Characterizing the Effect of Dopamine on Markers of Lymph Re-circulation in Fontan-associated Protein-losing Enteropathy

For infants and newborns who have a heart defect at birth that leaves them with one
functional ventricle, there is a series of surgeries that are required to allow survival.
These surgeries ultimately lead to a common heart and great blood vessel circulation called a
cavopulmonary anastomosis (Fontan). This has allowed for survival into adulthood from
universally fatal outcome in infancy. However, the non-physiologic blood flow patterns of the
Fontan pathway do result in certain complications, including protein losing enteropathy
(PLE), which occurs in 3.7-13.4% of patients. PLE is denoted by the loss of protein, fats,
and other key nutrients into the intestines, which can lead to significant morbidity. Recent
evidence suggests that this is in part mediated by impaired flow of lymph from the
intestines, which is carried by the parallel vascular system called the lymphatic system.
Lymphatics return these nutrients and the fluid that leaks out of the blood vessels
throughout the body back into the blood circulatory system by functioning as a series of
pumps with one-way valves. While few treatments exist from PLE, evidence demonstrates
continuous infusion of dopamine can help resolve PLE symptoms. Studies of isolated lymphatic
vessels demonstrate that dopamine may increase the ability of lymphatic vessels to pump
harder. This suggests the mechanism of action of dopamine in PLE is increasing the return of
lymph in the non-physiologic blood flow patterns of Fontan patients. However, the link
between improved return of lymph and improvement in PLE has not been established. Therefore,
the investigators have designed this study to test whether markers of lymphatic flow and
heart pump function improve when patients start continuous dopamine therapy (a standard
practice at the University of Michigan for PLE). This involves tracking markers of lymphatic
recirculation through serial testing of blood and monitoring of PLE symptoms before and after
the start of dopamine and other standard of care therapies. From these data, the
investigators will correlate the monitored changes in lymph recirculation with changes in PLE
symptoms.

Inclusion Criteria:

- Males and females with Fontan physiology of any age

- Must have protein losing enteropathy with current worsening who require additional
therapies

- Participant consent or parental/guardian consent and participant assent

Exclusion Criteria:

- Patients with inflammatory bowel disease (i.e Crohn's, ulcerative colitis)

- Patients with systemic autoimmune disease (i.e. Systemic Lupus Erythematous)

- Patients with primary immunodeficiency syndromes

- Patients with nephrotic syndrome

- Patients with anemia

- Patients less than 31 pounds