Exam 1: Arrhythmias & ECG Flashcards
Anatomy of the Cardiac Conduction System include
- SA node
- Bachmann’s Bundle
- AV node
- Bundle of His
- Left and Right Bundle Branch
- Purkinje Fibers
Polarization includes
Positive or negative
Types of Polarization include
- Atrial Depolarization
- Ventricular Depolarization
- Ventricular Repolarization
ECG Cardiac Cycle
- P Wave
- PR Interval
- QRS Interval
- ST Segment
- T Wave
- QT Interval
EKG Paper
Time measure in seconds
Amplitude measured in mV
Small box
0.04 secs and 0.1 mV amplitude
Large box
5x5 small boxes = 0.2 secs and 0.5 mV amplitude
Methods of Measuring Rate
- Number of QRS complexes in one minute
- Six second strip
- Number of small boxes between two R waves
- Triplicate method
What are the three types of sinus rhythms?
Normal Sinus Rhythm
Sinus Tachycardia
Sinus Bradycardia
Normal Sinus Rhythm Characteristics
Rate: Normal Duration P Wave: 0.06-0.12 sec P-R interval: 0.12-0.20 sec QRS: <0.12 sec Rhythm: 60-100 bpm
Sinus Tachycardia Characteristics
Rate: Normal Duration P Wave: Normal P-R Interval: Normal QRS: Normal Rhythm: 101-200 bpm
Sinus Bradycardia Characteristics
Rate: Normal Duration P Wave: Normal P-R Interval: Normal QRS: Normal Rhythm: <60 bpm
The four types of Atrial Rhythms include
- Premature Atrial Contraction
- Atrial Flutter
- Atrial Fibrillation
- Supraventricular Tachycardia
Premature Atrial Contraction Characteristics
P Wave: Distorted (d/t ectopic signal travels across the atria by an abnormal pathway) OR hidden by the T-wave
P-R Interval: May be shorter/or longer but still falls w/in normal limits
QRS: Normal <0.12 or Abnormal >0.12
Rhythm: irregular
Atrial Flutter Characteristics
Atrial rate 200-350 bpm & Ventricular rate about 150 bpm
P Wave: Recurring, regular, saw tooth shape waves
P-R Interval: Variable and not measurable.
QRS: Usually normal
Rhythm: Tachydsyrhytmia
Atrial Fibrilation Characteristics
Atrial: 350-600 bpm Ventricular: 60-100 bpm P Wave: Chaotic, fibrillatory waves P-R Interval: Not measurable QRS: Usually normal shape and duration Rhythm: Irregular
Supraventricular Tachycardia Characteristics
Rate: 150-220 bpm P Wave: Often hidden in the preceding T wave P-R: Shorten or normal QRS: Usually normal Rhythm: Regular/slightly irregular
The three types of Ventricular Rhythms include
- Premature Ventricular Contraction
- Ventricular Tachycardia
- Ventricular Fibrillation
Premature Ventricular Contraction Characteristics
Rate: Ectopic focus in the ventricles P Wave: Rarely visible, usually lost in the QRS complex QRS: wide/distorted shape; >0.12 T-Wave: Large and opposite in direction Rhythm: Irregular
Ventricular Tachycardia Characteristics
P Wave: Occurs independently of QRS complex; usually buried in the QRS complex
P-R Interval: Not measurable
QRS: Wide/distorted in appearance; >0.12 sec
T Wave: Opposite direction of QRS complex
Rhythm: Regular or irregular
Ventricular Fibrillation Characteristics
Rate: Not measurable
P Wave: Not measurable
QRS: Not measurable
Rhythm: Irregular and chaotic
AV Block Types
First Degree
Second Degree Type I
Second Degree Type II
Third Degree
First Degree AV Block Characteristics
Rate: HR normal P Wave: Normal P-R interval: PROLONGED >0.20 sec QRS: Shape/duration usually normal Rhythm: Regular (Wife(P Wave) waits for husband(QRS) to come home. He comes home later than normal but he always comes home at the same time each night.)
Second Degree AV Block Type I Characteristics
Rate: Normal, maybe bradycardia P Wave: Normal shape P-R Interval: GRADUAL LENGTHENING QRS: Normal Rhythm: PROGRESSIVE LENGTHENING (Wife(P Wave) waits for husband(QRS) to get home. Each night he comes home later and later, until he doesn’t come home at all.)
Second Degree AV Block Type II Characteristics
P Wave: Normal shape
P-R Interval: Normal or prolonged in duration; remains constant on conducted beats.
QRS: Usually >0.12 d/t bundle branch block.
Rhythm: Atrial = regular, Ventricular = may be irregular.
(Wife(P Wave) waits for her husband(QRS) to come home. Sometimes he comes home, sometimes he doesn’t. But when he does come home, he shows up at the same time each night.)
