Implantable Cardiac Pulse Generators:

Pacemakers&

In The Name of God

&Implantable Cardiac Defibrillators (ICDs)

Omid Aghadavoudi, MDAssociate Professor of Anesthesiology

Synonyms

• Cardiac Implantable Electronic Device(CIED)

• Cardiac Rhythm Management Device(CRMD)( )

Pacemakers

• Overview• Pacemaker Codes• Pacemaker Indications• Pacemaker Magnets• Preanesthesia Evaluation

and Pacemaker• Reprogramming

Implantable Cardioverter-Defibrillators (ICD)

• Overview• Indications• Magnets• Preanesthesia Evaluation

and Reprogramming• Intraoperative or• Reprogramming

• Intraoperative orProcedural Managementof pacemakers

• Pacemaker Failure• Postanesthesia

Pacemaker Evaluation

pProcedural Management of

• PostanesthesiaImplantable Cardioverter –Defibrillator Evaluation

Transcutaneous pacemaker

Miniature temporary cardiac pacemaker

Internal Pacemaker

History

• Pacemaker � In 1958 by CW Lillehei (a cardiothoracicsurgeon) and Earl Bakken (an electrical technician)

• Implantable pacemaker� A few years later by WilsonGreatbatch, a cardiologist

• lCD � 1980 by Michael Mirowski (Baltimore, MD).• First approved by the U.S. FDA � in 1985, required a

thoracotomythoracotomy

Overview

� The complexity of pacemakers and ICDs�Multitude of programmable parameters�Population aging�Enhancements in implantable technology�Enhancements in implantable technology�New indications for implantation�Patients with a pulse generator (PG) often

have significant comorbid diseases

Not all electronic generators implanted in the chest arecardiac devices

• Pulse generator implantation has been approved bythe FDA for:

1. Pain control2. Thalamic stimulation to control Parkinson's disease3. Phrenic nerve stimulation to stimulate the diaphragm in3. Phrenic nerve stimulation to stimulate the diaphragm in

paralyzed patients4. Vagus nerve stimulation to control epilepsy• Vagus nerve stimulation for heart failure & obesity

Overview

• Pacemaker manufacturers: 26 companies• more than 2,500 models to date.• Currently, more than 250,000 adults and children

in the United States undergo new pacemakerl t hplacement each year.

• Nearly 2 million patients have pacemakers today.

Transvenous endocardial VVIpacemaker

A: conventional single lead pacemakerB: implantable cardioverter-defibrillator (ICD)

Radiographic identifiers for somegenerator manufacturers

Pacemaker Indications

• Symptomatic diseases of impulse formation(sinus node disease)

• Symptomatic diseases of impulse conduction(disease of the atrioventricular node)

• Long QT syndrome• Hypertrophic obstructive cardiomyopathy• Dilated cardiomyopathy

COMMON USES FOR PERMANENT PACEMAKER

Pacemaker System

• Impulse generator• Leads

– Transvenous– Epicardial

• Leadsunipolar (one– unipolar (oneelectrode per lead),

– bipolar (twoelectrodes per lead)

– multipolar (multipleelectrodes)

Examples of single-chamber and dual-chamberpacemakers with both unipolar and bipolar leads.

Pacemakers

• Unipolar leads– The second electrode will be the metal generator case– Requires that the generator pocket be devoid of gas– Electrical continuity has reportedly been disrupted by the

use of nitrous oxide.– More sensitive to the effects of electromagnetic

interference (EMI)– Produce larger "spikes" on an analogue recorded

electrocardiogram.• Bipolar pacing

– usually requires less energy– more resistant to interference from muscle artifacts or

stray electromagnetic fields.– Often can be identified on the chest film since they will

have a ring electrode 1 to 3 cm proximal to the lead tip.

pacemaker wire

The pacing lead system in situ

Excitation threshold & Spike

NASPE/BPEG Revised (2002) GenericPacemaker Code (NBG)

Position I: PacingChamber(s)

Position II:SensingChamber(s)

Position III:Response(s) toSensing

Position IV:Programmability

Position V:Multisite Pacing

O= none O= none O= none O= none O= none

A= atrium A= atrium I= inhibitedR= ratemodulation

A= atrium

V= ventricle V= ventricle T= triggered V= ventricleD= dual (A + V) D= dual (A + V) D= dual (T + I) D= dual (A + V)

North American Society of Pacing and Electrophysiology (NASPE) nowcalled Heart Rhythm Society (HRS)

British Pacing and Electrophysiology Group (BPEG)

The NBG code: NASPE and BPEG Generic code

Pacemaker sensing

• VAT• AAI

Position III NBG Code• D (Dual):

– DDD pacing provides atrioventricular (AV) synchrony. In the DDD setting,atrial pacing will take place in the “inhibited” mode; that is, the pacingdevice will emit an atrial pulse if no sensed atrial event (or interveningventricular event because any ventricular event will reset atrial timing)takes place within the appropriate timeframe. In DDD or VDD devices,once an atrial event has occurred (whether native or paced), the pacingdevice will ensure that a ventricular event follows (up to the uppertracking rate [UTR]).tracking rate [UTR]).

• I (Inhibited):– The appropriate chamber is paced unless intrinsic electrical activity is

detected during the pacing interval. For the DDI mode, AV synchrony isprovided only when the atrium is paced. If intrinsic atrial activity ispresent, no AV synchrony is provided by the pacing function.

• T (Triggered):– The pacing device will emit a pulse only in response to a sensed event.

The triggered mode is used when the device is being tested.