Threshold tests Flashcards
What is a pacing threshold?
Minimum amount of energy required to consistently capture the cardiac tissue
When to do a threshold test?
When auto test info is abnormal or absent, or to verify a recent measurement
In an amplitude decrement test, what is held constant?
Pulse width
In a pulse width decrement test, what is held constant?
Amplitude
What is the end point of a threshold test?
Observing loss of capture
What are the 6 temporary test parameters to adjust/look at so that the device will pace in the selected chamber?
Pace polarity (where applicable)
Mode
Lower rate
AV delay
Amplitude
Pulse width
What to consider when selecting the lower rate for a threshold test?
It should be high enough to provide consistent pacing during the test
In an RV threshold test, what modes should we consider shortening the AV delay for and why?
DDD, DDI, VDD. To provide a consistently paced ventricular rhythm. Eg: 130ms
What to consider when choosing a starting amplitude and pulse width?
Need to be high enough to ensure consistent capture
What should we check on the EGM before starting thr threshold test?
The P waves and QRS complexes should be easily visualised so we can tell when LOC occurs
How to tell when loss of capture occurs in the atria?
A pacing spike is seen with no P-wave immediately after it
How to tell when loss of capture occurs in the RV?
A pacing spike is seen with no paced QRS complex straight after it
In Medtronic, what icon do we click on to review the EGM from the test?
Test strip icon at the bottom
What do we check after we have our threshold value?
Check that permanently programmed amplitude and pulse width are at an adequate safety margin
What should we consider when choosing a pacing amplitude and pulse width?
Lead maturation
