ECG ECG Troubleshooting 2

Question 1

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

Accepted Answer

Second-degree AV block Mobitz I (Wenckebach)

Answer

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

Question 2

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

Accepted Answer

Ask the patient to hold their breath briefly during acquisition

Answer

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

Question 3

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?

Accepted Answer

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

Answer

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.

Question 4

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?

Accepted Answer

Right arm and left arm lead reversal

Answer

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.

Question 5

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

Accepted Answer

Peaked, narrow, symmetric T waves

Answer

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

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ECG ECG Troubleshooting 2