ECG Rhythm Interpretation Flashcards

A patient's ECG shows a regular rhythm at 150 bpm with narrow QRS complexes and no visible P waves. Which rhythm is most likely?

Answer: Atrial flutter with 2:1 block

Atrial flutter typically produces a ventricular rate of 150 bpm when 2:1 AV conduction is present, often hiding flutter waves in the QRS or T wave.

Which ECG feature best distinguishes Wolff-Parkinson-White (WPW) syndrome from a bundle branch block?

Answer: Delta wave and short PR interval

WPW is characterized by a delta wave (slurred QRS upstroke) and a short PR interval (<0.12 sec) due to accessory pathway pre-excitation.

An ECG shows regular P waves at 75 bpm, but only every other P wave conducts. The PR interval of conducted beats is constant. What is the rhythm?

Answer: Second-degree AV block, Mobitz type II

2:1 conduction with a constant PR interval on conducted beats and non-conducted P waves is consistent with Mobitz type II second-degree AV block.

What is the significance of a U wave on the ECG?

Answer: It often indicates hypokalemia when prominent

Prominent U waves are a classic ECG sign of hypokalemia; they appear after the T wave and can mimic a prolonged QT interval.

A patient with no pulse has an ECG showing organized electrical activity. What is this condition called?

Answer: Pulseless electrical activity (PEA)

PEA is defined as organized cardiac electrical activity on ECG without a corresponding palpable pulse, requiring CPR and treatment of reversible causes.

On a 12-lead ECG, ST elevation in leads II, III, and aVF most likely indicates ischemia in which territory?

Answer: Inferior wall

Leads II, III, and aVF view the inferior surface of the heart, supplied primarily by the right coronary artery.

Which finding on ECG is characteristic of hyperkalemia?

Answer: Tall, peaked T waves

Hyperkalemia classically produces tall, narrow, peaked (tent-shaped) T waves, especially in precordial leads, as an early ECG manifestation.