Download 211 Atrial Dysrhythmias notes

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Atrial Dysrhythmias
John Miller
The Cardiac Cycle and Cardiac Output
 Systole and diastole
 Cardiac output (CO) = HR × SV
 Factors influencing CO
o Activity level
o Metabolic rate
o Physiologic and psychologic stress responses
o Age
o Body size
Heartrate, Contractility, and Preload
 Heart rate
o Direct stimulation by sympathetic, parasympathetic nerves
 Contractility
o Ability of cardiac muscle fibers to shorten
 Preload
o Amount of cardiac muscle fiber tension at the end of diastole
Afterload and Indicators of Cardiac Output
 Afterload
o Force the ventricles must overcome to eject their blood volume
o Pressure in the arterial system ahead of the ventricles
 Clinical indicators of CO
o Cardiac index (CI)
 Adjusted for patient's body surface area (BSA)
The Conduction System of the Heart
 Intrinsic conduction
o Complex electrical circuit that perpetuates cardiac cycle
 Sinoatrial (SA) node
 Atrioventricular (AV) node
Cardiac rate and rhythm assessment
 Tachycardia or bradycardia
 Dysrhythmia
 Sinus node
o Decrease in number of pacemaker cells
The Patient with a Cardiac Dysrhythmia
 Disturbance or irregularity in the electrical system of the heart
 Reasons for development
o Not all pathologic
o Exercise
o Fear
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Properties that allow effective heart function
 Automaticity
o Altered rates caused by various pacemaker cells.
o Example: sinus bradycardia
 Excitability
 Conductivity
o Speed at which impulse travels through the SA, AV node and Purkinje fibers.
o Example: AV heart block
 Reentry of impulses
o Reactivated muscle for a second time by the same impulse.
o Example: atrial fibrillation
 Contractility
Cardiac conduction system
 SA node
 AV node
o Atrial kick
 Extra bolus of blood to ventricles before they contract
Pathophysiology
 Categories of dysrhythmias
o Tachydysrhythmias
o Bradydysrhythmias
o Ectopic rhythms
 Ectopic beats
 Heart block
 Reentry phenomenon
o Functional reentry
Risk factors
 Myocardial ischemia: angina and MI
 Hypoxia
 Vagal stimulation (autonomic nervous system)
 Lactic acidosis
 Electrolyte imbalances
 Drug toxicity
 Shock
Sources of Cardiac Impulses
 Supraventricular rhythms
 Ventricular rhythms
 AV conduction blocks
Assessment
 Reduced cardiac output
o Palpitation, dizziness, syncope, pallor, diaphoresis, altered mental status, hypotension / shock,
edema, oliguria, SOB, chest pain, fatigue, seizures
o Heart rate below 50 or above 140, very irregular heart rate, or rate that does not change with
exercise.
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Electrocardiogram Assessment
 EKG (ECG) Lead Patterns
o Electricity travels from the negative electrode to the positive one.
o Lead II
 Right arm or shoulder lead is negative. Left leg or abdomen/lower chest is positive. Third
lead is a ground.
 Follows the same direction as an impulse traveling from SA node to ventricles.
o MCL1 is a modification of a 12 lead’s V1 lead.
o Twelve lead EKG
 Twelve different pictures with four extremity leads and five chest leads.
12 Lead ECG
The basics of the ECG in 5 min https://youtu.be/HDyqXNHLjug
Cardiac Conduction System and Understanding ECG, Animation. https://youtu.be/RYZ4daFwMa8
ECG Waves
 P wave
o First upright wave, close to atrial contraction
 QRS wave
o 3 waves or less
o Q is first downward wave, R is second upright wave, and S is second downward wave.
o Close to ventricular contraction.
 P-R interval
o Space between beginning of P-wave and the beginning of the Q wave (if Q absent, then the R
wave)
o Impulse traveling from the SA node into the AV node.
 ST segment, T wave
o Ventricular repolarization
 QT Interval
ECG Waves
EKG analysis basic steps
 Calculate heart rate, which should be between 60-100.
 Measure regularity of R waves (R to R interval) and P waves (P to P interval).
 Examine P waves for their preceding each QRS (R wave) and their sameness.
