Effects of Right Ventriculotomy upon Activation of the Epicardial Surface of the Canine Right Ventricle

The sequence of activation of the epicardial surface of the right ventricle has been studied before and after right ventriculotomy. Normally, the area of the right ventricle adjacent to the anterior interventricular groove is activated first, the midportion of the wall second, and the area adjacent to the posterior interventricular groove and the anterior basal area are activated last. Activation of the entire epicardial surface of the right ventricle requires 25 to 40 msec. Right ventriculotomy does not alter the sequence of activation or the time of activation of the right ventricular epicardium if the incision passes medial to the free-running Purkinje fibers or through their arborization on the right, ventricular wall. When the ventriculotomy is made lateral to the arborization of these fibers, activation of that portion of the wall lateral to the incision is delayed, and activation of the entire ventricular surface requires 42 to 52 msec. There is no electrocardiographic evidence of bundle-branch block, complete or partial, following right ventriculotomy, regardless of the location of the incision.