Pulmonary-to-systemic shunt


A pulmonary-to-systemic shunt is a cardiac shunt which allows, or is designed to cause, blood to flow from the pulmonary circulation to the systemic circulation. This occurs when:
  1. there is a passage between two or more of the great vessels; and,
  2. pulmonic pressure is higher than systemic pressure and/or the shunt has a one-way valvular opening.
A pulmonary-to-systemic shunt functions as follows:
  1. right-to-left in the absence of arterioventricular discordance.
  2. left-to-right if the great vessels are transposed.