Congenital Tricuspid Atresia:
Clinical:
In tricuspid atresia there is no opening from the RA to the RV which results in right heart hypoplasia. There must be an obligatory right to left shunt at atrial level for survival. Some blood will reach RV (and subsequently the lungs) via a VSD if present. The larger the VSD, the more developed the right ventricle will be. If there is no VSD, then there is no flow to induce development of a right ventricle (ie: an absent right ventricle). In these cases, pulmonary flow is via the aorta through a patent ductus arteriosus. Patients with tricuspid atresia present at birth with severe cyanosis which worsens with crying. The EKG shows left axis deviation. Treatment consists of the Fontan procedure in which the ASD is closed and a RA to pulmonary artery valved conduit constructed [2]. The Fontan circuit is also used to palliate most forms of a single functional ventricle [2]. Associated defects include: ASD (or patent foramen ovale) and a VSD which are needed for survival, pulmonic stenosis is commonly seen, and hypoplastic right heart.Transposition of the great vessels is found in 30% of cases. In these patients there is usually NO associated pulmonic stenosis. The aorta arises from the hypoplastic RV and the pulmonary artery from the LV- hence, these patients typically have INCREASED pulmonary blood flow.
X-ray:
CXR will demonstrate RA enlargement which may be massive if the ASD is small, a normal or small heart with LV enlargement, markedly decreased pulmonary blood flow, and a small concave main pulmonary artery segment.MR demonstrates replacement of the anterior atrioventricular ring by fat and no evidence of continuity between the markedly enlarged right atrium and right ventricle.
REFERENCES:
(1) Pediatric Clinics of North America 1999; Waldman JD, Wernly JA.
Cyanotic congenital heart disease with decreased pulmonary blood flow in
children. 46(2): 385-402
(2) AJR 2007; Rodriguez E, et al Postoperative imaging in cyanotic congenital heart diseases: Part I, normal findings. 189: 1353-1360
