[Clinical significance of incomplete right bundle branch block]

In authors' opinion the majority of the physicians speak about an incomplete right bundle branch block in cases of a terminal r'wave in lead V1 of the ECG, when the QRS complex is not wider than 0.12 sec. These ECG anomalies are not properly separated in the literature, either. Authors define 4 groups whose separation is possible by the analysis of leads V1 and V2. 1. Right ventricular conduction defect--the ECG width is 0.09-0.13 sec. This picture generally signs normal or only slight higher right ventricular pressure. 2. Real incomplete right bundle branch block--the terminal vector directs forward only in this group and it causes also an r' in V2 next to the high R' in lead V1. This group can be harmless, only a conduction defect, but it can mean an advanced stadium of serious right ventricular systolic or diastolic overloading, too. 3. Right ventricular diastolic overloading--the QRS width is normal. We saw this picture in slight forms of atrial septal defect. One of our conclusions was that in case of normal V1 a haemodynamic significant ASD I or ASD II can be excluded. 4. Normal variant: normal QRS width and only a very low r' in lead V1. It was seen in young patients or in patients with flat chest. Authors remark that this pattern can possibly be seen in childhood or in case of inexact ECG (V1) registration.