[MCQs] Electrocardiography- Part 1

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Electrocardiography- Part 1

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Congratulations - you have completed Electrocardiography- Part 1 . You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%

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Question 1

ECG leads displays ?

A	Instantaneous differences in electrical potential between electrodes
B	Differences in electrical potential between electrode and neutral
C	Differences in electrical potential between electrode & maximum positive charge
D	Differences in electrical potential between electrode & maximum negative charge

Question 2

Electric currents that spread through the heart can be produced by ?

A	Cardiac pacemaker cells
B	Specialized conduction tissue
C	Heart muscle
D	All of the above

Question 2 Explanation:

Depolarization of the heart is the initiating event for cardiac contraction. The electric currents that spread through the heart are produced by cardiac pacemaker cells, specialized conduction tissue, and heart muscle. The ECG records only the depolarization (stimulation) and repolarization (recovery) potentials generated by the atrial and ventricular myocardium.

Question 3

AV junction is constituted by ?

A	Atrioventricular (AV) node
B	AV node and His-bundle
C	AV node, His-bundle and fascicles
D	AV node, His-bundle, fascicles & Purkinje fibres

Question 3 Explanation:

AV nodal region & His-bundle area together constitute AV junction

Question 4

Ventricular repolarization is represented by ?

A	ST segment
B	T wave
C	U wave
D	ST-T-U complex

Question 4 Explanation:

QRS complex represents ventricular depolarization& ST-T-U complex (ST segment, T wave & U wave) represents ventricular repolarization

Question 5

J point is the junction between ?

A	End of P wave & beginning of QRS complex
B	End of QRS complex & beginning of ST segment
C	End of ST segment & beginning of T wave
D	End of T wave & beginning of U wave

Question 5 Explanation:

J point is the junction between the end of QRS complex and the beginning of ST segment.

Question 6

Atrial repolarization wave may become apparent in ?

A	Acute pericarditi
B	Acute pericarditi
C	PSVT
D	Wandering pacemaker

Question 7

Atrial repolarization wave may become apparent in ?

A	Acute rheumatic fever
B	Cardiomyopathy
C	PSVT
D	Atrial infarction

Question 7 Explanation:

Atrial repolarization is usually too low in amplitude to be detected, but it may become apparent in acute pericarditis or atrial infarction.

Question 8

Rapid upstroke of the action potential that corresponds to the onset of QRS is called ?

A	Phase 0
B	Phase 1
C	Phase 2
D	Phase 3

Question 9

Plateau of the action potential that corresponds to isoelectric ST segment is called ?

A	Phase 0
B	Phase 1
C	Phase 2
D	Phase 3

Question 9 Explanation:

The QRS-T waveforms of the surface ECG correspond with the different phases of simultaneously obtained ventricular action potentials. Rapid upstroke (phase 0) of the action potential corresponds to the onset of QRS. Plateau (phase 2) corresponds to the isoelectric ST segment, and active repolarization (phase 3) corresponds to the inscription of the T wave

Question 10

Which of the following prolong phase 2 of the cardiac muscle action potential and increase the QT interval ?

A	Hyperkalemia
B	Amiodarone
C	Digitalis
D	Hypercalcemia

Question 10 Explanation:

Factors that decrease slope of phase 0 by impairing influx of Na+ (hyperkalemia & flecainide) tend to increase QRS duration. Conditions that prolong phase 2 (amiodarone, hypocalcemia) increase QT interval. Shortening of ventricular repolarization (phase 2) by digitalis administration or hypercalcemia, abbreviates ST segment.

Question 11

The action potential of the His-Purkinje system and ventricular myocardium has ?

A	Two phases
B	Three phases
C	Four phases
D	Five phases

Question 11 Explanation:

Action potential of the His-Purkinje system has five phases.

Question 12

Resting membrane potential in ventricular myocardium is ?

A	Phase 1
B	Phase 2
C	Phase 3
D	Phase 4

Question 12 Explanation:

Rapid depolarizing current (phase 0) is due to influx of Na+ into myocardial cells followed by influx of Ca++. Repolarization phases of action potential (phases 1 to 3) are due to outward flux of K+. Resting membrane potential is phase 4

Question 13

Automaticity is normally observed in ?

A	Sinus node
B	Specialized fibers of His-Purkinje system
C	Some specialized atrial fibers
D	All of the above

Question 13 Explanation:

Automaticity is normally observed in sinus node, specialized fibers of His-Purkinje system & some specialized atrial fibers. It is the property of a cardiac cell that causes it to depolarize spontaneously during phase 4 of the action potential leading to the generation of an impulse

Question 14

Polarized resting myocardial cells carry an electric charge on their surface of about ?

