RELATION OF BIOPHYSICAL RESPONSE OF COARCTED AORTIC SEGMENT TO BALLOON DILATATION WITH DEVELOPMENT OF RECOARCTATION FOLLOWING BALLOON ANGIOPLASTY OF NATIVE COARCTATION

Objective-To evaluate the role of biophysical response of the coarcted segment to balloon dilatation in the causation of aortic recoarctatio n. Setting-Tertiary care centre/university hospital. Design-Retrospect ive case series. Methods-Records of 67 consecutive infants and childre n undergoing balloon angioplasty of native aortic coarctations were ex amined for an 8.7 year period ending September 1993. At 12 months (med ian) follow up catheterisation, 15 (25%) of 59 children developed reco arctation, defined as a gradient > 20 mm Hg. Stretch (balloon circumfe rence - preballoon coarcted segment circumference/preballoon coarcted segment circumference), gain (postballoon coarcted segment circumferen ce - preballoon coarcted segment circumference), and recoil (balloon c ircumference - postballoon coarcted segment circumference) were calcul ated from measurements obtained from cineangiograms performed before a nd immediately after balloon dilatation. Results-The stretch in 44 chi ldren without recoarctation (2.18 (1.23)) was similar (p > 0.1) to tha t in 15 children with recoarctation (1.90 (0.65)), implying that simil ar balloon dilating stretch was applied in both groups. Greater gain ( p < 0.05) was observed in the group without recoarctation (8.8 (8.0) m m) than in the recoarctation group (5.7 (2.7)mm) but this was not subs tantiated in the infant population. However, the recoil was greater (p < 0.001) in the group without recoarctation (5.1 (4.3) mm) than in th e recoarctation group (2.1 (1.1) mm); this was also true in the infant group. Conclusions-Greater recoil in the patients without recoarctati on implies preservation of intact elastic tissue in the coarcted segme nt. In the recoarctation group, with less recoil, the elastic properti es may not have been preserved, thereby causing recoarctation. There m ight be a more severe degree of cystic medial necrosis in the recoarct ation group than in the no recoarctation group. This needs confirmatio n in future studies.