Third Degree AV Block (Complete Heart Block) Characteristics
P Wave: Normal shape
P-R interval: Variable, no relationship between the P wave and the QRS complex
Rhythm: atrial and ventricular rhythms are regular but unrelated to each other.
(Wife(P Wave) is no longer waiting for her husband(QRS). They are on completely different schedules. There is no longer a relationship)
Cardiac Arrest Rhythms
VT
VF
PEA
Asystole
Common Etiologies of Cardiac Arrest Rhythms
H’s and T’s
C-A-B
Chest compression, Airway, Breathing
C-A-B: Compressions
Should be initiated within 10 second of recognition of arrest
Given at a rate of at least 100/min and each set of 30 compression should take 18 seconds or less.
Depth at least 2 inches for adult, 1/3 of chest for children, 1/3 of chest for infant.
C-A-B: Airway
Cricoid pressure not recommended
C-A-B: Breathing
Briefly check fo no breathing or no normal breathing.
AFTER 30 compressions, the airway is opened then deliver 2 breaths.
AED Automatic External Defibrillator
Children 1-8 years old
Infants <1 year old
SA node
Start of impulse
Dominant stimulator
Sends impulse all throughout the atrium -> atrium contraction
Distance from SA to AV node allows
Emptying of the atrium
Bundle of His
Separates into right and left ventricles
Time to get bundle of his allows filling of ventricles
Purkinje Fibers
Stimulates ventricles to contract -> CO
Vagus Nerve
Decreases firing of SA node
Depolarization
Contraction
Repolarization
Relaxation
Nerve Fibers of sympathetic
Increases firing of SA node
Most common Lead ECG’s include
Lead 2 and 5
Lead 2
Easiest way to see P wave
Do NOT rely on paper only; assess patient to what you see on lead 2.
12 Leadd ECG shows changes suggesting
Structural and conduction disturbances
Damage
Electrolyte Imbalances
Drug toxicity
Dysrhythmias result from disorders of:
Impulse formation
Conduction of impulse formation
OR both
When SA fires more slowly then secondary pacemakers,
AV node rate = 40-60 times/min
His-purkinje system = 20-40 times/min
When the secondary pacemakers fire more rapidly than normal SA,
Triggered beats (early or late) can come from an area outside the normal conduction pathway (ectopic focus/accessory pathway) in atria, AV node or ventricle.
Holster monitor
Continuous recording of ECG while pt is ambulatory/ADLS; pt records activities and symptoms
What drugs can contribute to sinus bradycardia?
B-blockers, CCB
Treating Sinus Bradycardia
Atropine (anticholinergic drug)
If ineffective, give transcutaneous pacing or dopamine or epinephrine infusion.
Treatment for Premature Atrial Contractions
Treat underlying cause.
Caffeine or sympathomimetic drugs may be needed.
B Blockers.
Premature Ventricular Contractions
Premature (early) occurrence of a QRS complex.
It is wide and distorted in shape compared to QRS complex.
Asystole
Represents the total absence of ventricular electrical activity.
Patients are unresponsive, pulseless and apneic.
Aystole Clinical Associations
Usually a result of advance heart disease, severe cardiac conduction system disturbances or end-Stage HF.
Clinical Significance of Asystole
End-stage heart disease and prolonged arrest cannot be resuscitated.
Treatment of Asystole
Consists of CPR w/ initiation of ACLS measures.
Includes drug therapy, epinephrine, and/or vasopressin and intubation.
Treatment for sinus tachycardia
Underlying cause
IV beta-adrenergic blockers
Adenosine
CCB
Premature Atrial Contraction
Starts from an ectopic focus in the atrium and comes sooner than the next expected sinus beat.
Premature Atrial Contraction can be a result from
Emotional stress or physical fatigue
Caffeine, tobacco or alcohol.
Hypoxia, electrolyte imbalances.
Hyperthyroidism, COPD, heart disease
Clinical Significance of Premature Atrial Contractions
In people with healthy hearts, isolated PACs are not significant.
Patients may report palpitations or a sense that heart skipped a beat.
In people with heart disease, may indicate enhanced automaticity of the atria or a reentry mechanism. (May warn of or start more serious dysrhythmias.)
Supraventricular Tachycardia
Starts in ectopic focus anywhere above the bifurcation of the bundle of His.
Occurs because of reentrant phenomenon (reexcitation of the atria when there is a one-way block).
Abrupt onset and ending. Termination is sometimes followed by a brief perio of asystole.
Supraventricular Tachycardia Clinical Associations
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Supraventricular Tachycardia
Clinical Significance
Treatment for Supraventricular Tachycardia
Fatal stimulation
Drug of choice: IV adenosine
If it is ineffective, pt become hemodynamically unstable, synchronized cardioversion is used.
