Subclavian flap angioplasty: Experimental study in growing piglets

Abstract

Persistent stenosis or recoarctation remains the major long-term complication of repair of coarctation of the aorta in infancy. This present study was undertaken to observe the growth of the thoracic aorta in piglets following subclavian flap angioplasty across normal and abnormal retained aortic segments utilizing two conventional suturing techniques. Subclavian flap angioplasty was performed with 6-0 monofilament polypropylene in 12 piglets (body weight 13.3 ± 2.3 kg SD) after measuring the aortic diameter and excising 50% of the aortic wall to simulate an aortic coarctation. In six piglets the medial and lateral sides of the subclavian flap were sewn into the aorta by means of a continuous suture technique (Group I); in the remaining animals suture lines were completed with an interrupted technique (Group II). In three animals in each group the remaining aortic isthmus was injected circumferentially and intramurally with a 10% neutral buffered formalin solution to simulate an abnormal aortic wall. The animals were killed 6 months following operation when their weight had increased eightfold. The thoracic aorta was excised, aortography was performed under high pressure, and the vessel diameters were measured. Burst testing for strength was carried out and photographs were made. There were no postoperative complications or deaths. All anastomoses were patent, and all vessels withstood burst testing at 300 mm Hg mean pressure. No hemodynamically significant strictures were seen in either group, with the greatest reduction and in diameter being 36%. However, in Group I animals intraluminal suture material was associated with adherent thrombus in one animal. These results indicate that, regardless of the suture technique or the growth potential of the retained aortic segment after subclavian flap angioplasty, subsequent satisfactory growth of the aortic area will occur. A strong, nonstenotic vessel results. However, the use of continuous suture technique in fashioning the subclavian flap angioplasty should be avoided, since suture material may erode into the lumen and may form a nidus for thrombus generation.