ECG Lead System Quiz

Question 1

According to Einthoven's Law, if Lead I records 1.0 mV and Lead II records 1.5 mV, what should be the voltage recorded in Lead III?

0.5 mV

1.0 mV

1.5 mV

2.5 mV

Question 2

Which of the following leads is considered a bipolar limb lead?

aVR

V3

Lead II

aVF

Question 3

In the standard 12-lead ECG, which leads are considered the precordial (chest) leads?

I, II, III

aVR, aVL, aVF

V1 through V6

RA, LA, RL, LL

Question 4

Which electrode placement is correct for the V4 precordial lead?

Fifth intercostal space, midclavicular line

Fourth intercostal space, right sternal border

Fifth intercostal space, anterior axillary line

Fourth intercostal space, left sternal border

Question 5

What is the primary purpose of the right leg (RL) electrode in an ECG circuit?

To detect ventricular depolarization

To serve as a reference ground for reducing common-mode noise

To measure atrial repolarization

To enhance high-frequency components of the ECG signal

Question 6

Which of the following leads has a positive electrode on the left arm and a negative electrode on the right arm?

Lead I

Lead II

Lead III

aVR

Question 7

From an electrical engineering perspective, what does the augmented vector lead aVF primarily measure?

The vertical component of the cardiac vector

The horizontal component of the cardiac vector

The superior-inferior axis only

The electrical activity of the atria

Question 8

What is the approximate angular orientation of Lead I in the frontal plane?

0°

60°

90°

120°

Question 9

Which lead would be most useful for detecting right ventricular hypertrophy?

V1

V5

aVL

Lead I

Question 10

The central terminal (Wilson Central Terminal) used for unipolar leads is created by:

Connecting the right arm, left arm, and left leg electrodes through equal resistors

Placing an electrode at the 5th intercostal space

Using only the right leg electrode as a reference

Connecting all precordial leads in parallel

Question 11

In Einthoven's triangle model, which statement is correct?

The heart is assumed to be at the center of an equilateral triangle formed by limb electrodes

The triangle represents the actual anatomical positions of the limbs

It only applies to precordial leads

It assumes the body is a perfect sphere with uniform conductivity

Question 12

Which lead is electrically opposite to lead aVR in the frontal plane?

Lead II

aVL

aVF

Lead I

Quiz Results & Explanations

Answers and Explanations