Pacemakers and ICDs Flashcards by Hannah Frank

Medical devices used to generate and deliver electrical impulses to the myocardium to stimulate a normal heartbeat

Artificial pacemakers

Some are external to body and provide temporary treatment, others are permanently implanted in the chest

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Temporary pacemakers are ________

Transcutaneous

Delivers electrical impulses through lead wires to electrode pads applied to surface of patient’s chest (UNCOMFORTABLE)

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Permanent pacemakers are implanted in ….

A surgically created pocket beneath the skin in the patient’s chest wall just below the clavicle

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Components of permanent pacemakers

Generator

Lead wire(s)

Power source (ie lithium battery)

Logic circuits that detect cardiac electrical activity and determine the appropriate response

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Conditions in which permanent pacemakers may be used

Symptomatic bradycardia

Sick sinus syndrome

Atrial fibrillation w/ bradycardia

3rd degree AV heart block

Symptomatic 2nd degree AV heart block type II

Sudden combo of AV block or BBB if patient has acute MI

Recurrent tachycardias (ICD only)

Synchronization of the heart beat in HF

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What is the Indication Paradigm with regards to permanent pacemakers?

NON-reversible

SYMPTOMATIC

BRADYCARDIA
• Sinus node dysfunction
•2nd/3rd Degree AVB
•AVN ablation

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Symptoms of Bradycardia

Syncope or pre-syncope
Dizziness
CHF
Mental confusion
Palpitations
SOB
Exercise intolerance
FATIGUE (relentless)

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Where are pacemaker electrodes positioned for single-chamber electrodes?

In the atrium or ventricle alone

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Where are pacemaker electrodes positioned for duel-chamber pacemakers or AV sequential pacemakers?

In both the atrium and ventricle

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How are permanent pacemakers programmed?

To receive and transmit data/programming instructions through the skin using electromagnetic waves

Adjustments can be made to output, sensitivity, refractory period, and rate adaption

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What is the pacing mode for single-chamber pacemakers?

One pacing lead is inserted into either the right atrium or right ventricle but not both

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What are pacing modes like for dual-chamber pacemakers?

Leads are placed into two chambers one lead paces atrium, other lead paces ventricle

By assisting the heart in coordinating the function between the chambers, it acts similarly to how the heart naturally paces itself

Most can be programmed to a single chamber mode (useful if atrial lead wire fails)

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Which pacing mode is this:

Paces the heart at a single, preset rate

Fixed-rate

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Which pacing mode is this:

Sensors identify increases or decreases in the patient’s physical activity and automatically adjusts base pacing rate to meet the body’s metabolic needs

Rate-responsive

Can boost HR in response to motion or increased respiration’s - good for those whose body cannot increase the HR during activity

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Which pacing mode is this:

Most common type

Demand

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Which pacing mode is this:

Fires only when the patient’s intrinsic HR falls below a given threshold level (ie 60 bpm)

Demand

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Which pacing mode is this:

Parameters in which device will activate

Lower/Upper Rate Limits

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Pacemaker mode and function are described by…

A 5-letter coding system (though in practice, only 3-4 are commonly used)

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Pacemaker coding system:

1st letter: _______

2nd letter: _______

3rd letter: _______

4th letter: _______

5th letter: _______

The chamber being PACED

The chamber being SENSED

How the pacemaker generator RESPONDS to sensing

Whether the RATE-RESPONSE FEATURE is activated

Indicates multisite pacing (rarely used)

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For the first letter of the pacemaker coding system, what letters are used and what do they mean?

Chamber being paced

O = none
A = atrium
V = ventricle
D = dual (both atrium and ventricle)

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For the second letter of the pacemaker coding system, what letters are used and what do they mean?

Chamber being sensed

O = none
A = atrium
V = ventricle
D = dual

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For the third letter of the pacemaker coding system, what letters are used and what do they mean?

How the pacemaker generator responds to sensing

O = none
T = triggers pacing
I = inhibits pacing
D = dual (triggers and inhibits)

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For the fourth letter of the pacemaker coding system, what letters are used and what do they mean?

Study These Flashcards

Whether the rate-response feature is activated

O = none
R = rate responsive

For the fifth letter of the pacemaker coding system, what letters are used and what do they mean?

Study These Flashcards

Indicates multisite pacing

O = none
A = atrium
V = ventricle
D = dual

What does this code mean: VOO

Asynchronous ventricular pacing • Ventricular pacing • Ø sensing • Ø response to sensing Do to surgery where bovine used causes interference or applied magnet DO NOT LEAVE PATIENT LIKE THIS

What does this code mean: VVIR

Ventricular inhibitory pacing with rate modulation • Ventricular pacing • Ventricular sensing • Inhibits ventricular pacing if activity sensed • Rate-response active Used for chronic afib patients, or those needing resynchronization (BIV)

What does this code mean: AAI

Atrial inhibitory pacing, no rate modulation • Atrial pacing • Atrial sensing • Inhibits atrial pacing if atrial activity sensed Used for SA node dysfunction, normal AV conduction (not a common mode)

