Pulmonary vascular disease in shunted and nonshunted patients with tetralogy of Fallot.

Histometric analysis of pulmonary vascular disease was performed in 13 shunted and 21 nonshunted patients with tetralogy of Fallot, and in 29 normal controls. There was no significant difference in the medial thickness of the small pulmonary arteries between cases of tetralogy of Fallot and normal controls, but the media in shunted cases of tetralogy of Fallot were thicker than in the nonshunted cases. Intimal fibrosis, regarded as organized thrombi, and thrombi of small pulmonary arteries were observed generally after 4 years of age in both the shunted and nonshunted cases of tetralogy of Fallot. Intimal proliferation of musculoelastosis which was formed of longitudinal smooth muscle bundles and elastic fibers was characteristic in shunted patients, especially after the central palliation procedure, Waterston anastomosis or modified Blalock-Taussig (BT) anastomosis using the Gore-Tex tube graft. However, it was not usually seen in the BT anastomosis cases. Unexpected pulmonary hypertension due to the shunt operation is thought to be the cause of musculoelastosis, because musculoelastosis was observed even in a patient with pulmonary hypertension only 3 weeks following surgery. We therefore recommend the original BT anastomosis as the shunt procedure. When considering the use of other shunt operations in which there is a possibility of placing a pressure load on the pulmonary vascular bed, attention must be given to the size of the anastomosis or artificial tube graft.