Dangerous heart rhythms: VT, VF, and the arrest rhythms

This guide is for learning to recognize rhythms on a simulated strip. It is not clinical guidance and not a treatment protocol. In real care, act on your assessment of the patient, your team, and your facility's and ACLS protocols. VitalSim Rhythm shows simulated waveforms and is not a medical device.

The dangerous rhythms are worth knowing cold so you recognize them instantly. Ventricular tachycardia is a fast, wide, organized ventricular rhythm; ventricular fibrillation is chaotic with no organized QRS; and the arrest rhythms — pulseless electrical activity and asystole — are why one rule matters most: what's on the monitor never proves there's a pulse.

VitalSim Rhythm's live ECG trainer on iPad, showing a frozen Normal Sinus rhythm on a calibrated grid with the heart rate and a rail of the five rhythm families color-coded

Ventricular tachycardia (VT)

A run of fast, wide QRS complexes from the ventricles — often regular and organized. It can be with or without a pulse; the patient, not the monitor, tells you which.

Ventricular fibrillation (VF)

Chaotic, disorganized electrical activity with no organized QRS — just a quivering baseline. It's the classic "shockable" arrest rhythm and the deadliest pattern on the monitor.

The arrest rhythms — and the pulse rule

Two more rhythms define cardiac arrest: pulseless electrical activity (PEA), where the monitor shows organized-looking electrical activity but there is no pulse, and asystole, the flat line. The lesson underneath them: electrical activity does not prove mechanical activity — always confirm the patient.

Recognize, then escalate

Your job with these rhythms is fast recognition and escalation — call for help and follow your team's and your facility's ACLS protocols. This guide (and the app) build the recognition; the response belongs to you, your team, and your protocols.

Practice spotting them — safely

VitalSim Rhythm lets you load VT, VF, and the arrest rhythms on a simulated strip and study their morphology as many times as you need — a safe place to build the pattern recognition you never get to rehearse on a real patient.

FAQ

What's the difference between VT and VF?

Ventricular tachycardia is fast, wide, and usually organized; ventricular fibrillation is chaotic with no organized QRS. VF is the classic shockable arrest rhythm.

Which rhythms are shockable?

Ventricular fibrillation and pulseless ventricular tachycardia are the shockable arrest rhythms; PEA and asystole are not. Always follow your ACLS and facility protocols.

What is PEA?

Pulseless electrical activity — organized-looking electrical activity on the monitor with no pulse. It's a reminder that what's on the screen doesn't prove there's a pulse.

VitalSim Rhythm