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Transcript
1
Dysrhythmias of the AV Node and Ventricles
John Miller
Atrioventricular (A-V) junctional dysrhythmias: AV Heart Block
 First degree AV block
o Etiology/risk factors
 CAD, vagal stimulation, digitalis toxicity
 Excessive calcium channel blockers, sodium channel blockers, beta blockers
 Hyper or hypokalemia
 Assessment
 ECG: NSR except for a prolonged P-R interval (greater than 0.20 seconds).
 No symptoms.
1st Degree Block ECG
First Degree AV Block Interventions
 Withhold AV nodal medications.
o Digoxin, calcium channel blockers, sodium channel blockers, beta blockers
 Treat hypo or hyperkalemia.
 Watch for more severe AV block.
 Oxygen
Second Degree AV Heart Block: Mobitz Type I (Wenckebach)
 Etiology/risk factors
o Vagal stimulation, digoxin
o Excessive calcium channel blockers, sodium channel blockers, beta blockers
o Hyper or hypokalemia
o Mildest form of second degree AV block, usually located in the AV node.
 Assessment
o ECG: P-R getting longer with each beat until a QRS is missing.
o Does not usually decrease cardiac output.
Second Degree Mobitz Type I ECG
Second Degree Type I Interventions
 Withhold AV nodal medications.
o Digoxin, calcium channel blockers, sodium channel blockers, beta blockers
 Treat hypo or hyperkalemia.
 Give anti-ischemia medications as needed.
 If symptomatic (low cardiac output) follow ACLS Bradycardia guidelines.
o Atropine
o Transcutaneous pacing
 Oxygen
2
Second Degree AV Heart Block: Mobitz Type II
 Etiology/risk factors
o Level of block is below AV node in bundle.
o Ischemia, MI, digoxin
o Excessive calcium channel blockers, sodium channel blockers, beta blockers
o Hyper or hypokalemia
 Assessment
 ECG: Constant P-R on beats, but some QRS’s are missing.
 Decreases cardiac output (hypotension, angina, CHF)
 Can quickly progress into third degree AV block.
Second Degree Mobitz Type II ECG
Second Degree Block Mobitz Type II Interventions
 Withhold AV nodal medications.
o Digoxin, calcium channel blockers, sodium channel blockers, beta blockers
 Treat hypo or hyperkalemia.
 Give anti-ischemia medications as needed.
 If symptomatic (low cardiac output) follow ACLS Bradycardia guidelines.
o Atropine
o Transcutaneous pacing
 Oxygen
Third Degree AV Heart Block (Complete Heart Block)
 Etiology/risk factors
o AV node or bundle block, atria and ventricles beat separately.
o MI, cardiac surgery, drug toxicity, cardiomyopathy
o Excessive calcium channel blockers, sodium channel blockers, beta blockers
o Hyper or hypokalemia
 Assessment
o ECG: more P-waves than QRSs, regular P-P and R-R intervals, irregular P-R interval, normal
appearing P-waves.
o Normal width QRS, less than 0.12 second: Ventricular beat comes from AV node
o Wide QRS, 0.12 or more second: Ventricular beat comes from the ventricles, similar to a
premature ventricular contraction.
o Causes sudden death.
Third Degree Block ECG
Third Degree Block Interventions
 Withhold AV nodal medications.
o Digoxin, calcium channel blockers, sodium channel blockers, beta blockers
 Treat hypo or hyperkalemia.
 Give anti-ischemia medications as needed.
 If symptomatic (low cardiac output) follow ACLS Bradycardia guidelines.
o Atropine
o Transcutaneous pacing
 Oxygen
 Temporary transvenous pacemaker insertion until a permanent pacemaker can be placed.
3
Ventricular dysrhythmias: Premature Ventricular Contraction (PVC)
 Etiology/risk factors
o Irritable ventricular foci
o Myocardial hypoxia, hypokalemia, hypocalcemia, acidosis, CAD, CHF, digoxin toxicity, exercise
 Assessment
o ECG
o Long QRS duration or width, 0.12 seconds or more, premature but next beat waits to reestablish
initial rate (compensatory pause).
PVC ECG
PVC Interventions
 Treat cause: hypoxia; magnesium, calcium or potassium abnormalities; MI; Digoxin toxicity
 Antidysrhythmics
o Beta blockers
o Sodium channel blockers, class 1B, lidocaine
 Treat dangerous PVCs that may lead to ventricular tachycardia and fibrillation.
o 6 or more per minute
o 2 or more in a row
o Multifocal (different shapes)
o PVC starting on a T wave
 Ablation
Ventricular Tachycardia (VTach, VT)
 Etiology/risk factors
o CAD, cardiomyopathy, MI with acidosis and hypoxia, CHF, digoxin toxicity, follow PVC on T wave
o Magnesium, calcium or potassium abnormalities
 Assessment
o ECG: 3 or more PVCs in a row, no P-waves, T is part of the QRS (short ST)
o Cardiac output may be slightly low or extremely low (cardiogenic shock)
o Causes sudden death.
