The Fontan circulation: looking deep and beyond

Children born with a functionally univentricular heart are currently palliated with a series of operations culminating in the Fontan circulation. This unphysiological circulation deteriorates over time, and long-term outcomes regarding morbidity and mortality are dire. This thesis focused on two important topics; one, we investigated predictors for the deterioration of the Fontan circulation. We found that GDF-15, a blood marker, as well as ventricular strain measured by MRI are valuable indicators of the status of a patient’s Fontan circulation. For the first time, serial measurements were done and showed additional predictive value. Furthermore, we found sex differences in ventricular dimensions of Fontan patients that exceed those found in the general population. The above mentioned findings are important in order to recognize patients at risk for deterioration of the Fontan circulation and are vital for initiation of treatment.
The second part of the thesis focused on a small group of functionally univentricular heart patients who survived without the Fontan operations. We collected all known survivors of double inlet left ventricle hearts in the Netherlands. We compared their cardiac anatomy and blood flows to that of the axolotl salamander, which naturally lives with a functionally univentricular heart. Both in human as well as in the axolotl we found anatomical characteristics of their hearts that facilitated streaming of blood and allowed them to survive. The results of this investigation indicate that some carefully selected functionally univentricular heart patients may benefit from a conservative treatment approach.