Twelfth Edgar Mannheimer lecture. Competition between aortic isthmus and ductus arteriosus; reciprocal influence of structure and flow.

The family of juxtaductal coarctation includes pseudocoarctation, local stenosis and hypoplasia, atresia or interruption of aortic arch or isthmus. The cause is usually VSD with LV outflow obstruction. Abnormal length of the preductal aorta is characteristic. VSD closure makes infantile hypoplasia evolve into adult stenosis, sometimes before birth. Normal subclavian 'migration' is interrupted in 2 out of 3 cases. So-called typical coarctation is either stenosis of the isthmic orifice or the isthmus in toto. Ductus wall tissue radiates too far into the descending aortic wall. Juxtaductal coarctation is displaced from a pre- into a postductal position by flow and secondary tissue formation. A straddling ductus does not straddle the stenosis but a circular fold in the descending aortic wall, caused by ductus tissue. Patent ductus arteriosus is too frequent a complication, prolonged as well as persistent. Ductus closure causes loss of femoral pulse pressure in different ways. Infantile hypoplasia is treated by promoting its development into adult stenosis, then resection.