ABSTRACT
It is commonly agreed that the electrocardiographic recognition of left ventricular hypertrophy (LVH) is difficult, or even impossible, in patients with bundle branch or fascicular block; the opposite, however, has been demonstrated by several studies. In the presence of intraventricular conduction disturbances, many criteria can reveal LVH, with sensitivity and specificity not inferior than that of electrocardiographic signs used in subjects with normal intraventricular conduction. The following criteria can be helpful in left bundle branch block: QRS voltage increase, left atrial enlargement, QRS duration > 155 ms. LVH is suggested by one or more of the following: Sokolow index > or = 35 mm, R wave in lead aVL > or = 11 mm, left axis deviation at -40 degrees or more, SV2 > 30 mm + SV3 >25 mm. In left anterior hemiblock, LVH is diagnosed whenever the sum of S wave in lead III plus the maximal R+S in a precordial lead is > or = 30 mm. Further criteria are SV1 + (R+S) in V5 or V6 > or = 25 mm, and the presence of secondary ST-T changes. In right bundle branch block, LVH is suggested by a left atrial enlargement pattern, secondary repolarization changes, and a sum of S wave in lead III plus the maximal R+S in a precordial lead > or = 35 mm.
