Congenital Heart Disease Medium-term results of experimental stent implantation into the ductus arteriosus Eric Rosenthal, MD, MRCP, Shakeel A. Qureshi, MB, FRCP, A. Hussein Tabatabaie, MB, Deo Persaud, SRN, Ashok P. Kakadekar, MB, MRCP, Edward J. Baker, MD, FRCP, and Michael Tynan, MD, FRCP London, England Balloon dilation is disappointing in maintaining patency of the arterial duct. In neonatal lambs, stent implantation in the arterial duct results in significantly larger ducts with greater pulmonary blood flow than balloon dilation. Little is known, however, about the duration of duct patency after stent im- plantation. The outcome of stent implantation into the arte- rial duct in 12 lambs was observed over a period of 1 to 24 months. Stents (Wallstent in 9, Tower stent in 3) were implanted after recanalizing the occluded duct at 2 to 7 days of age. Heparin was given only during the procedure, but no further anticoagulants were used. Angiographic or postmor- tem evaluations were made at 1, 1.5, 2, 3, 4, 6, 12, 16, and 21 months in a subgroup of 9 lambs who did not undergo rein- terventions. The duct was patent in all these except for one studied at 16 months. Neointima initially developed in the center of the stent before extending toward the orifices, eventually burying the metal strands in contact with the wall. From 4 to 6 months onward stenoses were present inside some of the stents. When the stent did not protrude into the aorta, neointima extended over the duct orifice. Metal strands that were not in contact with the duct wall were incompletely covered with endothelial cells, platelets, and fibrin strands, but no thrombi were noted. Late balloon dilation of the stented duct was performed in two lambs increasing the pulmonary artery blood flow. In one lamb the neointimal lin- ing was successfully removed at 14 months with an atherec- tomy catheter. Stent implantation into the arterial duct can maintain patency up to 21 months and could be considered as an alternative to neonatal systemic to pulmonary artery shunt operations. Neointimal proliferation and stenosis for- mation, however, is a major limitation that may eventually lead to a reduction in the pulmonary artery blood flow. (Am Heart J 1996;132:657-63.) From the Department of Paediatric Cardiology, Guy's Hospital. Dr. Rosentha] is supported by a grant from the British Heart Foundation. Received for publication Sept. 26, 1995; accepted Dec. 21, 1995. Reprint requests: S.A. Qureshi, MD, Department of Paediatric Cardiology, Guy's Hospital, St. Thomas St., London, SE1 9RT, UK. Copyright © 1996 by Mosby-Year Book, Inc. 0002-8703/96/$5.00 + 0 4/1/73668 In duct-dependent cyanotic congenital heart disease, prolonged ductal patency may provide substantial palliation until corrective surgery can be under- taken. Preservation of patency of the arterial duct either by formalin infiltration at thoracotomy or by transcatheter techniques (balloon and laser-balloon dilation of the duct) has been successful only to a limited degree, thus making it of little value clinical- ly. 1-3 Recently percutaneous implantation of stain- less-steel mesh stents have been used to maintain short-term arterial duct patency in lambs. 46 Little is known, however, about the medium- to long-term ef- ficacy ofstent implantation into the arterial duct. We report on such a study in newborn lambs. METHODS Stent implantation. Stent implantation was attempted in 32 newborn Dorset lambs aged 2 to 9 days (mean 4.2 _+ 1.4 days) who weighed 2.4 to 7.3 kg (mean 4.6 _+ 1.0 kg). The acute results in the first 17 lambs have been pre- viously reported,6 as has the early outcome in the whole group. 7 General anesthesia was induced with 10 mg/kg in- tramuscular ketamine and maintained by ventilation with 50% nitrous oxide and oxygen supplemented by 2% to 8% enflurane. After a cutdown over the femoral vessels or percutaneous puncture, 5 to 7F hemostatic sheaths were placed in the femoral artery and vein, and 100 U/kg hep- arin was administered. The closed arterial duct was recanalized with 5 or 6F end-hole catheters and floppy- tipped guide wires from either the aortic end or the pulmonary artery end. A 0.018-inch guide wire was then placed across the duct from the aortic end to enable implan- tation of the stents retrogradely by a short sheath in the femoral artery. In some lambs, balloon dilation of the arte- rial duct was performed either before or after stent implan- tation. No further anticoagulants or antiplatelet agents were given. All procedures were performed under lisence from and in accordance with Home Office guidelines, s 657