Light on wide-QRS tachycardia, part 2: ECG diagnosis, treatment

In patients with wide-QRS tachycardia (WQRST), atrioventricular dissociation, fusion complexes, and capture complexes are uncommon but important findings, because the presence of any of these characteristics indicates ventricular tachycardia (VT) and not supraventricular tachycardia (SVT). The Wellens criteria, based on the morphology of the QRS complex, can lead to an accurate diagnosis of the nature of WQRST in 80% to 90% of cases. Applying criteria based on QRS concordance increases the diagnostic yield to 95%. In hemodynamically unstable patients, electrical cardioversion is the safest and most effective way of terminating WQRST, regardless of the mechanism. VT in stable patients may be terminated with lidocaine, procainamide, bretylium tosylate, or amiodarone. Maneuvers that enhance vagal tone may terminate SVT; if they fail, adenosine can be used.