Timing Intervals Flashcards
Which interval prevents double counting of atrial events?
Atrial Blanking
What is the nominal setting for the PAV and SAV?
- PAV = 150ms
- SAV = 120ms
The Atrial Blanking period begins with an atrial or ventricular event?
atrial event
What is the purpose of the Post Atrial Ventricular Blanking (PAVB) period?
- to prevent crosstalk from AP to ventricular channel
- is part of the ventricular EGM
What event triggers the Post Atrial Ventricular Blanking (PAVB) period?
an Atrial Pace (AP)
What is the term for when a lead in one chamber senses an intrinsic cardiac event of a different chamber?
far-field
What is the term for when a lead in one chamber senses a Paced event of a different chamber?
cross-talk
What is the definition of Far-Field?
when a lead in one chamber senses an intrinsic cardiac event of a different chamber
What is the definition of Cross-Talk?
when a lead in one chamber senses a Paced event of a different chamber and may inhibit a needed pace
What is the purpose of the Post Ventricular Atrial Blanking (PVAB) period?
- prevents Atrial sensing of vent events
- prevents far-field R-wave sensing
What is the purpose of the Post Ventricular Atrial Refractory Period (PVARP)?
- to prevent rapid pacing of the ventricles in response to atrial tachyarrhythmias
- prevents PMT
What components make up the Total Atrial Refractory Period (TARP)?
SAV and PVARP
How does PVARP prevent PMT?
- atrial events occurring in this period are sensed but not tracked so they don’t reset the SAV/PAV timer
- no tracking = no high rate pacing of the ventricles
What are the causes of Pacemaker Mediated Tachycardia?
- PVC cause retrograde P-wave that is tracked
- loss of atrial capture
- atrial undersensing
- atrial oversensing
What is the purpose of the Ventricular Refractory Period (VRP)?
- prevents T-wave oversensing
What is the purpose of the Ventricular Blanking (VB) period?
- prevents double counting of ventricular events
What is the purpose of the Total Atrial Blanking (TAB) period?
atrial events in this period are ignored and not counted for arrhythmia detection purposes
What is the Total Atrial Refractory Period (TARP)?
- the highest rate device will track atrial events in the ventricles before 2:1 block occurs
What will happen if the below occurs:
- upper tracking rate < atrial rate < TARP rate
- Pacemaker Wenchebach will occur
- the PAV will get longer until an atrial event falls into the refractory period (AR) and is not tracked and paced by the ventricles
What will happen if the below occurs:
upper tracking interval < TARP interval
- Pacemaker Wenchebach will occur
- the PAV will get longer until an atrial event falls into the refractory period (AR) and is not tracked (no VS/VP)
What will happen if the below occurs:
TARP < upper tracking interval
- 2:1 block will occur
- every other atrial event will fall into refractory (AR) and not be tracked by the ventricles (no VS/VP)
What will happen if the below occurs:
TARP rate < atrial rate
- 2:1 block will occur
- every other atrial event will fall into refractory (AR) and not be tracked by the ventricles (no VS/VP)
What will happen if the below occurs:
atrial rate < TARP rate and upper tracking rate
1:1 tracking (this is the goal)
The Upper Tracking Rate should be programmed _______ than the TARP rate by __________?
- lower
- by at least 30bpm
What happens to the HR when 2:1 block occurs?
the ventricular HR drops to half of the atrial rate, causing possible negative symptoms
