Pacemakers and ICDs

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Pacemakers and ICDs

• Chris McCrossin
• Thanks to Margriet Greidanus, Gord McNeil, Nadim
  Lalani, Juliette Sacks

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Outline

• Pacemakers
• Function
• Malfunction
• General complications and ED management
• Rhythm recognition
• ICDs
• Function
• Malfunction
• ED management of common ICD presentations
• TV Pacemaker Insertion
• When to do it
• When not to do it
• How to do it
• Settings

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Class I indications for Permanent Pacing in Adults

1. Third-degree AV block at any anatomic level
2. Symptomatic bradycardia resulting from 2nd degree
   AV block
3. Chronic bifascicular or trifascicular block with
   intermittent 3rd degree AV bock or type II 2nd
   degree AV block
4. Chronic bifascicular or trifascicular block with
   intermittent 3rd degree AV block or type II 2nd
   degree AV block
5. Sinus node dysfunction with symptomatic
   bradycardia or chronotropic incompetence
6. Recurrent syncope caused by carotid sinus
   stimulation

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Pacemaker Functions

1. Stimulate cardiac depolarization
2. Sense intrinsic cardiac function
3. Respond to increased metabolic demand by
   providing rate responsive pacing
4. Provide diagnostic information stored by the
   pacemaker

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Pacemaker Components

• Pulse Generator battery
• Leads
• Cathode
• Anode

Lead
IPG
Anode
Cathode
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Lead System

• Bipolar
• Lead has both negative (cathode) and anode
  (positive) electrodes
• Separated by 1 cm
• Larger diameter more prone to fracture
• Compatible with ICD

• Unipolar
• Negative (cathode) electrode in contact with the
  heart
• Positive (anode) electrode metal casing of pulse
  generator
• Prone to oversensing
• Not compatible with ICD

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Bipolar

• Current travels short distance
• Small pacing spike (lt 5 mm)

Anode
Cathode
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Unipolar

• Current travels a longer distance between
  electrodes
• Larger pacing spike (gt 20 mm)

Anode
Cathode
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Pacemaker Code
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Pacemaker Code

• Five letter code
• First 3 letters refer to anti-bradycardic
  function
• Fourth letter refers to programmability
• Fifth refers to anti-tachycardic function
• Last two letters may be left off the code if no
  programmable features or anti-tachycardic
  features exist

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Pacemaker Code

• First letter
• Chamber of the heart that is paced
• A Atrium
• V Ventricle
• D Dual

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Pacemaker Code

• Second Letter
• Chamber sensed
• Third Letter
• Response to sensing of an electrical impulse
• I inhibited by a sensed event
• T triggered by a sensed event

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Pacemaker Code

• Fourth letter
• Many pacemakers have rate modulating features
• Allows the HR to rise in response to physiologic
  demand
• Designated by an R

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Pacemaker Code Examples

• VVI
• Ventricles paced, ventricles sensed, when it
  senses it stops from triggering a beat
• DDD
• Both Chambers paced, both chambers sensed,
  inhibits if ventricular depolarization is sensed,
  triggers if only atrial depolarization is sensed
• VDD
• Capable of pacing only the ventricle, senses both
  atrial and ventricular activity, responds by
  inhibition of ventricular pacing if ventricular
  depolarization is sensed, triggers a beat if only
  atrial depolarization is sensed

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Pacemaker Complications

• Pocket Complications
• Infection
• Thrombophlebitis
• Pacemaker syndrome
• Abnormal Pacemaker function
• Failure to Pace
• Failure to Sense
• Failure to Capture
• Oversensing
• Pacemaker Mediated Tachycardia
• Psychiatric (ICDs) - Not covered

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Case

• 67 y/o M
• Pacemaker placed 2 weeks ago
• Presents with pain redness over site (looks
  infected)
• Afebrile, vitals normal, looks well
• Pain easily controlled with PO analgesics

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Pocket Complications

• Infection
• 25 with local infection have positive blood
  cultures
• Can have bacteremia without evidence of local
  infection
• Bacteriology
• Staph aureus and Staph epidermidis
• Vancomycin empirically until cultures are back

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Pocket Complications

• Thrombophlebitis
• 30-50 incidence of venous obstruction
• Thrombosis may include
• Axilla, subclavian, innominate veins, SVC
• Chronic thrombosis of the upper limb is usually
  asymptomatic b/c of collaterals
• Sequelae
• Edema, SVC syndrome, ? PE

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Case A Mrs Non Specific

• 55 yo F
• Had a dual chamber PM placed two weeks ago
• Presents complaining of feeling not quite right
• Lightheaded, fatigued
• Indication for pacemaker? well its for my
  heart

