Objective: Patients frequently undergo cardiac catheterization before the Fontan operation because of the limited echocardiographic windows in the region of the superior cavopulmonary connection and branch pulmonary arteries. Patients with obstruction to pulmonary blood flow are at increased risk for prolonged length of hospital stay after the Fontan operation. Cardiac magnetic resonance has unlimited imaging windows and can quantify both the branch pulmonary artery size and net flow distribution and thereby serve as a method for identifying patients at increased risk for prolonged length of stay.
Methods: We retrospectively reviewed 24 cardiac magnetic resonance studies of patients (mean age, 3.1 +/- 1.0 years) referred before the Fontan operation. Cardiac magnetic resonance measured the cross-sectional area and flow to each branch pulmonary artery. Post-Fontan hospital course data were acquired from the medical record.
Results: Prolonged length of stay after the Fontan operation is observed among patients with one branch that is less than 25% of the total cross-sectional area (18.0 +/- 5.5 vs 8.2 +/- 3.8 days, P = .01) or with less than 40% flow to one branch (12.5 +/- 6.9 vs 7.6 +/- 1.5 days, P = .04). There is moderate correlation between the total branch pulmonary area and length of stay (r = -0.75).
Conclusions: Cardiac magnetic resonance noninvasively assesses the branch pulmonary area size and flow before the Fontan operation. These data predict which patients are more likely to experience a prolonged hospital course.