In patients with an ICD, the development of MCD is an independent predictor of cardiac and arrhythmic mortality. If this finding is confirmed in larger studies, it may help to identify patients in whom other therapeutic alternatives, ie, heart transplantation, should be considered during follow-up after ICD implantation.

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This ventriculoatrial index can identify accurately and in the absence of tachycardia whether concentric retrograde conduction is proceeding over a posteroseptal accessory pathway or over the normal conduction system.

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Introduction: Cleidocraneal dysplasia (CCD) is a rare skeletal autosomal dominant syndrome characterized by dental anomalies and bone abnormalities. These clinical manifestations do not require treatment in most cases. The disease is caused by mutation in the gene RUNX2 (CBAF1), located on the short arm of chromosome 6. Objective: To report a case of CCD and perform a literature review focused on clinical manifestations and diagnosis. Case report: A 3 year old patient, who was clinically diagnosed with CCD since birth. The patient showed incomplete development of cranial bones, bell-shaped thorax, adequate dentition and presence of clavicles. Molecular analysis reported that the patient is carrying the pathogenic variant c.674G>A in the RUNX2 gene, confirming the diagnosis. Conclusions: The CCD is a rare condition, with special clinical features. It is important to establish early diagnosis in these patients in order to offer a better quality of life, and if necessary, appropriate treatment.

The pseudodisappearance during tachycardia or ventricular pacing of a bipolar atrial electrogram present during sinus rhythm is associated with a good outcome during radiofrequency ablation of concealed accessory pathways. These observations may help to ablate accessory pathways and to avoid missing appropriate sites for ablation when the atrial activation is not clearly visible at the local electrogram.

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Although RF ablation is an effective treatment of arrhythmias due to atrioventricular accessory pathways, there are cases refractory to conventional catheter ablation. Irrigated tip catheter ablation causes larger and especially deeper lesions than conventional ablation. This article discusses using irrigated tip catheter ablation in cases of right posteroseptal accessory pathways resistant to conventional ablation. Four consecutive patients with no structural heart disease and symptomatic arrhythmias related to right posteroseptal accessory pathways underwent irrigated tip catheter ablation. Conventional RF ablation had been unsuccessful in at least two procedures at more than one center (in three patients at the authors' center). The irrigated tip catheter (Chilli, Cardiac Pathways Corporation) uses a cooling system that is a closed circuit with a saline solution circulating at 0.6 mL/s. Temperature, power, and impedance were monitored during the RF applications. The procedure was successful in all four cases with no complications. In three of them, only one or two applications were necessary. Patients showed no recurrent arrhythmia during several months of follow-up. The results of the present study suggest that RF ablation using an irrigated tip catheter can be useful (and seems to be safe) for the treatment of some right posteroseptal accessory pathways resistant to conventional ablation.