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EKG Certification > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

Pacemaker

A

Battery powered device that delivers an electrical current to the heart to stimulate depolarization

Consists of a pulse generator and pacing leads

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2
Q

Pacing lead

A

Insulated wire that is used to carry an electrical impulse from the pacemaker to the patients heart and information about the hearts electrical activity back to the pacemaker

Triggering - start

Inhibition - stop

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3
Q

Pulse generator (power source)

A

Houses a battery and electronic circuitry

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4
Q

Temporary pacing routes

A

An artificial pacemaker can be external (temporary intervention) or implanted

Pulse generator of temporary pacemaker is located externally

External pacemakers may be used to control transient disturbances in the heart rate or conduction

Can be accomplished through transvenous, epicardial, or transcutaneous means

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5
Q

Transvenous pacing

A

Transvenous pacemakers stimulate the endocardium of the right atrium of ventricle (or both)

Electrode is introduced into a central vein, such as the subclavian, femoral, bronchial, internal jugular, or external jugular vein

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6
Q

Epicardial pacing

A

Epicardial pacing is the placement of pacing leads directly onto or through the epicardium

May be used when a patient is undergoing cardiac surgery and the hearts outer surface is easy to reach

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7
Q

Transcutaneous pacing (TCP)

A

Uses electrical stimulation through two pacing pads positioned on a patients torso to stimulate contraction of the heart

Electrical stimulus exists from the negative terminal on the machine (and subsequently the negative electrode) and passes through the chest wall to the heart

Range of output current varies depending on the manufacturer

(Doesn’t work too well)

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8
Q

Transcutaneous pacing - complications

A

-coughing
-skin burns
-interference with sensing
-discomfort from electrical stimulation of the skin and muscles
-failure to recognize that the pacemaker is not capturing
-tissue damage, including third degree burns
-pacing threshold changes

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9
Q

Permanent pacemakers

A

Patients who have chronic dysrhythmias that are unresponsive to medication therapy and that result in decreased cardiac output may require the surgical implantation of a permanent pacemaker or an implantable cardioverterdefibrillator (ICD)

Pacemakers and ICDs are called cardiovascular implantable electronic devices (CIEDs)

Used to treat disorders of the Sinoatrial (SA) node, disorders of the AV conduction pathways, or both, that produce signs and symptoms as a result of inadequate cardiac output

Pacemakers pulse generator is usually implanted under the local anesthesia into the subcutaneous tissue of the anterior chest just below the right or left clavicle

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10
Q

Pacemaker leads

A

Pacemaker lead systems may consist of single, double, or multiple leads
-separate lead is used for each heart chamber paced

Electrode
- the exposed portion of the pacing lead that is placed in direct contact with the heart

Unipolar electrode
-has one pacing electrode located at its distal tip
-less commonly used than bipolar lead systems

Bipolar lead system
-contains a positive and negative electrode at the distal tip of the pacing lead wire

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11
Q

Leadless pacemakers

A

Consists of self contained generator and lead systems

Inserted through the femoral vein and into the right ventricle, eliminating the need for a chest incision and creating a pocket in the patients chest to house a pulse generator

First generation leadless pacemakers provide only single chamber ventricular pacing

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12
Q

Pacing principles

A

Pacing occurs when the pacemakers pulse generator delivers energy (milliamperes [mA]) through the pacing electrode to the myocardium

A pacemaker responds to the information received either by sending a pacing stimulus to the heart (triggering) or by not sending a pacing stimulus to the heart (inhibiting)

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13
Q

Fixed rate pacemakers

A

Continuously discharge at a preset rate (usually 70-80 impulses/min) regardless of patients heart rate or metabolic demands

Simple circuitry

Does not sense patients own cardiac rhythm
-may result in competition between the patients cardiac rhythm and that of the pacemaker

Not often used today

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14
Q

Demand pacemakers

A

Discharge when the patients heart rate drops below the pacemakers rate limit

Expressed in paced pulses per minute (PPM)

Set up depending on what your heart needs

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15
Q

Capture

A

Capture
-the successful conduction of an artificial pacemakers impulse through the myocardium, resulting in depolarization

Electrical capture
-can be seen as a pacemaker spike followed by an atrial or ventricular complex on the ECG depending on the chamber that is being paced

Mechanical capture
-assessed by palpating the patients pulse

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16
Q

Atrial pacing

A

Pacing electrode placed in the right atrium

Produces a carmaker spike followed by a P wave

May be used when SA node is diseased or damaged but conduction through AV junction and ventricles is normal

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17
Q

Ventricular pacing

A

Pacing electrode placed in right ventricle

Produces pacemaker spike followed by a wide QRS, resembling a ventricular ectopic beat

Pacemaker spike in front of QRS (wide)

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18
Q

Pacemaker syndrome

A

Because a ventricular demand pacemaker does not coordinate pacing with the patients intrinsic atrial rate, it can result in asynchronous contraction in the atrium and ventricle

Loss of AV synchrony can result in a loss of the atrial contribution to cardiac output, decreased stroke volume and decreased cardiac output

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19
Q

Dual chamber pacemaker

A

Two lead system placed in the heart
-one lead is placed in the right atrium
-a second lead is placed in the right ventricle

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20
Q

Atrial synchronous pacemaker (VDD)

A

Senses both atrial and ventricular activity but paces only the ventricle when a spontaneous ventricular depolarization does not occur

Used for patients who have impaired AV conduction but an intact SA node

Presence of SA node disease is a contraindication for a VDD pacemaker

21
Q

AV sequential pacemaker (DVI)

