Reversibility of hypertensive vascular changes after coarctation repair in dogs

A silk ligature was tied around the aorta at the site of the ligamentum arteriosum in beagle puppies aged 8 wk, and the aortic coarctation was corrected 8 mo later, when the aortic peak-to-peak systolic pressure gradient was 6.0 (SD 0.7) kPa. Similar thoracotomy was performed as a sham operation on the control animals on both occasions. One y after the coarctation repair, there was practically no systolic pressure gradient across the aortoplasty site at rest [0.5 (1.0) kPa]. Histologic examination 12 mo after the correction operation showed the medial and intimal layers of the aortic arch in the aortoplasty group (n = 8) were significantly thicker than those in the control group (n = 7) [media 1.86 (0.06) versus 1.78 (0.08) mm and intima 53.2 (13.3) versus 38.3 (10.9) microns, respectively, p less than 0.05 for both]. The thicknesses of both intima and media of the left anterior descending and circumflexing coronary arteries and descending aorta distal to the aortoplasty site were similar in both groups. The increased vascular wall thickness may cause reduced compliance of the vascular bed above the coarctation site and hypertension after correction of the coarctation. Our results support the finding that patients with repaired aortic coarctation have an increased risk of permanent vascular changes.