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The histological image of a surgically removed stenotic 3.5 mm modified polytetrafluoroethylene (PTFE) Blalock-Taussig shunt is shown here. The shunt had been implanted in a 7 week old infant with double outlet left ventricle, transposition of the great arteries, ventricular septal defect, and severe pulmonary stenosis. Eleven months later a coronary stent (MAC 17 × 4 mm, AMG International GmbH, Raesfeld-Erle, Germany) was successfully implanted into the shunt because of progressive shunt narrowing. After a period of one year with the infant in a stable condition, a gradual decline of oxygen saturation was noted. Follow up angiography revealed significant narrowing at the pulmonary end of the stented shunt. Subsequently, the shunt was removed during corrective surgery at the age of 31 months. The excised tissue specimen was fixed in formalin and embedded in hydroxyethylmethacrylate (Technovit 7200, Kulzer & Co, Wehrheim, Germany). Sections were obtained by sectioning of the resin block using a diamond cutter and subsequent grinding. Histology demonstrates significant narrowing of the lumen. The stent struts are neighbouring the PTFE material indicating effective stenting at the time of implantation 18 months before explantation. The bulk of obstruction is caused by neointima formation. Histology reveals the contribution of thrombus apposition to lumen narrowing in addition to neointima hyperplasia. Further neointimal growth at the lumen sided surface of the thrombus indicates a time interval of several weeks between thrombus formation and explantation.