Pacemaker Overview

Pacemaker Overview
Stuart Allen
Technical Head
Southampton General
Stuart Allen 06

Indications for Pacing The normal & pathological ECG Stuart Allen 06

Impulse Formation and Conduction Disturbances Stuart Allen 06

“ Normal Heart Rhythm” (Function) Stuart Allen 06

Normal Heart Function Stuart Allen 06 Sinoatrial Node

Normal Heart Function Stuart Allen 06 Atrioventricular Node

Normal Heart Function Stuart Allen 06 Bundle of HIS

Normal Heart Function Stuart Allen 06 Left Bundle Branch (LBB) Anterior Fascicle of LBB Posterior Fascicle of LBB Right Bundle Branch (RBB)

Normal Heart Function Stuart Allen 06 Purkinje Fibers

Normal Heart Function Stuart Allen 06 Vent. Systole

Normal Heart Function Stuart Allen 06 Vent. Diastole

Stuart Allen 06 The ECG

Normal Values
PR Interval: 120 to 210 msec
QRS Interval: 80 to 110 msec
Stuart Allen 06

60,000 Interval = Heart Rate Stuart Allen 06 Rate:Interval Relationship

Rate:Interval Relationship Stuart Allen 06 The Rate is : ? ? Interval : 750 msec

Stuart Allen 06 The Rate is : 750 Interval : 750 msec 60,000 80 bpm Rate:Interval Relationship

Stuart Allen 06 The interval is : 50 Rate : 50 bpm 60,000 1200 ms Rate:Interval Relationship

Stuart Allen 06 Rate:Interval Relationship Interval (ms) 200 400 600 800 1000 1200 1400 1600 Rate (bpm/ppm) 300 150 100 75 60 50 43 37.5 At a paper speed of 25mm/sec

Stuart Allen 06 Rate:Interval Relationship 25 mm is 1 sec. 5 mm = 0.2 sec. 1 mm = 0.04 sec . 25 mm/second

“ Abnormal Heart Rhythm” (Indications for Pacing) Stuart Allen 06

Definitions....
Bradycardia: R < 60 bpm
Tachycardia: R > 100 bpm
Flutter: R > 250 bpm
Fibrillation: R > 350 bpm
Stuart Allen 06

Pacemaker Indication Classifications
Class I – Conditions for which there is evidence and/or general agreement that permanent pacemakers should be implanted
Class II – Conditions for which permanent pacemakers are frequently used but there is divergence of opinion with respect to the necessity of their insertion
Class IIa: Weight of evidence/opinion is in favor of usefulness/efficacy
Class IIb: Usefulness/efficacy is less well established by evidence/opinion
Class III – Conditions for which there is general agreement that pacemakers are unnecessary
Stuart Allen 06 JACC Vol. 31, no. 5 April 1998, 1175-1209

Pacemaker Indication Classifications
Evidence supporting current recommendations are ranked as levels A, B, and C:
Level A: Data derived from multiple randomised clinical trials involving a large number of individuals
Level B: Data derived from a limited number of trials involving comparatively small numbers of patients or from well-designed data analysis of nonrandomised studies or observational data registries
Level C: Consensus of expert opinion was the primary source of recommendation

Sinus Node Dysfunction
Sick Sinus Syndrome
Sinus bradycardia
Sinus arrest
SA block
Brady-tachy syndrome
Chronotropic incompetence (CI)
Stuart Allen 06

Class I Indications
Sinus node dysfunction with documented symptomatic sinus bradycardia
Symptomatic chronotropic incompetence
Class II Indications
Class IIa: Symptomatic patients with sinus node dysfunction and with no clear association between symptoms and bradycardia
Class IIb: Chronic heart rate < 30 bpm in minimally symptomatic patients while awake
Class III Indications
Asymptomatic sinus node dysfunction
Sinus Node Dysfunction – Indications for Pacemaker Implantation Stuart Allen 06 JACC Vol. 31, no. 5 April 1998, 1175-1209

Sinus Node Dysfunction – Sinus Bradycardia
Persistent slow rate from the SA node. The parameters from this waveform include:
Rate = 55 bpm
PR interval = 180 ms (0.18 seconds)
Stuart Allen 06

