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