Unformatted text preview: BASIC PACING
CONCEPTS
CONCEPTS PART-I Electrophysiology
Electrophysiology Pacing Systems
Pacing Dr.M.Mohsin Hossain MBBS, FCPS,MD
Assistant Professor of Cardiology
Assistant Professor
NICVD, Dhaka Electrophysiology The Heart Has an Intrinsic Pacemaker 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 During Conduction, an Impulse Begins in the
During
Sinoatrial (SA) Node and Causes the Atria to Contract
Sinoatrial Atria
Sinoatrial (SA) Node Ventricles Atrioventricular (AV) Node Then, the Impulse Moves to the Atrioventricular (AV) Node and Down
Then,
the Bundle Branches, Which Causes the Ventricles to Contract
the Atria
SA node Ventricles AV node Bundle branches Impulse Formation and Conduction Normal Heart Function
Normal
Sinoatrial Node Normal Heart Function
Normal Atrioventricular Node Normal Heart Function Bundle of HIS Normal Heart Function
Normal Left Bundle Branch (LBB) Posterior Fascicle of LBB Anterior Fascicle of LBB Right Bundle Branch (RBB) Normal Heart Function
Normal Purkinje Fibers Normal Heart Function
Normal Normal Heart Function
Normal Intervals Are Often Expressed
in Milliseconds
in
One millisecond = 1 / 1,000 of a second Normal Sinus Rhythm
Normal Atrial rate: 60-100 bpm
– PR interval: 120-200 ms (.12-.20 seconds)
– QRS interval: 60-100 ms (.06-.10 seconds)
– QT interval: 360-440 ms (.36-.44 seconds) Diseased Heart Tissue May: Prevent impulse
generation in the SA node
Inhibit impulse
conduction SA node AV node ARTIFICIAL CARDIAC PACING
ARTIFICIAL
• External energy sources can be used to stimulate
the heart when disorder in impulse formation
and/or conduction leading to symptomatic
arrhythmias.
• Pacemakers are integrated system that monitor
cardiac rhythms as well as deliver electrical
impulses to the myocardium
• Cardiac pacing can be done to treat
bradyarrhythmia and tachyarrhythmia. Pacemakers Perform Three
Basic Functions
Basic Pacing
Pacing Sensing
Sensing Timing
Timing Pacing Systems Basic Components of Pacemaker System Lead wire(s) EPG IPG Pulse generator :
- Power source
- Electric circuitry Pacemaker Components Combine with
Pacemaker
Body Tissue to Form a Complete Circuit
Body
Pulse generator: power
source or battery Lead Leads or wires
Cathode (-ve electrode)
Anode (+ve electrode) IPG Anode Body tissue
Cathode The Pulse Generator:
Contains a battery that
provides the energy for
sending electrical
impulses to the heart
Houses the circuitry
that controls
pacemaker operations Circuitry Battery Pacemaker Leads
Leads Are Insulated
Leads
Wires That:
Wires
Deliver electrical
impulses from the pulse
generator to the heart
Sense cardiac
depolarization Lead Types of Leads Endocardial or transvenous leads
Myocardial/Epicardial leads Cathode
Cathode An electrode that is
in contact with the
heart tissue
Negatively charged
when electrical
current is flowing
Cathode Anode
Anode
An electrode that
receives the electrical
impulse after
depolarization of
cardiac tissue
Positively charged
when electrical
current is flowing Anode Conduction Pathways
Conduction Body tissues and
fluids are part of the
conduction pathway
between the anode
and cathode Anode Tissue
Cathode During Pacing, the Impulse:
Impulse onset Begins in the pulse
generator
Flows through the lead
and the cathode (–)
Stimulates the heart
Returns to the anode (+) * Unipolar Pacing System Contains a Lead with Only One Electrode Within the Heart In This System, the Impulse: Flows through the tip
electrode (cathode)
Stimulates the heart
Returns through body
fluid and tissue to the
IPG (anode) +
Anode Cathode Bipolar Pacing System Contains a Lead with Two Electrodes Within the Heart
Contains
In This System, the Impulse: 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 Anode Cathode Unipolar leads
Unipolar
Unipolar leads may have a smaller
diameter lead body than bipolar leads
Unipolar leads usually exhibit larger
pacing artifacts on the surface ECG Bipolar leads
Bipolar
Bipolar leads are less susceptible to
oversensing noncardiac signals
(myopotentials and EMI) Coaxial Lead Design Single-Chamber Pacing System
Single-Chamber The pacing lead is
implanted in the atrium
or ventricle, depending
on the chamber to be
paced and sensed Paced Rhythm Recognition
Paced AAI / 60 Paced Rhythm Recognition
Paced VVI / 60 Dual-Chamber Pacing System
Dual-Chamber Systems
Dual-Chamber
Have Two Leads:
Have One lead implanted in
the atrium
One lead implanted in
the ventricle Paced Rhythm Recognition
Paced DDD / 60 / 120 Paced Rhythm Recognition
Paced DDD / 60 / 120 Paced Rhythm Recognition
Paced DDD / 60 / 120 Paced Rhythm Recognition
Paced DDD / 60 / 120 Most Pacemakers Perform Four Functions:
Stimulate cardiac depolarization
Sense intrinsic cardiac function
Respond to increased metabolic demand
by providing rate responsive pacing
Provide diagnostic information stored by
the pacemaker ...
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Full Document
- Fall '11
- Dr.Aslam
- Sinoatrial node, Electrical conduction system of the heart, Cardiac pacemaker, Normal Heart Function, Pacing Systems
-
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