Sinus Node Dysfunction – Sinus Arrest
Failure of sinus node discharge resulting in the absence of atrial depolarisation and periods of ventricular asystole
Rate = 75 bpm
2.8 second arrest
Stuart Allen 06 2.8-second arrest

Sinus Node Dysfunction – SA Exit Block
Transient blockage of impulses from the SA node
Rate = 52 bpm
2.1-second pause
Stuart Allen 06 2.1-second pause

Sinus Node Dysfunction – Brady-Tachy Syndrome
Intermittent episodes of slow and fast rates from the SA node or atria
Rate during bradycardia = 43 bpm
Rate during tachycardia = 130 bpm
Stuart Allen 06

Chronotropic Incompetence (CI) Stuart Allen 06 Max Rest Heart Rate Time Start Activity Stop Activity Quick Unstable Slow Normal CI

AV Block
First-degree AV block
Second-degree AV block
Mobitz types I and II
Third-degree AV block
Stuart Allen 06

Class I Indications
3rd degree AV block associated with:
Symptomatic bradycardia (including those from arrhythmias and other medical conditions)
Documented periods of asystole > 3 seconds
Escape rate < 40 bpm in awake, symptom-free patients
Post AV junction ablation
Post-operative AV block not expected to resolve
Second degree AV block regardless of type or site of block, with associated symptomatic bradycardia
AV Block – Indications Stuart Allen 06 JACC Vol.. 31, no. 5 April 1998, 1175-1209

AV Block – Indications
Class IIa:
Asymptomatic CHB with a ventricular rate > 40 bpm
Asymptomatic Type II 2nd degree AV block
Asymptomatic Type I 2nd degree AV block within the His-Purkinje system found incidentally at EP study
First-degree AV block with symptoms suggestive of pacemaker syndrome and documented alleviation of symptoms with temporary AV pacing
Class IIb:
First degree AV block > 300 ms in patients with LV dysfunction in whom a shorter AV interval results in haemodynamic improvement

AV Block – Indications
Asymptomatic 1st degree AV block
Asymptomatic Type I 2nd degree AV block at supra-Hisian level
AV block expected to resolve and unlikely to recur (e.g., drug toxicity, Lyme Disease)

First-Degree AV Block
AV conduction is delayed, and the PR interval is prolonged (> 210 ms or 0.21 seconds)
Rate = 79 bpm
Stuart Allen 06 340 ms

Second-Degree AV Block – Mobitz I (Wenckebach)
Progressive prolongation of the PR interval until a ventricular beat is dropped
Ventricular rate = irregular
Atrial rate = 90 bpm
PR interval = progressively longer until a P-wave fails to conduct
Stuart Allen 06 200 360 400 ms ms ms No QRS

Second-Degree AV Block – Mobitz II
Regularly dropped ventricular beats
2:1 block (2 P waves to 1 QRS complex)
Ventricular rate = 60 bpm
Stuart Allen 06 P P QRS

Third-Degree AV Block
No impulse conduction from the atria to the ventricles
Ventricular rate = 37 bpm
PR interval = variable
Stuart Allen 06

Bifascicular / Trifascicular Block Stuart Allen 06

Class I Indications
Intermittent 3rd degree AV block
Type II 2nd degree AV block
Class IIa:
Syncope not proved to be due to AV block when other causes have been exluded, specifically VT
Prolonged HV interval ( > 100 ms)
Pacing-induced infra-Hisian block that is not physiological
Class IIb: None
Asymptomatic fascicular block without AV block
Asymptomatic fascicular block with 1st degree AV block
Bifascicular and Trifascicular Block (Chronic) – Indications Stuart Allen 06 JACC Vol. 31, no. 5 April 1998, 1175-1209

Bifascicular Block Stuart Allen 06 Right bundle branch block and left posterior hemiblock

Bifascicular Block Stuart Allen 06 Right bundle branch block and left anterior hemiblock

Bifascicular Block Stuart Allen 06 Complete left bundle branch block

Trifascicular Block
Complete block in the right bundle branch and complete or incomplete block in both divisions of the left bundle branch
Stuart Allen 06

ECG Recording:
Rate
Rhythm
regular or irregular?
if irregular, is there a pattern? (e.g. 2:1 or 3:1 block or Wenckebach)
QRS-complexes? Width?
P-waves? In what relation to QRS-complexes?
PR-Interval with normal duration (120-210 ms) or irregular? Continuously increasing P-R interval?
Stuart Allen 06

