ECG Troubleshooting Flashcards

A patient's ECG shows a regularly irregular rhythm with a pattern of grouped beating. Which arrhythmia is most likely?

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

Wenckebach block produces grouped beating due to progressive PR prolongation until a beat is dropped, creating a regularly irregular pattern.

When troubleshooting a wandering baseline artifact on a 12-lead ECG, which corrective action is most effective?

Answer: Ask the patient to hold their breath briefly during acquisition

Respiratory movement is the primary cause of wandering baseline, and having the patient hold their breath during recording eliminates this motion artifact.

An ECG shows QRS complexes preceded by P waves in leads I and aVL but inverted P waves before QRS in lead II. What does this indicate?

Answer: Ectopic atrial rhythm originating in the low atrium or near the AV node

Inverted P waves in the inferior leads (II, III, aVF) with upright P in lateral leads suggest a low atrial or junctional ectopic pacemaker firing retrogradely.

A technician records an ECG and notices the QRS in lead I is negative and in aVR is positive. What is the most likely cause?

Answer: Right arm and left arm lead reversal

Reversal of the right and left arm electrodes produces a negative QRS in lead I and a positive QRS in aVR, the mirror image of normal.

What ECG finding is characteristic of hyperkalemia at serum potassium levels above 6.5 mEq/L?

Answer: Peaked, narrow, symmetric T waves

Hyperkalemia first manifests as tall, peaked, narrow, symmetric (tent-shaped) T waves due to accelerated ventricular repolarization.

A patient with a permanent pacemaker has an ECG showing pacemaker spikes without subsequent QRS complexes. What is the most likely diagnosis?

Answer: Pacemaker failure to capture

Failure to capture occurs when the pacemaker spike fires but fails to depolarize the myocardium, producing spikes not followed by QRS complexes.

Which ECG change is most consistent with acute pericarditis?

Answer: Diffuse ST elevation with concave morphology in multiple leads

Acute pericarditis produces diffuse saddle-shaped (concave) ST elevation in multiple leads without reciprocal changes, distinguishing it from myocardial infarction.