Basic Pacing ConceptsBasic Pacing ConceptsPart IPart I

Identify the components of pacing systems and their respective functions

Define basic electrical terminology

Describe the relationship of amplitude and pulse width defined in the strength duration curve

Explain the importance of sensing

Discuss sources of electromagnetic interference (EMI) and patient/clinician guidelines related to these sources

Understand the need for and types of sensors used in rate responsive pacing

ObjectivesObjectives

Pacing SystemsPacing Systems

The heart generates electrical impulses that travel along a specialized conduction pathway

This conduction process makes it possible for the heart to pump blood efficiently

The Heart Has an Intrinsic PacemakerThe Heart Has an Intrinsic Pacemaker

Ventricles

Sinoatrial (SA) Node

Atrioventricular (AV) Node

Atria

During Conduction, an Impulse Begins in the During Conduction, an Impulse Begins in the Sinoatrial (SA) Node and Causes the Atria to ContractSinoatrial (SA) Node and Causes the Atria to Contract

Atria

Ventricles

Bundle branches

AV node

SA node

Then, the Impulse Moves to the Atrioventricular (AV) Node and Down Then, the Impulse Moves to the Atrioventricular (AV) Node and Down the Bundle Branches, Which Causes the Ventricles to Contractthe Bundle Branches, Which Causes the Ventricles to Contract

SA node

Prevent impulse generation in the SA node

Inhibit impulse conduction

AV node

Diseased Heart Tissue May:Diseased Heart Tissue May:

Implantable pulse generator (IPG)

Lead wire(s)

Implantable Pacemaker Systems Implantable Pacemaker Systems Contain the Following Components:Contain the Following Components:

Pulse generator: power source or battery

Leads or wires

Cathode (negative electrode)

Anode (positive electrode)

Body tissue

IPG

Lead

Anode

Cathode

Pacemaker Components Combine with Pacemaker Components Combine with Body Tissue to Form a Complete CircuitBody Tissue to Form a Complete Circuit

Contains a battery that provides the energy for sending electrical impulses to the heart

Houses the circuitry that controls pacemaker operations

Circuitry

Battery

The Pulse Generator:The Pulse Generator:

Deliver electrical impulses from the pulse generator to the heart

Sense cardiac depolarization

Lead

Leads Are Insulated Wires That:Leads Are Insulated Wires That:

Endocardial or transvenous leads

Myocardial/Epicardial leads

Types of LeadsTypes of Leads

Transvenous Leads Have Transvenous Leads Have Different “Fixation” MechanismsDifferent “Fixation” Mechanisms

Passive fixation

– The tines become lodged in the trabeculae(fibrous meshwork) of the heart

Transvenous LeadsTransvenous Leads

Active Fixation

– The helix (or screw) extends into the endocardial tissue

– Allows for lead positioning anywhere in the heart’s chamber

Myocardial and Epicardial LeadsMyocardial and Epicardial Leads

Leads applied directly to the heart

– Fixation mechanisms include:

Epicardial stab-in

Myocardial screw-in

Suture-on

CathodeCathode

An electrode that is in contact with the heart tissue

Negatively charged when electrical current is flowing

Cathode

AnodeAnode

An electrode that receives the electrical impulse after depolarization of cardiac tissue

Positively charged when electrical current is flowing

Anode

Conduction PathwaysConduction Pathways

Body tissues and fluids are part of the conduction pathway between the anode and cathode

Tissue

Cathode

Anode

Begins in the pulse generator

Flows through the lead and the cathode (–)

Stimulates the heart

Returns to the anode (+)

During Pacing, the Impulse:During Pacing, the Impulse:

Impulse onset

*

Flows through the tip electrode (cathode)

Stimulates the heart

Returns through body fluid and tissue to the IPG (anode)

A Unipolar Pacing System Contains a Lead with Only One A Unipolar Pacing System Contains a Lead with Only One Electrode Within the Heart; In This System, the Impulse:Electrode Within the Heart; In This System, the Impulse:

Cathode

Anode

-

+

Anode

Flows through the tip electrode located at the end of the lead wire

Stimulates the heart

Returns to the ring electrode above the lead tip

A Bipolar Pacing System Contains a Lead with Two A Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart. In This System, the Impulse:Electrodes Within the Heart. In This System, the Impulse:

Cathode

Unipolar and Bipolar LeadsUnipolar and Bipolar Leads

Unipolar leadsUnipolar leads

Unipolar leads may have a smaller diameter lead body than bipolar leads

Unipolar leads usually exhibit larger pacing artifacts on the surface ECG

Bipolar leadsBipolar leads

Bipolar leads are less susceptible to oversensing noncardiac signals (myopotentials and EMI)

Coaxial Lead Design

Lead Insulation May Be Silicone Lead Insulation May Be Silicone or Polyurethaneor Polyurethane

