Bradyarrhythmia and heart blockMANAGEMENT

CARDIOVASCULAR PRESENTATIONS · 12 SECTIONS

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461 items

☷ Legend

01Approach to the Critical Patient/attcp67

Immediate priorities

›Unstable bradyarrhythmia approach

›Airway compromise

›If apnea or severe hypoventilation, bag valve mask and advanced airway pathway

›Oxygenation and ventilation targets

›SpO2 94 to 98 percent

›Perfusion failure features

›Hypotension

›Altered mental status

›Ischemic chest discomfort

›Acute pulmonary edema

›If perfusion failure features present, immediate ACLS bradycardia algorithm pathway

›Monitoring and access

›Cardiac monitor with pacing capability

›Defibrillator pads in anterior posterior position

›Noninvasive blood pressure cycling every 1 to 3 minutes

›If shock or vasoactive infusion, arterial line when feasible

›IV access

›Two large bore peripheral IV lines

›Point of care glucose

›If hypoglycemia, immediate dextrose therapy

›Rhythm confirmation workflow

›12 lead ECG within 10 minutes

›Rate

›PR interval

›QRS width

›AV association

›If bradycardia with wide QRS, high likelihood infranodal disease

›Higher risk atropine failure

›If second degree Mobitz II or third degree AV block, pacing first strategy

›Atropine not relied on as definitive therapy

Rapid causes and reversible triggers

›Immediate reversible causes screen

›Ischemia or infarction

›STEMI pathway if indicated

›Drugs and toxicologic

›Beta blockers

›Calcium channel blockers

›Digoxin

›Antiarrhythmics

›Opioids or sedatives

›Hypoxia

›Airway or ventilation failure

›Electrolyte abnormality

›Hyperkalemia

›Hypothermia

›Endocrine

›Hypothyroidism myxedema

›Increased vagal tone

›Vomiting

›Pain

›Carotid sinus hypersensitivity

ECG based classification

›Bradyarrhythmia patterns

›Sinus bradycardia

›P waves present with fixed PR

›Junctional rhythm

›Absent or inverted P waves

›Ventricular escape rhythm

›Wide QRS with very slow rate

›First degree AV block

›PR over 200 ms

›Second degree AV block Mobitz I

›Progressive PR prolongation then dropped QRS

›Second degree AV block Mobitz II

›Fixed PR with intermittent dropped QRS

›High grade AV block

›Two or more consecutive nonconducted P waves

›Third degree AV block

›AV dissociation with independent atrial and ventricular rates

02History/hx50

Symptom pattern and timeline

›Presenting syndrome

›Syncope or near syncope

›Exertional syncope

›Supine syncope

›Dizziness or lightheadedness

›Positional association

›Dyspnea

›Orthopnea

›Paroxysmal nocturnal dyspnea

›Chest pain

›Typical ischemic features

›Palpitations with pauses

›Post tachycardia pauses

›Fatigue and exercise intolerance

›New functional decline

›Time course clues

›Sudden onset minutes to hours

›Ischemia

›Drug ingestion

›Subacute days to weeks

›Myocarditis

›Lyme disease exposure

›Chronic months to years

›Degenerative conduction disease

›Sleep apnea related bradycardia

Risk factors and context

›Conduction disease risks

›Known structural heart disease

›Prior MI

›Cardiomyopathy

›Prior cardiac surgery

›Valve surgery

›Transcatheter aortic valve implantation history

›New conduction delay risk

›Infiltrative or inflammatory disease

›Sarcoidosis

›Amyloidosis

›Chagas disease

›Medication and toxin exposures

›Recent dose change

›Beta blocker up titration

›Calcium channel blocker up titration

›Polypharmacy with AV nodal blockade

›Beta blocker plus nondihydropyridine calcium channel blocker

›Digoxin use

›Renal dysfunction or dehydration

›Infectious exposure

›Tick exposure and rash

›Lyme carditis concern

›Viral prodrome

›Myocarditis concern

03Physical Exam/exam39

Hemodynamic and perfusion findings

›Perfusion assessment

›Blood pressure trend

›MAP under 65 mmHg

›Mental status

›Confusion or decreased responsiveness

›Skin

›Cool clammy

›Delayed capillary refill

›Urine output history

›Oliguria

›Respiratory status

›Work of breathing

