Registered Cardiovascular Invasive Specialist (RCIS) Practice Test

What type of shunt is suggested by the following oxygen saturations: SVC sat= 67%, IVC sat= 71%, RA sat= 85%, RV sat= 85%, PA sat= 85%, LA sat= 98%, LV sat= 98%, AO sat= 98%?

1. R to L shunt

2. L to R shunt

3. Non-shunted

4. Congenital heart defect

The correct answer is: L to R shunt

The situation presented involves analyzing the oxygen saturations at various locations within the cardiovascular system. In this case, the saturation levels indicate a left-to-right shunt. When examining the given saturations, it's clear that the systemic (aortic) oxygen saturation is high at 98%, which suggests that there is a significant amount of oxygenated blood entering the left atrium and left ventricle. The right-sided saturations, including those from the superior vena cava (SVC) and inferior vena cava (IVC), are significantly lower—67% and 71%, respectively. This indicates that deoxygenated blood is mixing with oxygenated blood, but primarily more oxygen is being directed from the left side of the heart to the right side. In a left-to-right shunt, oxygenated blood from the left side of the heart flows back to the right side, resulting in higher oxygen saturation levels in the left heart chambers and lower levels in the right heart chambers. The oxygen saturation of the right atrium and right ventricle standing at 85% does indicate that some mixing is occurring, but it remains elevated relative to the SVC and IVC saturation levels. In summary, the higher saturations on the left side (left atrium