Cardiac Imaging in Patients After Fontan Palliation: Which Test and When?

Abstract

The Fontan operation represents the final stage of a series of palliative surgical procedures for children born with complex congenital heart disease, where a "usual" biventricular physiology cannot be restored. The palliation results in the direct connection of the systemic venous returns to the pulmonary arterial circulation without an interposed ventricle. In this unique physiology, systemic venous hypertension and intrathoracic pressures changes due to respiratory mechanics play the main role for propelling blood through the pulmonary vasculature. Although the Fontan operation has dramatically improved survival in patients with a single ventricle congenital heart disease, significant morbidity is still a concern. Patients with Fontan physiology are in fact suffering from a multitude of complications mainly due to the increased systemic venous pressure. Consequently, these patients need close clinical and imaging monitoring, where cardiac exams play a key role. In this article, we review the main cardiac imaging modalities available, summarizing their main strengths and limitations in this peculiar setting. The main purpose is to provide a practical approach for all clinicians involved in the care of these patients, even for those less experienced in cardiac imaging.

Keywords: Fontan operation; cardiac CT; cardiac MRI; congenital heart disease; echocardiography.

Figure 1

Pulmonary artery stenosis (red arrow) seen by CMR. Axial SSFP-cine view shows the left pulmonary artery is compressed between the dilated aortic root (AO) and the descending aorta (DAO).

Figure 2

Inferior caval vein (IVC)-to-pulmonary artery stenosis (red arrow) seen by CMR. SSFP-coronal view demonstrates focal stenosis of the IVC-to-pulmonary artery pathway (red arrow). The superior caval vein (SVC) shows normal size.

Figure 3

Different types of ventricle anatomy in patients with Fontan Palliation seen by CMR (4-chamber views). (A) Tricuspid Atresia. (B) Hypoplastic Left Heart Syndrome. (C) Double Inlet Left Ventricle. (D) Pulmonary Atresia and intact Ventricular Septum with hypoplastic right ventricle.

Figure 4

Hepatocellular carcinoma in a 30-year-old man with Fontan palliation. Axial T2- and T1-weighted MR images (A,B) show a 4 cm paracaval solid lesion with smooth margins and posterior hepatic capsule bulge (arrows). The tumor shows heterogeneous hyperintensity in the arterial phase of the dynamic contrast-enhanced sequence (C), and typical washout in the delayed phase (D). The background liver is diffusely heterogeneous after contrast injection, with multiple small arterial-enhancing foci [dotted blue arrow in (C)] without delayed washout, in keeping with hypervascular regenerative hepatic nodules.

Figure 5

MR Lymphangiography in a Patient treated with TCPC palliation complicated by plastic bronchitis. Static T2-SPACE coronal image (A) demonstrates abnormal supraclavicular (green arrows) and peri-hilar (blue arrows) lymphostasis. Dynamic contrast-enhanced MIP coronal image (B) after intranodal contrast injection shows rapid filling of retroperitoneal lymphatics and of the thoracic duct (yellow arrow), with marked reflow into supraclavicular (red arrow) and mediastinal channels (dotted blue arrow).

Figure 6

Use of CCT in the acute setting. (A) contrast-enhanced axial image shows early post-operative left pulmonary artery thrombosis with a filling defect extended from the cavo-pulmonary anastomosis to the left hilum (red arrow). (B) CMR axial SSFP view performed 2 months after surgical reintervention demonstrates vessel patency.

Figure 7

Potential pitfalls of CCT with single-injection protocol. (A) Coronal image shows mixing of contrast material from the superior vena cava (SVC) and unopacified blood from inferior vena cava (IVC), generating pseudo-filling defects in the left pulmonary artery (LPA) during the early arterial phase (red arrow). (B) The same image obtained during venous recirculation of contrast reveals regular patency of the Fontan circuit.

Figure 8

Stent assessment with CCT. (A) Coronal image in a Fontan patient with left pulmonary artery stenting (red arrow) illustrates how stent lumen patency can be evaluated during the venous phase with a homogeneus opacification of all vessels. (B) Coronal image in a Fontan patient with IVC-to-pulmonary artery conduit stenting (red arrow) demonstrates that ruling out in-stent restenosis can sometimes be difficult due to beam-hardening artifacts.

Figure 9

Veno-venous collateral vessel seen by Cardiac Catheterization. After injection in the left arm a large vessel (red arrow) arising from the left brachiocephalic venous system is visualized. The vessel courses inferiorly connecting to the left pulmonary veins.