Cardiac Ct - Radiographer Flashcards
Pros of cardiac CT
Minimally invasive
Quick
Relatively cheap compared to the cath lab
Ability to visualise non-flow limiting plaques
Low dose compared to cath lab
Cons of CT
Unable to precede to treatment
Struggles with fast/irregular heart rate
? Functional info
What are the clinical indications for cardiac CT
- Family history of heart disease
*atypical chest pain (negative tropin)
*previous stents
*previous grafts
*planning for ablation therapy
What are the contraindications for cardiac CT
~ arrhythmia or bradycardia
~ contrast contraindications
~ asthma - uncontrolled
What is the flow rate through the canula
7-8 mls/sec
Green or bigger (18 G)
What does mAs equal ?
Ma X time
What does a lower mAs give?
Higher noise
What are the two possible phases of the cardiac cycle that we can scan during?
End diastole ( preferred)
End systole ( can be used in patients with faster HRs)
At what % of the R-R do we want to aim to scan at?
75%
What are the 3 scan modes?
~ Helical retrospective (no modulation)
~ Helical retrospective ( modulation)
~ Axial prospective
What do we need to consider before giving beta blockers?
- IV or Oral
- any contraindications
- Complete heart block
- Asthma
- heart failure
- other medications
How can we slow the Heart rate?
Beta blockers
Pt education
Environment
How can we scan faster?
Faster rotation speeds
2 tubes
Faster table movement ( for helical acquisition)
How does AF affect scanning? And any solutions?
The scanner predicts the next beat from the last. AF causes irregular rates so this messes with the scanner.
It’s ok if there is a constant rhythm
Solutions :
- Smart arrhythmia management (SAM)
- End systolic triggering
What are ectopic beats and how can they affect scanning?
What can we do to reduce their effects?
Ectopic beats are random unpredictable heart beats.
The machine can get confused as a Beat occurs when it’s not expecting one.
We can use ectopic rejection software.