What is a Pacemaker? Stuart Allen 06

What is a Pacemaker? A Pacemaker System consists of a Pulse Generator plus Lead (s) Stuart Allen 06

Pulse generator: power source or battery
Leads or wires
Cathode (negative electrode)
Anode (positive electrode)
Body tissue
Implantable Pacemaker Systems Contain the Following Components: Stuart Allen 06 IPG Lead Anode Cathode

Contains a battery that provides the energy for sending electrical impulses to the heart
Houses the circuitry that controls pacemaker operations
The Pulse Generator: Stuart Allen 06 Circuitry Battery

Stuart Allen 06 Battery Connector Hybrid Telemetry antenna Output capacitors Reed (Magnet) switch Clock Defibrillation protection Atrial connector Ventricular connector Resistors Anatomy of a Pacemaker

Stuart Allen 06 Components of an IPG

Deliver electrical impulses from the pulse generator to the heart
Sense cardiac depolarisation
Leads Are Insulated Wires That: Stuart Allen 06 Lead

Pacing Lead Components
Conductor
Connector Pin
Insulation
Electrode
Stuart Allen 06 Conductor Tip Electrode Insulation Connector Pin

How do pacemakers work? Stuart Allen 06

How do pacemakers work?
Modes and Codes
NBG Code
Mode Selection
Indications for Pacing
Pacing Modes
Sensing & Pacing
Pacemaker Timing
Pacemaker Therapies (Operation) & Diagnostics
Stuart Allen 06

Modes and Codes Stuart Allen 06

NBG Code Stuart Allen 06 V: Ventricle V: Ventricle T: Triggered P: Simple programmable P: Pace A: Atrium A: Atrium I: Inhibited M: Multi- programmable S: Shock D: Dual (A+V) D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S) O: None O: None O: None R: Rate modulating O: None S: Single (A or V) S: Single (A or V) O: None I Chamber Paced II Chamber Sensed III Response to Sensing IV Programmable Functions/Rate Modulation V Antitachy Function(s)

Mode Selection for Optimal Pacing Therapy Stuart Allen 06

Providing Optimal Pacing Therapy
Heart rate increase
Stroke volume maximisation
Atrial based pacing
Normal ventricular activation sequence
(Patient outcomes and costs if optimal pacing therapy/mode is not chosen)
Stuart Allen 06

Cardiac Output Cardiac Output (l/min)= Heart Rate x Stroke Volume Stuart Allen 06

Heart Rate Stuart Allen 06 x x x x SV x HR Age 65-80 (N=16) 130 120 110 100 90 80 70 Heart Rate (BPM) Stroke Volume (mL/Min) Cardiac Output (L/Min) Rodehefer RJ, Circ .; 69:203, 1984. 6 7 8 9 10 11 12 13 14 15 16 13 17 18 70 80 90 100 110 120 130 140 150 160 x

Proven Benefits of Atrial Based Pacing Stuart Allen 06 Study Results Higano et al. 1990 Gallik et al. 1994 Santini et al. 1991 Rosenqvist et al. 1991 Sulke et al. 1992 Improved cardiac index during low level exercise (where most patient activity occurs) Increase in LV filling 30% increase in resting cardiac output Decrease in pulmonary wedge pressure Increase in resting cardiac output Increase in resting cardiac output, especially in patients with poor LV function Decreased incidence of mitral and tricuspid valve regurgitation

Proven Benefits of Atrial Based Pacing Stuart Allen 06 Study Results Rosenquist 1988 Santini 1990 Stangl 1990 Zanini 1990 Less atrial fibrillation (AF), less CHF, improved survival after 4 years compared to VVI Less AF, improved survival after 5 years average Less AF, improved survival after 5 years compared to VVI Suppression of atrial dysrhythmias Improved morbidity (less AF, CHF, embolic events) after 3 plus uears, compared to VVI

Patient Mode Preference Stuart Allen 06 DDDR 59% DDIR 13% Any Dual 9% No Preference 9% DDD 5% VVIR 5% Sulke N, et al. J AM Coll Cardiol; 17(3):696-706, 1991

