Activation of the Free Wall of the Right Ventricle Experimental Right Bundle Branch Block

Right bundle branch block was produced in dogs, and activation of the free wall of the right ventricle was studied by means of multipolar electrodes. After block, accession spread radially at the earliest activated endocardial point and tangentially at later activated points. Direct current stimulation of selected endocardial points resulted in patterns of activation resembling those obtained after right bundle branch block in controls and after block. It is concluded that the Purkinje network does not participate in normal fashion in endocardial spread of the excitation impulse after right bundle branch block.