CARDIAC IMPLANTABLE ELECTRONIC DEVICES (CIED) :

PACEMAKERS,IMPLANTABLE CARDIOVERTER

DEFIBRILLATORS(ICD)

Moderator : Dr Manju Mani

www.anaesthesia.co.in

anaesthesia.co.in@gmail.com

BRIEF HISTORY First totally implantable pacemaker :

into the chest of 43 yr old Arne Larsson by Dr Ake Senning in Stockholm on Oct 8 ,1958.

Introduction of external defibrillators in 1962

First internally implanted defibrillator in 1980

PACEMAKERDevice that provides electrical

stimulation to cause cardiac contraction when intrinsic cardiac electrical activity is slow or absent

PACEMAKER FUNCTIONS1. Stimulate cardiac depolarization2. Sense intrinsic cardiac function3. Respond to increased metabolic

demand by providing rate responsive pacing

INDICATIONS FOR PACEMAKER

1. Aquired AV block

- 30 AV block

Symptomatic bradycardiaAsystole >3 sec or escape rhythm <40bpmPost op AV block not expected to resolveNeuromuscular disease with AV block

- 20 AV block

Permanent or intermittent symptomatic bradycardia

2. After MI

Symptomatic 20 AVB or 30 AVB Infranodal AV block with LBBB

3. Bifascicular or Trifascicular block

intermittent complete heart block with symptoms

2 AV block Bundle branch block

4. Sinus Node Dysfunction - with symptoms as a result of long term

drug therapy - symptomatic chronotropic

incompetence

5 . Hypertensive carotid sinus & neurocardiac symptoms

- recurrent syncope associated with carotid sinus stimulation

- Asystole of > 3 sec duration in absense of any medication

PACEMAKER COMPONENTS

AND ANATOMY

PACEMAKER COMPONENTS

Pulse Generator Electronic Circuitry Lead System

PULSE GENERATOR Subcutaneous or submuscular Lithium battery 4-10 years lifespan long life and gradual decrease in power

sudden pulse generator failure is an unlikely cause of pacemaker malfunction

ELECTRONIC CIRCUITRY Sensing circuit Timing circuit Output circuit

LEAD SYSTEMBipolar Lead has both

negative, (Cathode) distal and positive, (Anode) proximal electrodes

Separated by 1 cm Larger diameter:

more prone to fracture

Compatible with ICD

Unipolar Negative

(Cathode) electrode in contact with heart

Positive (Anode) electrode: metal casing of pulse generator

Prone to oversensing

Not compatible with ICD

BIPOLAR

current travels only a short distance between electrodes

small pacing spike: <5mm

Anode

Cathode

+

-

UNIPOLAR

current travels a longer distance between electrodes

larger pacing spike: >20mm

Anode

Cathode

+

-

PACED RHYTHM RECOGNITION

VVI / 60

PACEMAKER CODE DEVELOPED AS JOINT PROJECT BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) - REVISED 2002

IChamber

Paced

IIChamberSensed

IIIResponseto Sensing

IVProgrammableFunctions/Rate

Modulation

VAntitachy

Function(s)

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 R: Rate modulating O: None

S: Single (A or V)

O: None

O: None

COMMON PACEMAKERS VVI

Ventricular Pacing : Ventricular sensing; intrinsic QRS Inhibits pacer discharge

VVIRAs above + has biosensor to provide Rate-

responsiveness DDD

Paces + Senses both atrium + ventricle, intrinsic cardiac activity inhibits pacer d/c, no activity: trigger d/c

DDDRAs above but adds rate responsiveness to

allow for exercise

RATE RESPONSIVE PACING

When the need for oxygenated blood increases, the pacemaker ensures that the heart rate increases to provide additional cardiac output

Adjusting Heart Rate to Activity

Normal Heart Rate

Rate Responsive PacingFixed-Rate Pacing

Daily Activities

DETERMINING TYPE OF PACEMAKER

Wallet card: 5 letter code

CXR: code visible

Single lead in ventricle: VVI

Separate leads DDD or DVI

SINGLE CHAMBER

VVI - lead lies in right ventricle

Independent of atrial activity

Use in AV conduction disease

DUAL CHAMBER

Typically in pts with nonfibrillating atria and intact AV conduction

PACEMAKER INTERVENTIONS

Magnet applicationNo universal function of magnetModel-specific magnet, some activate reed

switch asynchronous pacing at pre-set rate

Interrogation / ProgrammingModel-specific pacemaker programmer can

non-invasively obtain data on function and reset parameters

COMPLICATIONS OF PACEMAKER IMPLANTATION

COMPLICATIONS OF PACEMAKER IMPLANTATION Venous access Infection Thrombophelbitis Pacemaker Syndrome

