# Regular narrow-complex tachycardia

Distinguish a compensatory fast rate from the adenosine or urgent-cardioversion pathway.

Population: Adult / adolescent. Scope: ALS.
Status: published. Source-linked OCEMS summary.
Summary updated: 2026-09-16.
Source checked: 2026-09-16.
Source version: See linked source for document revision and implementation dates..
Canonical page: https://www.ocmedic.com/guides/narrow-complex-tachycardia/
Official source: [SO-C-025 — Narrow Complex QRS Complex Tachycardia](https://www.ochealthinfo.com/sites/hca/files/import/data/files/34670.pdf)

Independent OC Medic summary. Does not replace the complete policy, current system notices, or clinical judgment.

## Key cautions & base contact

- Do not administer adenosine to a wide, irregular rhythm.
- A regular narrow rhythm does not by itself prove a primary arrhythmia; assess suspected hypovolemia and stability first.

## Source documents

- [SO-C-025 — Narrow Complex QRS Complex Tachycardia](https://www.ochealthinfo.com/sites/hca/files/import/data/files/34670.pdf)

## Confirm the rhythm & assess perfusion

- This adult order applies to a regular rhythm above 100/min with QRS width below 0.12 seconds. Record a rhythm strip.
- Assess BP, consciousness, chest symptoms, oxygenation, and evidence of hypovolemia. Provide oxygen for SpO₂ below 95% as described by the source.

## Address suspected volume depletion

- For suspected hypovolemia with clear lungs/no CHF, give 250 mL normal saline, repeating up to 1 L to maintain perfusion.
- Reassess lung sounds; stop fluid infusion if rales develop. This assessment applies to both the 100–150 range and the faster-rate pathway.

## Rate at least 150: choose the branch

- With mild chest discomfort, lightheadedness, or diaphoresis: attempt Valsalva. If the regular narrow-complex rhythm persists, give adenosine 12 mg rapid IV; may repeat once after 3 minutes.
- With cardiac chest discomfort, altered mental status, or systolic BP below 90: synchronized cardioversion at 100 J initially, then once at maximum energy if needed, or use the manufacturer’s recommended settings.

## Reassess & transport

- Document conversion or persistent rhythm and reassess BP, consciousness, chest symptoms, and perfusion. Provide ALS escort to the nearest ERC or contact base as needed.
- A regular rate near 150 may represent flutter and may not respond to adenosine. The source warns that an unstable patient may require immediate cardioversion without premedication; if synchronization fails, unsynchronized treatment may be needed.