Deck 18: Interpreting the Electrocardiogram

Question 1

What structure serves as the backup pacemaker for the heart?

A) Atrioventricular (AV) node
B) Sinoatrial (SA) node
C) Bundle of His
D) Purkinje fibers

Answer 1

A
Explanation: After leaving the atria, the impulse moves to the AV node, located in the intraventricular septum in the inferior aspect of the right atrium. The AV node is the "backup" pacemaker because it has the second greatest degree of automaticity in the healthy heart.

Question 2

What is the normal maximum length of the P wave?

A) 1 mm
B) 3 mm
C) 5 mm
D) 7 mm

Answer 2

B
Explanation: Atrial hypertrophy may cause the P wave to enlarge to a height and length beyond the normal parameters.

Question 3

Which of the following waves represents repolarization of the ventricles?

A) P wave
B) QRS wave
C) T wave
D) U wave

Answer 3

C
Explanation: The wave of repolarization occurring in the ventricles immediately after depolarization is the T wave.

Question 4

Your patient has a normal ECG reading. What does this finding tell you about the patient's likelihood of having a myocardial infarction in the immediate future?

A) Less than a 10% chance
B) Less than a 30% chance
C) Less than 50% chance
D) No predictive value

Question 5

What is implied by an abnormally prolonged PR interval?

A) Atrioventricular block
B) Bundle-branch block
C) Myocardial infarction
D) Valvular detachment

Question 6

Which of the following axis placements represents right-axis deviation?

A) +60
B) +90
C) +120
D) +190

Question 7

What structure normally paces the healthy heart?

A) Atrioventricular (AV) node
B) Sinoatrial (SA) node
C) Bundle of His
D) Purkinje fibers

Question 8

At what part of the cardiac conduction system does the electrical impulse travel most rapidly?

A) Bundle of His
B) Bundle branches
C) Intraatrial pathways
D) Purkinje fibers

Question 9

Which of the following is a potential complication for a patient with atrial fibrillation?

A) Asthma
B) COPD
C) Blood clot formation
D) Renal failure

Question 10

What term is used to define the ability of certain cardiac cells to depolarize without stimulation?

A) Automaticity
B) Polarization
C) Contraction
D) Autopolarization

Question 11

What parameter is measured on the vertical axis of the ECG paper?

A) Time
B) Voltage
C) Cardiac contraction rate
D) Blood flow

Question 12

A run of three or more PVCs should be called:

A) ventricular tachycardia.
B) ventricular fibrillation.
C) atrial tachycardia.
D) supra ventricular tachycardia.

Question 13

What is the width of the normal QRS complex?

A) Not wider than 1 mm
B) Not wider than 3 mm
C) Not wider than 5 mm
D) Not wider than 7 mm

Question 14

Why is the electrical impulse temporarily delayed at the atrioventricular (AV) node?

A) To allow complete emptying of the ventricles
B) To allow more sodium buildup in the myocardial cells
C) To allow better filling of the ventricles
D) To allow complete filling of the atria

Question 15

Which of the following ECG abnormalities is most life threatening?

A) Narrow QRS complex
B) Shortened PR interval
C) Elevated ST segment
D) Peak P waves

Question 16

The QRS of an ECG falls on a dark vertical line of the ECG paper. Subsequent QRS complexes fall on every other dark line (10 mm apart). What is the ventricular rate?

A) 300/min
B) 200/min
C) 150/min
D) 100/min

Question 17

Which of the following waves represents depolarization of the ventricles?

A) P wave
B) QRS wave
C) T wave
D) U wave

Question 18

What is suggested by inverted T waves on the ECG?

A) Atrial enlargement
B) Myocardial ischemia
C) Ventricular hypertrophy
D) Dextrocardia

Question 19

What condition is often associated with right-axis deviation?

A) Cor pulmonale
B) Congestive heart failure (CHF)
C) Mitral valve prolapse
D) Left ventricular hypertrophy

Question 20

What is the normal period of time for the PR interval?

