Pathologic findings in atrial musculature seven years after the intraatrial tunnel Fontan.

Surgical specimens of the atrial wall were microscopically investigated 7 years after total cavopulmonary connection. The intima of the morphologically right atrium was thicker in the part used for the high-pressured venous channel than in the other portion placed for the low-pressured atrial cavity supporting the systemic circulation. The number of myocardial cells was smaller, and the area of interstitial fibrosis was greater, in both circumstances, when compared with the normal right atrium.