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Case B Mrs Still Ticking

• 86 yo F presents with 24 hours of chest pain
• Had dual chamber pacemaker inserted 5 weeks ago
  for SSS
• No complications
• PMHx non-contributory

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Abnormal Pacemaker Function

• Clinical Features
• In general symptoms are non-specific
• May present with palpitations, syncope,
  dizziness, chest pain, dyspnea, orthopnea,
  paroxysmal nocturnal dyspnea, or fatigue

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Abnormal Pacemaker Function

• Investigations
• Electrolytes (incl Ca, Mg, PO4)
• Troponin (as indicated)
• ECG
• CXR
• Application of magnet
• Having the pacemaker nurse interrogate the
  pacemaker

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Case
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Failure to Pace(AKA failure to generate output)

• Diagnosis
• Pacemaker does not fire when expected
• There should be a pacemaker spike between two
  native complexes occuring at an interval longer
  than the LRLI
• A complete absence of pacer spikes immediately
  after an exceeded LRLI indicates failure to
  generate output
• Application of magnet yields no pacing spikes
• What do you think is happening if you see
  intermittent pacemaker spikes on the ECG?
• Suggests that pacemaker is oversensing and NOT
  failing to generate output

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Failure to Pace

• Etiology
• Lead fracture
• Loose connection
• Insulation defect
• Battery depletion
• Oversensing

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Case
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Oversensing

• Diagnosis
• Resulting rhythm is a bradycardia
• May see intermittent or an absence of spikes
• In absence of spikes it is difficult to tell
  between failure to generate output
• Suspect if time b/w two native beats is longer
  than the LRLI without an intervening pacemaker
  spike

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Oversensing

• Etiology
• Extracardiac
• Myopotentials (pectoralis)
• Electrocautery
• Intracardiac
• Large T or U waves
• Crosstalk (dual chamber pacemakers)

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Case
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Failure to Capture

• Fusion Beat
• Pseudofusion Beat
• Indicates failure to capture

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Failure to Capture

• Diagnosis
• Pacing spike is seen on the tracing but there is
  no evidence of depolarization
• Must differentiate between fusion and
  pseudo-fusion beats

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Failure to Capture

• Etiology
• Lead Issues
• Lead dislodgment (most common)
• Twiddlers syndrome
• Perforation (rare)
• Increased threshold for capture
• Electrolytes (especially hyperK)
• Ischemia
• Scar tissue
• Metabolic disturbances (acidosis, hypothyroidism,
  hypoxemia)
• Drugs (antiarrhythmics)

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Mrs Non Specific cont

• Labs Normal
• I dont have a copy of the ECG but here is her
  CXR

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Case cont.
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Case
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Failure to Sense (AKA Undersensing)

• Diagnosis
• Occurs when a previous electrical potential is
  not detected by the pacemaker
• Detected by finding a pacemaker beat that is
  immediately followed by a native beat at an
  interval less than the LRLI
• Pacemaker output competes with the intrinsic
  rhythm of the heart
• Responsible for 1.3 of pacemaker replacements
• Example
• Pacemaker spike occurs between the QRS and the T
  wave

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Failure to Sense

• Etiology (anything that changes amplitude,
  vector, or frequency of electrical signals)
• All causes of failure to capture
• New BBBs
• PVCs
• Atrial or ventricular tachydysrhythmias
• Functional undersensing
• Complexes occur during the pacemakers refractory
  period
• Electrolyte abnormalities severe enough to widen
  the QRS

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Failure to Sense

• Management
• You dont need a magnet
• Call EPS

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Pacemaker Syndrome

• Pathophysiology
• Occurs in pacemakers that pace only the ventricle
  (e.g. VVI)
• AV sychrony is lost ? retrograde VA conduction ?
  atrial contraction against closed MV TV valve ?
  jugular venous distension atrial dilation ? sx
  of CHF and reflex vasodepressor effects

• Symptoms
• Pre/syncope
• Orthostatic dizziness
• Fatigue
• Exercise intolerance
• Weakness
• Lethargy
• Chest fullness or pain
• Cough
• Uncomfortable pulsations in neck or abdomen
• RUQ pain

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Pacemaker Syndrome

• Diagnosis
• Difficult diagnosis
• Suggested by lack of AV synchrony
• Retrograde P waves suggest ventriculoatrial
  conduction which in the context of AV
  dyssynchrony may cause atrial overload
• May also see SBP drop of gt 20 mmHg when a native
  rhythm converts to a paced rhythm

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Case
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Pacemaker Syndrome

• Management
• 1/3 of patients adapt and symptoms resolve
• 1/3 require placement of a dual chamber pacer
• Caution Symptoms of pacemaker syndrome are
  non-specific and the same as patients presenting
  with pacemaker malfunction

