Practical Content and Preparation Flashcards

A patient's ECG shows a PR interval of 0.28 seconds with no dropped beats. Which condition does this represent?

Answer: First-degree AV block

First-degree AV block is defined by a PR interval >0.20 seconds with every P wave conducted to the ventricles.

Which electrode placement error would most likely cause an artificially inverted P wave in lead II?

Answer: Reversing the right arm and left arm electrodes

Swapping the right arm (RA) and left arm (LA) electrodes inverts leads I and aVL and reverses the polarity of lead II, causing an inverted P wave.

When preparing a patient for a 12-lead ECG, the technician should instruct the patient to:

Answer: Remain still and avoid talking

Patient movement and speech introduce artifact, so the patient must remain still and quiet during the recording.

On standard ECG paper running at 25 mm/sec, one large box (5 mm) represents which time interval?

Answer: 0.20 seconds

At 25 mm/sec, each large box (5 mm) equals 0.20 seconds; each small box (1 mm) equals 0.04 seconds.

Which finding on a rhythm strip most reliably confirms sinus rhythm?

Answer: Positive P wave in lead II preceding each QRS

Sinus rhythm requires that the SA node drive the heart, confirmed by an upright P wave in lead II before every QRS complex.

A patient arrives for an ECG with lotion on the chest. The best immediate action is to:

Answer: Clean the skin with an alcohol prep pad and allow it to dry

Alcohol prep pads remove oils and lotion that impair electrode adhesion; allowing the skin to dry fully ensures good contact.

The ST segment on an ECG represents which phase of cardiac electrical activity?

Answer: Ventricular repolarization plateau (phase 2)

The ST segment corresponds to the plateau phase of ventricular action potentials, during which all ventricular cells are depolarized.