Cardiac pacing for beginners
Resident Phattarasit
2008/F.ABUDAYAH 2
Clinical objectives
• Define pacemaker• Differentiate types of pacemaker• List function of pacemaker• Complication• management
First pacemaker
Arne Larsson
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
1. Third-degree AV block at any anatomic level associated with any of the following
– Symptomatic bradycardia presumed secondary to AV block
– Symptomatic bradycardia secondary to drugs required for dysrhythmia management or other medical condition
– Documented periods of asystole lasting more than 3 seconds or an escape rate of less than 40 beats/min in an awake, asymptomatic patient
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
1. Third-degree AV block at any anatomic level associated with any of the following
– After catheter ablation of the AV node – Postoperative AV block that is not expected to
resolve – Neuromuscular disease with AV block (e.g., the
muscular dystrophies)
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
2. Symptomatic bradycardia resulting from second-degree AV block regardless of type or site of block
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
3. Chronic bifascicular or trifascicular block with intermittent third-degree AV block or type II second-degree AV block
LAFBFar LAD (-30 to -90)
qR qR
rS rS rS
LPFB
LPFB + RBBB (bifascicular block)
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
4. After acute myocardial infarction with any of the following conditions:
– Persistent second-degree AV block at the His-Purkinje level with bilateral bundle branch block or third-degree AV block at the level of or below the His-Purkinje system
– Transient second- or third-degree infranodal AV block and associated bundle branch block
– Symptomatic, persistent second- or third-degree AV block
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
5. Sinus node dysfunction with symptomatic bradycardia (including sinus pauses) or chronotropic incompetence
Class I Indications for Permanent Pacing in Adults (AHA/ACC)
6. Recurrent syncope caused by carotid sinus stimulation
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Clinical Indication
1. Symptomatic bradycardia2. Symptomatic heart block
– 2nd degree heart block – 3rd or complete heart block– Bifasicular or trifasicular bundle branch blocks.
3. Prophylaxis
Pacemaker Components
• Pulse Generator (battery)• Electronic Circuitry• Lead system
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Pulse Generator (battery)
• In permanent pacemaker is encapsulated in a metal can ,to protect the generator from electromagnetic interference
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PaPulse Generator (battery)cemaker Design
• Temporary pacing system generator is externally contained in a small box
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Pulse Generator (battery)
• Transcutanus external pacing system house the generator in a piece of equipment similar to portable ECG monitor.
Pulse Generator
• Lithium-iodine cell is the current standard battery
• Advantages:– Long life – 4 to 10 years– Output voltage decreases gradually with
time making sudden battery failure unlikely
Electronic Circuitry
• Determines the function of the pacemaker itself
• Utilizes a standard nomenclature for describing pacemakers
Pacemaker Terminology
I II III IV VChamber Paced
Chamber Sensed
Response to Sensing
Rate Modulation, Programmability
Anti-tachycardia Features
A=Atrium A=Atrium T=Triggered P=Simple P=Pacing
V=Ventricle V=Ventricle I=Inhibited M=Multi-programmable
S=Shock
D=Dual D=Dual D=Dual R=Rate Adaptive D=Dual
O=None O=None O=None C=Communicating
O=None
Common Permanent Pacemakers
Lead Systems
• Endocardial leads which are inserted using a subclavian vein approach
• Actively fixed to the endocardium using screws or tines
• Unipolar or bipolar leads
Apex
Apex
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Pacemaker function
1. Pacing function2. Sensing function3. Capture function
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Pacing function
Atrial pacing: stimulation of RT atrium produce spic on ECG
preceding P wave
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Pacing function
Ventricle pacing :stimulation of RT or LT ventricle produce a spic
on ECG preceding QRS complex.
Electrocardiogram During Cardiac Pacing
• VVI- senses intrinsic cardiac activity in the ventricle and when a preset interval of time with no ventricular activity occurs it depolarizes the right ventricle causing ventricular contraction
Pacer spike
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Pacing function
AVpacing:direct stimulation of RT atrium and either
ventricles mimic normal heart conduction
Atrial Spike Ventricular Spike
AV Pacing Ventricular Pacing
DDD
DDD
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Sensing function
Sensing :Ability of the cardiac pace maker to see
intrinsic cardiac activity when it occurs.
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Sensing function
Demand: • pacing stimulation delivered only if the heart
rate falls below the preset limit.Fixed:• no ability to sense. constantly delivers the
preset stimulus at preset rate.Triggered: delivers stimuli in response to
(sensing )cardiac event.
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Capture function
Capture: Ability of the pacemaker to generate a
response from the heart (contraction) after electrical stimulation.
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Capture function
1. Electrical capture : indicated by P or QRS following and
corresponding to a pacemaker spike.2. Mechanical capture: palpable pulse corresponding to the
electrical event.
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Pacing types
• Permanent• Temporary• biventricular
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Types of pacing
1. Permanent pacemaker• Used to treat chronic heart condition • Surgically placed transvenuosly under local
anesthesia• Pulse generator placed in a pocket
subcutaneously ,can be adjusted externally
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Permanent pacemaker
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2. Temporary pacemaker• Placed during emergencies• Indicated for pts’ high degree
heart block or unstable bradycardia
• Can be placed transvenosly, epicardially,transcutanusly or transthorasicly
Types of pacing
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3. Biventricular pacemaker• Used in sever heart failure• Utilize three leads in right atrium, right ventricle and left ventricle to coordinate ventricular coordination and improve cardiac out put
Types of pacing
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INSERTION SITES
• Left Subclavian (most reliable) • Internal jugular (lower incidence of
pneumothorax) • Femoral vein • Brachial vein
Complications of Implantation
Infections
• Pacemaker insertion is a surgical procedure:– 1% risk for bacteremia– 2% risk for wound or pocket infection
• Usually occur soon after pacer insertion• Presence of a foreign body complicates
management
Complications of Implantation
Infection
• Cellulitis or pocket infection:– Tenderness and redness over the
pacemaker itself– Avoid performing a needle aspiration –
damage the pacer
Complications of Implantation
Infection
• Bacteremia: – Staphylococcus aureus and Staphylococcus
epi 60-70% of the time– Empiric antibiotics should include
vancomycin pending culture
Complications of Implantation
Infection
• Consult the pacemaker physician• Draw blood cultures• Give appropriate antibiotics• Frequently the pacer and lead system
need to be removed
Complications of Implantation
Thrombophlebitis
• venous obstruction : 30% – 50%– axillary, subclavian, and innominate veins or the
superior vena cava (SVC).
