Ajmaline Utilization in the Diagnosis and Treatment of Cardiac Arrhythmias

Inclusion Criteria: * AF: Patients with isolated, idiopathic, sustained, symptomatic, recent onset(\>10 minutes to \<24 hours) atrial fibrillation. * VT: Patients with ventricular tachycardia with good haemodynamic tolerability attending the emergency room or induced at the electrophysiology lab during testing for ventricular arrhythmias. * Brugada Sd (BrS): First-degree relatives of a patient with Brugada Syndrome with a ECG non-diagnostic of the BrS. Exclusion Criteria: * General: Pregnancy * AF: Pre-existing heart disease. * Secondary AF * 2nd and 3rd degree AV block or RBBB associated with LAFB or LPFB (bifascicular block). * LVF\<40%. * Moderate-severe liver failure. * AF with haemodynamic compromise. * VT:VT with haemodynamic compromise. * BrS:Pre-existing heart disease. * 2nd and 3rd degree AV block or RBBB associated with LAFB or LPFB (bifascicular block). * Moderate-severe liver failure.