 Measure the P-R interval, which should be between 0.12-0.20 seconds.
 Measure the duration (or width) of the QRS, which should be less than 0.12 seconds.
 Examine the ST segment, which should be neither elevated or depressed.
 Examine the T wave, which should be upright and 1/3 the height of the QRS.
 Examine the QT interval.
Calculate heart rate
 Count the number of small squares between two R-waves and divide it into 1500.
 This method is more accurate than others.
 EKG paper
 EKG paper has small boxes on it.
 As it comes out of the machine, the horizontal axis of the boxes measures time in seconds.
 Each small box represents 0.04 seconds.
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Supraventricular rhythms
 Normal sinus rhythm
 Sinus node dysrhythmias
o Sinus arrhythmia
o Sinus tachycardia
o Sinus bradycardia
o Sick sinus syndrome
 Supraventricular dysrhythmias
o Premature atrial contractions (PAC)
o Paroxysmal supraventricular tachycardia (PSVT)
o Atrial flutter
o Atrial fibrillation
 Increases risk for formation of thromboembolism
ECG Paper Boxes
Normal Sinus Rhythm (NSR or SR)
 Rhythm
o Regular P-P and R-R intervals, varying only up to 3 mm (less than 3 small boxes).
 Rate
o 60-100 beats / minute
 P waves (atrial contraction)
o One precedes each QRS (ventricular contraction)
 P-R interval: 0.12-0.20 seconds
 QRS complex: less than 0.12 seconds
 QT interval: less than 0.40 seconds
The ECG Course - Sinus Rhythms https://youtu.be/vK0XgMIYAqs
Normal Sinus Rhythm
Dysrhythmia Management
 Control the dysrhythmia rate.
 Remove the dysrhythmia.
 Reduce potential complications.
Sinus Bradycardia Assessment
 Etiology/risk factors
o Vagal stimulation (including Valsalva), drugs, MI, hyperkalemia, athletes
 Clinical manifestations
o ECG: NSR except for HR < 60
o Symptoms of low cardiac output
 Assess for reduced cardiac output.
 Sinus Bradycardia
 Sinus Bradycardia Treatment
 If symptomatic:
o Treat cause
o First line of drugs: Atropine
o Second line of drugs: Epinephrine or dopamine
o Temporary pacemaker (transcutaneous)
 Stop digoxin, beta blockers (i.e. metoprolol, etc.), and calcium channel blockers (i.e. diltiazem, verapamil,
nifedipine, etc.
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Epinephrine http://www.mediccast.com/blog/wp-content/uploads/2014/12/epi-1-10000.jpg
Atropine, http://www.pharmedium.com/uploads/cms/images/Atropine_Front.jpg/imagefull;max$900,900.ImageHandler
External Cardiac Pacing https://youtu.be/rePqJpt7RoQ
Sinus Tachycardia Assessment
 Etiology/risk factors
o Heart failure, fluid loss, shock, respiratory distress, drugs, exercise, stress, pain
 Clinical manifestations
o ECG: NSR except for HR > 100
 Assess for reduced cardiac output.
Sinus Tachycardia
Sinus Tachycardia Treatment
 Treat cause, O2
 Beta Blockers or Calcium Channel Blockers
 IV fluids
 Reduce stimulants.
Paroxysmal Supraventricular Tachycardia Assessment
 Also known as SVT, PSVT, PAT
 Etiology and risk factors
o CAD, MI, cardiomyopathy, extreme emotions, caffeine, cor pulmonale, digitalis toxicity,
hypokalemia.
 Clinical manifestations
o Assess for reduced cardiac output.
 Palpitations, dizziness
Supraventricular tachycardia (SVT) https://youtu.be/eCrQDI1OAeU
Paroxysmal Supraventricular Tachycardia
Paroxysmal Supraventricular Tachycardia Treatment
 Carotid sinus massage (vagal stimulation)
 Beta or calcium channel blockers, digoxin, amiodarone, propafenone
 Cardioversion
 Ablation
Premature Atrial Contraction (PAC) Assessment
 Etiology/risk factors
o Ectopic foci
o Valve problems, CHF (atrial enlargement)
o Stress, CAD, medications, pulmonary problems
o Palpitation
 ECG
o PAC: P wave is early, differ from the other P waves, and an early QRS follows the early P.
