ECG Rhythm Interpretation Flashcards

A PR interval that is consistently prolonged beyond 0.20 seconds but every P wave conducts to a QRS indicates which rhythm?

Answer: First-degree AV block

A fixed, prolonged PR interval with every beat conducting defines first-degree AV block.

A rhythm shows progressive PR interval lengthening until a QRS is dropped, then the cycle repeats. This describes which block?

Answer: Second-degree AV block Type I (Wenckebach)

Progressive PR lengthening followed by a dropped beat is the pattern of Mobitz I (Wenckebach).

In third-degree (complete) AV block, what is the relationship between P waves and QRS complexes?

Answer: They are completely independent of each other

In complete heart block the atria and ventricles beat independently, so P waves and QRS complexes have no fixed relationship.

A premature, wide, bizarre QRS complex that occurs earlier than expected with no preceding P wave is called what?

Answer: Premature ventricular contraction (PVC)

A wide, early QRS without a preceding P wave is a premature ventricular contraction.

Second-degree AV block Type II (Mobitz II) is characterized by what pattern?

Answer: Constant PR interval with intermittent dropped QRS complexes

Mobitz II shows a fixed PR interval with sudden non-conducted P waves and dropped QRS complexes.

A junctional rhythm arising from the AV node typically produces which finding?

Answer: Inverted or absent P waves with a rate of 40-60 bpm

Junctional rhythms arise near the AV node, causing inverted or absent P waves at a rate of about 40-60 bpm.

Three or more PVCs in a row at a rate over 100 bpm should be identified as what?

Answer: Ventricular tachycardia

A run of three or more consecutive PVCs above 100 bpm meets the definition of ventricular tachycardia.