Bradycardia & AV-Block Algorithm
When a slow rhythm needs action and when it doesn't — the treatment ladder plus a clean side-by-side of the AV blocks.
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<a href="https://rcispracticetest.com/cheat-sheets/bradycardia-algorithm.html">Bradycardia & AV-Block Algorithm — RCIS Practice Test</a>Educational use only — not medical advice. Values are standard adult references; always confirm against current guidelines and your institution’s protocols.
The treatment ladder
| Step | Action |
|---|---|
| 1. Bradycardia | Heart rate < 60 bpm (usually symptomatic when < 50) |
| 2. Symptomatic? | Hypotension, shock, altered mental status, ischemic chest pain, acute heart failure |
| 3. If stable | Monitor, identify and treat the cause (drugs, ischemia, electrolytes) |
| 4. If symptomatic | Atropine 0.5–1 mg IV, repeat to a max of 3 mg |
| 5. If atropine fails | Transcutaneous pacing and/or dopamine or epinephrine infusion; prepare transvenous pacing |
Telling the AV blocks apart
| Block | ECG hallmark | Risk / action |
|---|---|---|
| First-degree | PR > 200 ms, constant; every P conducts | Benign; no treatment |
| Second-degree Mobitz I (Wenckebach) | Progressive PR lengthening, then a dropped QRS | Usually benign; atropine if symptomatic |
| Second-degree Mobitz II | Constant PR, sudden dropped QRS | High risk; often needs pacing |
| Third-degree (complete) | AV dissociation — P waves and QRS independent | Pacing (transcutaneous → transvenous/permanent) |
Recognize these fast with the ECG bank and the rhythm interpretation guide.
Frequently asked questions
What is the first drug for symptomatic bradycardia?
Atropine 0.5–1 mg IV, repeated to a maximum of 3 mg. If it fails, move to transcutaneous pacing or a dopamine/epinephrine infusion.
Why might atropine not work in heart block?
In Mobitz II and complete heart block with a wide escape rhythm, the block is below the AV node (infranodal), where atropine is ineffective — pacing is needed.
How do you tell Mobitz I from Mobitz II?
Mobitz I (Wenckebach) shows progressive PR lengthening before a dropped beat; Mobitz II has a constant PR with a sudden dropped QRS and is more dangerous.
Can I print this bradycardia algorithm?
Yes — use the 'Print / Save as PDF' button at the top.
Sources & further reading
- Cardiovascular Credentialing International (CCI)
- American College of Cardiology
- American Heart Association
- MedlinePlus (U.S. National Library of Medicine)
External links are provided for reference; always confirm current details with the official source.