A wide-complex tachycardia at approximately 180 bpm with regular rhythm and no visible P waves in an unstable patient. What is the most likely rhythm?

Prepare for the Cleveland Clinic EKG Test with flashcards and multiple choice questions. Gain insights with hints and explanations. Ace your exam today!

The main idea is recognizing when a wide-complex tachycardia is most likely ventricular in origin. A rate around 180 beats per minute with a clearly wide QRS and a regular rhythm strongly points to ventricular tachycardia, especially in an unstable patient. In VT, the ventricles are being activated from an ectopic focus or reentry circuit, so the QRS complexes are wide because the impulse doesn’t travel through the normal His-Purkinje system. P waves are often not visible or are dissociated from the ventricular activity, which fits the finding of no clear P waves.

In contrast, sinus tachycardia would typically show narrow QRS complexes and visible P waves, since the impulse follows the normal conduction pathway. Atrial fibrillation with rapid conduction would be irregular rather than perfectly regular. Supraventricular tachycardia with aberrancy can produce a wide QRS, but P waves are usually present (even if obscured) and the rhythm is often not as uniformly regular at high rates in the unstable setting.

So, the combination of wide QRS, regular high-rate tachycardia, and absence of identifiable P waves in an unstable patient makes ventricular tachycardia the most likely rhythm.