ECG Troubleshooting and Artifacts Flashcards

A rhythm strip shows regular QRS complexes intermixed with artifact spikes from a patient's implanted pacemaker. How can you best distinguish paced beats from artifact?

Answer: Paced beats are followed by a wide QRS complex after each pacemaker spike

True pacemaker spikes are immediately followed by a ventricular depolarization (wide QRS), while artifact spikes from external sources have no consistent relationship to cardiac complexes.

Standard ECG paper runs at which speed?

Answer: 25 mm/sec

Standard ECG paper speed is 25 mm/second, making each small box (1 mm) equal to 40 ms and each large box (5 mm) equal to 200 ms.

Which chest electrode position is placed at the fourth intercostal space to the right of the sternum?

Answer: V1

V1 is placed at the fourth intercostal space just to the right of the sternal border, providing the key reference lead for P wave morphology and bundle branch block analysis.

A patient with shivering produces ECG artifact that closely resembles which serious arrhythmia?

Answer: Atrial fibrillation

Muscle tremor artifact from shivering produces irregular rapid baseline oscillations that can mimic the irregular fibrillatory baseline of atrial fibrillation.

When performing a 12-lead ECG, the RL (right leg) electrode serves primarily which purpose?

Answer: Electrical ground/reference to reduce common-mode noise

The right leg electrode serves as the ground electrode, providing a common reference point that helps the ECG machine cancel out common-mode electrical noise affecting all leads equally.

Improper placement of the V4 electrode (placed too high, at the 4th ICS instead of 5th) would most likely affect which finding?

Answer: R wave progression and ST segment changes in the precordial leads

Misplacing V4 alters the precordial R wave progression pattern and may falsely suggest poor R wave progression or anterior ischemia, since each lead records a different spatial perspective of the heart.