›Accessory muscle use

›Lung exam

›Rales suggesting pulmonary edema

›Cardiac exam

›Heart sounds

›Cannon A waves suspicion with AV dissociation

›JVP

›Elevated with heart failure

›Peripheral edema

›Volume overload

Clues to cause

›Ischemia clues

›Diaphoresis

›Associated chest discomfort

›Toxicologic clues

›Miosis

›Opioid exposure

›Wheeze or bronchospasm

›Beta blocker toxicity

›Endocrine and temperature

›Hypothermia

›Shivering or low measured temperature

›Hypothyroid features

›Dry skin

›Periorbital edema

›Neurologic

›Focal deficits

›Stroke pathway if present

04Differential Diagnosis/ddx31

Life threatening and time sensitive

›Critical causes of bradycardia

›Acute coronary syndrome with conduction involvement

›Inferior MI with AV nodal ischemia

›Anterior MI with infranodal block

›Complete heart block

›ICD 10 I44.2

›High grade AV block

›ICD 10 I44.1

›Sick sinus syndrome

›ICD 10 I49.5

›Hyperkalemia

›ICD 10 E87.5

›Beta blocker poisoning

›ICD 10 T44.7X1A

›Calcium channel blocker poisoning

›ICD 10 T46.1X1A

›Digoxin toxicity

›ICD 10 T46.0X1A

›Myocarditis

›ICD 10 I40.9

›Cardiac tamponade

›ICD 10 I31.4

Mimics and related syndromes

›Non conduction etiologies presenting with low pulse

›Frequent PVCs with pulse deficit

›Apparent bradycardia on palpation

›Atrial fibrillation with slow ventricular response

›AV nodal blocker effect

›Vasovagal syncope

›Transient bradycardia

›Increased intracranial pressure

›Cushing response

05Laboratory Tests/lt35

Core labs for unstable or symptomatic bradycardia

›Initial laboratory panel

›Electrolytes

›Potassium in mmol/l

›Magnesium in mmol/l

›Calcium in mmol/l

›Renal function

›Creatinine for drug clearance risk

›Glucose

›Hypoglycemia as reversible cause

›CBC

›Anemia contributing to demand ischemia

›Venous blood gas

›pH

›pCO2 in mmHg

›Cardiac ischemia labs

›High sensitivity troponin per local pathway

›Rising pattern supporting ACS

›BNP or NT proBNP if heart failure suspected

›Volume overload correlation

Targeted labs by suspected cause

›Cause directed labs

›TSH if hypothyroidism suspected

›Myxedema coma support

›Digoxin level if digoxin exposure

›Timing at least 6 hours after last dose if possible

›Serum osmolality and tox screen when ingestion unclear

›Co ingestants that worsen hypotension

›Lyme serology when compatible exposure

›ECG findings plus systemic signs

Pitfalls and interpretation

›Laboratory limitations

›Normal troponin does not exclude conduction system ischemia early

›Serial testing with ECG trend

›Potassium measurement delays in severe instability

›Empiric hyperkalemia therapy when ECG suggests

›Drug levels availability delays

›Clinical toxidrome driven treatment

06Diagnostic Tests/dt41

Scoring Systems

›Risk stratification adjuncts

›Syncope risk tools when syncope is presenting complaint

›Canadian Syncope Risk Score framework use

›Admission preference if high risk features

›ECG risk features for malignant bradyarrhythmia

›QRS 120 ms or more suggesting infranodal block

›Escape rhythm under 40 per minute

›Pauses 3 seconds or more with symptoms

MRI

›Cardiac MRI indications

›Suspected myocarditis

›Conduction disease with viral prodrome

›Suspected cardiac sarcoidosis

›AV block in younger patient without other cause

›Suspected amyloidosis

›Low voltage ECG plus heart failure signs

›MRI practical constraints

›Hemodynamic instability

›Deferred until stabilized

›Temporary pacing hardware

›MRI conditional device requirements

›CT indications related to bradycardia presentation

›CT pulmonary angiography if PE suspected

›Hypoxia with risk factors

›CT head if new focal neurologic deficit or head trauma from syncope

›Anticoagulation use increases bleed risk

›CT chest for aortic pathology if suggestive chest pain and pulse deficit

›Secondary conduction abnormalities possible with ischemia

›CT limitations

›Contrast nephropathy risk

›Renal dysfunction mitigation

Ultrasound (or US)

