Atrial remodeling after the Fontan operation.

The hemodynamics after Fontan surgery are notable for hypertension and dilation of the right atrium (RA). The effect of this stress on atrial cytoarchitecture has not been systematically studied and might be relevant to arrhythmias and their treatment. Morphologic and histopathologic analyses were performed on tissue from the RA and left atrium (LA) from autopsy specimens of Fontan hearts (n = 47). The findings were compared to those from control samples from young patients with normal atrial hemodynamics (n = 15). Most Fontan specimens were from young patients who died after a relatively short duration of Fontan physiology. The tissues were analyzed for wall thickness, fibrosis content, and fibrosis pattern. The mean wall thickness for the RA (3.0 ± 1.0 mm) and LA (2.3 ± 0.6 mm) in the Fontan hearts was significantly greater than that in the control hearts (RA, 1.8 ± 0.4 mm; LA, 1.8 ± 0.5 mm; p