Optimal Pacing Mode (BPEG)
Sinus Node Disease - AAI (R)
AVB - DDD
SND + AVB - DDDR + DDIR
Chronic AF + AVB - VVI (R)
CSS / MVVS - DDI
Stuart Allen 06

Alternative Pacing Mode
Sinus Node Disease - AAI
AVB - VDD
SND + AVB - DDD + DDI
Chronic AF + AVB - VVI
CSS - DDD / VVI
MVVS - DDD
Stuart Allen 06

Inappropriate Pacing Mode
Sinus Node Disease - VVI + VDD
AVB - AAI + DDI
SND + AVB - AAI + VVI
Chronic AF + AVB - AAI/DDD/VDD
CSS - AAI+VDD
MVVS - AAI/VVI/VDD
Stuart Allen 06

Mode Selection Decision Tree Stuart Allen 06 DDIR with SV PVARP DDDR with MS N VVI VVIR Are they chronic? Y Y N DDD, VDD DDDR DDDR Y N Is AV conduction intact? Is SA node function presently adequate? Symptomatic bradycardia Are atrial tachyarrhythmias present? Is SA node function presently adequate? Is AV conduction intact? Y Y N AAIR DDDR DDD, DDI with RDR N N (SSS) (CSS, VVS) N

Summary of Pacemaker Indications
Sinus node dysfunction
AV block (Congenital, acquired, surgical)
Bifascicular and trifascicular block
Hypersensitive Carotid Sinus Syndrome (CSS)
[ Malignant Vasovagal Syncope (MVVS) ]
Pacing after cardiac transplantation
Heart Failure / HOCM / AF
( AHA/ACC and BPEG indications )
Stuart Allen 06

Pacing Modes Stuart Allen 06

Pacing Modes Stuart Allen 06 Output circuit VVI AMP Ventricular Demand

Stuart Allen 06 Pacing Modes Programmed lower rate 50 mm/s VVI

Pacing Modes Stuart Allen 06 Output circuit VVIR AMP Sensor Ventricular Demand

Pacing Modes Stuart Allen 06 VVI R Programmed lower rate 50 mm/s Sensor indicated rate

Pacing Modes Stuart Allen 06 Programmed lower rate 50 mm/s Sensor indicated rate VVI R

Pacing Modes Stuart Allen 06 Output circuit AAI AMP Atrial Demand

Pacing Modes Stuart Allen 06 Programmed lower rate 50 mm/s AAI

Pacing Modes Stuart Allen 06 Output circuit AAIR AMP Atrial Demand Sensor

Pacing Modes Stuart Allen 06 Programmed lower rate 50 mm/s AAIR Sensor indicated rate

Pacing Modes Stuart Allen 06 Output circuit VAT AMP Atrial Synchronised

Pacing Modes Stuart Allen 06 Output circuit DVI AMP A-V Sequential Output circuit Output circuit VDD AMP AMP

Pacing Modes Stuart Allen 06 VDD = Refract.Sensing = Blanking = Refract.periode = Stimulatie = Sensing V A

Pacing Modes Stuart Allen 06 Output circuit DVI AMP A-V Sequential Output circuit

Pacing Modes Stuart Allen 06 Programmed lower rate 50 mm/s DVI

Pacing Modes Stuart Allen 06 Output circuit DVIR AMP A-V Sequential Output circuit Sensor

Pacing Modes Stuart Allen 06 Output circuit DDI(R) AMP Output circuit Timing & Control AMP A-V Universal Sensor

Pacing Modes Stuart Allen 06 Output circuit DVI AMP A-V Sequential Output circuit Output circuit DDD AMP A-V Universal Output circuit Timing & Control AMP

Stuart Allen 06 Pacing Modes Output circuit DVI AMP A-V Sequential Output circuit Output circuit DDDR AMP A-V Universal Output circuit Timing & Control AMP Sensor

Pacing Modes - Summary Stuart Allen 06 Output circuit VVI AMP Ventricular Demand Output circuit VAT AMP Atrial Synchronised Output circuit AAI AMP Atrial Demand Output circuit DVI AMP A-V Sequential Output circuit Output circuit VDD AMP Atrial synchronised Ventricular Inhibited AMP Output circuit DDD AMP A-V Universal Output circuit Timing & Control AMP

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Pacemaker Overview

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