›Point of care ultrasound applications

›Cardiac POCUS for shock with bradycardia

›Pericardial effusion and tamponade physiology

›Global LV systolic function

›Lung ultrasound for dyspnea

›B lines supporting pulmonary edema

›IVC assessment

›Volume status adjunct

›POCUS pitfalls

›Normal LV function does not exclude ischemia

›ECG and troponin correlation

07Disposition/dispo28

Level of care decisions

›Admission indications

›Symptomatic bradycardia requiring intervention

›Atropine response with recurrence risk

›Mobitz II or high grade AV block

›Telemetry and pacing capability

›Third degree AV block

›ICU or monitored unit with immediate pacing access

›Suspected ACS

›Cardiology admission pathway

›ICU indications

›Need for transcutaneous pacing

›Frequent capture loss or high thresholds

›Need for vasoactive infusion

›Epinephrine or dopamine infusion

›Need for transvenous pacing

›Bridge to permanent pacemaker

Transfer and follow up

›Transfer triggers

›No transvenous pacing capability locally

›Immediate transfer after stabilization

›STEMI with bradyarrhythmia

›PCI capable center transfer

›Discharge criteria for benign bradycardia

›Asymptomatic sinus bradycardia with stable vitals

›Athlete baseline pattern

›First degree AV block without symptoms

›Outpatient follow up

›Clear reversible medication cause corrected with stable observation period

›Shared decision making and close follow up

08Treatment/t80

ACLS symptomatic bradycardia pathway

›Initial temporizing therapy

›Atropine

›1 mg IV or IO bolus

›Repeat every 3 to 5 minutes

›Maximum total 3 mg

›Lower expected efficacy in infranodal block

›Mobitz II

›Third degree AV block with wide QRS

›Transcutaneous pacing

›If unstable and atropine ineffective or inappropriate

›Set rate 60 to 80 per minute

›Increase mA until capture then 10 percent above threshold

›Analgesia and sedation if conscious

›Fentanyl IV titration in small aliquots

›Close respiratory monitoring

›Midazolam IV titration in small aliquots

›Hypotension risk

›Epinephrine infusion

›2 to 10 microg per minute IV infusion

›Titrate to perfusion targets

›Tachyarrhythmia risk monitoring

›Dopamine infusion

›5 to 20 microg per kg per minute IV infusion

›Titrate to perfusion targets

›Extravasation precautions

›Escalation therapy

›Transvenous pacing

›If high grade block with instability or refractory to above

›Bridge to permanent pacing evaluation

›Early cardiology and electrophysiology consultation

›High grade AV block

›Suspected pacemaker indication

Cause specific therapies

›Hyperkalemia with ECG changes

›Calcium gluconate IV

›Repeat dosing guided by ECG response

›Continuous ECG monitoring

›Insulin with dextrose

›Frequent glucose checks

›Hypoglycemia prevention

›Nebulized beta agonist

›Tachycardia expected

›Dialysis pathway for refractory or severe renal failure

›Emergent nephrology activation

›Beta blocker toxicity

›Glucagon IV

›Nausea and vomiting prophylaxis

›High dose insulin euglycemia therapy

›ICU monitoring required

›Vasopressors

›Epinephrine or norepinephrine titration

›Calcium channel blocker toxicity

›Calcium chloride or calcium gluconate IV

›Repeat dosing guided by hemodynamics

›High dose insulin euglycemia therapy

›ICU monitoring required

›Vasopressors

›Norepinephrine titration

›Digoxin toxicity

›Digoxin specific antibody fragments

›Indications

›Life threatening arrhythmia

›Severe hyperkalemia

›Myxedema coma suspected

›Levothyroxine IV per institutional protocol

›Adrenal insufficiency coverage

›Hydrocortisone IV before thyroid hormone

Permanent pacing indications overview

›Permanent pacemaker considerations

›Class I indications per guideline based recommendations

›Symptomatic sinus node dysfunction with correlation

›Syncope with documented pauses

›Acquired Mobitz II second degree AV block not due to reversible cause

›High risk progression

›Acquired high grade AV block not due to reversible cause

›Two or more consecutive nonconducted P waves

›Acquired third degree AV block not due to reversible cause

›Persistent AV dissociation

