Differential Diagnosis of Wide QRS Tachycardia by Electrocardiogram

ABSTRACT

The criteria for differentiation of wide QRS tachycardias by electrocardiogram were evaluated in 24 cases of ventricular tachycardia(VT) and 8 cases of supraventricular tachycardia with wide QRS of various causes. There were some differences in Koreans from western countries due to plenity of idiopathic ventricular tachycardias(VTs) and infrequency of VTs by ischemic heart diseases. The characteristics were as follows : 1) Heart rate, QRS duration, QRS axis, distribution of RBBB and LBBB patterns, and QRS configurations of V1 and V6 leads were of limited values for differentiation of wide QRS tachycardias. 2) AV dissociation with or without capture beat and fusion bear was found in 63 % of VTs and very useful for differential diagnosis. Concordance of precordial leads was not frequently noted(2 cases) and and usually favored VT. 3) In LBBB patterns, notching of S wave, interval from Q wave to nadir of S wave greater than or equal to 60 msec, and R wave duration greater than or equal to 30 msec in V1 or V2 lead were present in 60%, 90%, and 29% of VTs respectively. The findings were also noted in accessory pathway conduction of supraventricular tachycardia. 4) Electrical alternans was present in 71% of VTs but also found in accessory pathway conduction of atrial fibrillation.