Atrial Flutter Clinical Associations
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Atrial Flutter Clinical Significance
Can cause HF w/ pt w/ underlying heart disease
Increases risk for stroke (d/t risk of thrombus formation/stasis of blood in the atrium)
Atrial Flutter Treatment
Warfarin (to prevent stroke = decrease ventricular response by increase AV block)
CCB, BB, antidysrhythmia drugs
Electrical cardioversion (for unstable pt)
Radio frequency catheter ablations - treatment of choice
Atrial Fibrillation Clinical Associations
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Atrial Fibrillation Clinical Association
Decreases CO
Thrombi form in the atria d/t blood stasis -> stroke (accounts for 17% of strokes)
Atrial Fibrillation Treatment
CCB (diltiazem) BB Dronedarone Digoxin Some pt. Pharmacologic or electrical conversion may be considered.
Premature Ventricular Contractions Clinical Association
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Premature Ventricular Contraction Clinical Significance
usually normally not harmful in patients w/ normal heart
In pts w/ heart disease: decrease CO -> angina and possible HF.
In CAD or acute MI indicates Ventricular irritability.
For patients with premature ventricular contractions, assess
Apical pulse and peripheral pulse since PVC often does not generate a sufficient ventricular contraction -> which an lead to a pulse deficit.
Treatment of Premature Ventricular Contractions
Hemodynamics status is important to determine if tx w/ drugs is needed (BB, procainamide or amiodarone)
O2 therapy for hypoxia and electrolyte replacement.
PVC: Ventricular bigeminy
Every other beat is PVC
PVC: Ventricular trigeminy
Every third beat is PCV
PVC: Couplet
Two consecutive PVC
PVC: Ventricular tachycardia
3 or more consecutive PVCs
Ventricular Tachycardia Clinical Associations
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Ventricular Tachycardia Clinical Significance
Stable = pulse Unstable = no pulse Hypotension Pulmonary edema Decreased cerebral blood flow Cardiopulmonary arrest
Treatment of Ventricular Tachycardia
W/o pulse is life threatening. To like VF; CPR, rapid defibrillation (first line of treatment)
Follow with administration of vasopressors (epi), antidysrhythmics (amiodarone) if defib is unsuccessful.
VT: Monomorphic/Stable Patient =
IV procainamide, sotalol or amiodarone is used.
VT: Polymorphic/QT prolonged =
IV magnesium, isoproterenol, phenytoin, or antitachycardia pacing.
Ventricular Fibrillation Clinical Associations
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Ventricular Fibrillation Clinical Significance
Unresponsive
Pulseless and apneic state (If not treated rapidly, patient will not recover)
Treatment for Ventricular Fibrillation
CPR and Advanced Cardiac Life Support (ACLS) w/ use of defibrillator and definitive drug therapy (epinephrine, vasopressin)
First Degree AV Block: Clinical Associations
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First Degree AV Block Clinical Significance
*Asymptomatic
Usually not serious but can be a sign of higher degrees of AV block
Treatment for First Degree AV Block
No treatment, monitor
Second Degree AV Block Type I: Clinical Associations
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Second Degree AV Block Type I: Clinical Significance
Results from MI or inferior MI.
Generally transient and well tolerated.
May be a sign for a more serious AV conduction disturbance (complete heart block)
Treatment for Symptomatic Second Degree AV Block Type I
Atropine (increases HR) or a temporary pacemaker may be needed (especially if pt has MI)
Treatment for Asymptomatic Second Degree AV Block Type I
Monitor w/ transcutaneous pacemaker on standby.
Bradycardia is more likely to become symptomatic when hypotension, HR or shock is present.
Second Degree AV Block Type II Clinical Associations
Rheumatic heart disease
CAD
Anterior MI
Drug Toxicity
Second Degree AV Block Type II Clinical Significance
Poor prognosis can lead to third degree AV block.
Reduced HR -> reduces CO = hypotension -> Myocardial ischemia.
Treatment for Second Degree AV Block Type II
Permanent Pacemaker
(If pt becomes symptomatic (hypotension, angina) insertion of a temporary pacemaker may be necessary before the insertion of the permanent one)
Third Degree AV Block: Clinical Associations
Severe Heart Disease (CAD, MI, myocarditis, cardiomyopathy, systemic disease, progressive system sclerosis)
Third Degree Block: Clinical Significance
Decreased CO Ischemia HR Shock Syncope Bradycardia or even periods of asystole
Treatment for Third Degree Block
Symptomatic: Transcutaneous pacemaker. Atropine, dopamine, epinephrine (temporarily increases HR and supports BP)
Permanent pacemaker ASAP