br Conventional mapping and ablation of ventricular tachycar

Conventional mapping and ablation of ventricular tachycardia
Substrate mapping during sinus rhythm
Technical issues
Conclusion
Conflict of interest
Introduction By eliminating the arrhythmogenic focus, catheter ablation can be a curative therapy of ventricular tachyarrhythmias (VTAs). Majority of ablations of VTA that were successful were performed using an endocardial approach because the arrhythmogenic focus, for instance, of idiopathic ventricular tachycardia originating from the outflow tract, is located near the endocardium. However, ablation of a subset of intramural or epicardial origin ventricular tachycardias from the endocardium may be challenging [1–4]. The depth of the arrhythmogenic focus or the perpendicular distance between the focus and the endocardial site of ablation is a major determinant of successful ablation procedures. Activation maps of intracardiac bipolar potentials recorded during on-going ventricular tachycardia can identify the site of earliest activation of the endocardial surface in contact with the tip of the catheter, although they prostanoid receptors do not clearly indicate whether the focus is endocardial, mid-myocardial or epicardial. In contrast, unipolar potentials, which can be recorded to locate accessory pathways or the origin of some tachyarrhythmias [5–15], also reflect the activation of sites located away from the recording surface [16,17]. We conducted this experimental study to examine the relationship between the morphology of unipolar potentials and the depth and horizontal distance of activation foci.
Methods
Results
Discussion
Conclusions
Conflict of interest
Introduction Since the recent demonstration of an association between an early repolarization pattern in the inferolateral leads of the ECG and sudden cardiac death [1–3], a distinct clinical entity referred to as early repolarization syndrome is now widely recognized. Early repolarization is a relatively common electrocardiographic feature; thus, risk stratification of subjects whose ECGs exhibit this feature is desirable for the prevention of sudden cardiac death. Brugada syndrome is also associated with life-threatening arrhythmias. Several tests have been vetted for use in risk stratification of Brugada syndrome patients. There have been many reports that ventricular arrhythmias are inducible during electrophysiological study in patients with Brugada syndrome, but whether such study results have predictive value for cardiac events remains controversial [4–8]. Because early repolarization syndrome and Brugada syndrome have similar clinical and electrocardiographic characteristics, some investigators hypothesize that these two syndromes represent points on a continuous spectrum of J-wave abnormalities called the J-wave syndrome [9]. However, unlike Brugada syndrome, inducibility of ventricular arrhythmias in early repolarization syndrome has not received much study.
Methods
Results From 10 centers in Japan, 79 patients (72 males, 91%) were studied. Mean age at the first event (aborted sudden cardiac arrest, VT, VF or syncope) before enrollment was 44±13 years. Twenty-one patients (27%) had early repolarization syndrome, and the remaining 58 patients (73%) had Brugada syndrome. Of the 58 patients diagnosed with Brugada syndrome, 20 exhibited early repolarization in the inferolateral leads as well. The first event was aborted sudden cardiac arrest in 5 (6%), VT/VF in 40 (51%) and syncope in 34 (43%) patients, respectively. Ten patients (13%) had a family history of sudden death or idiopathic VT/VF. Clinical characteristics were compared according to ECG type (Table 1). Brugada syndrome patients were more likely to experience syncope as the first cardiac event (61% of those without early repolarization; 50% with early repolarization), as compared to patients with early repolarization (5%). QRS widths were shortest in patients with early repolarization alone and greatest in Brugada syndrome patients with early repolarization.