results We used a computational model of propagation through electrically excitable tissue to test the effects of ablation on excitation patterns of progressively greater complexity, from fixed rotors to multi-wavelet re-entry. Our results indicate that (i) focal ablation at a spiral-wave core does not result in termination; (ii) termination requires linear lesions from the tissue edge to the spiral-wave core; (iii) meandering spiral-waves terminate upon collision with a boundary (linear lesion or tissue edge); (iv) the probability of terminating multi-wavelet re-entry is proportional to the ratio of total boundary length to tissue area; (v) the efficacy of linear lesions varies directly with the regional density of spiral-waves. Conclusion We establish a theoretical framework for re-entrant arrhythmias that explains the requirements for their successful treatment. We demonstrate the inadequacy of focal ablation for spatially fixed spiral-waves. Mechanistically guided principles for ablating multi-wavelet re-entry are provided. The potential to capitalize upon regional heterogeneity of spiral-wave density for improved ablation efficacy is described.

We report the case of a 30-year-old man with situs inversus totalis, recurrent orthodromic reciprocal tachycardia, and the Wolff-Parkinson-White syndrome. He underwent, in our department, radiofrequency ablation of an accessory pathway (AP) located in the lateral mitral atrioventricular ring. Ablation of the AP was carried out successfully through a patent foramen ovale under fluoroscopic guidance, in a right anterior oblique projection with a 30° tilt and in anteroposterior views. We also used a mirror reversal of electrocardiogram (ECG) leads to better judge the site of the AP by using existing ECG algorithms. Complete situs inversus is a rare disorder, which has no consequence for the patient in the absence of cardiac or extracardiac involvement. Ablation of APs in situs inversus has been previously reported in only three cases of complete situs inversus and one case of situs ambiguous. In patients with mirror-image dextrocardia, APs seem more often located on the 'left' free wall (mitral annulus), as in the normal population. Radiofrequency ablation is feasible and safe after mirror reversion of the ECG electrodes and fluoroscopy.

A 65-year-old man with atrial tachycardia (AT) after mitral valve replacement via the superior transseptal approach (STA) underwent ablation. With the entrainment pacing and three-dimensional activation map, tachycardia was diagnosed as peri-mitral AT. Interestingly, the continuous fractionated potentials, accounting …

A 41-year-old man had undergone pulmonary vein isolation and linear ablation at the roof and mitral isthmus (MI) for persistent atrial fibrillation. He subsequently experienced atrial tachycardia (AT). The activation map during the AT revealed macro-re-entrant AT with impulse propagation …

We read with great interest the article: ‘Value of the aVR lead in differential diagnosis of atrioventricular nodal reentrant tachycardia’ by Haghjoo et al. 1 in a recent issue of the journal. We would like to comment that the specificity of an electrocardiographic sign guarantees that in the presence of this sign, the likelihood of the disease in question is high. On the contrary, the sensitivity of a particular sign guarantees that in the absence of this sign, …