VT ECG
VT Interventions
 Treat cause: hypoxia; magnesium, calcium or potassium abnormalities; MI; Digoxin toxicity
 Has pulse and is conscious
o Antidysrhythmics: Sodium channel blockers, class IA or IB, procainamide or lidocaine; or
Potassium channel blockers, class III, amiodarone
o Cardioversion (synchronized electrical shock to stop rhythm)
o Avoid beta blockers, calcium channel blockers, and digoxin.
o Ablation
 Oxygen
 Pulseless and unconscious
o Treat like Ventricular Fibrillation
4
Ventricular Fibrillation (VFib or VF)
 Etiology/risk factors
o CAD, cardiomyopathy, MI with acidosis and hypoxia, CHF, follow PVC on T wave or Ventricular
Tachycardia
o Magnesium, calcium or potassium abnormalities
 Assessment
o ECG: no P-waves, QRS complexes, or T waves; disorganized fibrillatory waves seen.
o No cardiac output and shortly after breathing will stop.
o Causes sudden death
VF ECG
VF Interventions
 Call code.
 CPR 5 cycles
 Defibrillate with AED or manual defibrillator: Stand clear, remove oxygen source
 Intubate as soon as possible
 CPR 5 cycles
 Epinephrine IV or intraosseous (IO-in bone)
 Defibrillate
 Potassium channel blocker, class III: Amiodarone
 Treat cause.
 Ablation or AICD for long term management.
Ventricular Asystole (standstill, cardiac arrest)
 Etiology/risk factors
o Hypoxia, hyper or hypokalemia, acidosis, drug overdose, hypothermia, follow ventricular
fibrillation or 3rd degree AV block
 Assessment
o ECG: no rhythm
o No cardiac output and no breathing
o Causes sudden death.
Asystole ECG
Asystole Interventions
 Verify rhythm in two leads. Check patient.
 CPR
 Intubate
 Epinephrine IV or IO
 Treat cause.
Medications: Sympathomimetics
 Epinephrine
 Use: Cardiac arrest, severe hypotension
 Therapeutic effects: Increased heart rate, contractility, and rate of conduction
 Adverse effects
o CV: Palpitations, tachycardia, ventricular fibrillation, pulmonary edema
o Resp: Dyspnea
5
Medications: Parasympatholytics (Anticholinergics)
 Atropine
 Use: Symptomatic heart block and other bradycardia
 Therapeutic effects: Increase heart rate
 Adverse effects:
o CV: Tachycardia, hypotension, ventricular fibrillation
o Skin: Dry mouth
o Neuro: Blurred vision
o GU: Urinary retention
o GI: Constipation
Medications: Sodium Channel Blockers
 Class IA: Procainamide
 Use: Ventricular tachycardia, premature ventricular contractions, SVT
 Therapeutic effects: Decrease electrical conduction, automaticity, rate of repolarization
 Adverse effects
o CV: Heart failure, hypotension, blocks, ventricular dysrhythmias
o Musc: Joint or muscle pain
o Resp: Flu symptoms
o Hem: Neutropenia, thrombocytopenia
Medications: Sodium Channel Blockers
 Class IB: Lidocaine
 Use: Ventricular tachycardia, premature ventricular contractions
 Therapeutic effects: Decrease electrical conduction and automaticity, increase rate of repolarization
 Adverse effects
o Resp: Arrest
o Neuro: Agitation, confusion, dizziness, nervousness, seizures
Medications: Potassium Channel Blockers
 Class III: Amiodarone
 Use: Ventricular tachycardia and fibrillation, SVT
 Therapeutic effects: Increases repolarization time and refractory period
 Adverse effects
o Resp: Dyspnea, cough
o Neuro: Vision problems including photosensitivity
o GI: Hepatitis, increased LFT
Pacemakers
 Lead: wire that connects to heart
 Pulse generator
o Battery
o Senses natural heartbeat.
o Provides electrical initiated heartbeat.
What Is a Pacemaker and How Does It Work? https://youtu.be/Y5rvTeAYuIY
6
Pacemakers: Purpose
 Slow ventricular rates
o Second degree or third degree heart block
 Fast ventricular rates
o Atrial fibrillation, atrial flutter, SVT
 Temporary
o Cardiac surgery
o Used before a permanent pacemaker
o Emergency, using transcutaneous method
Getting a Pacemaker https://youtu.be/WNN4Fw2EWxI
Pacemakers: Insertion Methods
 Most common
o Transvenous approach attaching to the endocardium (inside) of right ventricle
 Local anesthesia, through a branch of the subclavian vein
 Less common
o Transthoracic approach attaching to the epicardium of heart outside surface
 Emergency
o Transcutaneous, where pads are attached to outside, similar to an AED attachment.
