Bradycardia - ACLS Algorithm
Definition :
Greek Bradykardía ( βραδυκαρδία ), "HEART SLOWNESS"
Bradycardia - Defined As A Heart Rate Of < 60 Beats Per Minute, Which May Be Physiologically Normal For Some Patients, Or May Be Inadequate For Others
Classification :
Based On Symptoms :
Symptomatic Bradycardia
Badycardia With Symptoms Such As : Fatigue, Weakness, Dizziness, Lightheadedness, Fainting, Chest Discomfort, Palpitations Or Shortness Of Breath
Asymptomatic Bradycardia :
Bradycardia Which Is Physiologically Normal
No Associated Symptoms
Based On Origin :
Atrial - Such As : Sinus Bradycardia And Sick Sinus Syndrome
Sinus Bradycardia
Usually Found In Young, Healthy Adults, And Athletes (50 - 85 %)
Due To :
Conditioned Heart Muscle - Higher Stroke Volume - Fewer Contractions To Circulate The Same Volume Of Blood
Vagal Tone Changes During Respiration :
Expiration - Increase Heart Rate
Sick Sinus Syndrome
Collection Of Conditions In Which The ECG Indicates Sinus Node Dysfunction
Bradycardia-Tachycardia Syndrome
Sinus Bradycardia, Sinus Arrest, Or Exit Block Combined With Sinoatrial And Atrioventricular Nodal Conduction Disturbances And Tachyarrhythmias
Characterized By Bursts Of Atrial Tachycardia Interspersed With Periods Of Bradycardia - Paroxysmal Atrial Flutter Or Fibrillation May Also Occur)
SICK SINUS SYNDROME
AV Nodal Bradycardia Or AV Juctional Rhythm
Due To :
Absence Of The Electrical Impulse From The Sinus Node,
Rate Of Depolarization Of The SA Node Falls Below The Rate Of The AV Node
Electrical Impulses From The SA Node Fail To Reach The AV Node Because Of SA Or AV Block
Electical Impulse Originating From An Ectopic Focus Somewhere In The AV Junction
ECG Findings :
Normal QRS Complex Accompanied With An Inverted P Wave Either Before, During, Or After The QRS Complex
Normal QRS Complex With Prolonged PR
Protective Mechanism For The Heart To Compensate For A SA Node That Is No Longer Handling The Pacemaking Activity, And Is One Of A Series Of Backup Sites That Can Take Over Pacemaker Function When The SA Node Fails To Do So
Etiology :
Physiologic Junctional Escape Complex :
Due To Excessive Vagal Tone On The SA Node
Pathological Junctional Escape Complex :
SInus Bradycardia, Sinus Arrest, Sinus Exit Block, Or AV Block
Ventricular
Known As Ventricular Escape Rhythm Or Idioventricular Rhythm
Above The His Bundle, Known As Junctional Rhythm
Range Between 40 And 60 Beats Per Minute With A Narrow QRS Complex
Below The His Bundle, Known As Ventricular Rhythm
Range Between 20 And 40 Beats Per Minute With A Wide QRS Complex
Compensatory Mechanism That Arises When There Is Lack Of Electrical Impulse Or Stimuli From The Atrium
Infantile Bradycardia
Normal Heart Rate Infants : 120 - 160 Beats Per Minute
Infantile Bradycardia : Infants With Heart Rate Of Less Than 100 Beats Per Minute
Management (ACLS Algorithm) :
Initial Treatment :
Support Of Airway And Breathing (Box 2)
Provide Supplementary Oxygen, Place The Patient On A Monitor, Evaluate Blood Pressure, And Oxyhemoglobin Saturation, And Establish Intravenous (IV) Access.
