Catecholaminergic polymorphic ventricular tachycardia. An important diagnosis in children with syncope and normal heart.

Syncope in children is primarily related to vagal hyperreactivity, but ventricular tachycardia (VT) way rarely be seen. Catecholaminergic polymorphic VT is a rare entity that can occur in children without heart disease and with a normal QT interval, which may cause syncope and sudden cardiac death. In this report, we describe the clinical features, treatment, and clinical follow-up of three children with syncope associated with physical effort or emotion and catecholaminergic polymorphic VT. Symptoms were controlled with beta-blockers, but one patient died suddenly in the fourth year of follow-up. Despite the rare occurrence, catecholaminergic polymorphic VT is an important cause of syncope and sudden death in children with no identified heart disease and normal QT interval.

[Catheter ablation of atrial flutter. Electrophysiological characterization of posterior and septal isthmus block]. / Ablação por cateter do flutter atrial. Caracterização eletrofisiológica da interrupção da condução pelos istmos posterior e septal.

PURPOSE: Evaluate the different types of conduction blocks obtained between inferior vena cava-tricuspid annulus (posterior isthmus) and between tricuspid annulus-coronary sinus ostium (septal isthmus) after radiofrequency (RF) catheter ablation of atrial flutter (AFL). METHODS: In 16 procedures, 14 patients (pts), 9 male, with type I AFL underwent RF ablation. Atrial activation around tricuspid annulus was performed with a 10-bipole "Halo" catheter (H1-2; H19-20). In sinus rhythm, isthmus conduction was evaluated during proximal coronary sinus (PCS) and low lateral right atrium (H1-2) pacing, before and after linear ablation. According to the wave front of impulse propagation we assessed absence of block (bidirectional conduction); incomplete block (bidirectional conduction with delay in one front of impulse propagation) and complete block (absence of conduction). The PCS/H1-2 interval was measured before and after ablation. RESULTS: Complete isthmus block was achieved in 7 (44%) and incomplete block in 4 (25%) procedures. Conduction block was not achieved in 5 procedures. At a mean follow-up of 12 months, there were no recurrences in the pts with complete block, whereas AFL recurred in the 6 pts with incomplete or no conduction block (p < 0.001). Pts with complete block had delta PCS/H1-2 interval (74.0 +/- 26.0 ms) greater than incomplete (30.5 +/- 7.5 ms) or absent block (p < 0.05). CONCLUSION: The verification of complete isthmus conduction block with atrial multipolar mapping is an effective strategy to assess electrophysiological success and absence of late recurrence in common atrial flutter ablation.

Ablaçäo por radiofreqüência - flutter atrial / Ablation of atrial flutter - case report

Os autores relatam o caso de uma paciente de 63 anos, portadora de flutter atrial crônico refratário ao tratamento clínico com amiodarona e sotalol. A mesma foi submentida à ablaçäo por radiofreqüência com sucesso. Preditores eletrofisiológicos de sucesso clínicos säo descritos, bem como a importância de um mapeamento detalhado da regiäo inferior do átrio direito (por meio de um catéter duodecapolar), possibilitando a definiçäo exata da linha e dos tipos de bloqueios.