Pacemakers Flashcards
Pacemakers
An electronic device tht is used to initate the heartbeat w/ the intrinsic electrical system of the heart cannot generate a rater adequate to support CO
Temporary Pacemaker
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Used supportively or prophylactically, until the condition responsible for the rate or conduction distrubance resolves
> urgent situations - A pacemaker system is a simple electrical circuit consisting of a pulse generator and a pacing lead (an insulated electrical wire) with one, two, or three eelectrodes
Permanent Pacemaker
Used for persistent rate or conduction distrubance despite adequate interventions
Fixed-Rate (Asynchronous)
- Basic, straight-forward; sometimes dangerous
- Delivers a pacing stimulus at a set rate regardless of occurence of spontaneous myocardial depolarization; occurs in nonsensing modes
Demand (Synchronous)
- Delivers a pacing stimulus onyl when the heart’s intrinsic pacemaker fails to function at a predetermined rate
- The pacing stimulus is either inhibited or triggered by the sensing of intrinsic activity
Pulse Generator
(under skin)
Generates the electrical current tht travels through the pacing leads and exits through an electrode tht is in direct contact with the heart
Sensing
The capacity of the pacemaker to sense the heart’s electrical (ECG rhythm) activity
Firing
When the pacemaker provides electrical stimulation (shock) to the myocardium
you can have fire w/out capture
Capture
The ability of the pacemaker to effectively stimulate the atria and/or ventricle to beat
Mitral valve dysfunc causes
Peaked P waves
Temporary Pacemaker Indications
- For temporary problems
-
Dysrhythmias tht are unresponsive to medication. Used until the condition responsible for conduction distrubance resolves
> heart blocks (not from drug OD)
> beta blocker drug OD
> right coronary artery occlusion until ischemic event resolves
> any brady arrhythmias
> if permanent PM battery is dead - Support of cardiac output after cardiac surgery
Pacing Leads & Routes
- Transcutaneous: patches on chest, a function on defibrillator
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Transvenous: large central vein
> usually femoral - Epicardial: after surgery, chest has to be cracked
Transvenous Temporary Pacemaker
- Temporary transvenous pacemakers are most commonly inserted in the internal jugular or femoral vein
-
What setting should be assessed by the nurse?
> rate, physician’s order
> output; a = atria output, v = ventricle output
> insertion site
> amnt of shock
> insertion length
Pacemaker Artifact
- The pacemaker firing is seen on the ECG tracking as “spikes” (a straight line) before the atria and/or ventricle. The size of the spike & whether you can see them at all is determined by the type of pacemaker
- The pacemaker fires directly into myocardium
Why does a paced beat result in wide waveforms on the ECG?
Artificial: Depolarizing backwards, takes more time
Atrial Pacemaker
If the pacemaker spike precedes a P wave
Ventricular Pacemaker
If the pacemaker spike precedes a QRS complex
AV Pacemaker
If the pacemaker spike precedes the P wave and QRS complex
Asynchronous Pacing (ventricle)
- A pacemaker tht paces at a programmed rate regardless of the heart’s intrinsic activity
- Spikes not in appropriate spots
Potential issues seen with asynchronous pacing (ventricle)
Vtach or Vfib
Synchronous (ventricular)
- Pacing in the ventricle, sensing in the ventricle. The response will be to pace or inhibit if intrinsic activity is sensed
- Only firing when HR drops below the set rate
Synchronous advantages over asynchronous mode
Synchronized w/ body, only used when needed, less scar tissue
Atrioventricular Sequential (Dual-Chamber)
-
Synchronized to pt’s intrinsinc activity on P wave & QRS complex
> can be synched to atrial contraction or ventricular contraction
> pacemaker fires, body responds; fires if P wave/QRS complex doesn’t happen naturally - Advantages: preserves AV synchrony (only used when needed) and permits maximal ventricular stroke volume & enhanced cardiac output
Pacemaker Malfunctions
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Most pacemaker malfunctions can be catagorized as abnormalities of pacing or of sensing
> problems with pacing involve failure of the pacemaker to deliver the pacing stimulus
> a pacing stimulus tht fails to depolarize the heart or an incorrect number of pacing stimuli per minute
Failure to Capture
The pacemaker fires (+ pacer spike) but fails to initiate a myocardial depolarization (no P and/or QRS follows it)
not enough mA (shock) to stimulate ventricle to contract
Failure to Capture - Causes & Troubleshooting
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Causes
> distal tip is dislodged, misplaced
> neeeed to incr mA; not enough shock -
Troubleshooting
> adjust mA, go up
> if no response from incrd mA, go back to cath lab
> if transvenous leads, try to reposition pt onto left side
Undersensing
-
The pacemaker fails to sense the p-waves and/or QRS compelxes
> essentially makes pacemaker asynchronous
Undersensing - Causes & Troubleshooting
-
Causes
> not sensing underlying rhythm, threshold
> pt changed settings to asynchronous
> leads malfunc -
Troubleshooting
> check cable connections
> change leads
> check settings
Permanent Pacemakers
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When is a permanent pacemaker necessary
> chronic conduction issue; brady or tachy arrhythmias
Resynchronization Therapy
- For pts with CHF
- For pts with symptomatic heart failure, in SR with a cardiac output less than 35%, and a prolonged QRS
- Synchronizing right ventricle to pump for efficiently to not go into vtach
Permanent Pacemaker - Nursing Management
- Monitor for complications
-
Pacemaker malfunction
> same as temporary -
Postoperative complications
> perforation
> tamponade; muffled heart sounds bc listening to blood
> pneumo
> hematoma around site
> lead displacement
> infection
Permanent Pacemaker - Documentation
-
Pacemaker settings
> programmed mode of pacing
> the lower rate setting -
EKG interpretation
> underlying rhythm
> % paced -
Insertion site assessment
> some bruising, should not be dark purple
> should not see pacemaker -
Circulation, motor, sensory (CMS) to extremity
> affected blood flow = diminished pulses - Vital signs
- Teaching performed