Obtain An ECG To Better Define The Rhythm
While Initiating Treatment, Evaluate The Clinical Status Of The Patients And Identify Potential Reversible Causes
SEARCH AND TREAT POSSIBLE CONTRIBUTING FACTORS :
6H - Hypovolemia, Hypoxia, Hydrogen Ion (Acidosis), Hypo / Hyperkalemia, Hypoglycemia, Hypothermia
6T - Toxins, Cardiac Tamponade, Tension Pneumothorax, Thrombosis, Thromboembolism, Trauma
IDENTIFY SIGNS & SYMPTOMS Of POOR PERFUSION Caused By Bradycardia (Box 3)
Such As : Acute Altered Mental Status, Ongoing Chest Pain, Hypotension, Or Others Signs Of Shock
Bradycardia With ADEQUATE PERFUSION (Box 4A) :
Observe And Monitor For Any Signs Of Deterioration (POOR PERFUSION)
Bradycardia With POOR PERFUSION (Box 4) :
Provide Immediate Therapy For Patients With Hypotension, Acute Altered Mental Status, Chest Pain, Congestive Heart Failure, Seizures, Syncope, Or Other Signs Of Shock Related To The Bradycardia
Prepare For Transcutaneous Pacing
CLASS I INTERVENTION FOR SYMPTOMATIC BRADYCARDIA
Non-Invasive, And Can Be Performed By ECC Providers At The Bedside
Indications :
Symptomatic Bradycardia
In Patients Who Do Not Respond To Atropine (Or Second-Line Drugs - If These Do Not Delay Definitive Management)
Use Without Delay In High-Degree AV Block (Mobitz Type 2 Second Degree AV Block, And Complete Heart Block) - Severely Symptomatic Patients
Limitation :
Painful And May Fail To Produce Effective Mechanical Capture
If Cardiovascular Symptoms Are Not Caused By The Bradycardia, The Patients May Not Improve Despite Effective Pacing
Verify Mechanical Capture And Re-Assess The Patient's Condition
Use Analgesia And Sedation For Pain Control, And Try To Identify The Cause Of The Bradyarrhythmia
If Transcutaneous Pacing Is Ineffective (INCONSISTENT CAPTURE) - Prepare For TRANSVENOUS PACING And Consider Obtaining EXPERT Consultation.
Consider Atropine
FIRST LINE DRUG For Acute Symptomatic Bradycardia (CLASS IIA)
Atropine Administration Should Not Delay Implementation Of External Pacing For Patients With POOR PERFUSION
Recommended Dose :
0.5 mg IV While Awaiting Pacer - May Repeat To A Total Dose (Maximum) Of 3 mg Every 3 To 5 Minutes
Doses Of < 0.5 mg May Paradoxically Result In Further Slowing Of The Heart Rate
Caution :
In The Presence Of Acute Coronary Ischemia Or Myocardial Infarction, Increased Heart Rate May Worsen Ischemia Or Increase The Zone Of Infarction
Likely To Be Ineffective Following Cardiac Transplantation
Transplanted Heart Lacks VAGAL INNERVATION)
Paradoxical Slowing Of The Heart Rage ANd High Degree AV Block During Administration Of Atropin In Patients Post Cardiac Transplantation
IF INEFFECTIVE - BEGIN PACING
Consider Epinephrine Or Dopamine While Awaiting Pacer Or If Pacing Ineffective
SECOND LINE DRUG - CLASS IIB - Epinephrine And Dopamine
Indications :
Symptomatic Bradycardia Or Hypotension, When The Bradycardia Is Unresponsive To Atropine And As Temporizing Measures While Awaiting The Availability Of A Pacemaker
Doses :
Epinephrine 2 - 10 mcg/min (INFUSION)
Start At 2 mcg/min, And Titrate To Patient Response
Dopamine 2 - 10 mcg/kgwt/min
α- And β-Adrenergic Actions
Start At 2 mcg/kgwt/min, And Titrate To Patient Response
Can Be Added To Epinephrine Or Administered Alone
Glucagon 3mg Initially, Then Followed By Infusion At 3mg/hr If Necessary
Improvement In Heart Rate, Symptoms And Signs Associated With Bradycardia Based On One Case Series
GIVEN TO IN-HOSPITAL PATIENTS With Symptomatic DRUG-INDUCED Bradycardia Which Are Not Responding To Atropine (β-Blocker Or Calcium Channel Blocker Overdose)
Assess Intravascular Volume And Support As Needed
Prepare For TRANSVENOUS PACING (Box 5).
Treat Contributing Causes
Consider Expert Consultation
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