NREMT Paramedic Exam 2026 – 400 Free Practice Questions to Pass the Exam

In a left-to-right shunt, oxygenated blood from the left side of the heart is redirected to the right side. This occurs because the pressure in the left atrium and ventricle is higher than that in the right atrium and ventricle, creating a pathway for blood to flow abnormally.

The primary issue with a left-to-right shunt is that it can lead to volume overload in the right heart and increased blood flow to the lungs, potentially causing pulmonary hypertension and other complications over time. Because the left side of the heart is pumping oxygen-rich blood toward the right side, the main effect is a mix of higher oxygen saturation in the right heart compared to typical levels, leading to an increase in the amount of oxygenated blood found in the right atrium and ventricle.

Deoxygenated blood, mixed blood, and venous blood do not primarily represent the flow dynamics of a left-to-right shunt. Deoxygenated blood, which typically comes from the right side of the heart, is not being pushed into the left side in this scenario. Instead, the mechanism involves oxygenated blood flowing back towards the right side, which may complicate the heart's function over time.