Ventricular tachycardia as a group , constitute a major group of cardiac arrhythmias. Most of the VTs are managed by cardioversion followed by medical management. Few require , implantable defibrillator when there is severe LV dysfucntion .(ICD) Localising the origin of VT and subsequent , ablation is the treatment of choice in some of the patients with VT.
Traditionally VT was thought to arise fro the endocardial aspects of myocardium. Now we realise many times VT originate from the epicardial aspects of ventricle.
Epicardial VT : Defintion
Epicardial ventricular tachycardia (VT) is defined as VT in which the critical sites of the reentrant circuit (or the ‘sites of origin’) are located exclusively in the subepicardial tissue, as shown by entrainment manoeuvres or VT that is terminated within 10 s with standard radiofrequency (RF) pulses, or both. E. SOSA,M. SCANAVACCA et all http://www.springerlink.com/content/w608142674154tp5/
How to recognise epicardial origin of VT by surface ECG ?
Terminal S wave in V2 and q in lead 1 strongly suggest VT of sub epicardial origin.