Pacemaker mediated tachycardia Flashcards
What is the underlying cause of PMT
A loss of AV synchrony
Give 5 examples of a loss of AV synchrony
1 - AF 2 - AVB 3 - PVC 4 - Atrial Oversense 5 - A Loss of capture
What MUST the patient also have for PMT to occur
Retrograde conduction in some form
Briefly describe PMT
Unsynchronized V beat travels retrograde to A where its sensed and tracked - resulting in VP
What modes must the pacemaker be programmed to
DDD / VDD
If the premature atrial contraction is sensed inside the refractory period, will this start at PMT
No - The PAC must happen outside the refractory period
Whats the limit speed wise for PMT
Can’t go faster than the max track rate
What 3 ways can you program around a PMT
PVARP extension
Rate Smoothing
Non-tracking mode
What 3 ways can I play around with the PVARP
1 - Extend PVARP
2 - Dynamic PVARP
3 - PVARP post PVC
Name two non tracking modes
DDI / VVI
Are non tracking modes a first or last resort when eliminating PMT
Last minute - only program if all other measures have failed
What is useful to calculate when dealing with PMT
Retrograde conduction time
Can retrograde conduction time change with age?
Yes - ensure to always check during follow-up
How to PMT algorhythms work
if there are 16 beats at MTR within 32ms of baseline - PVARP extended.
Why is PMT nominally programmed off
Because its defunct technology - use PVC response instead
What does PVC response do
Increases PVARP >400ms after every PVC
What does PVAB do and how long is it
Prevents crosstalk / 30ms
What is the normal length of PVARP
250 - 350ms
What happens is PVARP is too long
TARP becomes too long, therefore lower wenkebach rate and 2:1 block - consideration in healthy young patients
AV delay + PVARP =
TARP
What type of wencebach occurs if PVARP is too long
Functional, its not real. Its due to programming