VENOUS ACCESS

Bleeding Pneumo / haemothorax Air embolism

INFECTION 2% for wound and ‘pocket’ infection 1% for bacteremia with sepsis S. aureus and S. epidermidisRx : If bacteremic: start antibiotics, remove

system, new system to be placed

THROMBOPHLEBITIS Incidence 30-50% b/c of collateralization only 0.5-3.5%

devp symptoms Swelling, pain, venous engorgement Rx Heparin, lifetime warfarin

PACEMAKER SYNDROME Presents with worsening of original

symp post-implant of single chamber pacer

- hypotension, syncope,vertigo, exercise intolerance etc

AV asynchrony retrograde VA conduction atrial contraction against closed MV + TV jugular venous distention + atrial dilation sx of CHF

Rx : dual chamber pacer

Pacemaker syndrome

PACEMAKER MALFUNCTION

4 BROAD CATEGORIES1. Failure to Output2. Failure to Capture3. Inappropriate sensing: under or over4. Inappropriate pacemaker rate

FAILURE TO OUTPUTabsence of pacemaker spikes despite

indication to pace dead battery fracture of pacemaker lead disconnection of lead from pulse

generator unit Oversensing Cross-talk: atrial output sensed by

vent lead

spikes not followed by a stimulus-induced complex

change in endocardium: ischemia, infarction, hyperkalemia, class III antiarrhythmics (amiodarone, bertylium)

FAILURE TO CAPTURE

Failure to sense or capture in VVI

INAPPROPRIATE SENSING: UNDERSENSINGPacemaker incorrectly misses an

intrinsic deoplarization paces despite intrinsic activity

Appearance of pacemaker spikes occurring earlier than the programmed rate: “overpacing”

may or may not be followed by paced complex: depends on timing with respect to refractory period

AMI, progressive fibrosis, lead displacement, fracture, poor contact with endocardium

UNDERSENSING Pacemaker does not “see” the intrinsic

beat, and therefore does not respond appropriately

Intrinsic beat not sensed

Scheduled pace delivered

VVI / 60

INAPPROPRIATE SENSING: OVERSENSINGDetection of electrical activity not of

cardiac origin inhibition of pacing activity

“underpacing” pectoralis major: myopotentials

oversensed

Electrocautery MRI

OVERSENSING

An electrical signal other than the intended P or R wave is detected

Marker channel shows intrinsic

activity...

...though no activity is present

VVI / 60

INAPPROPRIATE PACEMAKER RATE Rare reentrant tachycardia seen w/

dual chamber pacers Premature atrial or vent contraction

sensed by atrial lead triggers vent contraction retrograde VA conduction sensed by atrial lead triggers vent contraction etc etc etc

Tx: Magnet application: fixed rate, terminates tachyarrthymia,

reprogram to decrease atrial sensing

CAUSES OF PACEMAKER MALFUNCTION Circuitry or power source of pulse

generator Pacemaker leads Interface between pacing electrode

and myocardium Environmental factors interfering with

normal function

PULSE GENERATOR

Loose connectionsSimilar to lead fracture Intermittent failure to sense or pace

MigrationDissects along pectoral fascial planeFailure to pace

Twiddlers syndromeManipulation lead dislodgement

TWIDDLER’S SYNDROME

LEADS

Dislodgement or fracture (anytime) Incidence 2-3%Failure to sense or paceDiagnosed with CXR, lead impedance

Insulation breaksCurrent leaks failure to captureDiagnosed with measuring lead impedance

(low)

CARDIAC PERFORATION

Early or late Usually well tolerated

Asymptomatic inc’d pacing threshold, hiccups

Diagnosis : hiccups, pericardial friction rub CXR, Echo

ENVIRONMENTAL FACTORS INTERFERING WITH SENSING

MRIElectrocauteryArc weldingLithotripsyMicrowavesMypotentials from muscle

PSEUDOMALFUNCTION: HYSTERESIS Allows a lower rate between sensed

events to occur; paced rate is higher

Lower Rate 70 ppm Hysteresis Rate 50 ppm

47

ANAESTHESIA FOR INSERTION

MACTo provide comfortTo control dysrhythmiasTo check for proper function/capture

Have external pacer & Atropine readyContinuous ECG and peripheral pulse

monitoring

48

PACEMAKER INSERTION

TEMPORARY PACING METHODS Invasive (Direct) cardiac Pacing

Epicardial Stainless steel Teflon coated wires.

