Final Prep - Lung Lecture R To L Shunt

Front 1

What is a Right to Left shunt?

Back 1

• Defect between right and left atrial septum OR
• Abnormality affecting cardiac blood vessels
  

Front 2

What causes and RtL shunt?

Back 2

• Congenital
• Surgical
  

Front 3

How does a RtL shunt affect Tc99m MAA perfusion studies?

Back 3

RP is not able to blockade pulmonary capillaries as some of the MAA bypasses the pulmonary artery to enter the left side of heart where it is pumped to the rest of the system

Front 4

Why would it be preferable to do a Nuc Med study to diagnose a RtL shunt?

Back 4

• Non-invasive
• Low radiation dose (~0.038mSv/MBq)
• Alternative is invasive (cardiac catheterization) and results in higher dose of radiation (~7mSv)
  

Front 5

You have just run a perfusion study on a patient. Your image shows counts coming from the brain, kidneys, and some other organs. This is indicative of what? Why?

Back 5

Right to Left Shunt. MAA particles have become lodges in the capillary beds of other organs throughout the body.

Front 6

Why must you inject freshly made MAA?

Back 6

MAA breaks down quickly.

Front 7

If conducting a quantitative analysis, what is the normal distribution of MAA expected outside the lungs?

Back 7

<10%

Front 8

How do you calculate the % RtL shunt?

Back 8

((Total Body Count - Total Lung Count)/Total Body Count) * 100%

Front 9

If you are aware of the patient having a RtL shunt, what precaution should be taken?

Back 9

Reduce the overall number of MAA particles in the dose.