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Pacemaker Syndrome

• Symptoms
• Pre/syncope
• Orthostasis
• Fatigue
• Exercise intolerance
• Weakness
• Lethargy
• Chest fullness/pain
• Cough
• RUQ pain

• 20 of patients present with new complaints or
  worsening of initial symptoms that led to
  pacemaker insertion
• More commonly with single chamber pacer
• AV synchrony is lost ? retrograde VA conduction
  ?atrial contraction against a closed MV TV ?
  jugular venous distention atrial dilation ?sx
  of CHF and reflex vasodepressor effects

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Pacemaker Mediated Tachycardia

• Pathophysiology
• Similar to AVNRT
• Occurs in patients with dual lead pacemakers
• Retrograde conduction from ventricle to atria
• Sensed by atria pacer as atria
• Ventricular lead fires sooner than expected
  thinking that an atrial depolarization has just
  occurred

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Pacemaker Mediated Tachycardia

• Management
• Rarely dangerous
• Doesnt exceed rate maximum set by pacemaker
  (140)
• Magnet can work to temporarily slow rate
• Pacemaker reprogramming

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Mrs Still Ticking cont
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Myocardial Perforation

• Can happen early or late (days to weeks) post
  implantation
• Need high index of suspicion because
• Often well tolerated due to small puncture size
• May auto-tamponade
• May be asymptomatic
• May have increased pacing threshold
• CXR, Echo (if cxr negative and highly suspicious)

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Myocardial Perforation

• Symptoms
• Pericardial chest pain
• Shoulder pain
• Diaphragmatic pacin
• Skeletal muscle pacing
• Dyspnea
• Hypotension
• Hiccups

• Signs
• Pericardial rub
• Intercostal or diaphragmatic pacing
• Failure to pace or sense
• New pericardial effusion (or tamponade!)

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Pacemaker Magnet

• Does not inhibit/turn off pacemaker
• Closes a reed switch in the circuit
• Converts to asynchronous pacing
• Indications for magnet
• Pacemaker Mediated Tachycardia
• Oversensing
• Repeated firing of ICD (will turn off defib
  function, not pacing function)
• Suspected failure to capture
• Suspected failure to generate output

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Disposition

• Who needs admission?
• Failure to capture
• Failure to generate output
• Failure to sense
• Lead perforation
• Lead dislodgment

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ICDs
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ICDs

• 4 Major Functions
• Sensing
• Detection
• Provision of therapy to terminate VF/VT
• Shock
• Antitachycardia pacing
• Pacing for bradycardia

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Defibrillation Threshold

• Minimum amount of energy that will reliably
  terminate the arrhythmia
• Measured by electrocardiologist in the lab
• Threshold may be altered by
• Ischemia
• CHF
• Drugs

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Drug Interactions

• Can slow VT to the point that sustained VT isnt
  within the threshold for defibrillation
• Drugs may have a pro-arrhythmic effect
• Drugs can alter the defibrillation threshold

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ICDs

• Indications
• Syncope with unstable VT
• Ventricular dysfunction
• Long QT
• Brugada
• HOCM
• (anyone at risk of sudden cardiac death)

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ICDs

• Patients reporting shock - three possibilities
• Appropriate Shock
• Inappropriate Shock
• Phantom Shock

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Case

• 64 y/o M
• Presents to the ED after having sustained 4
  shocks from his ICD
• How should we begin?

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more history

• HPI
• Had 4 shocks, all within a matter of 30 minutes
• Was sitting at the computer, no syncope or
  pre-syncope
• Feeling unwell for 1 week nausea, vomiting,
  diarrhea
• PMHx
• Had ICD put in 1 year ago following MI
• Had prob with ICD in 1st month (multiple shocks)
  but resolved with setting adjustments
• DM II, 2 PPD smoker, CHF

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Causes of ICD Shocks

• Appropriate Shocks
• Ventricular fibrillation
• Monomorphic ventricular tachycardia
• Polymorphic ventricular tachycardia
• Torsades de pointes

• Inappropriate Shocks
• A fib
• A flutter
• A tachycardia
• SVT
• Junctional tach
• Sinus tach
• Multiple PVCs
• Oversensing of T waves
• Electromagnetic interference
• Oversensing due to lead failure or insulation
  break

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Case

• O/E
• HR 105, BP 122/80, SaO2 95 R/A
• Chest clear
• Sysolic mumur, reg rhythm, min edema, JVP 1 cm
  ASA

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ICDs

• ED presentations of patients with ICDs
• Isolated shock
• Multiple isolated shocks
• Multiple shocks within short sequence
• Electrical Storm
• Patient may symptomatic (e.g. CP/SOB/Syncope) or
  asymptomatic for any of the above

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ICDs

• Approach
• Single or multiple shocks?
• If multiple how far apart?
• Symptomatic or asymptomatic?
• Interrogation of ICD
• Determines appropriate vs inappropriate shock

