Ventricular Complexes in Heart Block

In electrocardiograms of complete A-V block, the ventricular complexes may be of normal supra- ventricular type, of typical bundle branch block (B.B. block) type, or may exhibit lesser degrees of widening and notching of QRS and T wave changes. The association of B.B. block with complete A-V block is recognized as common. Campbell (1944) found B.B. block in 19 of 64 cases of complete block. Similar findings have been recorded by White and Viko (1923) who found evidence of intraventricular block in 15 out of 27 cases of complete heart block, and by Fatzer (1946) who described intraventricular block in 60 per cent of cases; Mouquin and Macrez (1947) in a series of 124 cases of complete heart block, found normal ventricular complexes in only 25 instances. Gray- biel and Sprague (1933) record 17 cases of complete A-V block in 395 cases of B.B. block, and Freund and Sokolov (1939) found complete A-V block in 5 per cent of 210 cases of B.B. block. It is also recognized that the form of QRS during complete A-V block may differ from that recorded during sinus rhythm in the same case.