**6.4 Valved pulmonary conduit**

This is commonly used to replace a failed or dysfunctional conduit that was placed in a previous operation as a part of the initial repair of congenital heart defects such as tetralogy of Fallot with pulmonary atresia, truncus arteriosus, and post-Ross and Rastelli procedures.

It is critical to keep in mind the location of the left main coronary artery (posterior) and the left anterior descending coronary artery (lateral) in relation to the conduit especially when anatomical details are unclear in the setting of repeat

### **Figure 9.**

*Intraoperative photo showing a surgically created pulmonary conduit by placing a bioprosthesis inside a Dacron tube graft which is sewn proximally and distally to the right ventricular outflow tract and the pulmonary arterial confluence respectively. RV: right ventricle, D: Dacron tube graft, P: pulmonary bioprosthesis.*

### *Surgical Options for Pulmonary Valve Pathology in the Current Era DOI: http://dx.doi.org/10.5772/intechopen.100297*

operations. The conduit itself while in most cases is located to the left of the sternum, and in certain congenital heart defects, it may be immediately behind the sternum, or in the midline such as cases of the previous repair of truncus arteriosus. This may require modification of the surgical technique during reoperation or initiation of cardiopulmonary bypass *via* peripheral cannulation to avoid injury to the conduit during repeat sternotomy. The majority of these conduits (homografts) are calcified to various degrees, which may increase the difficulty during the replacement. It may also require a complete explantation of the conduit to be able to replace a new one.

We have used different techniques in these situations depending on the quality of the previous conduit and the degree of calcification present:


Regarding mechanical prostheses, it is important not to oversize them even if there is enough room to place a large prosthesis. Having a mild gradient across the prosthesis (10-15 mmHg) and a higher velocity facilitate leaflet mobility in a more effective way. When the prosthesis is oversized and the gradient is quite low (<5 mmHg), then only one disk may open properly, while the other is poorly moving, which increases the risk of thrombosis.

Finally, the heart is adequately de-aired and cardiopulmonary bypass is discontinued. Post-procedure TEE is performed, and direct pressure measurements of the right ventricular and pulmonary arterial pressures are obtained.
