Pacing
Hussam Tayeb
Cardiac Conduction: P Wave
Cardiac Conduction: AV Node
Cardiac Conduction: Bundle Branches
The Solution
Capture
QRS Morphologies
Undersensing
Oversensing
RV Pacing is Bad
Really Bad
RVOT Pacing
Dual Chamber Pacing
Lower Rate
Upper Tracking Rate
APVP
ASVP
PAV SAV
200 ms 170 ms
AV Intervals
SENSE!
Blanking Refractory
Time
5.0 mV
2.5 mV
1.25 mV
Sensing
Refractory Periods
The VRP is intended to prevent self-inhibition such as sensing of T-waves
AP
VPVentricular Refractory Period
(VRP)
VRP
Post Ventricular Atrial Refractory Period (PVARP)
Refractory Periods
AP
VP
A-V Interval(Atrial Refractory)
Total Atrial Refractory Period (TARP)
Dual Chamber Pacing
AP-VP AP-VS AS-VS
Dual Chamber Pacing
AS-VP
What to do when intrinsic rate becomes higher than the upper tracking rate?
PVARP
Wenckebach Operation
Prolongs the SAV until upper rate limit expires
AS AS AR APVPVP VP
TARP
SAV PAV PVARP SAV PVARP
P Wave Blocked (unsensed or unused)
TARP TARP
Upper Tracking Rate
Wenkebach
P P
2:1 Block
Mode Switching
DDD to DDI or VVI
Kenny ; The nuts and bolts of Paced ECG Interpretation
Mode Switch
Shortening SAV Lengthening SAV
Dual Chamber Pacemakers
Try to Minimise Ventricular
Pacing
Hysteresis
Normal Algorithms
Biventricular PacingCRT
Biventricular PacingCRT
CRT algorithms are
designed to maximise
ventricular pacing
Magnets
Pacemaker
ICD
Asynchronous pacing at 85 or 65 bpm
ICD detection temporarily inhibited
No permanent changes to device programming
No effect on pacing therapy
RV pacing is bad
CRT is good …………….mostly
Dual Chamber and CRT troubleshooting can be very complex make it easy on yourself and call a friend