FATE OF TRILEAFLET EQUINE PERICARDIAL EXTRACARDIAC CONDUIT USED FOR THE CORRECTION OF ANOMALIES HAVING PULMONIC VENTRICLE PULMONARY ARTERIAL DISCONTINUITY

Background. External conduits used for the repair of congenital heart diseases having discontinuity between the pulmonic ventricle and the p ulmonary artery still carries a high risk of reoperation. Between June 1983 and June 1992, handmade equine pericardial conduit with fabricat ed trileaflet valve had been the conduit of choice in our institute. T he aim of this study is to clarify the temporal sequence of conduit ob struction in this material and to formulate the optimal surgical strat egies for this disease entity. Methods. One hundred forty-three patien ts have undergone extracardiac conduit repair using this conduit. Post operative catheterization performed within 2 months showed pulmonary t o systemic ventricular systolic pressure ratio of 0.57 +/- 0.17 with t he pressure gradient between pulmonic ventricle and pulmonary artery o f 21.1 +/- 17.2 mm Hg. In 63 patients among the survivors, a series of Doppler two-dimensional echocardiographic images could be clearly obt ained. Results. Moderate-to-severe degree of pulmonary insufficiency r epresented only 3.2% of all cases within 3 months, which rapidly incre ased to 14.3% at 1 to 3 years and 32.8% at 3 to 5 years, However, the rate of increase of pulmonary insufficiency diminished beyond 5 years with 34.9% at 5 to 7 years and 40.0% at 7 to 9 years. Estimated pressu re gradient calculated by Bernoulli's equation applied in the same pat ient subset was 4.1 +/- 7.9 mm Hg within 3 months, which progessively increased to 7.1 +/- 11.8 mm Hg at 1 to 3 years, 21.0 +/- 24.0 mm Hg a t 3 to 5 years, 40.2 +/- 25.9 mm Hg at 5 to 7 years, and 71.3 +/- 34.0 mm Hg at 7 to 9 years. Among patients with a pressure gradient across the conduit of more than 40 mm Hg at follow-up catheterization, the p rimary cause of the obstruction was attributed to degeneration of the valve in 7 patients, whereas sternal compression was strongly suspecte d as the primary cause in the other 8 patients. Intimal peel was not o bvious in the excised specimens. Conclusions. Degeneration of the valv e in the equine pericardial conduit became prominent at 3 to 5 years a fter the operation, whereas the pressure gradient across the conduit c ontinued to progress thereafter. A thick and hardened valve from degen eration and varying degrees of external compression by the sternum wer e delineated at the site of stenosis. (C) 1997 by The Society of Thora cic Surgeons.