CHANGES IN VENTRICULAR GEOMETRY EARLY AFTER FONTAN OPERATION

Acute removal of a ventricular volume overload, in the face of relativ ely unchanging ventricular mass, results in geometric alterations that can impair diastolic ventricular performance after Fontan operation. We investigated whether geometric alterations were (1) more severe aft er Fontan operation than after hemi-Fontan operation, (2) more severe in infants than in children, and (3) more severe in the morphologic ri ght ventricle than in the morphologic left ventricle. We studied 22 pa tients, 11 with hypoplastic left heart syndrome and 11 with a function ally single morphologic left ventricle. After Fontan operation, right ventricular end-diastolic volume declined by 52% from 36.6 +/- 12.2 to 17.5 +/- 9.3 mL. Right ventricular wall thickness increased from 6.8 +/- 1.3 to 7.5 +/- 1.8 mm. Left ventricular end-diastolic volume dimin ished by 40% from 57.6 +/- 23.3 to 34.8 +/- 17.6 mL. Left ventricular wall thickness increased from 7.0 +/- 2.1 to 8.7 +/- 1.9 mm. The alter ations in right ventricular geometry are more marked early after Fonta n operation than early after the hemi-Fontan procedure. Geometric alte rations in the left ventricle appear to be more severe in infants than in children. Finally, alterations in the morphologic right ventricle appear to be of similar magnitude to those in the morphologic left ven tricle.