A

First stimulates the right atrium and then the right ventricle but senses only the ventricle

May be used for patients with severe sinus bradycardia

Asynchronous atrial pacing and the potential for AV asynchrony (with possible pacemaker syndrome) can occur

22
Q

Optimal sequential pacemaker (DDD)

A

Also called physiologic or universal pacemaker

Used when the SA node is intact but AV conduction is impaired

In DDD mode, both the atrium and ventricle are paced (D), both chambers are sensed (D), and the pacemaker has both a triggered and inhibited mode of response (D)

Programmed to wait between atrial and ventricular stimulation, stimulating the usual delay in conduction through the AV node

23
Q

Failure to pace

A

Failure to fire

Pacemaker malfunction that occurs when the artificial pacemaker fails to deliver an electrical stimulus at its programmed time

Battery is dying

Lead got cut or disconnected

Recognizing on ECG as an absence of pacemaker spikes and a return of the underlying rhythm for which pacing was initiated

24
Q

Causes of failure to pace

A
  1. Battery failure
  2. Broken or loose connection between the pacing lead and the pulse generator
  3. Displacement of the electrode tip
  4. Electromagnetic interference
  5. Fracture of the pacing lead wire
  6. Pulse generator failure
  7. Sensitivity set too high
25
Q

Failure to pace - possible interventions

A
  1. Adjusting sensitivity setting
  2. Replacing pulse generator battery
  3. Replacing pacing lead
  4. Replacing pulse generator unit
  5. Tightening connections between pacing lead and pulse generator
  6. Removing source of electromagnetic interference
26
Q

Failure to capture

A

Inability of the artificial pacemaker stimulus to depolarize the myocardium

Recognized on the ECG by visible pacemaker spikes not followed by P waves (if electrode in atrium) or QRS complexes (if electrode in right ventricle)

Pacemaker worked, but heart did not respond to stimuli — no electrical activity

27
Q

Failure to capture — causes

A
  1. Battery life
  2. Displacement of pacing lead wire (common cause)
  3. Edema or scar tissue formation at the electrode tip
  4. Faulty connections
  5. Fracture of the pacing lead wire
  6. Increased stimulation threshold as a result of medications of electrolyte imbalance
  7. Output energy set too low
    Ventricular perforation
28
Q

Failure to capture - possible interventions

A

Slowly increasing the output setting until capture occurs

Repositioning the patient to the left side

29
Q

Failure to sense

A

Sensitivity

Extent to which an artificial pacemaker recognizes inartistic electrical activity

30
Q

Undersensing

A

Occurs when the artificial pacemaker fails to recognize spontaneous myocardial depolarization

Recognized on ECG by the following

Pacemaker spikes that occur within P waves
Pacemaker spikes that follow too closely behind the patients QRS complex
Pacemaker spikes that appear within T waves

In simple terms, heart works better than the pacemaker thinks — pacemaker gets reading heart rhythm is not pacing properly, but it is

Overprotected heart pacemaker

31
Q

Oversensing

A

Pacemaker malfunction that results from inappropriate sensing of extraneous electrical signals

Recognized on ECG as pacemaker spikes at a rate slower than the pacemakers preset rate or no paced beats even though the pacemakers preset rate is greater than patients inartistic rate

Pacemaker thinks the heart is working properly, so no stimuli, but heart is not

32
Q

Failure to sense — causes

A
  1. Battery life
  2. Circuitry dysfunction
  3. Decreased P wave or QRS voltage
  4. Displacement of the electrode tip (most common cause)
  5. Fracture of pacing lead wire
  6. Increased sensing threshold from antiarrhythmic medications
  7. Myocardial perforation
  8. Sensitivity setting too high
  9. Severe electrolyte disturbances
33
Q

Failure to sense — possible interventions

A

Increasing sensitivity setting

Replacing pulse generator battery

Replacing or repositioning pacing lead

34
Q

A vertical line on the ECG that indicates the pacemaker has discharged

A

Pacemaker spike

35
Q

A pacemaker malfunction that occurs when the artificial pacemaker fails to recognize spontaneous myocardial depolarization

A

Undersensing

36
Q

A pacemaker malfunction that occurs when the artificial pacemaker stimulus is unable to depolarize the myocardium

A

Failure to capture

37
Q

The period between two consecutive paced events in the same cardiac chamber

A

Paced interval

38
Q

This type of pacemaker uses an atrial and ventricular lead

A

Dual chamber

39
Q

An artificial PR interval

A

AV interval

40
Q

This type of pacemaker discharges only when the patients heart rate drops below the preset rate for the pacemaker

A

Demand

41
Q

The ability of a pacemaker to increase the pacing rate in response to physical activity or metabolic demand

A

Rate modulation

42
Q

This type of pacemaker continuously discharges at a preset rate regardless of the patients intrinsic activity

A

Fixed rate

43
Q

A pacemaker malfunction that results from inappropriate sensing of extraneous electrical signals

A

Oversensing

44
Q

The power source that houses the battery and circuitry for regulating a pacemaker

A

Pulse generator

45
Q

The rate at which the pacemakers pulse generator initiates impulses when no intrinsic activity is detected; expressed in pulses per minute

A

Lower rate limit

46
Q

The minimum amount of voltage needed to obtain consistent capture

A

Threshold

47
Q

Pacemaker response in which the output pulse is suppressed when an intrinsic event is sensed

A

Inhibition

48
Q

A pacemaker malfunction that occurs when the pacemaker fails to deliver an electrical stimulus at its programmed time

A

Failure to pace

EKG Certification (11 decks)

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