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ICDs

• Management
• Single asymptomatic shock
• F/U with electrophysiologist within 1 week (dont
  need to come to ED)
• Single symptomatic shock (CP, Syncope, CHF, SOB)
• Rule out ACS, suboptimal CHF tx, electrolyte
  imbalance
• Interrogate ICD to see if appropriate shock
• If appropriate and no cause found may be referred
  to electrophysiologist as an outpatient

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ICDs

• Management
• Multiple shocks
• History/Interrogate ICD
• Inappropriate therapy?
• Adjustment of ICD detection zones (ICD nurse or
  electrophysiologist can do this)
• Rule out mechanical malfunction (lead
  malfunction, lead fracture)
• If still receiving multiple shocks in ED can
  disarm with magnet
• Appropriate therapy?
• Electrical storm
• Embolic events

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ICDs

• Multiple Shocks
• Management
• ICD inactivation
• Magnet application (2 types)

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ICDs

• Electrical Storm
• Perspective
• Defined as 3 or more episodes of sustained
  ventricular arrhythmia in a 24 hour period
• Patients with ICDs can present after receiving
  repetitive shocks
• Incidence of 15 of patients with ICDs

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ICDs

• Electrical Storm
• Management
• Rule out reversible triggers (lytes, ischemia,
  drugs, new change in settings)
• Amiodarone is considered 1st choice in the
  absence of reversible triggers
• Second line
• Sympathetic blockade (BBs, stellate ganglionic
  blockade, Class I antiarrhythmics),
• Sedation (propofol)
• Overdrive pacing
• Emergent catheter ablation (last resort)
• Some patients may choose to discontinue ICD
  therapy

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Approach to ICDs in ED
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Contraindicated procedures

• Electrocautery
• Lithotripsy
• MRI

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ICD in Cardiac Arrest

• Assume the ICD has failed
• Check rhythm
• Standard ACLS management

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Emergency Pacing
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Indications

• Bradycardia
• AV block
• BBB
• Tachycardias
• Drug induced bradycardias

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Contraindications

• Absolute Contraindications
• None
• Relative Contraindications
• Hypothermia
• Asystolic arrest
• Traumatic cardiac arrest
• Prosthetic tricuspid valve
• Sepsis

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Site Location

• All central venous access sites have been
  described
• Things to consider
• RIJ LSC have the most direct anatomical access
• SC sites are where the pacemaker is the most
  stable
• Jugular and femoral ? risk of displacement

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Procedure

• Obtain CV access
• Test balloon
• Turn pacer on
• Rate b/w 60-80
• Sensing lowest setting (asynchronous)
• Output Maximal setting (I.e. 20 mA)
• Insert the pacer to the 15 cm mark
• Inflate balloon once you are past the 15 cm mark
• Advance until you get capture
• Deflate the balloon

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Procedure

• Verification of function
• Sensing threshold
• Set the rate 10 bpm below the patients rate
  and dial up the sensitivity (pacemaker will now
  be inhibited)
• Next lower the sensing knob until the pacemaker
  starts firing again (this is the sensing
  threshold)
• Pacemaker should be lowered to just below this
  number

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Procedure

• Verification of function
• Pacing threshold
• Minimum current needed to obtain capture
• Start at a high output (20mA) and dial down until
  you lose capture
• Current should be set 2-2.5 times the threshold
  to ensure capture
• Typical setting is 2-3 mA (if gt 5mA then consider
  repositioning)

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TVP Placement under ECG Guidance

• Tip of the TVP acts as an intracardiac ECG lead
• The negative electrode from the end of the TVP
  catheter is attached to any of the precordial
  leads on the ecg machine using an alligator clip

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TVP under ECG Guidance

• High right atrium/ superior vena cava
• Negative/biphasic P waves and negative QRS
  complexes
• Low amplitude

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TVP under ECG Guidance

• Mid to low right atrium
• P wave become larger
• Inflate the balloon

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TVP under ECG Guidance

• Low right atrium to tricuspid annulus
• P wave starts to become bipolar and then positive

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TVP under ECG Guidance

• Right ventricle
• Signaled by a small positive P wave followed by a
  deeply negative QRS
• Deflate the balloon

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TVP under ECG Guidance

• Contact with the right ventricular cardium
• When the tip engages the RV endocartium the QRS
  complex will show a current of injury with STE

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TVP under ECG Guidance

• Surface ECG demonstrating capture

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Summary

• Pacemakers
• Pocket Complications
• Failure to pace, failure to capture, failure to
  capture
• PMT
• Pacemaker syndrome
• ICDs
• Function
• Malfunction
• Pacemaker Placement
• Blind technique
• ECG guided technique
• Confirmation of placement and proper settings

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The End