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Abnormal enlargement or malposition of any vascular structure or mass adjacent to the airway can cause extrinsic airway compression. In children with previous surgery for congenital heart disease, mass effect from prosthetic devices or alteration in the anatomic position of normal structures can lead to extrinsic airway compression. Because many children have complex medical problems after cardiac surgery, wheezing may be attributed to cardiac causes and airway compression may not be investigated. Furthermore, the distal airway compression seen in these children often is not visualized on chest radiographs. MR imaging can be useful in evaluating extrinsic airway compression in these patients. We present the MR imaging of two patients with symptomatic extrinsic airway compression secondary to pulmonary arterial conduits.

From 1985 to 1990, 89 patients underwent placement of 41 aortic and 54 pulmonic cryopreserved allograft valved conduits between the right ventricle and the pulmonary arteries. Six patients underwent replacement with a second allograft conduit. Median age at operation was 4.3 years, and 20 patients were infants less than 1 year of age. Conduit sizes averaged 11 mm in the conduits placed in 20 infants and 20 mm in the 75 placed in patients more than 1 year of age. There were 7 early deaths in 89 patients (7.8%, 70% confidence levels 5.4% to 11.3%) and 9 late deaths in 82 hospital survivors (11%, 70% confidence levels 8% to 15%). Actuarial survival was 81% (70% confidence levels 75% to 86%) at 33 months, and no deaths were due to conduit problems. Late reoperation was required in 13 patients (7 for conduit obstruction, 1 for conduit valve insufficiency, and 5 for nonconduit-related problems). Six of the eight reoperations were done in patients who had small (< or = 13 mm) conduits placed during infancy. Conduit failure was similar between pulmonic and aortic allografts. There were no deaths in the eight patients who required conduit reoperation. Actuarial freedom from reoperation for conduit dysfunction was 80.5% (70% confidence levels 72% to 86%) at 53 months for the entire group and 94% (confidence levels 88% to 97%) at 44 months for patients more than 1 year of age. Cryopreserved allograft conduits have good early and midterm results and are comparable to porcine xenograft conduits. Despite a likely need for replacement within 3 years, we continue to favor the use in infants of an allograft valved conduit over a xenograft Dacron conduit. The need to replace a cryopreserved allograft conduit appears similar for conduits of aortic or pulmonic origin.

Eighty-five patients operated on before January 1976 have survived at least 30 days after insertion of a valved external conduit by the venous ventricle (usually the right) and the pulmonary arteries as a part of the repair of their congenital heart disease. Follow-up information is available on 83 patients, and mean follow-up time has been 27.7 months. Seven patients have required reoperation because of obstructive complications. Actuarial analysis indicates that the proportion of patients requiring reoperation is 4.0 +/- 2.8% at 2 years, 12.9 +/- 5.5% at 3 1/2 years, and 30.4 +/- 12.1% at 5 years. In five patients compression of the conduit between the sternum and heart was the primary cause of the obstruction. The proportion requiring reoperation for conduit compression is 2.0 +/- 2.0% at 2 years, 8.6 +/- 4.9% at 3 1/2 years, and 27 +/- 12.4% at 5 years. Age at operation is not related to the proportion of patients requiring reoperation, nor is the type of conduit. No patients have yet required reoperation for conduit compression whose operation has been done since we began systematically to position the conduit well away from the sternum. By actuarial analysis the proportion of patients surviving 5 years is 76.7%. Of those alive at follow-up examination, 78% were without limitation of activity.