ECG of the month. Vignettes in electrocardiography: exploring initial QRS forces--a diagnostic clue to wide QRS tachycardia.

摘要

The ECG shows monomorphic wide QRS tachycardia with left bundle branch block (LBBB) and right axis morphology (+ 120 degree).There is cycle length variation especially in the first half of the recording though subsequently it is apparently regular. P waves like deflection is present preceding each QRS (saw tooth like positive wave in inferior leads, negative in aVL, equiphasic in VI). Even though QRS is very wide, initial component of QRS is sharp and follows the aberrancy pattern. A right axis rather than a normal / inferior axis is against aberrancy pattern, as QRS axis should remain normal with pure rate related aberrancy. However, in the presence of preexisting bundle branch block with structural heart disease related axis shift, the QRS axis during supra ventricular tachycardia with aberrancy will be the same as that of the preexisting bundle branch block. The notching in the QRS suggests myocardial disease. First possibility should be atrial flutter with LBBB aberrancy.