Cardiac pacing in incomplete atrioventricular block with atrial fibrillation.

are described; two had ischaemic heart disease, and one had cardiomyopathy. In thefirst case the slow ventricular response to atrialfibrillation was a result of incomplete atrioventricular nodal block, and in the other two His bundle electrograms demonstrated that the slow ventricular response was due to bilateral bundle-branch block. The association of atrial fibrillation and conduction delays in the atrioventricular node and bundlebranches is discussed. The value of His bundle recordings in the investigation of these cases is shown and the importance of cardiac pacing in treatment is stressed.