[Pathogenesis of venous congestion symptoms after Fontan operation]

To evaluate a possible common pathogenetic denominator, we compared hemodynamic data of 18 patients who had an uneventful long-term course after a Fontan procedure, with the respective data of patients who developed symptoms of central venous congestion either in the immediate postoperative period (n = 10) or during late follow-up (n = 6). We found a coincidence of increased early postoperative venous pressures (CVP; 17.1 +/- 2.9 mm Hg) with relatively high cardiac indices (3.6 +/- 0.6 l/min.m-2) as compared to 2.4 l/min.m-2 in the group of patients with a symptom-free long-term course but no significant difference in total pulmonary resistance between the two groups. The increased CVP (17.2 +/- 2.9 mm Hg) in patients with late chronic central venous congestion is primarily due to increased total pulmonary resistance (552 +/- 131 dyn s/cm5.m-2). Both groups of patients with central venous congestion display a ratio of systemic to total pulmonary resistance lower than 4.5 whereas symptom-free patients have a significantly higher resistance ratio (6.8 +/- 2.3) and a highly significant increase in peripheral resistance to values of 2687 +/- 527 dyn s/cm5.m-2 as compared to 1486 +/- 340 dyn s/cm5.m-2 in the early postoperative group. Correspondingly, mean arterial pressure of the symptom-free patients is significantly elevated (93 +/- 11 mm Hg) as compared to a control group (81 +/- 11 mm Hg). Based on our theory an increase in systemic arterial resistance may lead to a fall in mean capillary filtration pressure and therefore counteract central venous congestion. To support this, we briefly present cases where pharmacologic enhancement of systemic arterial resistance was effective in the treatment of venous congestion whereas pharmacologic lowering of systemic resistance induced venous congestion.