CPT® Code 33770

1. Indications

The procedure described by CPT® Code 33770 is indicated for patients diagnosed with transposition of the great arteries (TGA) who also present with a ventricular septal defect (VSD) and subpulmonary stenosis. The following conditions are explicitly recognized as indications for this surgical intervention:

• Transposition of the Great Arteries (TGA) - A congenital heart defect where the aorta arises from the right ventricle and the pulmonary arteries arise from the left ventricle, leading to improper circulation of oxygenated and deoxygenated blood.
• Ventricular Septal Defect (VSD) - An abnormal opening in the ventricular septum that allows for the mixing of oxygen-rich and oxygen-poor blood, which can complicate the hemodynamics of the heart.
• Subpulmonary Stenosis - A narrowing of the main pulmonary artery just below the pulmonary valve, which can impede blood flow from the right ventricle to the lungs, necessitating surgical intervention.

2. Procedure

The surgical procedure for CPT® Code 33770 involves several critical steps to effectively repair the transposition of the great arteries while addressing the associated VSD and subpulmonary stenosis. The following procedural steps are undertaken:

• Accessing the Heart - The procedure begins with the surgeon gaining access to the heart through a median sternotomy or thoracotomy. This allows for direct visualization and manipulation of the cardiac structures.
• Resection of the Thymus - The thymus gland is resected to provide better access to the heart and surrounding structures during the repair process.
• Incision of the Pericardium - The pericardium, the fibrous sac surrounding the heart, is incised, and a section is harvested for later use as a patch graft in the repair.
• Cannulation and Cardiopulmonary Bypass - The aorta and superior and inferior vena cava are cannulated to establish cardiopulmonary bypass, allowing the heart to be temporarily stopped while maintaining circulation and oxygenation of the blood.
• Cross-Clamping the Aorta - The aorta is cross-clamped to facilitate the surgical repair of the heart structures without blood flow interfering with the procedure.
• Incision of the Right Atrium - An incision is made in the right atrium to access the ventricular septal defect through the infundibulum.
• Construction of a Baffle - A baffle is constructed to divert blood flow through the VSD to the aorta. This baffle can be made from synthetic material, autologous pericardium, an allograft, or a xenograft (such as bovine pericardium or dura). If the VSD is not sufficiently large, it may be enlarged to accommodate the baffle.
• Resection of the Atrial Septum - The atrial septum is resected to facilitate proper blood flow and redirect systemic venous blood from the superior and inferior vena cava to the orifice of the mitral valve.
• Patch Placement - A patch made of synthetic material, autologous pericardium, or a xenograft is used to redirect systemic venous blood, while pulmonary venous blood is excluded and directed around the baffle to the tricuspid valve. Alternatively, native atrial septum and atrial wall flaps may be utilized to construct the intra-atrial baffles.
• Patching the Atrial Wall - The atrial wall is patched using the previously harvested section of pericardium to ensure structural integrity and proper function.
• 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 improve blood flow to the lungs.
• Closure of the Sternum - Following the completion of the repair, the sternum may be closed or left open, with the option to close it in a subsequent procedure. Chest tubes are placed as needed to manage any postoperative drainage.

3. Post-Procedure

After the surgical repair is completed, patients typically require close monitoring in a postoperative setting. The expected recovery may involve managing pain, monitoring for any complications, and ensuring proper heart function. The placement of chest tubes is common to facilitate drainage and prevent fluid accumulation around the heart. Depending on the individual patient's condition and the extent of the surgery, the sternum may be closed immediately or left open for later closure. Follow-up care will be essential to assess the success of the repair and to monitor for any potential complications related to the procedure.