ECG Electrocardiogram Knowledge Answers and Questions 3

Question 1

60-cycle (AC) interference on an ECG usually appears as:

Accepted Answer

Uniform, thick, regular fine spikes across the tracing

Answer

AC interference produces a consistent 60 Hz fuzzy pattern from nearby electrical sources.

Question 2

The SA node, the heart's natural pacemaker, is located in which chamber?

Accepted Answer

Right atrium

Answer

The sinoatrial node sits in the upper wall of the right atrium.

Question 3

Which precordial lead is placed at the 5th intercostal space, midclavicular line?

Accepted Answer

V4

Answer

V4 is located at the 5th intercostal space along the midclavicular line.

Question 4

A wandering baseline artifact is most commonly caused by:

Accepted Answer

Poor electrode contact or patient movement/respiration

Answer

Loose electrodes, lotion on skin, or breathing cause the baseline to drift.

Question 5

The PR interval measures the time from:

Accepted Answer

Start of the P wave to the start of the QRS complex

Answer

The PR interval reflects conduction from the atria through the AV node to the ventricles.

ECG (Electrocardiogram) Practice Test