Growth of composite conduits utilizing longitudinal arterial autograft in growing lambs

We examined the growth potential of a longitudinal strip of autologous aortic wall incorporated in an autologous pericardial conduit in 10 lambs (mean age 26 days, mean weight 10.1 kg). A 15 mm length of descending thoracic aorta (diameter 11.5 +/- 7 mm) was excised and replaced with a composite autograft conduit of autologous pericardium with a longitudinally inserted aortic strip 5 mm in width taken from the excised aortic tissue. Radiopaque markers along all suture lines allowed determination of growth of the aortic strip relative to growth of the composite conduit and descending aorta, in addition to growth assessment by pathologic analysis. Plain x-ray films and aortograms were performed at 7 days (baseline) and at 3, 6, 9, and 12 months. No graft became stenotic or aneurysmal. The diameter of the descending aorta distal to the conduit increased from 11.7 +/- 1.3 mm to 18.7 +/- 2.1 mm. Appropriate growth of the autograft conduit was demonstrated by a minimal change in the diameter ratio of conduit to distal aorta from 1.00 to 1.02 during a period of 12 months. The aortic strip increased to 172% +/- 19%, 148% +/- 15%, and 256% +/- 31% of baseline width, length, and area, respectively (p less than 0.05). Histologic study confirmed the maintenance of normal architecture in the aortic strip and colonization of the pericardial tissue by aortic intimal and medial elements. A clinical implant with an autologous aortic strip in an aortic homograft in a 4-year-old child with tetralogy and pulmonary atresia has also grown, according to angiography, from 15 to 21 mm in diameter at 1 year's follow-up. This study confirms that the incorporation of a free autologous arterial patch graft as part of cardiovascular reconstructive procedures permits growth.