Pulmonary atresia with ventricular septal defect

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Pathophysiology

Pulmonary atresia with ventricular septal defect illustration

Pulmonary atresia with ventricular septal defect is characterized by underdevelopment of the right ventricular outflow tract with atresia of the pulmonary valve, a large VSD, and overriding of the aorta. There is a wide spectrum of severity dependent on the development of the pulmonary arteries. When a large patent ductus arteriosus is associated, pulmonary atresia with VSD is managed as a severe form of tetralogy of Fallot. In this subtype, the pulmonary arteries are usually normal in size and distribute blood to all segments of the lungs. When a small patent ductus arteriosus is present, or when there is no patent ductus arteriosus, pulmonary artery blood supply is provided partially or entirely by major aorticopulmonary collateral arteries (MAPCAs). This form of pulmonary atresia with VSD is discussed here. Intermediate forms of this cardiac anomaly exist and are approached individually, depending on the specific anatomy.

Surgical technique

The surgical technique employed to repair pulmonary atresia with ventricular septal defect with MAPCA dependent pulmonary blood supply is variable and depends on individual anatomy and surgeon preference. The vast anatomic variability seen in pulmonary atresia with VSD makes the surgical approach patient specific. The ultimate goal is complete repair, achieved by constructing central pulmonary arteries from the MAPCAs, closing the VSD, and establishing continuity between the right ventricle and reconstructed pulmonary arteries.

A staged approach to repair by performing sequential aorticopulmonary collateral artery unifocalization, or recruitment procedures, has been used in the past. However, it has largely been supplanted by early single stage total repair. Regardless of the approach

chosen for repair of this lesion, total repair with VSD closure should proceed as early as the patient’s pulmonary anatomy will allow. Measurement of right ventricular pressure following complete repair will help determine adequacy of reconstruction. Exit angiography is sometimes performed. Angiographic analysis helps identify potential areas of stenosis or areas of decreased pulmonary perfusion. Balloon dilation and/or stenting is sometimes required later.

Postoperative considerations

The postoperative course following repair of pulmonary atresia with VSD and MAPCAs may vary, and depends on individual anatomy and surgical course. Invasive monitors used include arterial and central venous catheters. An LA line is used when needed for hemodynamic management. LA pressure acts as a surrogate for left ventricular end diastolic pressure, an excellent indicator of left ventricular performance. Non-invasive monitors include NIRS (near infrared spectroscopy) probes to assess adequacy of regional and global perfusion and traditional pulse oximetry. Vasoactive agents might include epinephrine and/ or milrinone. Numerous other agents are available and are tailored to the specific needs of the patient, targeting adequate oxygen delivery to the tissues of the body and optimization of cardiac output.

Excessive postoperative bleeding can occur when extensive pulmonary artery angioplasty is required for repair. Atrioventricular conduction abnormalities are occasionally encountered, as ventricular septal defect closure requires manipulation near atrioventricular conduction tissue. Atrioventricular pacing capability should be readily available. Arterial oxygen saturation and intracardiac pressures should be normal following surgery. Length of hospital stay required following repair is variable, but 1 to 2 weeks is average.

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