Role of Cardiovascular Computed Tomography Angiography in the Evaluation for Functional Single Ventricle After the Fontan Procedure

Introduction: Functional single ventricle (FSV) includes a spectrum of severe congenital heart disease and is associated with high mortality, morbidity and resource usage. The Fontan procedure has been treated as the relatively ideal surgical treatment for these patients, but pathophysiological complications of the Fontan circulation are frequent and the anatomic structures of FSV patients are also complex. Even though echocardiography, CT and MRI can disclose and characterise common postoperative problems in patients with the Fontan palliation, no single imaging method is comprehensive in any given patient. Cardiovascular computed tomography angiogra phy (CCTA), with advanced technologies and markedly decreased radiation dose, can provide better information with lower risk than other modalities. This article aims to assess CCTA modality in the evaluation for FSV with the Fontan palliation.

Materials and methods: Twenty-eight cases of FSV patients after the Fontan procedure were included in this retrospective single-center study. All of patients underwent CCTA examination on the same CT scanner. The diameters of left pulmonary artery, right pulmonary artery and descending aorta (level of diaphragm) were measured for the calculation of McGoon index to indicate the development of pulmonary artery. The qualitative evaluation of anatomic structure and postoperative complication were also completed by CCTA data. Additionally, the data’s of cardiac catheterization for these FSV patients were collected for comparison with that of CCTA.

Results: The diameters of pulmonary artery each was (1.33 ± 0.23, left), (1.38 ± 0.15, right), and the McGoon index calculated was (1.55 ± 0.13). The diameters of both left and right pulmonary arteries related well to the pressure of pulmonary arteries (left: r=-0.865 systole, r=-0.829 diastole, r=-0.867 average; right: r=-0.704 systole, r=-0.758 diastole, r=-0.743 average; P<0.001 respectively). The McGoon index also had good correlation with the resistant index of pulmonary artery (r=-0.887, P<0.001). In addition, 8 cases of Y-graft Fontan, 2 cases of atriopulmonary connection, 8 cases of lateral tunnel Fontan, and 10 cases of extracardiac Fontan procedures were detected from our study. And 2 cases of diffuse pulmonary arteriovenous malformations and 2 cases of aortopulmonary collaterals were defined as complications of the Fontan procedures.

Conclusion: With improved spatial resolution, rapid image acquisition and image post-processing technology, CCTA can supply sufficient information for both detection of anatomic structure and evaluation for FSV patients after the Fontan procedure. It has become an essential modality for congenital heart disease.

Author(s): Yu Sun, Jie Hou, Junrui Xiao, Chang Liu, Miao Jing, Mingyu Zou and Benqiang Yang

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