A	70 mV
B	80 mV
C	90 mV
D	100 mV

Question 15

PR interval is related to ?

A	Atrial musculature conduction
B	AV node
C	AV junction area
D	All of the above

Question 15 Explanation:

PR interval measures the time (normally 120 - 200 ms) between atrial & ventricular depolarization, which includes the physiologic delay imposed by stimulation of cells in the AV junction area

Question 16

Extremity ECG leads record potentials transmitted onto ?

A	Frontal plane
B	Vertical plane
C	Horizontal plane
D	Diagonal plane

Question 17

ECG chest leads record potentials transmitted onto ?

A	Frontal plane
B	Vertical plane
C	Horizontal plane
D	Diagonal plane

Question 17 Explanation:

Six extremity leads record potentials transmitted onto the frontal plane & the six chest leads record potentials transmitted onto the horizontal plane.

Question 18

ECG Lead V6 is placed at ?

A	Anterior axillary line
B	Midaxillary line
C	Posterior axillary line
D	Scapular line

Question 18 Explanation:

Positions of six unipolar chest leads are : V1 = IV ICS just to the right of sternum, V2 = IV ICS,

Question 19

Number of intercostal spaces used for placing unipolar chest leads in ECG are ?

A	1
B	2
C	3
D	4

Question 19 Explanation:

IV and V intercostal spaces.

Question 20

In the hexaxial diagram representing frontal plane (limb or extremity) leads, 0° corresponds to which lead ?

A	Lead I
B	Lead II
C	Lead III
D	Any of the above

Question 20 Explanation:

Each lead axis is designated by their angular position relative to the positive pole of lead I (0°).

Question 21

In ECG, if the mean orientation of the depolarization vector is at right angles to a given lead axis, which of the following will happen ?

A	Positive wave will be recorded
B	Negative wave will be recorded
C	Biphasic wave will be recorded
D	Flat wave will be recorded

Question 21 Explanation:

ECG leads are configured so that a positive (upright) deflection is recorded in a lead if a wave of depolarization spreads toward the positive pole of that lead, and a negative deflection if the wave spreads toward the negative pole. If the mean orientation of depolarization vector is at right angles to a given lead axis, a biphasic (equally positive & negative) deflection is recorded

Question 22

ECG leads I, II, and III are called ?

A	Unipolar leads
B	Bipolar leads
C	Tripolar leads
D	Multipolar leads

Question 23

ECG leads aVR, aVL, and aVF are called ?

A	Unipolar leads
B	Bipolar leads
C	Tripolar leads
D	Multipolar leads

Question 23 Explanation:

Six extremity leads are 3 bipolar leads (I, II& III) and 3 unipolar leads (aVR, aVL& aVF) leads. Each bipolar lead measures the difference in potential between electrodes at two extremities

Question 24

Bipolar lead I measures the difference in potential between ?

A	Left arm-right arm voltages
B	Left leg-right arm voltages
C	Left leg-left arm voltages
D	Left leg-right leg voltages

Question 25

Bipolar lead II measures the difference in potential between ?

A	Left arm-right arm voltages
B	Left leg-right arm voltages
C	Left leg-left arm voltages
D	Left leg-right leg voltages

Question 26

Bipolar lead III measures the difference in potential between ?

A	Left arm-right arm voltages
B	Left leg-right arm voltages
C	Left leg-left arm voltages
D	Left leg-right leg voltages

Question 26 Explanation:

Each bipolar lead measures the difference in potential between electrodes at two extremities: lead I = left arm–right arm voltages, lead II = left leg–right arm, and lead III = left leg–left arm

Question 27

In unipolar leads, the lowercase “a” stands for ?

A	Added
B	Augmented
C	Arithmatic
D	Apparent

Question 28

Electrical augmentation of unipolar potentials in unipolar leads is by ?

A	25 %
B	50 %
C	75 %
D	100 %

Question 28 Explanation:

The lowercase “a” indicates that these unipolar potentials are electrically augmented by 50%. The right leg electrode functions as a ground. Unipolar leads measure the voltage at one locus relative to an electrode (called central terminal or indifferent electrode) that has approximately zero potential. Thus, aVR = right arm, aVL = left arm, and aVF = left leg.

