Complete heart block induced during cardiac catheterization of patients with pre-existent bundle-branch block. The hazard of bilateral bundle-branch block.

or bundle of His. Blockage of both the right and left bundle branches would be tantamount to block at these locations. This is the well-established concept of bilateral bundle-branch block.1-3 It highlights a hazard inherent in catheterization of the ventricle opposite that which is already the site of bundle-branch block. Since the advent of cardiac catheterization, numerous reports have been published of the induction of transient right bundlebranch block due presumably to fortutitouLs injury of the right bundle branch by the tip or side of an exploring catheter.4 16 If such a patient happened already to be affected with left bundle-branch block, right ventricular catheterization could then induce bilateral bundle-branch block and all the possible consequences of suddenly developed complete atrioventricular block. Wood7 reported the development of 2:1 atrioventricular block during right ventricular catheterization of a patient with pre-existent