 May be early sign of atrial fibrillation or flutter.
o Stretching of atrial causes ectopic beats.
o Assess for CHF.
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Premature Atrial Contractions
Premature Atrial Contraction (PAC) Treatment
 Treat cause, O2
 Digoxin, metoprolol, verapamil
Atrial Flutter Assessment
 Etiology/risk factors
o Ectopic foci or rapid reentry, with atrial contraction up to 350 times per minute
o CAD, mitral valve disease, PE, cardiac surgery
 Clinical manifestations
o ECG: inverted or bidirectional, saw-toothed P-waves, with possibly a constant P-wave to QRS
ratio such as 2:1 or 3:1 from AV blocking.
 Assess for low cardiac output.
Atrial flutter (AFL) https://youtu.be/0URl8p39wQo
Atrial Flutter
Atrial Flutter Treatment
 Cardioversion (similar to defibrillation) or
 Drugs:
o Convert to NSR: procainamide, flecainide, propafenone, dofetilide, ibutilide
o Slow ventricular response: verapamil, diltiazem, amiodarone, adenosine
Emergency Cardioversion https://youtu.be/xCtQ-ESsvqM
Atrial Fibrillation Assessment
 Etiology/risk factors
o Rapid chaotic atrial depolarization, up to 700 times per minute.
o No atrial contraction: loss of atrial kick (decreasing cardiac output 20-30%), thrombi formation in
atria
o AV node blocking of some impulses
o Apical-radial pulse deficit
o Hypoxia, CHF
 Clinical manifestations
o ECG: erratic baseline without P-waves, very irregular R to R intervals
o Assess for low cardiac output.
Atrial Fibrillation Anatomy, ECG and Stroke, Animation. https://youtu.be/tPqs4xKPG3A
Atrial Fibrillation
Atrial Fibrillation Treatment
 Thrombi and embolism prevention
o Parenteral anticoagulation: Heparin (unfractionated or LMWH)
o Oral anticoagulation
 Warfarin
 Direct thrombin inhibitors
 Dabigatran, rivaroxaban, apixaban
 Reduce ventricular rate
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

o Digoxin, beta or calcium channel blockers
Stop dysrhythmia
o Chemical cardioversion
 Class I drugs: Flecainide, dofetilide, propafenone, ibutilide
 Class IIa drugs: Amiodarone
o Electrical cardioversion
MAZE surgery, ablation
New Anticoagulants for Stroke Prevention in Atrial Fibrillation https://youtu.be/p-gNmqiTCEw
MAZE Procedure. The most effective and reliable treatment of Atrial Fibrillation (AF)
https://youtu.be/UA2-B3o_sAA
Catheter Ablation For Atrial Fibrillation (AFIB) https://youtu.be/SZ_uIfj-hIQ
Treatment Goals for Dysrhythmias Generally
 Major goals of care
o Identify the dysrhythmia
o Evaluate its effect on physical and psychosocial well-being
o Treat the underlying cause
Diagnosis for Dysrhythmias Generally
o Serum electrolytes
o Drug levels
o Arterial blood gases
o Electrocardiogram
o Cardiac monitoring
 Continuous cardiac monitoring
 Telemetry
 Home monitoring
o Electrophysiology studies
Nursing Care
 Diagnoses, outcomes, and interventions
o Decreased Cardiac Output
 Continuity of care
o Coping strategies
o Lifestyle changes
o Discuss fears related to treatment, implanted devices
 Diagnoses, outcomes, and interventions
o Ineffective Tissue Perfusion: Cerebral
o Impaired Spontaneous Ventilation
o Spiritual Distress
o Disturbed Thought Processes
o Fear
 Risk for future episode of near SCD
 Community training in CPR
ECG Apps for phones and tablets
 Play Store: https://play.google.com/store/search?q=ecg%20simulator&hl=en
 ITunes
The 6 Second ECG Simulator http://www.skillstat.com/tools/ecg-simulator
ECG Simulator Practical Clinical Skills.com http://www.practicalclinicalskills.com/ecg-simulator.aspx