[A histologic study on prevention of surgical conduction disturbance, with special reference to the relationship between the central portion of the A-V bundle and adjacent structures].

UNLABELLED

The present study was aimed to examine the course of the proximal portion of the His bundle (HB). Twenty-six hearts was histologically investigated, 5 normal, 13 with isolated perimembranous ventricular septal defect (VSD) and with tetralogy of Fallot (TOF). Following items were analyzed by serial sectioning: 1. Distance from axis of the nonbranching bundle (NBB) to the lower irm of VSD. 2. Deviation of the penetrating bundle (PB) and the NBB to the right ventricular septal endocardium. 3. Distance from the HB to the attachment of the tricuspid septal leaflet (ALS). 4. Level of the HB under the provision that the ASL level is zero. 5. Length and distance of the HB.

RESULTS

1. In inlet type VDSs, the NBB-VSD distance was 0.40 +/- 0.27 mm, indicating that the conduction system maintained nearly the same level as the ASL. 2. In trabecular and infundibular type VDSs, the NBB-VSD distances were 1.57 +/- 0.80 mm and 1.75 +/- 0.35 mm, and the HB-ASL distances were 1.70 +/- 1.23 mm and 1.10 +/- 1.13 mm, respectively. 3. In membranous type TOF, the NBB lay more superficially than in muscular type.

CONCLUSION

inlet type VSD and perimembranous type TOF have anatomic features in which the proximal His bundle tends to be jeopardized by suturing for VSD closure.