Endocardial Flow directed balloon electrodes Catheter with guidewire With PA catheter- Side port for ventricular pacing

Non Invasive (Indirect) Transcutaneous Pacing

Combined pacing, cardioversion and defibrillation with ECG monitoring in a single unit

Instituted quickly Safely by minimally trained person

CONT.. Disadvantages of transcutaneous pacing

Inability to obtain reliable capture in Emphysema Pneumothorax Morbid obesity

Difficulty with lead placement Surgical Field Patient position

Failure of TCP to preserve AV synchrony For patients with poor ventricular diastolic

function

TRANSESOPHAGEAL PACING Uses

Noninvasive electrophysiological studiesTermination of reentrant tachydysrhythmiasTemporary bradycardia pacing

DisadvantagesNot suitable for ventricular pacing Intact AV conduction is required

IMPLANTABLE CARDIOVERTER DEFIBRILLATOR

S

AUTOMATED IMPLANTABLE CARDIOVERTER DEFIBRILLATOR (AICD) Indications

Recurrent VT/VFNot responding to medical therapyPoor risk for surgical ablation

2/3rd patients still require medical therapy

High cost Survival rate is similar

54

SETTINGS

Gives a shock at 0.1-30 joules Usually 25 joulesTakes 5-20 seconds to sense

VT/VFTakes 5-15 seconds more to

charge 2.5-10 second delay before next

shock is administeredTotal of 5 shocks, then pausesIf patient is touched, may feel a

buzz or tingleIf CPR is needed, wear rubber

gloves for insulation

AICD IN SITU

ICD

PG assembly 2010

209 cc 120 cc 80 cc 80 cc 72 cc 54 cc

62 cc 49 cc 39.5 cc 39.5 cc 36 cc38 cc39.5 cc

Implantable Defibrillators (1989-2003)

PG assembly 2010

GENERIC DEFIBRILLATOR CODE DEVELOPED AS JOINT PROJECTS BY NORTH AMERICAN SOCIETY OF PACING & ELECTROPHYSIOLOGY (NASPE) AND BRITISH PACING AND ELECTROPHYSIOLOGY GROUP (BPEG) - REVISED 2002

Position 1Shock chambers

Position 2Anti tachycardia pacing chambers

Position 3Tachycardia detection

Position 4Anti bradycardia pacing chambers

O = none O = none E = electrocardiogram

O = none

A = atrium A = atrium H = haemodynamic

A = atrium

V = Ventricle V = ventricle V = ventricle

D = dual (A+ V) D = dual (A + V)

D = dual (A + V)

SURGICAL TECHNIQUES Non thoracotomy (More common)

Fluoroscopically Transvenous Monitored anesthesia care. General anesthesia- if repeated induction of

arrhythmia. Thoracotomy ( For Pediatric patients- epicardial

leads)Median sternotomyLeft thoracotomySubxiphoid approachSubcostal approach

61

ANESTHESIA

MAC vs GeneralUsually general due to induction of

VT/VF so AICD can be checked for performance

Lead is placed in heart

Generator is placed generally in upper chest

ASA PRACTICE ADVISORY FOR PERI OPERATIVE MANAGEMENT OF PATIENTS WITH CARDIAC IMPLANTABLE ELECTRONIC DEVICES

PRE OPERATIVE EVALUATIONA. Establish whether a patient has a

cardiac rhythm management device (CIED).

1. Conduct a focused history (patient interview, medical records review, and review of available chest x-rays, electrocardiograms, or any available monitor or rhythm strip information).

2. Conduct a focused physical examination (check for scars and palpate for device).

3. Define the type of CIED.

a. Obtain manufacturer’s identification card from patient or other source.

b. Order chest x-ray if no other data are available.

