Role of Catheter Ablation in Arrhythmogenic Right Ventricular Dysplasia

Arrhythmogenic right ventricular dysplasia/cardiomyopathy is a disorder characterized by frequent ventricular tachycardia originating from the right ventricle and fibro-fatty replacement of right ventricular myocardium. Though the disorder was originally described during surgical ablation of refractory ventricular tachycardia, catheter ablation of tachycardia is one of the options for patients not responding to anti arrhythmic agents. Direct current fulguration was used in the initial phase followed by radiofrequency catheter ablation. In the present day scenario, all patients with risk for sudden cardiac death should receive an implantable cardioverter defibrillator. Radiofrequency catheter ablation remarkably reduces the frequency of defibrillator therapies. Direct current fulguration can still be considered in cases when radiofrequency ablation fails, though it requires higher expertise, general anesthesia and carries a higher morbidity. Newer mapping techniques have helped in identification of the site of ablation. In general, the success rate of ablation in arrhythmogenic right ventricular dysplasia is less than in other forms of right ventricular tachycardias like right ventricular outflow tract tachycardia

Epsilon Waves: The Gate to Understand Arrhythmogenic Right Ventricular Dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD), first recognized in 1977, is an inherited cardiomyopathy mostly due to mutations in both desmosomal and non-desmosomal genes. ARVD is considered as a leading cause of sudden cardiac death in the young and the athlete. It is characterized by an abnormality in the development of the right ventricular (RV) musculature. The final diagnosis of ARVD was pathologically based on the findings characterized by fibro-fatty infiltration and cardiomyocyte loss predominantly affecting the RV. Epsilon waves are a feature of ARVD reflecting postexcitation of the myocytes in the RV that are interspersed between fibrous and fatty tissue. Epsilon waves are considered to be one of the major diagnostic criteria of ARVD and appear to correlate with the extent of ARVD and arrhythmic risk. In this review, we will briefly review the discovery of ARVD and Epsilon waves, discuss the electrogenesis and various methods for recording Epsilon waves, provide evidence to assist in understanding the pathological and functional changes of the heart in ARVD, thus promoting the management of this disease in patients and family members

Fragmented endocardial signals and early afterdepolarizations during torsades de pointes tachycardia

Background: Bradycardia-induced torsade de pointes (TdP) tachycardia in patients with spontaneous high-degree atrioventricular block (AVB) is common. The aim of this study was to analyze endocardial recordings during TdP in spontaneous high-degree AVB in humans to better understand the electrophysiological mechanisms underlying this phenomenon. Methods: The study group consisted of 5 patients with typical episodes of TdP during spontaneous high-degree AVB. A standard (USCI) temporary bipolar endocardial catheter positioned at the apex of the right ventricle (RV) and bipolar chest leads from two precordial leads V1 and V4 were used to record the tracings during TdP. Results: The presence of a wide spectrum of fragmentations was noted on endocardial electrograms (EGMs), which were invisible on the surface electrocardiogram (ECG) tracing. Endocardial signals indicated that TdP started in the proximity of the RV apex, since the local EGM began prior to the QRS complex on the surface ECG. Early afterdepolarizations (EADs) were observed in 2 out of 5 cases confirming a common opinion about the mechanism of TdP. However, this phenomenon was not observed in 3 other patients suggesting that the arrhythmia was the result of a different mechanism originating in proximity to the RV apex. Conclusions: This work demonstrated early endocardial signals in the RV apex during TdP associated with high-degree AVB in humans, and exhibits a spectrum of fragmented signals in this area occurring on a single or multiple beats. These fragmentations indicate areas of poor conduction and various degrees of intramyocardial block, and therefore a new mechanism of TdP tachycardia in some patients with spontaneous high-degree AVB