Purpose: To evaluate different MR methods (ventricle and flow measurements) for the postoperative follow-up of hemodynamics in patients with extra- or intracardial TCPC.
Materials and methods: Twenty-eight consecutive patients (14 female, 14 male) within the ages of two to thirty-eight years were examined using a 1.5 T Gyroscan ACS-NT scanner (Philips, Best, Netherlands). 7 patients had an extracardial (eTCPC), and 21 an intracardial (iTCPC) tunnel. The calculation of the ventricular function and muscle mass was performed using "multislice-multiphase" technique by summing up the end-diastolic and end-systolic areas; the flow measurements were evaluated by phase shift velocity mapping in the superior vena cava (SVC), inferior vena cava (IVC), right (RPA) and left (LPA) pulmonary artery. Besides peak and mean velocity, the mean and maximal flow volumes (ml/min) were calculated.
Results: Ejection fraction (EF) of the functionally single ventricle was within the normal range (mean 57%) in 22/28 patients while mean muscle mass was elevated in the group with eTCPC (mean 121 g/m2). The mean flow volumes and the peak velocities in all vessels were higher in the group with iTCPC as compared to the one with eTCPC. Clinically relevant retrograde flows in the IVC were only found in the group with iTCPC (7/21), as well as a significant predominant flow distribution towards the RPA (p < 0.05; Wilcoxon signed-rank test); in the group with eTCPC towards the LPA (n.s.).
Conclusions: MRI is a useful method for the assessment of ventricular function and muscle mass in the follow-up after the modified Fontan operation. MRI flow measurements additionally provided clinically relevant information about the hemodynamics in Fontan patients.