Further observations on conduction tissues in univentricular hearts—surgical implications

Two univentricular hearts are described with particular reference to the surgical anatomy of their conduction tissues. The first was of left ventricular type with right-sided outlet chamber. The findings in this heart confirmed that the conduction tissues in univentricular hearts of left ventricular type originate from an anterior node. When the rudimentary chamber of right ventricular type is right-sided, the bundle descends directly on to the trabecular septum without coming into relation with the pulmonary outflow tract and annulus. This is unlike the arrangement in similar hearts where the rudimentary chamber is left-sided, and confirm the previous findings described by Wenink. The second case was a univentricular heart of indeterminate type, in which the ventricular conduction tissues descended from an anterior node on to a prominent trabecula, which partially separated the body of the ventricle from the pulmonary outflow tract. These findings indicate first of all the significance of distinguishing univentricular hearts of indeterminate type from other forms, particularly the right ventricular type. Then they show the necessity to treat free-standing trabeculae with respect if operating on such hearts since very frequently they carry the ventricular conduction tissues.