Chapter 9 - Cyanotic lesions with diminished pulmonary blood flow

Abstract

This chapter explains cyanotic lesions with observably diminished pulmonary blood flow. In pulmonary atresia with ventricular septal defect, the ventricular septal defect lies in the same position as in tetralogy of Fallot or even more anteriorly, but there is complete obstruction to flow of blood from the right ventricle to the pulmonary artery. All the right ventricular blood enters the aorta while the site of atresia varies. Pulmonary atresia with intact ventricular septum comprises less than 1% of all cardiac malformations. In pulmonary atresia with intact ventricular septum, the trabecular portion is frequently almost obliterated by myocardial hypertrophy leaving a two-portion right ventricle. The degree of stenosis at the pulmonary valve is severe, resulting in a very high right ventricular pressure causing a high right atrial pressure and the foramen ovale is forced open so that a right-to-left shunt at atrial level develops. Ebstein's anomaly is rare and affects less than 1% of children with congenital heart disease; the degree of the abnormality varies and there is a whole spectrum of malformations ranging from mild to severe forms.