The anatomic substrate for preexcitation in XXXX .

@entity713 @entity4263 @entity1757 @entity4924
We report three cases of @entity4263 ( @entity4263 ), all with @entity4924 , @entity1757 ( @entity1757 ) and ventricular preexcitation. In cases 1 and 2, the ECG revealed sinus rhythm, with type A fusion preexcitation QRS complexes, suggesting left-sided Kent bundles and intact @entity713 ( @entity713 ). Complete serial section (SS) of the @entity713 in both cases revealed an anterior @entity713 and a Kent bundle in the posteroseptal wall of the morphologic right ventricle (MRV). Case 3 had intermittent preexcitation, with periods of complete @entity713 with narrow QRS escape rhythm. The preexcitation complexes suggested the presence of a left lateral Kent bundle. SS of the @entity713 revealed a blind posterior and two anterior AV nodes, one on either side of the pulmonary trunk. The left anterior AV node was blind. The right anterior node formed the anterior bundle, which ended blindly. This bundle emerged again and joined a posterior bundle to form an interrupted sling around the closed @entity1757 . In addition, there was a tenous Kent bundle at the posterolateral wall of the MRV. In summary: (1) preexcitation in @entity4263 with @entity4924 of the left AV valve is associated with Kent bundles; (2) fusion complexes reflected intact @entity713 ; and (3) intermittent preexcitation with @entity713 was associated with the presence of tenuous Kent bundl and discontinuity of the @entity713 .
