Deck 17: 12 Lead ECGS

Question 1

Which of the following are characteristics of the normal ECG?

A) Waveforms and intervals that appear at regular intervals at a rate of 60 to 90 beats per minute (in the adult).
B) Upright and slightly asymmetrical P waves, each followed by a QRS complex of normal upright contour, duration, and configuration
C) A PR interval (PRI) with a duration of 0.12 to 0.24 seconds that precedes each QRS complex.
D) A flat ST segment followed by an inverted, symmetrical T wave.

Answer 1

A PR interval (PRI) with a duration of 0.12 to 0.24 seconds that precedes each QRS complex.

Question 2

The initiation of the impulse in the SA node and its movement through the atria produces a:

A) P wave.
B) PR interval.
C) QRS complex.
D) T wave.

Answer 2

P wave.

Question 3

Which of the following are characteristics of sinus P waves?

A) They are inverted and round waveforms.
B) There is one P wave preceding each QRS complex.
C) Their amplitude is 0.5 to 3.5 mm
D) Their duration is 0.08 to 0.12 seconds.

Answer 3

There is one P wave preceding each QRS complex.

Question 4

The PR interval:

A) is normally 0.12 to 0.20 seconds in duration.
B) represents ventricular depolarization.
C) is the distance from the beginning of the P wave to the beginning of the S wave.
D) extends across 5 to 10 small squares.

Question 5

The QRS complex:

A) is larger in appearance than the P wave and consists of three parts.
B) is generally wide and sharply pointed.
C) normally has a duration of 0.12 to 0.20 seconds and an amplitude of 5 to 30 mm.
D) represents movement of the electrical impulse through the atria causing their contraction.

Question 6

The pause that follows the QRS complex is referred to as the:

A) QT interval.
B) PR interval.
C) U wave.
D) ST segment.

Question 7

The J point is the:

A) point at which the QRS meets the ST segment.
B) first negative deflection following the PR segment.
C) peak of the R wave.
D) area that connects the ST segment to the T wave.

Question 8

The T wave:

A) is larger than the P wave and completely symmetrical.
B) has a peak which is closer to the end than the beginning.
C) is normally 15-20 mm in height in the limb leads.
D) is normally oriented in the same direction as the preceding QRS complex.

Question 9

The QT interval:

A) is the distance from the onset of the QRS complex until the end of the T wave.
B) measures the duration of ventricular depolarization.
C) is typically the same irrespective of the age, sex, or heart rate.
D) has a normal duration of 0.20 to 0.36 seconds.

Question 10

The typical ECG, representing the normal cardiac rhythm, consists of:

A) biphasic P waves occurring before each QRS complex.
B) a rate of 60 to100 beats per minute.
C) PR intervals of 0.20 to 0.32 seconds
D) upright QRS complexes with a duration of 0.12 to 0.20 seconds.

Question 11

A calibration mark is:

A) 10 mm tall (2 squares high).
B) used to check the power supply of the ECG machine.
C) created automatically by all ECG machines.
D) included just on those ECG tracings which are abnormal.

Question 12

Artifact:

A) is produced by chaotic electrical activity found in the heart.
B) makes it easier to accurately interpret the ECG.
C) is usually consistent across the rhythm strip.
D) can mimic life-threatening dysrhythmias.

Question 13

An electrical current traveling toward a positive electrode produces a waveform that:

A) points upward.
B) points downward.
C) is both up and down (biphasic).
D) is mostly flat.

Question 14

The leads arranged on the frontal plane:

A) provide a posterior view of the heart.
B) provide inferior, superior, and lateral views of the heart.
C) are called the chest leads.
D) include leads I, II, III, V4, V5, and V6.

Question 15

Precordial leads:

A) provide anterior and posterior views as well as a lateral view of the heart.
B) are also referred to as limb leads.
C) include V1, V2, V3, aVR, aVL, and aVF.
D) are placed on the patient's arms and legs.

Question 16

Which of the following is true regarding bipolar leads?

A) Bipolar leads have two additional electrodes which act as a ground.
B) A bipolar lead records the difference in electrical potential between six selected electrodes.
C) They require two electrodes of opposite polarity (positive and negative).
D) The bipolar leads include leads I, II and III, aVR, aVL, and aVF

Question 17

To view the limb leads, we place electrodes on the:

A) right side of the chest.
B) right arm (RA), left arm (LA) and left leg (LL).
C) left side of the chest.
D) right arm (RA), left arm (LA) and right leg (RL).

Question 18

Leads I, II, III are:

A) augmented (enhanced) by approximately 50%.
B) unipolar leads.
C) referred to as standard limb leads.
D) placed on the patient's arms and legs but not their chest.

Question 19

With Lead II the positive electrode is positioned on the:

A) left leg.
B) right arm.
C) right side of the chest.
D) left shoulder.

Question 20

The waveforms in lead II are mostly:

A) upright.
B) inverted.
C) biphasic.
D) flat.

Question 21

The ECG waveforms produced by lead aVR are mostly:

A) large.
B) upright.
C) inverted.
D) biphasic.

Question 22

The ECG waveforms produced by lead V6 are mostly:

A) small.
B) upright.
C) inverted.
D) biphasic.

Question 23

The horizontal plane is a transverse cut through the middle of the heart.

Question 24

Unipolar leads use only one positive electrode and a reference point which is calculated by the ECG machine.