Advantages of Silicone-Insulated LeadsAdvantages of Silicone-Insulated Leads

Inert

Biocompatible

Biostable

Repairable with medical adhesive

Historically very reliable

Advantages ofAdvantages ofPolyurethane-Insulated LeadsPolyurethane-Insulated Leads

Biocompatible

High tear strength

Low friction coefficient

Smaller lead diameter

A Brief History of PacemakersA Brief History of Pacemakers

Single-Chamber and Dual-Chamber Single-Chamber and Dual-Chamber Pacing SystemsPacing Systems

Single-Chamber SystemSingle-Chamber System

The pacing lead is implanted in the atrium or ventricle, depending on the chamber to be paced and sensed

Paced Rhythm RecognitionPaced Rhythm Recognition

AAI / 60

Paced Rhythm RecognitionPaced Rhythm Recognition

VVI / 60

DisadvantagesDisadvantagesAdvantagesAdvantages

Advantages and Disadvantages of Advantages and Disadvantages of Single-Chamber Pacing SystemsSingle-Chamber Pacing Systems

Implantation of a single lead

Single ventricular lead does not provide AV synchrony

Single atrial lead does not provide ventricular backup if A-to-V conduction is lost

One lead implanted in the atrium

One lead implanted in the ventricle

Dual-Chamber Systems Have Two Leads:Dual-Chamber Systems Have Two Leads:

Paced Rhythm RecognitionPaced Rhythm Recognition

DDD / 60 / 120

Paced Rhythm RecognitionPaced Rhythm Recognition

DDD / 60 / 120

Paced Rhythm RecognitionPaced Rhythm Recognition

DDD / 60 / 120

Paced Rhythm RecognitionPaced Rhythm Recognition

DDD / 60 / 120

Stimulate cardiac depolarization

Sense intrinsic cardiac function

Respond to increased metabolic demand by providing rate responsive pacing

Provide diagnostic information stored by the pacemaker

Most Pacemakers Perform Four Functions:Most Pacemakers Perform Four Functions:

General Medtronic Pacemaker DisclaimerINDICATIONS

Medtronic pacemakers are indicated for rate adaptive pacing in patients who may benefit from increased pacing rates concurrent with increases in activity (Thera, Thera-i, Prodigy, Preva and Medtronic.Kappa 700 Series) or increases in activity and/or minute ventilation (Medtronic.Kappa 400 Series).

Medtronic pacemakers are also indicated for dual chamber and atrial tracking modes in patients who may benefit from maintenance of AV synchrony. Dual chamber modes are specifically indicated for treatment of conduction disorders that require restoration of both rate and AV synchrony, which include various degrees of AV block to maintain the atrial contribution to cardiac output and VVI intolerance (e.g., pacemaker syndrome) in the presence of persistent sinus rhythm.

9790 Programmer

The Medtronic 9790 Programmers are portable, microprocessor based instruments used to program Medtronic implantable devices.

9462

The Model 9462 Remote Assistant™ is intended for use in combination with a Medtronic implantable pacemaker with Remote Assistant diagnostic capabilities.

CONTRAINDICATIONS

Medtronic pacemakers are contraindicated for the following applications:

       Dual chamber atrial pacing in patients with chronic refractory atrial tachyarrhythmias.

       Asynchronous pacing in the presence (or likelihood) of competitive paced and intrinsic rhythms.

       Unipolar pacing for patients with an implanted cardioverter-defibrillator because it may cause unwanted delivery or inhibition of ICD therapy.

       Medtronic.Kappa 400 Series pacemakers are contraindicated for use with epicardial leads and with abdominal implantation.

WARNINGS/PRECAUTIONS

Pacemaker patients should avoid sources of magnetic resonance imaging, diathermy, high sources of radiation, electrosurgical cautery, external defibrillation, lithotripsy, and radiofrequency ablation to avoid electrical reset of the device, inappropriate sensing and/or therapy.

9462

Operation of the Model 9462 Remote Assistant™ Cardiac Monitor near sources of electromagnetic interference, such as cellular phones, computer monitors, etc. may adversely affect the performance of this device.

See the appropriate technical manual for detailed information regarding indications, contraindications, warnings, and precautions.

 Caution: Federal law (U.S.A.) restricts this device to sale by or on the order of a physician.

Medtronic Leads

For Indications, Contraindications, Warnings, and Precautions for Medtronic Leads, please refer to the appropriate Leads Technical Manual or call your local Medtronic Representative.

 

Caution: Federal law restricts this device to sale by or on the order of a Physician.

Note:

This presentation is provided for general educational purposes only and should not be considered the exclusive source for this type of information. At all times, it is the professional responsibility of the practitioner to exercise independent clinical judgment in a particular situation.

Continued inContinued in

Basic Pacing ConceptsBasic Pacing ConceptsParts II and IIIParts II and III