Decreased Diastolic Ventricular Kinetic Energy in Young Patients with Fontan Circulation Demonstrated by Four-Dimensional Cardiac Magnetic Resonance Imaging

Abstract

Four-dimensional (4D) flow magnetic resonance imaging (MRI) enables quantification of kinetic energy (KE) in intraventricular blood flow. This provides a novel way to understand the cardiovascular physiology of the Fontan circulation. In this study, we aimed to quantify the KE in functional single ventricles. 4D flow MRI was acquired in eleven patients with Fontan circulation (median age 12 years, range 3-29) and eight healthy volunteers (median age 26 years, range 23-36). Follow-up MRI after surgical or percutaneous intervention was performed in 3 patients. Intraventricular KE was calculated throughout the cardiac cycle and indexed to stroke volume (SV). The systolic/diastolic ratio of KE in Fontan patients was similar to the ratio of the controls' left ventricle (LV) or right ventricle (RV) depending on the patients' ventricular morphology (Cohen´s κ = 1.0). Peak systolic KE/SV did not differ in patients compared to the LV in controls (0.016 ± 0.006 mJ/ml vs 0.020 ± 0.004 mJ/ml, p = 0.09). Peak diastolic KE/SV in Fontan patients was lower than in the LV of the control group (0.028 ± 0.010 mJ/ml vs 0.057 ± 0.011 mJ/ml, p < 0.0001). The KE during diastole showed a plateau in patients with aortopulmonary collaterals. This is to our knowledge the first study that quantifies the intraventricular KE of Fontan patients. KE is dependent on the morphology of the ventricle, and diastolic KE indexed to SV in patients is decreased compared to controls. The lower KE in Fontan patients may be a result of impaired ventricular filling.

Keywords: CMR; Congenital heart disease; Fontan; Kinetic energy; MRI; Magnetic resonance imaging.

Fig. 1

Kinetic energy in the ventricle during the cardiac cycle. Right ventricular (RV) morphology is shown in solid line. Left ventricular (LV) morphology is shown in broken line. The left column shows Fontan patients with complications. The right column shows patients with Fontan circulation without complications and a graph showing RV and LV of the control group. Patients with APC (aortopulmonary collaterals) are marked with a star. Patient 1 had a fenestrated extracardiac conduit which makes the assessment of APC difficult

Fig. 2

Ventricular kinetic energy (KE) in a Fontan patient superimposed on CMR images to visualize the anatomical location of KE. The upper panel shows an oblique sagittal view in systole (a) and diastole (b). Systolic peak KE can be seen in a ventricular septal defect leading the blood to the aorta. Diastolic peak KE is located from the atrioventricular valve into the ventricle. The lower panel visualizes KE in an oblique transversal view in the same patient in systole (c) and diastole (d). AAo ascending aorta; VSD ventricular septal defect; V ventricle; A atrium; AV valve atrioventricular valve; AoV aortic valve; DAo descending aorta; T lateral tunnel

Fig. 3

Kinetic energy (KE) indexed to stroke volume. The left column shows peak KE during systole and the right column peak KE during diastole. a and b shows all Fontan patients and the left ventricle in the control group. c and d shows Fontan patients with LV morphology and the left ventricle in the control group. e and f shows Fontan patients with RV morphology and the right ventricle in the control group. Error bars show mean ± SD

Fig. 4

KE throughout the cardiac cycle in three patients before and after surgical or percutaneous intervention. Details of the intervention are listed in Table 2. Heart rate (beats/minute) pre-intervention/post-intervention was in patient 4: 103/87, patient 5: 85/83, patient 6: 63/80