The Use of the Autologous Innominate Vein as a Substitute for the Pulmonary Arteries in Pulmonary Atresia and Absent PAs

Surgically repairing pulmonary atresia is a challenging problem when there is complete absence of pulmonary arteries. To restore the continuity and confluence of the lung hila, a tubal structure is required. 

Although different types of biologic or nonbiologic materials have been used for this purpose, calcification, thrombosis, peeling formation by intimal hyperplasia, shrinkage, fibrosis,strictures, and the lack of growth potential are the major drawbacks of tubes made of diverse materials, such as synthetic materials—for example, homografts, xenografts, or the pericardium. 

The authors speculated that the native innominate vein may have advantages in this situation, such as the possibility of growth, lack of immune reaction, and the absence of calcification. The innominate vein shares the same length and width as the pulmonary arteries, is accessible through the same incision, and the extensive collateral venous system facilitates the secure interruption of this pathway (1). 

The patient was a six-month-old boy who had pulmonary aresia, VSD, and no central pulmonary arteries. Both lung hila were connected to the aorta through two separate ducti arteriosus, and no large collateral existed. The gaps between the two lung hila were approximately 5 centimeters (2). 

The pulmonary arteries were reconstructed through a median sternotomy on a normothermic beating heart cardiopulmonary bypass. The innominate vein was temporarily clamped for 5 minutes before cardiopulmonary bypass, and the venous pressure in the left side of the clamping site was measured directly to check for a significant pressure change. The innominate vein was transected from its connection to the left jugular and subclavian vein and connected to the left hilar stamp with a wide anastomosis. Then, it was transected on the right side at its junction with the superior vena cava, passing behind the ascending aorta, and anastomosed to the right hilum. A 5 millimeter shunt interposed between the ascending aorta and the conduit near the right hilum. The patient tolerated the procedure well with no facial or arm edema. 

The second operation was performed one year later for total repair of the defects. The innominate wall was thicker than the original, but the tissue was flexible, stretchable, and soft, with no signs of fibrosis, calcification, or internal peeling formation. However, the internal lumen appeared to be dynamically narrow, despite elastic and stretchable wall tissue. The ventricular septal defect was an 18 millimeter Contegra graft, which was used to establish continuity between the right ventricle and the innominate vein. The Contegra graft had to cross anteriorly toward the right side due to the extremely large aorta completely deviating to the left. 

The patient was generally well in the next five years, however, serial echocardiography and CT angiography showed progressive aneurysmal dilatation of the Contegra graft and a moderate increase in gradient at the anastomotic sites between the graft and the pulmonary arteries. Aneurysmal Contegra graft dilation in some patients have been previously reported, and the mechanism(s) of failure are unknown, but mechanical stress and/or immunologic factors could be involved (3). To ensure that the Contegra graft dilatation was not secondary to distal stenosis, both pulmonary artery origins were stented. However, the dilatation continued so the decision was made to reoperate and replace the graft. 

The operative finding was the presence of a thin wall aneurysmal dilatation in the body of the Contegra graft. The innominate vein tissue was relatively thick, yet supple and slender, devoid of calcification or fibrosis. The Contegra graft was replaced with a 25 millimeter porcine valved conduit, and the pulmonary arteriess with the central stents were opened widely and anteriorly enlarged by a piece of Dacron patch with a central opening to connect to the valved conduit. The postoperative echocardiography revealed no narrowing of the pathway between the RV and the lung hila on either side. The patient is currently nine years old and is fully active in NYHA class 1 without any symptoms. 

Conclusion 

Regarding the observed acceptable quality of the innominate vein, the innominate vein may be considered as an option to substitute for the pulmonary arteries in selected patients. Possible dynamic narrowings may be managed by stenting, as the tissue is soft and not calcifie

References

1. Amirghofran, A. A., Jamshidi, K., Edraki, M., Amoozgar, H., Peiravian, F., & Nirooei, E. (2021). Using the autologous innominate vein as a substitute for pulmonary arteries in a patient with pulmonary atresia and absent pulmonary arteries. Journal of Cardiothoracic Surgery, 16, 1-4.
2. Bautista-Hernandez, Victor, et al. "True aneurysmal dilatation of a Contegra conduit after right ventricular outflow tract reconstruction: a novel mechanism of conduit failure." The Annals of Thoracic Surgery 86.6 (2008): 1976-1977.
3. Chitoor B, Sudhakar S, Elefteriades JA. Safety of left innominate vein division during aortic arch surgery. Ann Thorac Surg. 2000;70:856–8.

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