CPT® Code 33771

1. Indications

The procedure described by CPT® Code 33771 is indicated for patients diagnosed with transposition of the great arteries (TGA) accompanied by a ventricular septal defect (VSD) and subpulmonary stenosis. The following conditions warrant this surgical intervention:

• Transposition of the Great Arteries (TGA) - A congenital heart defect where the aorta and pulmonary arteries are incorrectly positioned, leading to inadequate oxygenation of blood.
• Ventricular Septal Defect (VSD) - An abnormal opening in the ventricular septum that allows for the mixing of oxygen-rich and oxygen-poor blood, necessitating repair to ensure proper blood circulation.
• Subpulmonary Stenosis - A narrowing of the main pulmonary artery below the pulmonary valve, which can obstruct blood flow and requires surgical intervention to alleviate the obstruction.

2. Procedure

The surgical procedure for CPT® Code 33771 involves several critical steps to repair the anatomical defects associated with TGA, VSD, and subpulmonary stenosis. The following procedural steps are undertaken:

• Accessing the Heart - The heart is accessed through a median sternotomy or thoracotomy, allowing the surgeon to reach the cardiac structures effectively. The thymus gland may be resected to facilitate access.
• Incising the Pericardium - The pericardium, which is the fibrous sac surrounding the heart, is incised, and a section is harvested for later use as a patch graft during the repair.
• Establishing Cardiopulmonary Bypass - The aorta and superior and inferior vena cava are cannulated to establish cardiopulmonary bypass, which temporarily takes over the function of the heart and lungs during the procedure. The aorta is then cross-clamped to control blood flow.
• Incising the Right Atrium - An incision is made in the right atrium to access the ventricular septal defect (VSD) through the infundibulum, which is the outflow tract leading to the pulmonary artery.
• Constructing a Baffle - A baffle is constructed to divert blood flow from the VSD to the aorta. This may involve the use of synthetic material, autologous pericardium, an allograft, or a xenograft (such as bovine pericardium or dura). If the VSD is not sufficiently large, it is enlarged to accommodate the baffle construction.
• Resecting the Atrial Septum - The atrial septum is resected to facilitate proper blood flow. A patch made of synthetic material, autologous pericardium, or a xenograft is then used to redirect systemic venous blood from the superior and inferior vena cava to the orifice of the mitral valve.
• Excluding Pulmonary Venous Blood - The pulmonary venous blood is excluded from the systemic circulation and is directed around the baffle to the tricuspid valve, ensuring proper separation of oxygenated and deoxygenated blood.
• Using Native Atrial Flaps - Alternatively, flaps of native atrial septum and atrial wall may be utilized to construct the intra-atrial baffles, depending on the specific anatomical considerations of the patient.
• Patching the Atrial Wall - The atrial wall is patched using the previously harvested section of pericardium to complete the reconstruction.
• Addressing Subpulmonary Stenosis - The subpulmonic stenosis is addressed by removing any obstructive tissue and/or enlarging the main pulmonary artery using a patch graft to ensure adequate blood flow to the lungs.
• Closing the Sternum - Following the completion of the repair, the sternum may be closed, or it may be left open to be closed in a subsequent procedure, depending on the clinical situation. Chest tubes are placed as needed to manage any postoperative fluid accumulation.

3. Post-Procedure

After the surgical repair of transposition of the great arteries with ventricular septal defect and subpulmonary stenosis, patients typically require close monitoring in a postoperative setting. Expected recovery may involve managing pain, monitoring for any complications, and ensuring proper respiratory function. The placement of chest tubes may be necessary to drain any excess fluid or air from the thoracic cavity. The surgical team will assess the patient's hemodynamic status and may perform imaging studies to evaluate the success of the repair. Follow-up care is essential to monitor the patient's recovery and to address any potential long-term complications associated with congenital heart defects.