Deck 9: Electrocardiography

Question 1

Which of the following components of the ECG impulse represents the ventricular depolarization?

A)P wave
B)P-R segment
C)QRS complex
D)ST segment

Answer 1

C
The QRS complex is the electrical stimulus of ventricular depolarization and is normally followed closely by ventricular contraction.

Question 2

The ability of cardiac muscle cells to spread impulses to adjoining cells very quickly BEST describes which of the following properties?

A)Automaticity
B)Rhythmicity
C)Conductivity
D)Electricity

Answer 2

C
The property of conductivity is one of three properties of cardiac muscle cells and describes the ability of the cardiac muscle cells to spread impulses to adjoining cells very quickly.

Question 3

The presence of a significant Q wave (one-third the size of the QRS complex)on an ECG indicates which of the following?

A)Acute infarction
B)Ischemia
C)Digitalis toxicity
D)Previous infarction

Answer 3

D
A significant Q wave is considered to be significant and indicative of a pathological condition (it persists as a permanent electrocardiographic "scar" from a previous infarction).Any ECG should include a scan for the presence of significant Q waves to identify previous infarctions.

Question 4

The rhythm strip reveals the following findings:all P waves are upright,normal in appearance,and exist before every QRS complex,the P-R interval is between 0.12 and 0.20 second,the QRS complexes are identical and are between 0.04 and 0.10 second,the R-R interval is regular,and the HR is >100 bpm.These findings BEST describe which of the following?

A)Sinus bradycardia
B)Sinus tachycardia
C)Normal sinus rhythm
D)Atrial arrhythmia

Question 5

Increased sympathetic activity through the release of norepinephrine and epinephrine from the adrenal gland results in which of the following changes in the heart?

A)Reduces conduction velocity throughout the atrioventricular node.
B)Decreases the irritability of the heart.
C)Increases the contractility of the heart muscle.
D)Depresses the automaticity of the heart.

Question 6

Which of the following changes on an ECG BEST indicates the presence of acute infarction?

A)ST-segment elevation
B)ST-segment depression
C)Enlarged QRS complex
D)Absence of P wave

Question 7

Which of the following types of myocytes have the highest rate of rhythmicity?

A)Mechanical myocytes
B)Nodal myocytes
C)Transitional myocytes
D)Purkinje cells

Question 8

The rhythm strip reveals the following findings:initially a P wave precedes each QRS complex,but eventually a P wave may stand alone,progressive lengthening of the P-R interval occurs,as the P-R interval increases,a QRS complex is dropped,the progressive lengthening of P-R interval and drop of QRS complex is repetitive,the QRS complex is normal with a duration between 0.04 and 0.10 second,the R-R interval is irregular,and heart rate varies.These findings BEST describe which of the following?

A)First-degree AV block
B)Wenkebach's heart block
C)Second-degree AV block type II
D)Third-degree AV block

Question 9

Which of the following components of the ECG impulse represents the atrial kick or the delayed conduction of the electrical impulse by the AV node one-tenth of a second?

A)P wave
B)P-R segment
C)QRS complex
D)ST segment

Question 10

Which of the following heart blocks is characterized by no communication between the atria and the ventricles,thus resulting in no coordination between the firing of the atria and the firing of the ventricles,creating a complete independence of the two systems?

A)First-degree AV block
B)Second-degree AV block,type I
C)Second-degree AV block,type II
D)Third-degree AV block

Question 11

Identification of significant Q waves in leads II,III,and aVF indicates an infarction in which of the following regions of the heart?

A)Inferior wall
B)Lateral wall
C)Posterior wall
D)Anterior wall

Question 12

The rhythm strip reveals the following findings:all P waves are upright and normal in appearance and occur before every QRS complex,the P-R interval is between 0.12 and 0.20 second,the QRS complexes are identical,the QRS complex is between 0.04 and 0.10 second,the R-R interval is regular,and the HR is between 60 and 100 bpm.These findings BEST describe which of the following?

A)Sinus bradycardia
B)Sinus tachycardia
C)Normal sinus rhythm
D)Atrial arrhythmia

Question 13

The rhythm strip reveals the following findings:P waves are absent,leaving a flat or wavy baseline,the QRS complexes are between 0.04 and 0.10 second,the R-R interval is characteristically defined as irregularly irregular,and the rate varies,but is called "ventricular response." These findings BEST describe which of the following?