• definitive diagnosis : duplex sonography, CT
• Tx : heparin with long term warfarin
Complications of Implantation
The “Pacemaker Syndrome”
• new complaints or report a worsening of the symptoms
• syncope or near-syncope• orthostatic dizziness• fatigue• exercise intolerance• weakness
Complications of Implantation
The “Pacemaker Syndrome”
• lethargy• chest fullness or pain• cough• uncomfortable pulsations in the neck or
abdomen• right upper quadrant painother nonspecific
symptoms
Complications of Implantation
The “Pacemaker Syndrome”
• loss of AV synchrony (VVI)• If sinus node function is intact atrial contract
when the tricuspid and mitral valves are closed
• jugular and pulmonary venous pressures and may produce symptoms of congestive heart failure.
• Atrial distention can result Elevated levels of B-type natriuretic peptide (BNP)
Complications of Implantation
Pacer spike
VVI
The “Pacemaker Syndrome” Complications of Implantation
The “Pacemaker Syndrome”
• Consultation with a cardiologist • Change VVI to DDI
Complications of Implantation
Magnet Placement• The EKG technician should perform a 12 lead
cardiogram and then a rhythm strip with a magnet over the pacer
• Does not inactivate the pacer as is commonly believed
• Activate a lead switch present in the pacemaker which converts the pacer to a asynchronous or fixed-rate pacing mode
• Inhibits the sensing function of a pacemaker• Magnets are usually manufacturer specific, as are
available external reprogramming devices
Pacemaker Malfunction
• Failure to capture• Undersensing • Oversensing• Inappropriate rate
Complications of Implantation
Failure to capture
• Lead disconnection, break, or displacement • Exit block (failure of an adequate stimulus to
depolarize the paced chamber)• Battery depletion
Complications of Implantation
Complications of Implantation
Failure to capture
Failure to capture
• Exit block (failure of an adequate stimulus to depolarize the paced chamber)– ischemia or infarction of the endocardium – systemic hyperkalemia– class III antiarrhythmic drugs, such as amiodarone
Complications of Implantation
Undersensing
• Lead displacement• Inadequate endocardial lead contact• Low-voltage intracardiac p waves and QRS
complexes• Lead fracture
Complications of Implantation
UndersensingComplications of Implantation
Complications of Implantation
Failure to capture
Oversensing
• Sensing extracardiac signals: myopotentials • T wave sensing • Electromagnetic interference
– digital cellular phone
Complications of Implantation
OversensingComplications of Implantation
Inappropriate Pacemaker Rate
• Battery depletion • Ventriculoatrial conduction with pacemaker-
mediated tachycardia• 1:1 response to atrial dysrhythmias (atrial flutter)
• magnet application usually converts the pacemaker to a fixed rate in a competitive mode and terminates the tachyarrhythmia.
Complications of Implantation
Management
• History & Physical Examination – pacemaker identification card– pacemaker malfunction present : syncope, near-
syncope, orthostatic dizziness, lightheadedness, dyspnea, or palpitations.
– wound infection or pocket infection typically arises with localized pain
– pacemaker syndrome
Management
• Chest Radiograph : PA, lateral– define pacing catheter tip position and to
determine the number of pacing leads
• 12-Lead Electrocardiogram
• Consult cariologist
Management
• Electrical defibrillation : safe distance (≥10 cm) from the pulse generator (≥8 cm ACLS 2010 )
• Immediate return of pacing (capture) may not occur after defibrillation
• Temporary transcutaneous pacing
Case 1
• 67 year old male presents to the emergency room 12 hours after insertion of a pacemaker complaining of left sided chest pain and shortness of breath
• PR 96 /min , RR 33 /min, BP 125/85, Oxygen saturation 88% RA
• CXR as shown
Pneumothorax
• Occurs during cannulation of the subclavian vien
• Incidence - ?? Cardiologist dependent• Treatment:
– Asymptomatic or small – observation– Symptomatic or large – tube thoracostomy
• Notify the pacemaker physician
Case 2
• 72 year old male presents to the emergency room after a fall, tripped over a bath mat, no LOC
• Shortened and rotated left leg• Past history – pacemaker, hypertension• Nurse does an routine pre-op CXR and EKG
Septal Perforation
• Usually identified at the time of pacer insertion but leads can displace after insertion
• Can occur with transvenous pacer insertion• Keys diagnosis are a RBBB pattern on EKG and
a pacer lead displaced to the apex of the heart on CXR
Septal Perforation
• Management:– Notify the pacer service– Pacer wire has to be removed but not
emergently– Small VSD which heals spontaneously
Conclusions
• Pacemakers are becoming more common everyday
• We need to understand basic pacing terminology and modes to treat patients effectively.
• Most pacer malfunctions are due to failure to sense, failure to capture, over-sensing, or in-appropriate rate
• Standard ACLS protocols apply to all unstable patients with pacemakers.
Thank you
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