A) Not longer than 0.20 sec
B) Not longer than 0.30 sec
C) Not longer than 0.45 sec
D) Not longer than 0.50 sec

Question 21

Which of the following clinical conditions are associated with tachycardia?
1) Anxiety
2) Hypoxemia
3) Pain
4) Hypothermia

A)2 and 4 only
B)1, 3, and 4 only
C)1, 2, and 3 only
D)1, 2, 3, and 4

Question 22

On inspection of an ECG rhythm strip from an adult patient, you notice the following: regular sawtooth-like waves occurring at a rate of 280/min and a regular ventricular rhythm occurring at a rate of approximately 140/min. What is the most likely interpretation?

A) Atrial fibrillation
B) Atrial flutter
C) Ventricular tachycardia
D) Ventricular fibrillation

Question 23

Which of the following are common causes of ventricular tachycardia?
1) Myocardial infarction
2) Coronary artery disease
3) Hypertensive heart disease
4) Pericarditis

A)2 and 3 only
B)1, 2, and 4 only
C)1 and 4 only
D)1, 2, and 3 only

Question 24

What is a possible serious complication associated with atrial fibrillation?

A) Pulmonary edema
B) Atrial thrombi
C) Cardiac tamponade
D) Cardiac standstill

Question 25

What type of medications may lead to first-degree heart block?

A) Bronchodilators
B) Corticosteroids
C) Beta blockers
D) Xanthines

Question 26

An unconscious patient is bought in by EMS into an ER trauma room. Patient has no detectable pulse, and the ECG baseline waveform shows grossly irregular fluctuations with a zigzag pattern. What is the course of action to treat this patient?
1) Rapid defibrillation
2) Cardiopulmonary resuscitation
3) Administration of oxygen
4) Administration of an antiarrhythmic medication

A)1, 2, and 3 only
B)2 and 4 only
C)3 only
D)1, 2, 3, and 4

Question 27

For which of the following arrhythmias would an electronic pacemaker be indicated?

A) First-degree block
B) Sinus tachycardia
C) Third-degree block
D) Ventricular fibrillation

Question 28

What medication is most useful for the treatment of premature ventricular contractions?

A) Digoxin
B) Atropine
C) Lidocaine
D) Digitalis

Question 29

Which of the following medications is used to treat symptomatic sinus bradycardia?

A) Atropine
B) Digitalis
C) Propranol
D) Lidocaine

Question 30

The ECG you are looking at has one P wave for every QRS complex and the PR interval is 0.30 sec. What is your interpretation?

A) First-degree heart block
B) Right-axis deviation
C) Third-degree heart block
D) Atrial hypertrophy

Question 31

A patient who has been diagnosed with myocardial infarction is getting an ECG. The ECG trace shows a series of nonconducted P waves followed by a P wave that is conducted to the ventricles. The ratio of nonconducted to conducted P waves is fixed at 4:1. What plan for treatment should this patient receive?
1) Rapid defibrillation
2) Atropine
3) Cardioversion
4) Pacemaker

A)1, 2, and 3 only
B)2 and 4 only
C)3 only
D)1, 2, 3, and 4

Question 32

While a patient is receiving an albuterol treatment, the nurse performs an ECG. The ECG shows the patient's heart rate had increased from 98 to 120 beats/min with narrow QRS complexes preceded by a P wave. What is the appropriate course of treatment for this patient?

A) Atropine.
B) Activate the rapid response team.
C) Lidocaine.
D) Discontinue the treatment.

Question 33

A patient taking an ECG shows a regular sawtooth pattern with 30 P waves within a 6-sec interval (30 large boxes). What course of treatment should this patient receive for this arrhythmia?
1) Calcium channel blockers
2) Digoxin
3) Cardioversion
4) Defibrillation

A)1, 2, and 3 only
B)2 and 4 only
C)3 only
D)1, 2, 3, and 4

Question 34

Which of the following is NOT a common characteristic of a premature ventricular complex (PVC)?

A) No P wave prior to the QRS complex
B) Widened QRS complex
C) Bizarre QRS complex
D) Narrow QRS complex

Question 35

Which of the following criteria applies to third-degree block?

A) There is no relationship between the P waves and the QRS complexes.
B) The PR interval becomes progressively longer.
C) The ventricular rate is twice that of the atrial rate.
D) The QRS complex is inverted compared to the P wave.