Interrupted aortic arch

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Patient families can visit our interrupted aortic arch (IAA) for more information and answers to common questions.

Pathophysiology

 

Interrupted aortic arch is characterized by interruption of the aortic arch distal to the left subclavian artery (Type A), proximal to the left subclavian artery (Type B), or between the innominate artery and the left common carotid artery (Type C). Blood supply to arterial distributions proximal to the interruption is provided by the ascending aorta. Blood supply to arterial distributions distal to the interruption is provided by a patent ductus arteriosus. Arterial oxygen saturation proximal to the interruption is normal, while the arterial oxygen saturation distal to the interruption is lower than normal. Closure of the patent ductus arteriosus in patients with interrupted aortic arch results in lower body hypoperfusion, acidosis, and shock. Infusion of prostaglandin E1 to maintain ductal patency is an important component of resuscitation and preoperative stabilization. Ventricular septal defect is a frequent association, especially with Types B and C. Surgical correction of this anomaly is performed during the neonatal period.

Surgical technique

Type A interrupted aortic arch without VSD or with a small VSD is usually repaired much like coarctation of the aorta with end-to-end anastomosis (see Coarctation of the Aorta). As the site of interruption moves more proximally, the patient is more likely to have a nonrestrictive VSD; a one stage repair of the aortic arch and intracardiac anomalies is performed. Repair of type B and C interrupted aortic arch requires cardiopulmonary bypass and aortic cross-clamping. Since there is interruption of the aorta, a unique cardiopulmonary bypass technique is used. The arterial limb of the cardiopulmonary bypass circuit is divided into two arms. Perfusion of the proximal aorta is accomplished with one arm, and perfusion of the distal aorta is accomplished with the other arm via cannulation of the patent ductus arteriosus. Antegrade cerebral perfusion is used during repair of the aortic arch. Direct anastomosis of the upper and lower aortic segments is usually possible. Associated defects, such as ventricular septal defect and atrial septal defect, are now repaired. Transesophageal echocardiography, proximal and distal aortic pressure measurements, and oxygen saturation comparison are used to confirm adequacy of repair. Delayed sternal closure is some-times required.

Postoperative considerations

The postoperative course following repair of type B or C interrupted aortic arch with ventricular septal defect can be variable. This operation represents a major undertaking for a neonate. Preoperative pulmonary overcirculation or recent resuscitation from ductal closure could contribute to hemodynamic instability in the postoperative period. 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. Postoperative bleeding is a rare complication, but it may occur since the surgical repair involves suture lines exposed to systemic level pressure. Atrioventricular conduction disturbance is a potential complication since the surgical procedure involves working near the atrioventricular conduction tissue. Temporary pacing capability should be readily available. Postoperative arterial oxygen saturation and intracardiac pressures should be normal. Length of hospital stay following repair of interrupted aortic arch is variable, but 2 weeks or more is average.