Repair of Truncus Arteriosus

Repair of simple truncus arteriosus

Stage I: Preparation

  • The room is cooled as much as possible to start surface cooling.
  • The patient is kept on minimal oxygen (usually room air) and maintained on relative hypoventilation.
  • Aprotinin, solumedrol (30 mg/kg), Regitine (0.1 mg/kg), and prophylactic antibiotics are administered.
  • Standard median sternotomy, harvesting of pericardium and fixation in glutaraldehyde, and heparinization are performed.
  • The right pulmonary artery is dissected free on the right side of the aorta, and a silk snare placed around it. In the event of hemodynamic instability, this can be snared down to increase coronary blood flow.
  • The aorta is cannulated high, well above the bifurcation of the truncus
  • The venous cannula is placed through the right atrial appendage.
  • Cardiopulmonary bypass is started, and the patient cooled to 18 - 20° C over a period of 20 minutes.
  • The left and right pulmonary arteries are completely mobilized past the takeoff of their first branches, and are snared and occluded.
  • During the initial cooling phase of bypass, the coronary arteries are identified, and the bifurcation of the truncal root is carefully examined. After aortic cross clamping and administration of cardioplegia, the pulmonary artery snares are removed.

Stage II: Repair

  • The pulmonary arteries are excised from the truncal root. This is performed under either circulatory arrest or about half-flow cardiopulmonary bypass. Adequate tissue should surround the orifices of the branch pulmonary arteries in order to facilitate the subsequent conduit anastomosis. Great attention is given to the location and origin of the coronary arteries so as to not injure them during excision of the pulmonary arteries.

  • If there is a main pulmonary artery segment before the bifurcation of the pulmonary artery branches, this is easily performed.

    If there is little or no main pulmonary artery tissue, then some to the truncal tissue surrounding the branch pulmonary arteries must also be removed.

    If the branch pulmonary arteries originate quite separately from each other, then the truncal root is transected proximally and distally to the take-off of the branch pulmonary arteries. This not only facilitates the excision of the pulmonary arteries, but also provides adequate tissue for the distal conduit anastomosis.

  • The defect in the truncal root is closed. Careful attention to the truncal valve and the coronary ostia is critical to this phase of the operation.

  • The defect is closed primarily in the majority of cases.

    In cases where some truncal tissue was excised during removal of the branch pulmonary arteries, it may be necessary to close the defect with a patch of pericardium.

    In cases of truncal transection, a primary end-to-end anastomosis of the truncal root to the ascending aorta is performed.

  • The ventricular septal defect is closed. A longitudinal incision is made into the right ventricle, beginning just below the truncal valve annulus. This exposes the ventricular septal defect. The incision is extended into the right ventricle just far enough to expose the defect and create a right ventricular opening of appropriate size for the conduit. If an anterior descending coronary artery or other large coronary branches cross this area, the incision must be modified to preserve this vessel. Because the outlet septum is absent, the superior aspect of the defect is closed by applying the patch to the cut edge of the right ventriculotomy just below the truncal valve.
  • The atrial septal defect is closed. The atrial septum is either retrograde through the tricuspid valve or through a small right atriotomy. If a patent foramen ovale is present, it is left alone. If a large secundum atrial septal defect is present, it is partially closed by overlapping the septum primum to the left side of the limbus, thus creating a small defect (2 to 3 mm) in the form of a patent foramen ovale. The atriotomy is closed
  • Cardiopulmonary bypass and core rewarming begun.
  • A valved allograft is then used to construct a right ventricular outflow tract. This is usually a size 8 - 12 mm conduit. The distal anastomosis is constructed first using running 6-0 polypropylene suture. The proximal end of the allograft is then sutured to the edge of the right ventriculotomy, often incorporating ventricular muscle and the superior rim of the patch on the ventricular septal defect. About 30% to 40% of the circumference of the graft is sutured in this way. A pericardial hood is then used to complete the reconstruction of the right ventricular outflow tract; the hood is attached to the remaining circumference of the allograft and to the remainder of the ventriculotomy incision.

Repair of truncus arteriosus with truncal valve replacement

Repair of truncus arteriosus with interrupted aortic arch