[Right bundle-branch block configuration in the pacemaker ECG--3 different observations].

We report on 3 cases of right bundle branch block configuration in the ECG after pacemaker implantation. In case 1 it was not noticed that the catheter had been directed through an unknown sinus venosus defect into the left atrium and the left ventricle. In case 2 the catheter reached the left ventricle via an iatrogenic perforation of the lower part of the atrial septum. In case 3 the catheter was situated correctly in the right ventricle, but the tip was penetrating the septum. Different possibilities of interpretation of this phenomenon are discussed, and a description of further pacemaker catheter misplacements which may be responsible for a right bundle branch block configuration is given. The authors take the view that a pacemaker catheter should not remain in the arterial area, in the pericardial space and in the coronary sinus. A lateral radiograph, a 12-lead ECG and an echocardiographic study are helpful for detecting and interpreting an unusual catheter position or a right bundle branch block configuration in the pacemaker ECG.