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