Pacemakers and ICDs

Chris McCrossin

Thanks to: Margriet Greidanus, Gord McNeil, Nadim Lalani, Juliette Sacks

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

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 block3. Chronic bifascicular or trifascicular block with intermittent 3rd

degree AV bock or type II 2nd degree AV block4. Chronic bifascicular or trifascicular block with intermittent 3rd

degree AV block or type II 2nd degree AV block5. Sinus node dysfunction with symptomatic bradycardia or

chronotropic incompetence6. Recurrent syncope caused by carotid sinus stimulation

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

Pacemaker Components

• Pulse Generator: battery

• Leads• Cathode• Anode

Lead

IPG

Anode

Cathode

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

Bipolar

• Current travels short distance

• Small pacing spike (< 5 mm)

Cathode

Anode

Unipolar

• Current travels a longer distance between electrodes

• Larger pacing spike (> 20 mm)

Anode

Cathode

Pacemaker Code

Table 1. Codes for Classification of Pacing Modes

ChamberPaced

ChamberSensed

Response toSensing

RateModulation*

Antitachycardia(AICDs)

0 = None 0 = None 0 = None 0 = None 0 = None

A = Atrium A = Atrium T = Triggered R = RateResponsive

P = Pacing

V = Ventricle V = Ventricle I = Inhibited S = Shock

D = DualChamber

D = DualChamber

D = Dual (T+I) D = Dual (P+S)

* This position may also be used to indicate the degree of programmability through thecodes P, M, and C.

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

Pacemaker Code

• First letter Chamber of the heart that is paced

• A = Atrium

• V = Ventricle

• D = Dual

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

Pacemaker Code

• Fourth letter Many pacemakers have rate modulating

features Allows the HR to rise in response to

physiologic demand Designated by an “R”

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

Pacemaker Complications

1. Pocket Complicationsa) Infectionb) Thrombophlebitis

2. Pacemaker syndrome3. Abnormal Pacemaker function

a) Failure to Paceb) Failure to Sensec) Failure to Captured) Oversensing

4. Pacemaker Mediated Tachycardia5. Psychiatric (ICD’s) - Not covered

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

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

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

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 it’s for my heart”

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

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

Abnormal Pacemaker Function

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

pacemaker

Case

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

Failure to Pace

• Etiology Lead fracture Loose connection Insulation defect Battery depletion Oversensing

Case

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

Oversensing

• Etiology Extracardiac

• Myopotentials (pectoralis)

• Electrocautery

Intracardiac• Large T or U waves

• Crosstalk (dual chamber pacemakers)

Case

Failure to Capture

• Fusion Beat• Pseudofusion Beat

Indicates failure to capture

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

Failure to Capture

• Etiology Lead Issues

• Lead dislodgment (most common)

• Twiddler’s syndrome

• Perforation (rare)

Increased threshold for capture• Electrolytes (especially hyperK)

• Ischemia

• Scar tissue

• Metabolic disturbances (acidosis, hypothyroidism, hypoxemia)

• Drugs (antiarrhythmics)

Mrs Non Specific cont…

• Labs Normal

• I don’t have a copy of the ECG; but here is her CXR…

Case cont.

Case

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

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 pacemaker’s refractory period Electrolyte abnormalities severe enough to widen the QRS

Failure to Sense

• Management You don’t need a magnet Call EPS

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

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 > 20 mmHg when a native rhythm

converts to a paced rhythm

Case

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

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

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

Pacemaker Mediated Tachycardia

• Management Rarely dangerous Doesn’t exceed rate maximum set by

pacemaker (~140) Magnet can work to temporarily slow rate Pacemaker reprogramming

Mrs Still Ticking cont…

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)

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!)

Lead dislodgmentLead fractureMyocardial fibrosisMIelectrolyte disturbances

Undersensing

Failure to Sense

Lead dislogmentTwiddler's syndromeLead fractureImproperly programmed

voltage

MIElectrolyte changesDrugs

Change in requiredvoltage

Battery failure

Failure to Capture

Lead fractureLoose connectionInsulation defectBattery depletion

IntracardiacExtracardiac

Oversensing

Crosstalk

Failure to Pace PacemakerSyndrome

Pacemaker Malfunction

Pacemaker Magnet

• Does not inhibit/turn off pacemaker• Closes a reed switch in the circuit

Converts to asynchronous pacing

• Indications for magnet1. Pacemaker Mediated Tachycardia2. Oversensing3. Repeated firing of ICD (will turn off defib

function, not pacing function)4. Suspected failure to capture5. Suspected failure to generate output

Disposition

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

ICDs

ICD’s

• 4 Major Functions1. Sensing

2. Detection

3. Provision of therapy to terminate VF/VTA. Shock

B. Antitachycardia pacing

4. Pacing for bradycardia

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

Drug Interactions

• Can slow VT to the point that sustained VT isn’t within the threshold for defibrillation

• Drugs may have a pro-arrhythmic effect

• Drugs can alter the defibrillation threshold

ICDs

• Indications Syncope with unstable VT Ventricular dysfunction Long QT Brugada HOCM

(anyone at risk of sudden cardiac death)

ICD’s

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

Case

• 64 y/o M

• Presents to the ED after having sustained 4 shocks from his ICD

• How should we begin?

… 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

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 PVC’s Oversensing of T waves Electromagnetic

interference Oversensing due to lead

failure or insulation break

Case

• O/E HR 105, BP 122/80,

SaO2 95% R/A Chest clear Sysolic mumur, reg

rhythm, min edema, JVP 1 cm ASA

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

ICDs

• Approach Single or multiple shocks?

• If multiple: how far apart?

Symptomatic or asymptomatic? Interrogation of ICD

• Determines appropriate vs inappropriate shock

ICDs

• Management Single asymptomatic shock

• F/U with electrophysiologist within 1 week (don’t 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

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

ICDs

• Multiple Shocks Management

• ICD inactivation Magnet application (2 types)

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

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 (BB’s*, stellate ganglionic blockade, Class I

antiarrhythmics), Sedation (propofol*) Overdrive pacing Emergent catheter ablation (last resort)

• Some patients may choose to discontinue ICD therapy

Approach to ICDs in ED

Contraindicated procedures

• Electrocautery

• Lithotripsy

• MRI

ICD in Cardiac Arrest

• Assume the ICD has failed

• Check rhythm

• Standard ACLS management

Emergency Pacing

Indications

• Bradycardia

• AV block

• BBB

• Tachycardias

• Drug induced bradycardias

Contraindications

• Absolute Contraindications None

• Relative Contraindications Hypothermia Asystolic arrest Traumatic cardiac arrest Prosthetic tricuspid valve Sepsis

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

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

Procedure

• Verification of function Sensing threshold

• Set the rate ~ 10 bpm below the patient’s 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

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 > 5mA then consider repositioning)

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

TVP under ECG Guidance

• High right atrium/ superior vena cava

• Negative/biphasic P waves and negative QRS complexes

• Low amplitude

TVP under ECG Guidance

• Mid to low right atrium

• P wave become larger• Inflate the balloon

TVP under ECG Guidance

• Low right atrium to tricuspid annulus

• P wave starts to become bipolar and then positive

TVP under ECG Guidance

• Right ventricle• Signaled by a small

positive P wave followed by a deeply negative QRS

• Deflate the balloon

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

TVP under ECG Guidance

• Surface ECG demonstrating capture

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

The End