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

Question 14

A QRS complex that is described as being wide and bizarre looking without a P wave and followed by a complete compensatory pause BEST indicates which of the following arrhythmias?

A)Premature ventricular complex (PVC)
B)Premature atrial contraction
C)Ventricular tachycardia
D)Ventricular fibrillation

Question 15

A single-lead tracing or rhythm strip can be used to determine all of the following EXCEPT:

A)heart rate.
B)heart rhythm.
C)presence of arrhythmia.
D)presence of ischemia.

Question 16

When a therapist is assessing the cardiac cycle for rhythm and rate disturbances,which of the following assessment approaches is used to evaluate the P-R interval?

A)Is the duration between 0.12 and 0.20 second?
B)Is the duration between 0.06 and 0.10 second?
C)Is it regular?
D)Does one occur before every QRS?

Question 17

The presence of T wave inversion,ST segment changes,or Q waves in ECG chest leads V1,V2,V3,and V4 indicates an infarction in which of the following regions of the heart?

A)Inferior wall
B)Lateral wall
C)Posterior wall
D)Anterior wall

Question 18

Which of the following changes on an ECG BEST indicate ischemia?

A)ST-segment elevation
B)ST-segment depression
C)Enlarged QRS complex
D)Presence of a significant Q wave

Question 19

The rhythm strip reveals the following findings:absence of P waves before QRS complex,but a retrograde P wave may be identified,the QRS complex is normal and its duration is between 0.04 and 0.10 second,the R-R intervals are regular,and the ventricular rate is between 40 and 60 bpm.These findings BEST describe which of the following?

A)Nodal or junctional arrhythmia
B)Junctional (or nodal)rhythm
C)Nodal (junctional)tachycardia
D)Wandering atrial pacemaker

Question 20

Which of the following heart arrhythmias is commonly found in young females who have a mitral valve prolapse?

A)Atrial flutter
B)Paroxysmal atrial tachycardia
C)Atrial fibrillation
D)Premature atrial complexes

Question 21

Repolarization of the ventricular is BEST described as which of the following?

A)T wave on ECG
B)Return of potassium ions into the cell
C)Movement of sodium ions out of the cell
D)All of the above

Question 22

Which of the following BEST defines atrial tachycardia?

A)R-R intervals are irregular.
B)Heart rate is >200 bpm.
C)Three or more premature atrial complexes in a row.
D)P-R intervals are irregular with a duration of 0.25 second.

Question 23

Which of the following ECG leads should be scanned to look for the presence of ventricular hypertrophy?

A)V1,V2,V3
B)V4,V5,V6
C)V1,V5,V6
D)I,II,aVR

Question 24

Which of the following sites is associated with a second-degree AV block,type II?

A)High in the AV junction
B)Impulse delayed between the SA and AV nodes
C)Above the ventricles
D)Below the bundle of His

Question 25

A 68-year-old male collapses in his yard while mowing.The EMTs immediately obtain an ECG strip that reveals grossly irregular up and down fluctuations of the baseline in an irregular zigzag pattern.Which of the following arrhythmias is potentially occurring?

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

Question 26

A trained athlete with an increased resting and exercise stroke volume may exhibit which of the following heart arrhythmias?

A)Sinus bradycardia
B)Sinus tachycardia
C)Sinus pause
D)Atrial arrhythmia

Question 27

The development of mural thrombi secondary to the coagulation of blood in the heart chamber subsequently leading to a potential stroke occurs in which of the following heart arrhythmias?

A)Atrial flutter
B)Atrial fibrillation
C)Atrial tachycardia
D)Sinus pause or block

Question 28

Both an ST-segment depression or elevation and significant Q wave are indicative of an acute infarction.

Question 29

On an ECG,a large R wave in V1 and V2 and ST-segment depression BEST indicate an infarction in which of the following regions of the heart

A)Anterior wall
B)Inferior wall
C)Lateral wall
D)Posterior wall

Question 30

A 21-year-old female college student was sitting in class listening to a lecture and reported that her heart was racing away and that she felt lightheaded.This episode of symptoms occurred a second time in the same class.Her past medical history is unremarkable.Which of the following arrhythmias is MOST likely occurring in this case?

A)Sinus tachycardia
B)Atrial flutter
C)Paroxysmal atrial tachycardia
D)Premature atrial complex