ECG Troubleshooting Flashcards

An ECG shows a rate of 150 bpm with narrow QRS complexes and no visible P waves. Which arrhythmia should be considered first?

Answer: Atrial flutter with 2:1 conduction

Atrial flutter at a typical atrial rate of 300 bpm with 2:1 AV conduction produces a ventricular rate of approximately 150 bpm; flutter waves may be hidden in the QRS or T wave.

When a patient's ECG shows motion artifact making interpretation difficult, what is the FIRST action the ECG technician should take?

Answer: Ask the patient to relax and lie still, then repeat the recording

Patient movement is the most common cause of artifact, and instructing the patient to remain still and relaxed should be the first step before any equipment adjustments.

Which finding on a 12-lead ECG is most suggestive of left ventricular hypertrophy (LVH)?

Answer: S wave in V1 plus R wave in V5 or V6 exceeding 35 mm

The Sokolow-Lyon criterion (SV1 + RV5 or RV6 ≥ 35 mm) is a widely used ECG voltage criterion for diagnosing LVH.

A 60-year-old male presents with chest pain. The ECG shows ST depression in leads V1-V3. Which condition should be ruled out first?

Answer: Posterior MI (reciprocal changes)

ST depression in V1-V3 may represent reciprocal changes of a posterior MI; posterior leads (V7-V9) should be obtained to look for ST elevation confirming posterior STEMI.

An ECG shows a short PR interval of 100 ms, a delta wave, and a wide QRS. What is the diagnosis?

Answer: Wolff-Parkinson-White (WPW) syndrome

WPW syndrome is characterized by a short PR interval, slurred upstroke (delta wave) of the QRS, and widened QRS due to ventricular pre-excitation via an accessory pathway.

Which electrode placement error causes leads V1 and V2 to appear reversed on an ECG?

Answer: Placing V1 at the 2nd intercostal space instead of the 4th

Placing V1 too high (2nd intercostal space instead of 4th) produces rS or QS morphology in V1 and V2, mimicking anteroseptal infarction or lead reversal.

What is the likely interpretation when an ECG shows varying QRS morphologies with no identifiable P waves and an irregularly irregular rhythm at 90 bpm?

Answer: Atrial fibrillation with aberrant conduction

Atrial fibrillation with aberrant conduction (rate-related bundle branch block) produces irregularly irregular rhythm with varying QRS morphology and absent P waves.