The monitor tells you what rhythm you are looking at. The patient tells you how fast to move. For regular narrow-complex tachycardia, two forks run the room.
Fork 1: Is the tachycardia causing instability? Fork 2: Is the rhythm regular and narrow?
Hypotension with poor perfusion, acutely altered mental status, shock, ischemic chest discomfort, or acute heart failure.
Get a 12-lead during the tachycardia if it will not delay care. Continuous monitor. Reliable IV. Pads nearby.
A septic patient with sinus tachycardia and hypotension is not unstable because of the rhythm. Treat the cause. Do not cardiovert the monitor.
Continuous ECG. Semi-recumbent bed. Manometer or 10 mL syringe. Enough hands to lower the bed and lift both legs immediately.
Generate 40 mmHg. A practical cue is blowing hard enough to move the plunger of a 10 mL syringe.
Stop the strain. Drop the backrest and passively raise both legs to 45°. The position change must be immediate.
Lower the legs. Return the backrest to 45°. Watch the monitor and assess the rhythm after 45 seconds.
Use a proximal, reliable IV. Tell the patient about the brief pressure, flushing, dyspnea, and dread.
The pause may expose flutter waves or atrial activity. No pause suggests poor delivery or antagonism. Pause without conversion means the rhythm may not depend on the AV node.
Only for a stable, confirmed regular narrow-complex rhythm. Do not stack IV beta-blocker and diltiazem.
Dipyridamole potentiates adenosine. Carbamazepine can intensify AV block. Caffeine and theophylline antagonize it.
Avoid adenosine in high-grade AV block or sick sinus without a pacemaker and in asthma or active bronchospasm. Avoid diltiazem in hypotension or systolic HF. Avoid metoprolol in decompensated HF or significant bronchospasm.
Did it reach the heart? What did the strip show? Atrial flutter, atrial tachycardia, and sinus tachycardia will not terminate just because the AV node pauses.
It does not belong in the routine regular narrow-complex sequence. If vagals and pharmacologic therapy fail, synchronized cardioversion is still appropriate.
Do not turn “WPW” into a blanket adenosine ban. Regular narrow-complex orthodromic AVRT uses the AV node. Adenosine is appropriate.
Pre-excited atrial fibrillation is different. QRS morphology often changes beat to beat. AV-nodal blockade can accelerate conduction down the accessory pathway and precipitate VF.
Procainamide or ibutilide. Expert involvement. Pads on. Immediate cardioversion capability.
| Capture | What it can reveal | Do not miss |
|---|---|---|
| 12-lead during tachycardia | Regularity, width, atrial activity | Save it before conversion if care is not delayed. |
| Continuous strip during adenosine | AV block, flutter waves, atrial tachycardia | The diagnostic pause may be the best tracing. |
| Post-conversion 12-lead | Short PR, delta wave, ischemic change | A clean ECG does not exclude a concealed pathway. |
Persistent or recurrent tachycardia, irregular or wide rhythm, diagnostic uncertainty, pre-excited AF, syncope, ischemia, heart failure, structural heart disease, or failed treatment.
Symptoms resolved. Post-conversion ECG reassuring. No high-risk features. Reliable follow-up. Teach the modified Valsalva and arrange cardiology or EP follow-up for recurrent symptomatic episodes.
The patient sets the urgency. The rhythm sets the treatment.
Unstable because of the tachycardia means synchronized cardioversion at 100 J.
Stable and regular-narrow means modified Valsalva, then adenosine 6 mg, then 12 mg.
Adenosine is a diagnostic pause. Record it.
The WPW emergency is pre-excited AF, not every regular narrow-complex SVT.
.SVTCURBSIDE Patient presented with a regular narrow-complex tachycardia at #HR bpm. Hemodynamic assessment showed #NO_FINDINGS attributable to the tachycardia. Rhythm treated with #MODIFIED_VALSALVA / ADENOSINE / SYNCHRONIZED_CARDIOVERSION. Continuous rhythm strip obtained during treatment. Conversion to sinus rhythm achieved at #TIME. Post-conversion 12-lead reviewed for ischemia and pre-excitation: #FINDINGS. Patient reassessed and remained #STATUS. Follow-up and return precautions discussed.