Ventricular Dysrhythmias and Life-Threatening Rhythms

What Are Ventricular Dysrhythmias?

Ventricular dysrhythmias originate below the bundle of His — in the ventricular myocardium itself rather than in the normal conduction pathway. Because the electrical impulse spreads cell-to-cell instead of through the fast His-Purkinje system, depolarization is slow and disorganized. On the rhythm strip this produces the hallmark of all ventricular beats: a wide, bizarre QRS complex measuring 0.12 seconds (120 ms) or greater. There is usually no preceding P wave related to the beat, and the T wave deflects opposite to the main QRS deflection (discordant T wave).

As an EKG technician you will not diagnose or treat these rhythms, but you must recognize them accurately and respond correctly. Life-threatening ventricular rhythms require immediate verbal notification of the supervising nurse or physician — every second counts.

Premature Ventricular Contractions (PVCs)

A PVC is a single early beat arising from a ventricular focus. Key features:

• Early — it interrupts the underlying rhythm before the next expected beat.
• Wide, bizarre QRS — 0.12 s or greater, with a discordant T wave.
• No preceding P wave related to the PVC.
• Compensatory pause — the RR interval surrounding the PVC usually equals two normal RR intervals because the SA node is not reset.

Pattern terminology you must know:

| Pattern | Definition |

|---|---|

| Unifocal | All PVCs look identical — one ectopic focus |

| Multifocal | PVCs have different shapes — multiple foci; more concerning |

| Couplet | Two consecutive PVCs |

| Bigeminy | Every other beat is a PVC |

| Trigeminy | Every third beat is a PVC |

| Run of VT | Three or more consecutive PVCs |

Isolated PVCs in a monitored patient should be documented accurately. Frequent, multifocal PVCs or couplets should be reported per facility protocol — note exactly what you see and when.

Ventricular Tachycardia (VT)

Ventricular tachycardia is defined as three or more consecutive PVCs at a rate typically between 100 and 250 bpm. The QRS complexes are wide and bizarre. P waves may be present but are unrelated to the QRS (AV dissociation). VT may be:

• Monomorphic — all QRS complexes have the same shape.
• Polymorphic — QRS shape varies (includes torsades de pointes).

VT may occur with a pulse (patient may be conscious) or without a pulse (pulseless VT is a cardiac arrest rhythm). You cannot determine pulse status from the strip alone — you must look at and assess the patient. If the patient is unresponsive or pulseless, activate emergency response immediately. Do not leave the patient to get help; use the call system or direct someone else to call.

Ventricular Fibrillation (VF)

VF is completely chaotic electrical activity in the ventricles. The strip shows irregular, wavy, disorganized deflections with no identifiable P waves, QRS complexes, or T waves. There is no effective cardiac output. VF is always a cardiac arrest.

Your response as an EKG technician:

1. Confirm the patient is unresponsive (tap shoulders, call out).

2. Activate the emergency response system (call out, use call light, pull emergency cord) — do not leave the patient.

3. Begin CPR if trained and per your facility protocol until the code team arrives.

4. Document the time you identified the rhythm and the actions taken.

Never delay calling for help to continue the EKG hook-up or to document first.

Idioventricular Rhythm

When higher pacemakers (SA node, AV node) fail, the ventricles may take over at their intrinsic escape rate of 20–40 bpm. This is called idioventricular rhythm (IVR). The strip shows wide QRS complexes at a very slow, regular rate with no related P waves. Accelerated idioventricular rhythm (AIVR) occurs at 40–100 bpm and is often seen during reperfusion after myocardial infarction.

IVR is a serious finding. Report it immediately — the patient may have severely compromised cardiac output even if technically not in full arrest.

Asystole

Asystole is the absence of any cardiac electrical activity — a flat line on the strip. Confirm in at least two leads, check lead connections, and ensure gain is adequate before concluding the line is truly flat. Asystole is a cardiac arrest requiring immediate emergency activation.

Complete Heart Block (Third-Degree AV Block) — A Life-Threat to Recognize

Though not a ventricular dysrhythmia by origin, third-degree (complete) heart block is classified as a life-threatening rhythm requiring the same urgent response. The atria and ventricles beat independently. P waves are regular, QRS complexes are regular, but there is no relationship between them. The ventricular rate is typically slow (20–40 bpm with wide ventricular escape beats, or 40–60 bpm with junctional escape beats). Notify the supervising clinician immediately.

Scope of Practice and Safety

As an EKG technician you identify and report — you do not interpret clinically, administer medications, or operate a defibrillator unless you hold additional certification and your facility grants that role. Your critical safety responsibilities are:

• Recognize life-threatening patterns.
• Notify the supervising nurse or physician immediately and by name if possible.
• Stay with the patient until help arrives.
• Document the time, the rhythm finding, who you notified, and the response.
• Never falsify, delay, or omit documentation of a life-threatening event.

Accurate rhythm recognition and a calm, immediate response are the two most important skills you bring to patient safety in this role.