Visualization and quantification of the atrioventricular conduction axis in hearts with ventricular septal defect using phase contrast computed tomography

Objective To visualize and quantify the atrioventricular conduction axis in the setting of ventricular septal defect using phase contrast computed tomography. Methods We used the SPring-8 synchrotron radiation facility in Hyogo prefecture in Japan, processing and reconstructing the data with 3-dimensional software. Results We studied 8 hearts obtained from patients known to have had ventricular septal defects, aged from 6 to 150 days, with a median of 24.5 days. None of the individuals, however, had undergone corrective surgery. The penetrating bundle was found at a median of 1.43 mm from the septal crest, with a range of 0.99 to 1.54 mm. The distance to the nonbranching bundle to the right ventricular endocardium was 1.10 mm, with a range from 0.49 to 2.49 mm, to the origin of the left bundle branch was 2.46 mm, with a range from 1.7 to 3.18 mm, and to the origin of the right bundle branch was 2.34 mm, with a range from 0.50 to 2.59 mm. The median distance from the edge of the caudal limb of the septomarginal trabeculation to the right bundle branch was 1.04 mm, with a range from 0.81 to 1.16 mm. Conclusions We were able to show the precise location of the axis, with our findings suggesting that longitudinal sutures placed along the posteroinferior rim should be effective in avoiding iatrogenic injury, but sutures should not be placed in the valley between the limbs of the septomarginal trabeculation.