What does this code mean: DDDR

``` Dual-chamber pacing • Dual pacing • Dual sensing • Dual response (inhibitors and triggers) • Rate modulating ``` AV sensed/AV pace/inhibited and triggered

What does this code mean: DDI

Dual chamber pacing without atrial-synchronous ventricular-pacing • Dual-paced • Dual-sensed • Inhibits ventricular pacing if ventricular activity sensed Indicates pacemaker unable to “track” atrial rate to direct ventricular pacing (mode switch) Avoids ventricular tracking of abnormally high atrial rates

What does this code mean: ODO

Pacemaker is OFF

Most pacemakers perform these four functions...

Stimulate cardiac depolarization Sense intrinsic cardiac function Respond to increased metabolic demand by providing rate responsive pacing Provide diagnostic info stored by the device (may dx atrial or ventricular arrhythmias)

What is Cardiac Resynchronization Therapy (CRT)?

Resynchronize biventricular contraction, a common problem in patients with heart failure Employs three leads (one in atrium, one in right ventricle, one inserted through coronary sinus to pace the free wall of the left ventricle)

Where are the three leads located in CRT?

Right atrium Right ventricle Through the coronary sinus to the free wall of the left ventricle

Name the system: Positive electrode is positioned in the heart tissue and the negative electrode is connected to the pulse generator

Unipolar system

Unipolar systems produce __________ spikes on the ECG

Tall pacing spikes

Name the system: Electrodes are only millimeters apart in the cardiac tissue

Bipolar system

Bipolar systems produce _______ spikes on ECG

Short pacemaker spikes

ECG features of a pacemaker depend on...

How many chambers are paced The firing of a pacemaker produces one or two narrow pacemaker spikes

What are the two features of a paced ECG complex?

Narrow “pacing spikes” which reflect the impulse depolarizing the paced chamber P wave or QRS complex that immediately follows the pacing spike

Reasons why your granddaddy’s pacemaker might not work right...

Failure to capture Failure to sense Failure to pace (oversensing) Pacemaker-mediated tachycardia

Presence of pacemaker spikes that are not followed by a P wave or broad QRS complex

Failure to capture

How do you recognize failure to capture?

Presence of pacemaker spikes that are not followed by a P wave or broad QRS complex

Presence of ECG pacemaker spikes that fall where they should have been inhibited

Failure to sense

How do you recognize failure to sense?

Presence of ECG pacemaker spikes that fall where they should have been inhibited

Absence of pacemaker spikes in the presence of a heart rate that is slower than the rate set for the pacemaker

Failure to pace (oversensing)

How do you recognize failure to pace on ECG?

Absence of pacemaker spikes in the presence of a HR that is slower than the rate set for the pacemaker

Fast HR with a pacemaker spike preceding each QRS complex on ECG

Pacemaker-mediated tachycardia

How do you recognize pacemaker-mediated tachycardia?

Fast HR with a pacemaker spike preceding each QRS complex on ECG

Implanted Cardioverter-Defibrillators (ICD) are implanted in patients who...

Are at risk of sudden cardiac death due to ventricular fibrillation and ventricular tachycardia

Implantable Cardioverter-Defibrillators are programmed to detect ________ and correct them by _______

Cardiac dysrhythmias Delivering paced beats, cardioversion, or defibrillation

What are the different types of therapies provided by ICD

Antibradycardia pacing Antitachydysrhythmia pacing Cardioversion Defibrillation

Which ICD therapy: Electrical pacing is used to increase the HR when it is too slow.

Antibradycardia pacing Most ICDs can pace one chamber at a preset rate. Some can sense and pace both chambers.

Which ICD therapy: Mode that generates a series of small, rapid electrical pacing pulses to interrupt ventricular tachycardia (by “capturing” the ventricle and breaking the reentry circuit) and return the heart to its normal rhythm

Antitachydysrhythmia pacing

Which ICD therapy: Mode that uses a low- or high-energy shock (up to 35 joules), which is timed to the R wave (which is detected by the right ventricular electrode) to terminate VT and return the heart to its normal rhythm

Cardioversion

Which ICD therapy: Mode that delivers a high-energy shock (up to 35 joules) to the heart to terminate ventricular fibrillation and return the heart to its normal rhythm

Defibrillation

Electromagnetic fields that may affect pacemakers are ______

Radio-frequency waves 50-60 Hz are most frequently associated with pacemaker interference Few sources of EMI are found in the home or office but several exist in hospitals

Sources of EMI that interfere with pacemaker operation include...

Electrocautery (if within 6 in of heart) Transthoracic defibrillation (if req’d do not withhold) Extracorporeal shock-wave lithotripsy (if abd device) Therapeutic radiation (requires device shielding) RF ablation (defer to EP doing case) TENS units (fine if bipolar system, avoid if unipolar) MRI (may compatible systems now)

Pacemakers and ICDs Flashcards

(57 cards)