Bradyarrhythmia (Bradycardia with Pulse)

ECG Criteria

Type of Bradycardia	Heart Rate	Rhythm	P Wave	PR Interval	QRS Complex
Sinus Bradycardia	< 60 bpm	Regular	Normal, precedes each QRS	Normal (120-200 ms)	Normal (≤ 120 ms)
1st Degree AV Block	Usually < 60 bpm	Regular	Normal, precedes each QRS	Prolonged (> 200 ms)	Normal
2nd Degree AV Block Type I	< 60 bpm	Irregular	Progressive prolongation	Progressively increases	Normal
2nd Degree AV Block Type II	< 60 bpm	Irregular (intermittent)	Normal, some P waves not followed	Normal or prolonged	Normal or widened
3rd Degree AV Block	< 40-60 bpm	Regular (A & V dissociation)	P waves independent of QRS	Variable (no relation to QRS)	Narrow or wide
Junctional Bradycardia	40-60 bpm	Regular	Absent, inverted, or retrograde	Shortened or absent	Normal
Idioventricular Rhythm	20-40 bpm	Regular	Absent	Absent	Wide (> 120 ms)

1. Rapid Clinical Assessment

- ABCD Approach

- Monitoring and Oxygenation:

Maintain SpO₂ > 95%.
Place the patient on a cardiac monitor.

- Establish intravenous (IV) access.

- Obtain a 12-lead ECG if available, but do not delay treatment.

- Look for Signs of Instability: HASIF

Hypotension
Altered Sensorium (Altered Mental Status)
Signs of Shock
Ischemic Chest Discomfort
Acute Heart Failure

2. Identify and Treat Underlying Causes

Ensure adequate oxygenation and ventilation.
Correct electrolyte imbalances.
Review medications that may cause bradycardia (e.g., beta-blockers, calcium channel blockers, digoxin).

Watchout for broad complex bradycardia - need to suspect severe hyperkalemia (esp. patient with u/l ESRF).

In suspected hyperkalemia, administered calcium gluconate and may trial of salbutamol nebulization with lytic cocktail while waiting for the blood result. Observe cardiac monitor if theres a changes.

3. If the Patient is Unstable:

i. Atropine:

First Dose: 0.5mg IV bolus.
- AHA use 1mg instead
Repeat every 3–5 minutes as needed.
Maximum Total Dose: 3mg.

If Atropine is Ineffective:

Begin Transcutaneous Pacing (TCP) AND / OR Dopamine or Adrenaline infusion

ii. Transcutaneous Pacing (TCP):

Preparation

i. Explain the procedure to the patient if conscious.

ii. Administer analgesia and sedation as needed:

Fentanyl: 1–2 mcg/kg.
Midazolam: 1–2 mg IV slowly.

Procedure

i. Place pacing pads on the patient.

ii. Set the pacing rate to 60–80 beats per minute (bpm).

iii. Set current output level (start at 1mA/kg)

iv. Increase the current slowly until electrical capture is achieved (evidenced by a widened QRS following each pacing spike).

v. Confirm mechanical capture (palpable pulse corresponding to paced rhythm).

iii. Dopamine or Adrenaline Infusion:

Dopamine:

Dosage: 5–20mcg/kg/min.
- Titrate to patient response; taper slowly.

Adrenaline:

Dosage: 2–10 mcg/min.
- Titrate to patient response.

iv. Consider Expert Consultation:

Consult cardiology for transvenous pacing or further management.

4. If the Patient is Stable:

i. Observation and Monitoring

ii. Monitor vital signs and cardiac rhythm closely.

iii. Prepare for possible deterioration:

Have atropine and pacing equipment readily available.

iv. Investigate Underlying Causes:

Obtain detailed history and physical examination.
Review medications.
Check laboratory tests (electrolytes, cardiac biomarkers, thyroid function tests).

5. Special Considerations

i. Atropine Precautions:

Use with caution in myocardial ischemia and hypoxia; may increase oxygen demand.
Not effective for heart transplant patients (denervated hearts).

ii. AV Block Types:

Second-Degree AV Block Type I (Mobitz I or Wenckebach):
- Usually transient and may not require treatment if asymptomatic.
Second-Degree AV Block Type II (Mobitz II) and Third-Degree AV Block:
- More likely to progress to asystole; prepare for pacing.

iii. Do Not Rely on Atropine Alone in:

High-degree AV blocks (Type II second-degree or third-degree).
Consider early pacing and/or catecholamine infusion.