The vanishing tricuspid annuloplasty. A new concept.

A tricuspid De Vega annuloplasty with absorbable 2-0 polydioxanone sutures was performed on 16 sheep supported by cardiopulmonary bypass. The anulus diameter was reduced by 2 to 6 mm. Four sheep died perioperatively. The 12 survivors were electively killed at 2-week intervals during a period of 6 months. Infective endocarditis was not observed. At the time of death no gradient was found on simultaneous pressure measurements of the right atrium and ventricle. Epicardial echocardiography did not reveal tricuspid stenosis or regurgitation. Macroscopically there was no thrombus and the tricuspid leaflets were of a normal appearance. A thin white cord was observed at the anulus in all animals killed after 12 weeks. The annular size remained as surgically induced until the fourth month, but it reverted to its preoperative size after 5 months. Histologically there was granulation tissue initially only around the foreign material, but then progressively it appeared also between the foreign filaments, with the development of multinucleated foreign body giant cells. At approximately 5 months most of the foreign material had been disrupted or absorbed, leaving a tenuous ring of granulation tissue, which allowed expansion of the tricuspid ring to its original circumference. By 6 months most of the foreign material had disappeared and was replaced by loose collagenous tissue. The concept of a "vanishing annuloplasty" is advanced, with particular application in children and in patients with functional tricuspid insufficiency.