The Fontan procedure in the absence of the interatrial septum. Failure of its principle?

The Fontan principle, defined as a procedure in which the right venticle is bypassed in order to convey desaturated venous blood from the right atrium to the lungs, is presently applied for a wide variety of congenital heart malformations including those in which there is no suitable ventricular pumping chamber. Recently, the procedure has also been advocated for complex malformations that require atrial septation or intra-atrial rerouting. The present report evaluates our experience in four patients with such complex malformations. Three had a complete form of atrioventricular septal defect with double-outlet right ventricle and one patient had left atrioventricular valve atresia. The common atrium was morphologically right in two patients and morphologically left in one. In each of these instances anomalous pulmonary venous connections were present, together with abnormal systemic venous connections. The results were unsatisfactory. Three of the four patients died. The only survivor had no pulmonary or systemic venous abnormalities. Severe impairment of pulmonary blood flow was one of the most important postoperative complications. The findings suggest that the complexities of rerouting the blood within the atria play an important role. The excess proportion of prosthetic material to atrial myocardium may result in excessive loss of contractile atrial myocardium and, probably equally significant, in a complex intra-atrial geometry of pathways that may cause a critical pressure gradient. The results clearly show that with an expanding horizon of the application of the Fontan principle, new pitfalls may arise which presently appear to be the prevailing factors limiting its success.