Electrocardiography (ECG/EKG) Techniques Flashcards

A technician notices the QRS complexes alternate in amplitude on an ECG strip. This finding is called:

Answer: Electrical alternans

Electrical alternans is characterized by beat-to-beat variation in QRS amplitude and can indicate pericardial effusion or cardiac tamponade.

Which electrode placement error causes the most clinically significant ECG distortion?

Answer: Left arm and right arm leads reversed

Reversing the left arm (LA) and right arm (RA) electrodes inverts lead I and swaps aVL and aVR, which can mimic dextrocardia or mask pathology.

The QTc interval is calculated to correct for heart rate. Which formula is most commonly used?

Answer: Bazett formula

The Bazett formula (QTc = QT / √RR) is the most widely used method for heart rate correction of the QT interval despite its limitations at extreme rates.

Posterior wall MI is best identified on a standard 12-lead ECG by which finding in leads V1–V2?

Answer: Tall R waves and ST depression

Posterior MI produces reciprocal changes in V1–V2: tall, broad R waves and ST depression representing the mirror image of posterior ST elevation and Q waves.

To reduce 60-Hz AC interference on an ECG tracing, a technician should first:

Answer: Check and re-prep electrode sites

Poor electrode-to-skin contact is the most common cause of AC interference; re-prepping the skin with abrasive prep and fresh gel usually eliminates it.

In a complete left bundle branch block (LBBB), which finding is expected in lateral leads I, aVL, V5, and V6?

Answer: Broad, notched R waves

LBBB produces broad, notched (M-shaped) R waves in lateral leads due to abnormal left ventricular depolarization.

Which ECG change is associated with hypokalemia?

Answer: Prominent U waves

Hypokalemia classically produces prominent U waves (often larger than the T wave), flattened T waves, and a prolonged QU interval.