In a patient with a left-to-right intracardiac shunt, accidental venous air embolism is more likely to be directed toward the pulmonary circulation rather than arterial circulation because which statement is correct?

In a patient with a left-to-right intracardiac shunt, accidental venous air embolism is more likely to be directed toward the pulmonary circulation rather than arterial circulation because which statement is correct?

• A. Air will go to the brain first
• B. Blood flow is from systemic to pulmonary circulation
• C. Air cannot travel through the shunt
• D. Pulmonary circulation is bypassed by the shunt

Answer: (B)

The key idea is that the direction of blood flow through an intracardiac shunt determines where an embolus will go. In a left-to-right shunt, blood moves from the left heart (systemic circulation) into the right heart and on to the pulmonary circulation. A venous air embolism enters the venous system and naturally travels to the right heart and then into the lungs. Because the shunt directs flow from systemic to pulmonary, the embolus follows the pulmonary route rather than entering the arterial system. Getting to the brain would require a right-to-left passage (paradoxical embolism) or reversal of pressures, which isn’t the default in a left-to-right shunt. Thus, air is more likely to be directed toward the lungs rather than the brain.

The key idea is that the direction of blood flow through an intracardiac shunt determines where an embolus will go. In a left-to-right shunt, blood moves from the left heart (systemic circulation) into the right heart and on to the pulmonary circulation. A venous air embolism enters the venous system and naturally travels to the right heart and then into the lungs. Because the shunt directs flow from systemic to pulmonary, the embolus follows the pulmonary route rather than entering the arterial system. Getting to the brain would require a right-to-left passage (paradoxical embolism) or reversal of pressures, which isn’t the default in a left-to-right shunt. Thus, air is more likely to be directed toward the lungs rather than the brain.