Radiofrequency catheter ablation for drug-refractory atrial tachyarrhythmias in a patient with catecholaminergic polymorphic ventricular tachycardia: A case report

Catheter Ablation for Channelopathies: When Is Less More?

Ventricular fibrillation (VF) is a common cause of sudden cardiac death in patients with channelopathies, particularly in the young population. Although pharmacological treatment, cardiac sympathectomy, and implantable cardioverter defibrillators (ICD) have been the mainstay in the management of VF in patients with channelopathies, they are associated with significant adverse effects and complications, leading to poor quality of life. Given these drawbacks, catheter ablation has been proposed as a therapeutic option for patients with channelopathies. Advances in imaging techniques and modern mapping technologies have enabled increased precision in identifying arrhythmia triggers and substrate modification. This has aided our understanding of the underlying pathophysiology of ventricular arrhythmias in channelopathies, highlighting the roles of the Purkinje network and the epicardial right ventricular outflow tract in arrhythmogenesis. This review explores the role of catheter ablation in managing the most common channelopathies (Brugada syndrome, congenital long QT syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). While the initial results for ablation in Brugada syndrome are promising, the long-term efficacy and durability of ablation in different channelopathies require further investigation. Given the genetic and phenotypic heterogeneity of channelopathies, future studies are needed to show whether catheter ablation in patients with channelopathies is associated with a reduction in VF, and psychological distress stemming from recurrent ICD shocks, particularly relative to other available therapeutic options (e.g., quinidine in high-risk Brugada patients).

Broad and narrow complex tachycardia resulting in cardiorespiratory arrest in a child: what is the optimal treatment strategy?

Background

We describe a child with a broad and narrow complex tachycardia causing haemodynamic collapse.

Case summary

A 9-year-old girl (weight 26 kg, height 114 cm) with a 5-year history of refractory 'epilepsy' presented with cardiorespiratory arrest and tonic-clonic seizure, witnessed by her mother. Electrocardiogram documented recurrent episodes of simultaneous broad and narrow tachycardias associated with haemodynamic compromise. Diagnostic electrophysiologic study (EPS) confirmed a dual tachycardia mechanism. The challenge in selecting the optimal treatment strategy is discussed. A diagnosis of dual tachycardia was made with catecholaminergic polymorphic ventricular tachycardia (CPVT) and simultaneous focal atrial tachycardia.

Discussion

Bidirectional ventricular tachycardia (VT) induced by isoproterenol in this clinical scenario is strongly suggestive of CPVT. Diagnostic EPS can be useful in challenging clinical situations to understand the mechanism of arrhythmias and to tailor the most appropriate treatment strategy. Combination therapy with nadolol and flecainide is highly effective in ventricular arrhythmia control. Implantable cardioverter defibrillator implantation is not without risk in CPVT as there is a potential of electrical storm driven by shock therapy that increases adrenergic drive. Cervical sympathectomy may be considered if further VTs occur in future despite optimum medical therapy.

Catecholaminergic Polymorphic Ventricular Tachycardia: A Review of Therapeutic Strategies

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome characterized by bidirectional or polymorphic ventricular arrhythmia provoked by exercise or emotion. Most cases are caused by pathogenic variants in the gene encoding the cardiac ryanodine receptor (RYR2). The options for treating patients with CPVT have increased during the years, and evidence suggests that these have led to lower arrhythmic event rates. In addition, numerous potential new therapies are being investigated. In this review, we summarize the state of knowledge on both established and potential future treatment strategies for patients with CPVT and describe our approach to their management.