FoamFrat Sandbox · Cardiology

Reentry Tachycardias — Circuit & ECG Lab

Pick a rhythm. Watch the impulse travel the conduction system on the left while the matching ECG draws in real time on the right. Each lap of the circuit makes a beat — so you can see why each rhythm looks the way it does on the monitor.
Conduction system
RA LA insulated annulus RV LV SA AVN
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Lead II rhythm strip (live)
Slow-mo 0.5×
active depolarization resting tissue ECG trace

Normal Sinus Rhythm

Rate
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QRS
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P waves
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On the monitor

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Breaking the loop

Every treatment for reentry interrupts the circuit. The whole decision hinges on one question: is the AV node part of the loop, and is the patient stable?

RhythmAV node in the loop?Stable first moveUnstable
AVNRTYesVagal → adenosine 6 mg, then 12 mgSynchronized cardioversion
Orthodromic AVRTYesVagal → adenosineSynchronized cardioversion
Atrial flutterNo (atrial loop)Rate control / cardioversion; adenosine only to diagnoseSync cardioversion (low energy)
WPW + AFibNode bypassedProcainamide; avoid AV-nodal blockersSynchronized cardioversion
Monomorphic VTNo (ventricular loop)Amiodarone / procainamide (stable, has pulse)Sync cardioversion; defib if pulseless
⚠ Two traps: Irregular + wide + fast → think WPW with AFib; AV-nodal blockers (adenosine, diltiazem, verapamil, beta-blockers, digoxin) can trigger VF. And wide + regular in a patient with cardiac history → treat as VT until proven otherwise; verapamil can be lethal here.

Teaching tool only. Doses and drug choices follow your local protocol and current resuscitation guidelines.