Magnetic Resonance Imaging Assessment of Blood Flow Distribution in Fenestrated and Completed Fontan Circulation with Special Emphasis on Abdominal Blood Flow

Abstract

Objective To investigate the regional flow distribution in patients with Fontan circulation by using magnetic resonance imaging (MRI). Materials and Methods We identified 39 children (18 females and 21 males; mean age, 9.3 years; age range, 3.3–17.0 years) with Fontan circulation in whom flow volumes across the thoracic and abdominal arteries and veins were measured by using MRI. The patients were divided into three groups: fenestrated Fontan circulation group with MRI performed under general anesthesia (GA) (Group 1, 15 patients; average age, 5.9 years), completed Fontan circulation group with MRI performed under GA (Group 2, 6 patients; average age, 8.7 years), and completed Fontan circulation group with MRI performed without GA (Group 3, 18 patients; average age, 12.5 years). The patient data were compared with the reference ranges in healthy controls. Results In comparison with the controls, Group 1 showed normal cardiac output (3.92 ± 0.40 vs. 3.72 ± 0.69 L/min/m 2 , p = 0.30), while Group 3 showed decreased cardiac output (3.24 ± 0.71 vs. 3.96 ± 0.64 L/min/m 2 , p = 0.003). Groups 1 and 3 showed reduced abdominal flow (1.21 ± 0.28 vs. 2.37 ± 0.45 L/min/m 2 , p < 0.001 and 1.89 ± 0.39 vs. 2.64 ± 0.38 L/min/m 2 , p < 0.001, respectively), which was mainly due to the diversion of the cardiac output to the aortopulmonary collaterals in Group 1 and the reduced cardiac output in Group 3. Superior mesenteric and portal venous flows were more severely reduced in Group 3 than in Group 1 (ratios between the flow volumes of the patients and healthy controls was 0.26 and 0.37 in Group 3 and 0.63 and 0.53 in Group 1, respectively). Hepatic arterial flow was decreased in Group 1 (0.11 ± 0.22 vs. 0.34 ± 0.38 L/min/m 2 , p = 0.04) and markedly increased in Group 3 (0.38 ± 0.22 vs. −0.08 ± 0.29 L/min/m 2 , p < 0.0001). Group 2 showed a mixture of the patterns seen in Groups 1 and 3. Conclusion Fontan circulation is associated with reduced abdominal flow, which can be attributed to reduced cardiac output and portal venous return in completed Fontan circulation, and diversion of the cardiac output to the aortopulmonary collaterals in fenestrated Fontan circulation.

Impact of liver fibrosis and nodules formation on hemodynamics in young adults after total cavopulmonary connection. A magnetic resonance study

“…The pathophysiology of an increased hepatic blood flow in Fontan patients can be explained initially by the hepatic arterial buffer response (HABR), a compensatory ability of the hepatic artery to increase flow in response to decreased portal flow (26), followed by subsequent gradual progression of the hepatic arterialization caused by the liver fibrosis and liver nodules formation (16,18,27). Indeed, in a detailed MRI study, a markedly increased hepatic arterial flow forming 45% of hepatic venous flow was observed in children after the Fontan procedure compared to non-significant arterial flow contribution to the hepatic venous flow in the control group (28). Interestingly, an increased cardiac output with elevated central venous pressure and preserved ventricular function was also associated with 10.3389/fcvm.2022.986653 increased mortality in young adults after various types of Fontan procedure (29).…”

Augmentation of pulmonary blood flow and cardiac output by non-invasive external ventilation late after Fontan palliation

“…All PC analyses were completed using commercially available tools (Q Flow 5.2; Medis Medical Imaging Systems, Leiden, The Netherlands) by a single radiologist blinded to clinical data (GRK) according to previously published methodology ( figure 2 ). 14 The sum of SVC and Fontan flows were used to represent total PBF given potential for inaccuracies of pulmonary artery flow sampling adjacent to surgical anastomotic sites. In control subjects, PBF was measured as a summation of flows directly sampled at the RPA and LPA.…”