Bradycardia resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]: Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2]

Definition

Sinus bradycardia is defined as a sinus rhythm with a rate below 60 beats per minute.

Causes

Life Threatening Causes

Life-threatening conditions which may result in death or permanent disability within 24 hours if left untreated.

• Hyperkalemia
• Hypoxia
• Inferior myocardial infarction
• Intracranial hypertension

Common Causes

• Amiodarone
• Amitriptyline
• Beta-blockers
• Cardiac glycosides
• Cardiomyopathy
• Carotid sinus hypersensitivity
• Clonidine
• Diltiazem
• Dronedarone
• Flecainide
• Heart transplant
• Hypertensive heart disease
• Hypothermia
• Hypothyroidism
• Ischemic heart disease
• Lithium
• Lyme disease
• Methyldopa
• Obstructive sleep apnea
• Pericarditis
• Phenothiazines
• Procainamide
• Propafenone
• Quinidine
• Reserpine
• Rheumatic fever
• Sepsis
• Trauma
• Vasovagal syncope
• Verapamil
• Viral myocarditis

Management

Figure 1: Management of patients with Bradycardia

Characterize the symptoms: ❑ Palpitations ❑ Lightheadedness ❑ Dyspnea ❑ Chest pain ❑ Altered mental status

Examine the patient: ❑ Heart rate < 50/min ❑ Signs of increased work of breathing ♦ Tachypnea ♦ Intercostal retractions ♦ Suprasternal retractions ♦ Paradoxical abdominal breathing ❑ Signs of poor perfusion ♦ Hypotension ♦ Signs of shock

Identify and treat underlying cause: ❑ Maintain patent airway; assist breathing as necessary ❑ Oxygen (if hypoxemic) ♦ Cardiac monitor to identify rhythm ♦ Monitor blood pressure and oximetry ❑ IV access ❑ 12-Lead ECG if available; don’t delay therapy

Persistent bradyarrhythmia causing: ❑ Hypotension? ❑ Acutely altered mental status? ❑ Signs of shock? ❑ Ischemic chest discomfort? ❑ Acute heart failure?

Yes

No

Atropine First dose - 0.5 mg IV bolus Repeat every 3-5 minutes Maximum 3 mg If atropine ineffective Transcutaneous Pacing OR Dopamine infusion (2-10 mcg/kg/min) OR Epinephrine infusion (2-10 mcg/min)

Monitor and observe

❑ Expert consultation ❑ Transvenous pacing

Algorithm based on the 2010 AHA guidelines for cardiopulmonary resuscitation and emergency cardiovascular care.

Do's

• Prepare for transcutaneous pacing if perfusion is poor
• If atropine is ineffective, pacing should begin
• The use of sodium bicarbonate should be considered for severe metabolic acidosis
• Atropine should be used with caution in the presence of myocardial ischemia because it increases oxygen demand and could worsen the ischemia

Don'ts

• Do not delay pacing if rhythm is Mobitz type II second degree block or third-degree AV block
• Avoid using atropine in hypothermic bradycardia and Mobitz type II/second degree AV block