Pacemaker for beginners

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Pacemaker for beginners

• KITA yosuke
• Iizuka Hospital

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Objectives

• Review basic pacemaker terminology and function
• Discuss diagnosis and management of pacemaker
  emergencies

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Historical Perspective

• Electrical cardiac pacing for the management of
  brady-arrhythmias was first described in 1952
• Permanent transvenous pacing devices were first
  introduced in the early 1960s

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Pacemaker Components

• Pulse Generator
• Electronic Circuitry
• Lead system

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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

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Electronic Circuitry

• Determines the function of the pacemaker itself
• Utilizes a standard nomenclature for describing
  pacemakers

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Pacemaker Nomenclature
I II III IV V
Chamber Paced Chamber Sensed Response to Sensing Rate Modulation, Programmability Anti-tachycardia Features
AAtrium AAtrium TTriggered PSimple PPacing
VVentricle VVentricle IInhibited MMulti-programmable SShock
DDual DDual DDual RRate Adaptive DDual
ONone ONone ONone CCommunicating
ONone
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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

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Electrocardiogram During Cardiac Pacing

• Pacemaker has two main functions
• Sense intrinsic cardiac electrical activity
• Electrically stimulate the heart
• 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

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Pacer spike
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Electrocardiogram

• Dual chamber pacer is more complicated because
  the pacer has the ability to both sense and pace
  either the atrium or the ventricle
• Possible to have only atrial, only ventricular or
  both atrial and ventricular pacing
• DDD pacer is a common example of this

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Atrial Spike
Ventricular Spike
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Ventricular Pacing
AV Pacing
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Magnet Placement

• The EKG technician should perform a 12 lead
  cardiogram and then a rhythm strip with a magnet
  over the pacer
• Often a very poorly understood concept by the
  non-cardiologist
• 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

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Class I Indications For Permanent Pacing

• Third degree AV block associated with
• Symptomatic bradycardia
• Symptomatic bradycardia secondary to drugs
  required for dysrhythmia management
• Asystole gt 3 seconds or escape rate lt 40
• After catheter ablation of the AV node
• Post-op AV block not expected to resolve
• Neuromuscular disease with AV block

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Indications

• Symptomatic bradycardia from second degree AV
  block
• Bifascicular or trifascicular block with
  intermittent third degree or type II second
  degree block
• Sinus node dysfunction with symptomatic
  bradycardia
• Recurrent syncope caused by carotid sinus
  stimulation

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Indications

• Post myocardial infarction with any of
• Persistent second degree AV block with bilateral
  bundle branch block or third degree AV block
• Transient second or third degree AV block and
  bundle branch block
• Symptomatic, persistent second or third degree AV
  block

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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

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Infection

• Cellulitis or pocket infection
• Tenderness and redness over the pacemaker itself
• Avoid performing a needle aspiration damage the
  pacer
• Bacteremia Staphylococcus
• aureus and Staphylococcus epi 60-70 of the time
• Empiric antibiotics should include vancomycin
  pending culture

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Infection

• Consult the pacemaker physician
• Draw blood cultures
• Give appropriate antibiotics
• Frequently the pacer and lead system need to be
  removed

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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
• PR96, RR 33, BP 125/85, Oxygen saturation 88 RA
• CXR as shown

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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

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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

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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

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Septal Perforation

• Management
• Notify the pacer service
• Pacer wire has to be removed but not emergently
• Small VSD which heals spontaneously

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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.