Right to left shunt

Overview
A right-to-left shunt is a cardiac shunt which allows, or is designed to cause, blood to flow from the right heart to the left heart.

A right-to-left shunt occurs when:
 * 1) there is an opening or passage between the atria, ventricles, and/or great vessels; and,
 * 2) right heart pressure is higher than left heart pressure and/or the shunt has a one-way valvular opening.

The most common cause of right-to-left shunt is the Tetralogy of Fallot, a congenital cardiac anomaly characterized by four co-existing heart defects. The four defects include:


 * 1) Pulmonary stenosis (narrowing of the pulmonary valve and outflow tract, obstructing blood flow from the right ventricle to the pulmonary artery)
 * 2) Ventricular septal defect (defect in the ventricular septum, which divides the left and right ventricles of the heart)
 * 3) Overriding aorta (aortic valve is enlarged and appears to arise from both the left and right ventricles instead of the left ventricle, as occurs in normal hearts)
 * 4) Right ventricular hypertrophy (thickening of the muscular walls of the right ventricle)

A right to left shunt frequently causes hypoxemia.

Acknowledgements
The content on this page was first contributed by: C. Michael Gibson, M.S., M.D.