Pacing and Device Jargon Made Simple. Dr Jonathan Timperley MB ChB MD FRCP Consultant Cardiologist Northampton General Hospital

Pacing and Device Jargon Made Simple Dr Jonathan Timperley MB ChB MD FRCP Consultant Cardiologist Northampton General Hospital

Disclosure Dr Jonathan Timperley Honorarium from Bayer

Arne Larson (1915 2001)

Pacing Lead Terminals

Unipolar Single tip electrode (cathode) Generator acts as anode Increased size of pacing artifact on ECG More susceptible to over sensing of non-cardiac signals Myopotentials EMI

Bipolar Tip electrode (cathode) and ring electrode (anode) If device allows can be programmed unipolar Reduced size of pacing artefact on ECG

WARNING At pulse generator replacement CHECK: Is the RV lead unipolar? Is the patient pacing dependent? CAN THE NEW DEVICE PACE UNIPOLAR OUT OF THE BOX????? (NOT ALL CAN)

Unipolarisation

DF4 and DF1

DF1 and DF4 Positives DF4 Smaller volume of leads in pocket Reduced risk of wrong lead into wrong port DF1 Can add azygos coil or array Can add new pace-sense IS-1 lead

Sensitivity

Sensitivity LESS SENSITIVITY = HIGHER NUMBER OF SENSITIVITY

Threshold, Output, Pulse Width, Rheobase

Strength-Duration Curve

Pacemaker Modes First Letter (PACED) Second Letter (SENSED) Third letter (ACTION WHEN EVENT SENSED) Fourth Letter ( IF PRESENT PRESENCE OF RATE RESPONSIVENESS) Fifth Letter (IF PRESENT INDICATES MULTISITE PACING) S Single A Atrial V Ventricular D Dual S Single A Atrial V Ventricular D Dual I Inhibited T Triggered D Dual (I and/or T) O No action R Rate response present A Atrial V Ventricular D Dual O Nil

VOO Asynchronous, competitive, magnent mode Risk of R-on-T Useful with diathermy interference

VVI After programmable VRB, LRI then stimulus UNLESS sensed event in that time

DDI Non-P synchronous pacing with dual chamber sensing Useful fall back mode if sensed atrial arrhythmia (often with ICD pre AAIR-DDD)

VDD Option on device but usually used with VDD pacing lead Ensures AV synchrony where possible without RA lead

DDD Physiological pacing with A -V synchrony Programmable components LRI, AVI, PVARP, VRP, URI

Refractory and Blanking Periods Atrial Blanking Period Post Atrial Ventricular Blanking Period Atrial Refractory Period Sensed AV Interval Paced AV Interval Ventricular Refractory Period Post Ventricular Atrial Refractory Period Total Atrial Refractory Period

Ventricular Safety Pacing Function to prevent inhibition of V Pacing due to far-field sensing causing asystole Without VSP, sensed event in the V channel after PAVB but before end of pavi will inhibit V pace With VSP, sensed event after PAVB but BEFORE end of VSP interval leads to V pacing VSP shorter than AV delay VSP lead to shorter AV delay and ensure that if the cause is a VE that it occurs in the safe phase of the QRS and not the T wave

Ventricular Safety Period Off

Ventricular Safety Period On

Pacemaker Mediated Tachycardia PMT or Endless loop tachycardia DDD when V paced beat conducts retrograde through AVN to generate P wave Triggered by: VPC with retrograde conduction Loss of atrial capture Atrial oversensing inhibits A pave then retrograde AV conduction Far-field A sensing of the tail of the QRS

PMT

Termination of PMT Programme longer PVARP after VPC so that retrograde P is not sensed

Reduction in RV Pacing

AV Search Hysteresis

Safe-R, MVP, AAIR-DDD RV pacing avoidance Appropriate switching between AAIR & DDD

Fusion and Pseudo Important especially with CRT Pseudofusion COUNTED in BiV pacing percentage BUT NO BiV pacing

ICD Can deliver (ATP), defibrillation and pacing Subcutaneous ICD increasingly used for primary prevention and VF secondary prevention Effective therapy for VT by interrupting the re-entrant VT circuit Programming of should be tailored where possible

ATP

Myopotentials Very high frequency low amplitude signals Related to skeletal muscle and diaphragm Increased risk with integrated bipolar lead and unipolar leads

Pacing Inhibition

VF and Pacing Inhibition

Battery Indicators ERI Elective Replacement Indicator Need generator replacement within 2 months EOL End of life Pacemaker will not function completely May revert to VOO pacing If pacing dependent or ICD admit and consider admission for all others unless very early slot for replacement available

RV Leadless Technology

LV Leadless Technology