B. Determine the dependence on pacing function of the CIED.

1. Patient has history of symptomatic bradyarrhythmia resulting in CIED implantation.

2. Patient has history of successful atrioventricular nodal ablation.

3. Patient has inadequate escape rhythm at lowest programmable pacing rate.

C. Determine CIED function.

1. Interrogate device (consultation with a cardiologist or pacemaker-ICD service may be necessary).

2. Determine whether the device will capture when it paces (i.e., produce a mechanical systole with a pacemaker impulse).

PRE OPERATIVE PREPERATIONA. Determine whether EMI (electromagnetic

interference) is likely to occur during the planned procedure.

The pacemeker senses cautery signal as electrical activity, & may be inhibited causing asystole.

In case of ICD, it may sense cautery as ventricular fibrillation and deliver a shock.

1. Determine whether reprogramming pacing function to asynchronous mode or disabling rate responsive function is advantageous.

2. Suspend antitachyarrhythmia functions if present.

3. consider use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel.

4. Temporary pacing and defibrillation equipment should be immediately available

INTRA OPERATIVE MANAGEMENT

Monitor operation of the CIED.

1. Conduct electrocardiographic monitoring per ASA standard.

2. Monitor peripheral pulse (e.g., manual pulse palpation, pulse oximeter plethysmogram, and arterial line).

3. Pacemaker is not an indication for insertion of pulmonary artery & central venous catheter.

INDUCTION & MAINTENANCE Narcotics & inhalational agents can be

used successfully.

Succinylcholine fasciculations can inhibit stimulation and hence should be avoided.

Etomidate & ketamine should be avoided : cause myoclonic movements

Cases of pacemeker dislodgement by IPPV

Nitrous oxide entrapment in pacemeker pocket.

Factors that increase pacing threshold:

- Acidosis / alkalosis- Hypothermia- Hyperkalemia- Hypoglycemia- Severe hypoxia- Hypothyroidism- Myocardial ischemia/ infarction

ELECTROCAUTERY

1.Assure that electrosurgical receiving plate is positioned so the current pathway does not pass through or near the CIED system. It placed on a site different from the thigh (e.g., the superior

posterior aspect of the shoulder contralateral to the generator position for a head and neck case).

2. Avoid proximity of the cautery’s electrical field to the pulse generator or leads.

3. use short, intermittent and irregular bursts at the lowest feasible energy levels.

4. consider the use of a bipolar electrocautery system or ultrasonic (harmonic) scalpel in place of a monopolar electrocautery system if possible

RADIOFREQUENCY ABLATION1. Avoid direct contact between the

ablation catheter and the pulse generator and leads.

2. keep the RF’s current path as far away from the pulse generator and lead system as possible.

LITHOTRIPSY1. Avoid focusing the lithotripsy beam

near the pulse generator.

2. If the lithotripsy system triggers on the R-wave, consider preoperative disabling of atrial pacing.

MAGNETIC RESONANCE IMAGING1. MRI is generally contraindicated in

patients with CIEDs.

2. If an MRI must be performed, consult with the ordering physician, the patient’s cardiologist, the diagnostic radiologist, and the CIED manufacturer.

RADIATION THERAPY

1. Radiation therapy can be safely performed in patients who have CIEDs.

2. Surgically relocate the CIED if the device will be in the field of radiation.

EMERGENCY DEFIBRILLATION OR CARDIOVERSION

A . terminate all sources of EMI while the magnet is removed.

b. Remove the magnet to reenable antitachycardia therapies.

c. If the above activities fail to restore ICD function, proceed with emergency external defibrillation or cardioversion.

FOR EXTERNAL DEFIBRILLATION

a. Position defibrillation/cardioversion pads or paddles as far as possible from the pulse generator.

b. Position defibrillation/cardioversion pads or paddles perpendicular to the major axis of the CIED to the extent possible by placing them in an anterior-posterior location.

c. If it is technically impossible to place the pads or paddles in locations that help to protect the CIED, then defibrillate/cardiovert the patient in the quickest possible way and be prepared to provide pacing through other routes.

POST OPERATIVE MANAGEMENTA. Continuously monitor cardiac rate and

rhythm and have back-up pacing and defibrillation equipment immediately available throughout the immediate postoperative period.

B. Interrogate and restore CIED function in the immediate postoperative period.

1. Interrogate CIED; consultation with a cardiologist or pacemaker-ICD service may be necessary.

2. Restore all antitachyarrhythmic therapies in ICDs.

3. Assure that all other settings of the CIED are appropriate

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