Figure 30–10 A permanent epicardial pacemaker. The pulse generator may be placed in subcutaneous
pockets in the subclavian or abdominal regions.
Pacing Leads
 Types
o Temporary with external box or pulse generator
o Permanent with internal pulse generator
 Pacing leads can be placed in
o Right ventricle
o Right atrium
Demand Pacing
 The pacemaker senses the client’s own heart beat and fires an impulse only when the heart needs it.
 This is the mode that pacemakers most commonly function in.
 Settings for pulse generator
o Heart rate: set at normal total rate of paced beats plus normal beats
o Sensitivity: senses own heart rate
o Milliamps of electricity: battery used up more if firing more
Pacing failure
 Failure to sense
o Is not detecting a natural heart beat
o Impulses can be sent out, competing with the heart
 Failure to pace
o Not sending out electricity when needed
 Failure to capture (does not cause ventricular contraction)
o Lead not in contact with heart or not enough electricity is sent to lead
7
Postoperative Care for Pacemakers
 Maintain lead contact by bed position and/or limiting arm movement.
o Sling or immobilizer
 Observe EKG for proper function
 Observe the incision for infection signs.
 Permanent type
o Two incisions to observe.
Pacemaker interference
 Causes of electrical interference that may prevent device from working properly
o Stay away from large electrical engines, welding, MRI, and diathermy (medical heat device).
o 6-12 inch distance acceptable: hair dryer, corded shaver, motors, cell phones
o Brief exposure acceptable: security scanners. Carry ID about with pacemaker info.
 Do not cause interference: microwave ovens, curling irons, kitchen appliances, battery powered shaver
Electromagnetic Compatibility Guide http://www.medtronic.com/content/dam/medtronic-comm/mdt/documents/emc_guide.pdf
Pacemaker followup
 Battery depletion or other failure
o Detected weeks earlier with monitoring equipment
o Home monitoring or office monitoring
o Check for symptoms of low cardiac output
A Pacemaker Patient Talks about her Experience with the MyCareLink Smart™ Patient Monitor
https://youtu.be/8NUnzz0onrY
Electrical shock to stop a dysrhythmia
 Electricity delivered which stops the dysrhythmia and causes a brief period of asystole, so that a better
rhythm will take over the heart.
 AEDs, crash cart defibrillator, and automatic internal cardioverter-defibrillator (AICD)
 Defibrillation
o Emergency procedure, no informed consent needed, uses more electricity than cardioversion.
o Consists of delivering a shock to a dysrhythmia, where no QRS or T wave is present.
 Synch switch is off if using a manual defibrillator instead of an AED. ACLS training is
required. Many machines on crash carts have both an AED and manual mode.
o Dysrhythmias: VT no pulse, VF
Cardioversion
 Elective procedure, need informed consent, analgesia, use less electricity than defibrillation.
 Use same machine as manual defibrillator but the synch switch is on, not off as in defibrillation.
 Deliver shock that avoids the T wave.
 The T wave is a very vulnerable period. If a shock is given then, it can cause ventricular fibrillation.
 For dysrhythmias: AFlutter, SVT, VT with pulse
Cardioversion Orders FHS
http://www.chifranciscan.org/uploadedFiles/For_Physicians/Provider_Orders/PHYORDER.032.pdf
Atrial Fibrillation Cardioversion (A MUST SEE) https://youtu.be/KIEFXJ8QHxw
8
Automatic Implanted Defibrillator (AICD)/Pacemaker Combination
 Indicated for those that need defibrillation or cardioversion.
 Insertion is similar to pacemakers.
 Nursing care is similar to pacemakers.
 The pulse generator is slightly larger.
 Patient teaching includes observing for shocks that did not occur when needed or occurred when not
indicated.
 Anxious due to ventricular fibrillation history.
New S-ICD (subcutaneous) defibrillator a safety net for cardiac patients https://youtu.be/C89PYbaHtcU
Code teams
 Members
o Designated ACLS certified teams chosen daily, using include staff from ED and ICU
 MDs
 In charge of the code
 Other MDs
 RNs, usually 3
 Medications
 IV, NG, foley insertion
 Charge of the code for nursing
 Nurse who called the code and cared for the patient
 Respiratory Therapy, Radiology, IV Therapy, Lab, Pharmacy, Security, Pastoral Care