›Reversible cause exclusion before permanent device

›Medication effect corrected

›Ischemia treated

›Metabolic cause corrected

09Special Populations/sp29

Pregnancy

›Pregnancy specific considerations

›Hemodynamic interpretation

›Lower baseline blood pressure

›Higher baseline heart rate

›Pacing considerations

›Transcutaneous pacing safe when indicated

›Transvenous pacing with obstetric input for fluoroscopy minimization

›Medication considerations

›Atropine use for symptomatic bradycardia when indicated

›Vasopressor infusion maternal fetal monitoring

Geriatric

›Older adult considerations

›Degenerative conduction disease prevalence

›Higher risk Mobitz II and complete heart block

›Polypharmacy risk

›AV nodal blockers and drug interactions

›Atypical presentation

›Falls as syncope equivalent

›Disposition bias toward observation or admission

›Silent ischemia risk

Pediatrics

›Pediatric considerations

›Normal heart rate varies by age

›Relative bradycardia definition age dependent

›Common causes

›Hypoxia

›Hypothermia

›Increased vagal tone

›Pacing and medication pathways

›Pediatric ACLS dosing differs from adult

›Early pediatric critical care involvement

10Background/b27

Epidemiology

›Frequency and distribution

›Bradyarrhythmia common in older adults

›Degenerative fibrosis of conduction system

›Higher grade AV block risk with structural heart disease

›Prior MI association

›Sinus bradycardia common in athletes and during sleep

›Often benign when asymptomatic

Pathophysiology

›Mechanisms

›Sinus node dysfunction

›Failure of impulse initiation

›Tachy brady syndrome with pauses

›AV nodal conduction delay

›First degree and Mobitz I patterns

›Infranodal conduction disease

›His Purkinje disease producing Mobitz II and wide QRS escape

›Escape rhythms

›Junctional escape typically narrow QRS

›Ventricular escape typically wide QRS and less reliable

Therapeutic Considerations

›Therapy principles

›Symptom driven and perfusion driven escalation

›Asymptomatic bradycardia often no acute therapy

›Atropine mechanism

›Antimuscarinic increasing SA and AV nodal conduction

›Pacing as definitive temporization for high grade block

›Transcutaneous then transvenous as needed

›Guideline concept

›Permanent pacing for symptomatic or high risk conduction disease not due to reversible cause

11Patient Discharge Instructions/pdi14

copy discharge instructions

›Discharge guidance for low risk bradycardia

›Medication plan

›Do not restart held AV nodal blockers unless clinician advises

›Bring all medications to follow up visit

›Follow up

›Primary care or cardiology within 3 to 7 days

›Ambulatory monitoring plan if arranged

›Return to ED now

›Fainting or near fainting

›Chest pain

›Shortness of breath

›New confusion or weakness

›Palpitations with dizziness

›Persistent heart rate under 50 per minute with symptoms

12References/r20

Clinical guidelines and algorithms

›Key guidelines

›AHA Adult Bradycardia With a Pulse Algorithm 2025

›Atropine 1 mg IV IO bolus repeat every 3 to 5 minutes maximum 3 mg

›Epinephrine infusion 2 to 10 microg per minute

›Dopamine infusion 5 to 20 microg per kg per minute

›2018 ACC AHA HRS Guideline on Bradycardia and Cardiac Conduction Delay

›Permanent pacing indicated for acquired Mobitz II high grade or third degree AV block not due to reversible causes

›2021 ESC Guidelines on Cardiac Pacing and Cardiac Resynchronization Therapy

›Pacing recommendations for AV block and device strategies in structural heart disease

Coding references

›Diagnostic coding anchors

›Sinus bradycardia ICD 10 R00.1

›SNOMED CT sinus bradycardia concept

›First degree AV block ICD 10 I44.0

›SNOMED CT first degree atrioventricular block concept

›Second degree AV block ICD 10 I44.1

›SNOMED CT second degree atrioventricular block concept

›Complete heart block ICD 10 I44.2

›SNOMED CT complete atrioventricular block concept

›Sick sinus syndrome ICD 10 I49.5

›SNOMED CT sinus node dysfunction concept

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed June 16, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.