Diltiazem in AF with RVR
Objective: Give diltiazem only to the stable patient with an irregular narrow-complex rhythm your protocol names. Do not give it for pre-excited atrial fibrillation or for a wide-complex rhythm. Check the blood pressure before and after. Your protocol card sets the amount.
Why this matters
Diltiazem is for stable irregular narrow-complex tachycardia, when your protocol names it. The monitor may show atrial fibrillation at 160 before anyone checks perfusion or QRS width.
An unstable patient gets electricity. An irregular wide rhythm may be pre-excited atrial fibrillation, Wolff-Parkinson-White. Do not give diltiazem, adenosine, or a beta-blocker for that rhythm. A drop in blood pressure is the common complication. Your protocol card sets the dose. Your job is to confirm the indication.
- Unstable means shock, severe ischemic pain, altered mental status, or acute heart failure from the rate. That patient gets synchronized cardioversion, not a calcium-channel blocker.
- If the QRS is wide and irregular, see the WPW lesson. Do not give diltiazem, adenosine, or a beta-blocker.
- If you give it, check the blood pressure before and after. Give it slowly, as labeled. If the pressure falls, stop and support perfusion. Cardiovert if the patient becomes unstable. Calcium treats calcium-channel-blocker overdose. Do not give calcium as an improvised rescue after a protocol dose unless your protocol lists it.
Clinical sequence
- Check the pulse, perfusion, and a 12-lead if that will not delay an unstable patient.
- Sort the rhythm with three questions. Narrow or wide. Regular or irregular. Stable or unstable.
- Unstable goes to cardioversion. Wide and irregular gets no AV-nodal blocker. Stable, narrow, and irregular may get diltiazem if the protocol and the blood pressure allow it.
- Reassess the rate and the blood pressure. If the patient becomes unstable, support perfusion and tell the emergency department what you gave. Do not add a beta-blocker ten minutes later.
Teaching points
- The indication is narrow, irregular, and stable. That is atrial fibrillation or atrial flutter with a rapid ventricular response. It is not SVT, not ventricular tachycardia, and not WPW.
- The dose is your protocol card. Usual teaching is a slow intravenous dose with a blood-pressure check, sometimes followed by an infusion. Do not keep giving it to lower the rate after the blood pressure falls. This site does not list milligrams.
- If the blood pressure falls, treat that as an effect of the drug. Give fluid if the patient can take it. Use a vasopressor or calcium only as your protocol says. Give an honest handoff.
- A beta-blocker is the alternative in some systems. Do not put diltiazem and a beta-blocker on a failing heart.
- Narrow, irregular, and stable: diltiazem is a possible treatment.
- Unstable: cardioversion, not diltiazem.
- Wide and irregular: no AV-nodal blocker.
- Blood pressure before and after.
Common errors
- Giving diltiazem for an irregular wide tachycardia because the monitor said atrial fibrillation.
- Giving it when the blood pressure is already 78 because the rate looked fast.
- Adding a beta-blocker ten minutes later.
Practice
One-minute check
Three rhythms. Drug or electricity for each? (1) Irregular narrow at 170, blood pressure 138, talking. (2) Irregular wide at 220, blood pressure 80. (3) Irregular narrow at 160, blood pressure 72, pulmonary edema.
Related: Pre-excited atrial fibrillation (WPW), Synchronized cardioversion.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language. Your protocol still decides.
- AHA 2025 Part 9: Adult ALS — Unstable tachycardia is treated with cardioversion. AV-nodal blockers are for selected stable narrow rhythms.
- 2023 ACC/AHA/ACCP/HRS Atrial Fibrillation Guideline — Rate control versus cardioversion. Pre-excited atrial fibrillation: no AV-nodal blockers.
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Questions drawn only from this lesson. After you check, the key is highlighted. Education practice — not a certification exam.