Open surgical repair of tetralogy of Fallot in dogs

Tetralogy of Fallot is a complex congenital heart defect characterized by r ight ventricular outflow tract (RVOT) obstruction, ventricular septal defec t (VSD), dextropositioned and overriding aorta, and right ventricular hyper trophy. Tetralogy of Fallot is the most important cyanotic heart defect in dogs and accounts for approximately 4% of cardiac malformations in dogs ove rall.(1) The defect occurs in several breeds of dog, including Keeshond, Po odle, Miniature Schnauzer, Beagle, English Bulldog, Collie, Shetland Sheepd og, and several terrier breeds.(1,2) The pathophysiologic consequences of tetralogy depend on the magnitude of R -VOT obstruction. With severe RVOT obstruction, the defect allows right-to- left shunt of blood from the right ventricle through the VSD into the syste mic circulation. The results are hypoxemia, cyanosis, progressive polycythe mia, debilitating weakness and exercise intolerance, and shortened life spa n. Surgical palliation of tetralogy of Fallot by creation of a systemic-to-pul monary shunt has been described in dogs.(2,3) Long-term palliation of tetra logy of Fallot by these shunts has not been demonstrated in dogs. Definitiv e open surgical repair is considered the only viable long-term treatment fo r this defect in human children.(+) This report describes the technique for definitive open surgical repair of tetralogy of Fallot in dogs. The interm ediate-term outcome of 2 severely affected dogs that underwent this correct ion is reported.