Ace the 2025 CCT Challenge – Boost Your Career with Cardiographic Confidence!

Premature ventricular contractions (PVCs) are characterized by wide and bizarre QRS complexes. This is because PVCs originate from the ventricles, which leads to a different conduction pathway through the heart compared to normal sinus rhythm. The wide QRS complexes typically measure greater than 120 milliseconds due to the slower depolarization of the ventricles, which does not follow the typical conduction through the His-Purkinje system. Additionally, the shape of the QRS complexes appears unusual or bizarre when viewed on an electrocardiogram (ECG).

The other features listed do not accurately represent PVCs. Narrow and peaked QRS complexes are more characteristic of supraventricular ectopic beats, while normal QRS complexes indicate the presence of normal sinus conduction. Inverted T waves can occur for various reasons but are not a defining feature of PVCs. Therefore, the defining characteristic of PVCs is indeed the presence of wide and bizarre QRS complexes.