VTach vs VFib: Recognizing Lethal Ventricular Rhythms on the Monitor

Learn to recognize ventricular tachycardia, ventricular fibrillation, Torsades de Pointes, and dangerous PVC patterns on the telemetry monitor. Know when seconds count.

The Rhythms That End Lives Ventricular rhythms are the emergencies you train for. These are the rhythms that cause cardiac arrest, that trigger code blue responses, that determine whether a patient lives or dies based on how fast they are recognized. As a monitor tech, you are often the first person to see a lethal ventricular rhythm develop — sometimes before the bedside nurse, sometimes before anyone in the room realizes something has changed. This guide covers the ventricular rhythms you must know cold: ventricular tachycardia, ventricular fibrillation, Torsades de Pointes, and the PVC patterns that warn you trouble may be coming. Ventricular Tachycardia (VTach): Wide, Fast, and Dangerous Ventricular tachycardia occurs when the ventricles take over the rhythm, firing at rates of 100 to 250 bpm. Because the impulse originates in the ventricular muscle rather than traveling through the normal His-Purkinje conduction system, the QRS complexes are wide — typically greater than 120 ms and often much wider. The result is a fast, wide-complex tachycardia that may or may not produce adequate cardiac output. Monomorphic VTach The most common form. Every QRS complex looks the same — same shape, same width, same direction. The rhythm is regular or very nearly so. The rate is typically 150 to 200 bpm but can be slower or faster. What it looks like: Wide, bizarre QRS complexes marching in rapid succession, all identical in morphology. No visible P waves (or if present, they are dissociated from the QRS complexes — the atria and ventricles are firing independently). The rhythm looks like a fast, regular series of wide humps with no isoelectric baseline visible between complexes at higher rates. Clinical significance: Monomorphic VTach can be sustained (lasting more than 30 seconds or causing hemodynamic instability) or non-sustained (lasting less than 30 seconds and self-terminating). Both are significant. Sustained monomorphic VTach is a medical emergency — the patient may have a pulse (unstable VTach requiring cardioversion) or may be pulseless (cardiac arrest requiring defibrillation and CPR). Polymorphic VTach Less common but more immediately dangerous. The QRS complexes change in shape, amplitude, and axis from beat to beat. The rhythm looks chaotic — the complexes are wide but constantly shifting in morphology. What it looks like: Fast, wide complexes that continuously change in appearance. The tracing looks unstable and disorganized, though not as disorganized as VFib. Polymorphic VTach frequently degenerates into ventricular fibrillation. Clinical significance: Polymorphic VTach almost always causes hemodynamic compromise. It tends to be poorly tolerated and frequently progresses to VFib and cardiac arrest if not treated immediately. Sustained vs Non-Sustained This distinction matters for escalation: - Non-sustained VTach (NSVT): Three or more consecutive ventricular beats at a rate above 100 bpm, lasting less than 30 seconds. The rhythm self-terminates. NSVT is common in patients with structural heart disease. It may not cause symptoms, but it is a warning sign that the ventricles are electrically irritable. Document it, note the duration and rate, and notify the nurse. - Sustained VTach: Lasts more than 30