The development of elevated pulmonary vascular resistance in man following increased pulmonary blood flow from systemic-pulmonary anastomoses

In three patients with the tetralogy of Fallot cardiac catheterization has revealed increased pulmonary vascular resistance four to ten years following construction of systemic to pulmonary anastomoses. The continuous murmur disappeared in two patients and became barely audible in another. The initial clinical improvement was reversed in all three. As the pulmonary artery pressure rose, the pressure gradient between the right ventricle and pulmonary artery diminished in four patients and disappeared in one. In one patient cyanosis had not yet developed and the continuous murmur was audible, although pulmonary hypertension was present. In another patient massive pulmonary artery dilatation was present and the pulmonary artery pressure rose, but pulmonary vascular resistance was not strikingly increased.