Case report
A 4-year-old boy from a foreign country was admitted to our hospital for staged management of his CHD. At the age of 8 months, he was diagnosed as having tricuspid atresia with absent pulmonary valve and intact ventricular septum in our hospital and underwent bidirectional cavopulmonary anastomosis concomitant with division of the main pulmonary artery (complete exclusion of the right ventricle).Reference Lee, Kim, Lee and Yoon1 At the time of admission, he had oxygen saturation of around 80% in room air. Echocardiography revealed asymmetrical ventricular septal hypertrophy without left ventricular outflow tract obstruction, good left ventricular systolic function, and mild left ventricular diastolic dysfunction. CT revealed widely patent cavopulmonary pathway and non-visualisation of the right ventricular cavity due to prior exclusion the right ventricle (Figure 1). Cardiac catheterisation was carried out. Mean pulmonary arterial pressure was 13 mmHg, left ventricular end-diastolic pressure was 10 mmHg, and pulmonary vascular resistance was calculated as 2.3 WU · m2. A collateral vessel from the innominate vein to the coronary sinus was observed and device embolisation of this collateral was performed. The patient was deemed a candidate for Fontan operation.
Pre-Fontan 3D digital blood pool model created using CT data viewed from front (a) and back (b). The right ventricular cavity is not visualised due to prior exclusion the right ventricle. IVC = inferior vena cava; LA = left atrium; LV = left ventricle; RA = right atrium; RPA = right pulmonary artery; SVC = superior vena cava.
Extracardiac conduit Fontan operation using an 18 mm polytetrafluoroethylene graft was performed with a 4 mm fenestration. Immediate postoperative central venous pressure in the operating room was around 10 mmHg, and oxygen saturation was around 80%. Postoperative CT revealed widely patent Fontan pathway (Figure 2). Echocardiography performed on the eighth postoperative day revealed no left ventricular outflow tract obstruction, good ventricular function, and scanty flow through the fenestration. Oxygen saturation was between 85 and 90% with supplemental oxygen. Cardiac catheterisation was carried out to evaluate the cause of low oxygen saturation. The Fontan pathway was widely patent. However, the central venous pressure was 18 mmHg and numerous collateral vessels originating from the innominate vein were observed (Supplementary video 1). Shunt flow through the fenestration was not observed. Embolisation of the collaterals was not performed because of the elevated central venous pressure. Sildenafil was prescribed to reduce the elevated central venous pressure. Hospital course was complicated by chylothorax, which was resolved by conservative management, and the patient was discharged on the twenty-third postoperative day.
Post-Fontan 3D digital blood pool model created using CT data viewed from front (a) and back (b), revealing widely patent Fontan pathway. IVC = inferior vena cava; LA = left atrium; LV = left ventricle; RA = right atrium; RPA = right pulmonary artery; SVC = superior vena cava; *polytetrafluoroethylene graft.
Discussion
Tricuspid atresia with absent pulmonary valve and intact ventricular septum is an exceedingly rare CHD, historically associated with a poor prognosis.Reference Litovsky, Choy and Park2 One of the characteristic morphologic features of this malformation is asymmetrical ventricular septal hypertrophy, which can potentially lead to the development of left ventricular outflow tract obstruction.Reference Lee, Kim, Lee and Yoon1,Reference Litovsky, Choy and Park2 Another possible morphologic feature is right ventricular dysplasia, in which large segments of the right ventricular myocardium are replaced with sinusoids and fibroelastic tissue.Reference Litovsky, Choy and Park2 This can cause aneurysmal change of the right ventricle and a case with overt coronary-to-right ventricular fistulas has also been reported.Reference Kasahara, Aeba and Yozu3,Reference Hasegawa, Iwai and Kugo4 The present follow-up report shows that this rare CHD can be safely palliated with Fontan operation.
For this rare malformation, only a few cases with completed Fontan operation have been reported in the literature.Reference Kasahara, Aeba and Yozu3–Reference Forrest, Bini and Wilkinson5 There is controversy regarding the surgical management of the non-functional right ventricle (Supplementary table 1). Leaving the main pulmonary artery connected to the right ventricle may cause suboptimal Fontan haemodynamics due to to-and-fro flow between the right ventricle and the pulmonary artery. Complete exclusion of the right ventricle by dividing the main pulmonary artery is another option. However, there are concerns regarding this approach due to the possibility of a potentially hypertensive right ventricle causing left ventricular outflow tract obstruction, especially in cases with right ventricular dysplasia. Hasegawa et al speculated that the inflow to the right ventricle, such as the Thebesian veins, could contribute to the increased right ventricular pressure.Reference Hasegawa, Iwai and Kugo4 For these reasons, fenestrated exclusion or no exclusion of the right ventricle were reported.Reference Kasahara, Aeba and Yozu3,Reference Hasegawa, Iwai and Kugo4,Reference Best, Vyas, Jaquiss and Sachdeva6 In our case, we have completely excluded the right ventricle at the time of bidirectional cavopulmonary anastomosis.Reference Lee, Kim, Lee and Yoon1 Our decision regarding the complete exclusion of the right ventricle was based on the absence of coronary-to-right ventricular fistulas. Long-term adverse effect of the excluded right ventricle was not observed during the pathway to Fontan completion. CT examined 4 years after the exclusion of the right ventricle revealed non-visualisation of the right ventricular cavity (Figure 1). We believe that, in the absence of significant coronary-to-right ventricular fistulas, complete exclusion of the right ventricle can be safely performed in this malformation.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1047951125001593.
Acknowledgements
We gratefully acknowledge the contributions of the MEDICAL IP (a 3D printing company, Seoul, Republic of Korea) to this study. The 3D digital models were created using software for segmentation (MEDIP Pro; MEDICAL IP, Seoul, Republic of Korea) and computer-aided design (Meshmixer; Autodesk, San Rafael, California, United States of America).
Financial support
None.
Competing interests
None.
Ethical standard
This study was reviewed and approved by the Institutional Review Board of Seoul St. Mary’s Hospital.
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