Bradycardia

Question 1

In the acute setting, what is most important to determine when a patient presents with bradycardia?

Answer 1

The most important step in the acute management of bradycardia is determining if the patient is unstable.

Question 2

What immediate action should be taken if a patient has unstable bradycardia?

Answer 2

Administer atropine

** Atropine is an anticholingeric agent that competitively blocks muscarinic receptor antagonist. It is used to tx symptomatic bradycardia, AV block, decrease salivation, and reverse neuromuscular blockade **

Question 3

What is the appropriate management of asymptomatic, stable bradycardia ?

Answer 3

Typically, no treatment is required

Question 4

Outline the management of bradycardia on the ward

Answer 4

1. ABCDE survey
   
   • Pulse?
     > No - Commence CPR
     > Yes - Continue stepwise through ABCDE survey
   • Identify & tx hypoxaemia: supp. O2 - aim >94%
   • ECG (if immediately available)
   • Monitoring + supportive care
2. Determine if stable or unstable?
   
   • Unstable bradycardia?
     > Administer atropine
   • Stable bradycardia?
     > Proceed to next step
3. Determine if symptomatic or asymptomatic?
   
   • Symptomatic + stable
     > Most patients: observe, no tx required
     > Patients with severe symptoms: Atropine
     > Patients with 2nd degree AV block, Mobitz II, 3rd degree AV block +
     symptomatic: transcutaneous pacing/transvenous pacing
   • Asymptomatic
     > Most patients: observe, no tx required
     > Patients with 2nd degree AV block, Mobitz II, 3rd degree AV block: consider
     transcutaneous pacing/transvenous pacing

Question 5

What are the signs of unstable bradycardia?

Answer 5

Signs of hypoperfusion 
   - poor capillary refill, low O2 sat, cool/dry skin, pallor
Respiratory distress
Chest pain
Pulmonary oedema
Shock
Altered mental status

Question 6

What is the initial management of bradycardia if it is stable, yet the patient is symptomatic?

Answer 6

Most patients can be observed, and no intervention will be required.

Only patients with high-grade AV block or severe symptoms should be treated.
> 1st line: atropine
> 2nd line: prep. for transvenous pacing + take steps as for unstable bradycardia
> + identify and tx hypoxia: supp. O2 - aim >94%

Question 7

In terms of broad categories (and some specifics), what are some of the major causes of bradycardia in the acute setting to be aware of when assessing a patient?

Answer 7

• Increased vagal tone: Physiological / vasovagal response / pain ++ others
• Ischaemia: AMI / unstable angina / ischaemic cardiomyopathy
• Inflammatory/infiltrative: Myocarditis, pericarditis ++ many more
• Infections: Infective endocarditis ++ many more less common infections
• Metabolic/endocrine: Electrolyte imbalance (hypo/hyperkalaemia), thyroid imbalance, adrenal hormone imbalance (pheochromocytoma, hypoaldosteronism)
• Iatrogenic: various
• Medications
  > antiarrhythmics (adenosine, amiodarone, etc.) /
  > antihypertensives (b blockers, calcium channel
  blockers, methyldopa, others)
  > psychoactive drugs (lithium, opioids, donepezil,
  phenytoin, SSRIs, TCAs)
  ** Intoxication w other agents: digoxin, propofol,
  muscle relaxants, cannabis
• Other: hypothermia, raised ICP, HTN ++ others