Left-Right Shunt

Definition
  • In a Left-to-Right Shunt blood from the left heart directly to the right heart without going through the systemic circulation
Physiological Consequences
  • The physiological consequences for LR Shunts are fairly minimal at low volumes
  • Oxygenated blood from the left heart just ends up in the right heart and thus slightly increases the PO2 and decreases the PCO2 of the blood reaching the alveoli.
  • This is no big deal, there is just less work to do for the alveoli in terms of oxygenating the blood.
  • Because all blood reaching the left heart continues to be oxygenated there is no hypoxemia that results from LR Shunts
  • The only real consequence is that the cardiac output of the of the left and right hearts becomes larger than the amount of blood flowing through the systemic circulation, so the left heart has to work a little harder.
Causes