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See all quizzes of the Electrocardiography at here:

Electrocardiography- Part 1 | Electrocardiography- Part 2 | Electrocardiography- Part 3

1.ECG leads displays ?
A. Instantaneous differences in electrical potential between electrodes
B. Differences in electrical potential between electrode and neutral
C. Differences in electrical potential between electrode & maximum positive charge
D. Differences in electrical potential between electrode & maximum negative charge

2. Electric currents that spread through the heart can be produced by ?
A. Cardiac pacemaker cells
B. Specialized conduction tissue
C. Heart muscle
D. All of the above

3. AV junction is constituted by ?
A. Atrioventricular (AV) node
B. AV node and His-bundle
C. AV node, His-bundle and fascicles
D. AV node, His-bundle, fascicles & Purkinje fibres

4. Ventricular repolarization is represented by ?
A. ST segment
B. T wave
C. U wave
D. ST-T-U complex

5. J point is the junction between ?
A. End of P wave & beginning of QRS complex
B. End of QRS complex & beginning of ST segment
C. End of ST segment & beginning of T wave
D. End of T wave & beginning of U wave

6. Atrial repolarization wave may become apparent in ?
A. Acute pericarditis
B. Cardiomyopathy

C. PSVT
D. Wandering pacemaker

7. Atrial repolarization wave may become apparent in ?
A. Acute rheumatic fever
B. Cardiomyopathy
C. PSVT
D. Atrial infarction

8. Rapid upstroke of the action potential that corresponds to the onset of QRS is called ?
A. Phase 0
B. Phase 1
C. Phase 2
D. Phase 3

9. Plateau of the action potential that corresponds to isoelectric ST segment is called ?
A. Phase 0
B. Phase 1
C. Phase 2
D. Phase 3

10. Which of the following prolong phase 2 of the cardiac muscle action potential and increase the QT interval ?
A. Hyperkalemia
B. Amiodarone
C. Digitalis
D. Hypercalcemia

11. The action potential of the His-Purkinje system and ventricular myocardium has ?
A. Two phases
B. Three phases
C. Four phases
D. Five phases

12. Resting membrane potential in ventricular myocardium is ?
A. Phase 1
B. Phase 2

C. Phase 3
D. Phase 4

13. Automaticity is normally observed in ?
A. Sinus node
B. Specialized fibers of His-Purkinje system
C. Some specialized atrial fibers
D. All of the above

14. Polarized resting myocardial cells carry an electric charge on their surface of about ?
A. 70 mV
B. 80 mV
C. 90 mV
D. 100 mV

15. PR interval is related to ?
A. Atrial musculature conduction
B. AV node
C. AV junction area
D. All of the above

16. Extremity ECG leads record potentials transmitted onto ?
A. Frontal plane
B. Vertical plane
C. Horizontal plane
D. Diagonal plane

17. ECG chest leads record potentials transmitted onto ?
A. Frontal plane
B. Vertical plane
C. Horizontal plane
D. Diagonal plane

18. ECG Lead V6 is placed at ?
A. Anterior axillary line
B. Midaxillary line
C. Posterior axillary line
D. Scapular line

19. Number of intercostal spaces used for placing unipolar chest leads in ECG are ?
A. 1
B. 2
C. 3
D. 4

20. In the hexaxial diagram representing frontal plane (limb or extremity) leads, 0° corresponds to which lead ?
A. Lead I
B. Lead II
C. Lead III
D. Any of the above

21. In ECG, if the mean orientation of the depolarization vector is at right angles to a given lead axis, which of the following will happen ?
A. Positive wave will be recorded
B. Negative wave will be recorded
C. Biphasic wave will be recorded
D. Flat wave will be recorded

22. ECG leads I, II, and III are called ?
A. Unipolar leads
B. Bipolar leads
C. Tripolar leads
D. Multipolar leads

23. ECG leads aVR, aVL, and aVF are called ?
A. Unipolar leads
B. Bipolar leads
C. Tripolar leads
D. Multipolar leads

24. Bipolar lead I measures the difference in potential between ?
A. Left arm-right arm voltages
B. Left leg-right arm voltages
C. Left leg-left arm voltages
D. Left leg-right leg voltages

25. Bipolar lead II measures the difference in potential between ?
A. Left arm-right arm voltages
B. Left leg-right arm voltages
C. Left leg-left arm voltages
D. Left leg-right leg voltages

26. Bipolar lead III measures the difference in potential between ?
A. Left arm-right arm voltages
B. Left leg-right arm voltages
C. Left leg-left arm voltages
D. Left leg-right leg voltages

27. In unipolar leads, the lowercase “a” stands for ?
A. Added
B. Augmented
C. Arithmatic
D. Apparent

28. Electrical augmentation of unipolar potentials in unipolar leads is by ?
A. 25 %
B. 50 %
C. 75 %
D. 100 %

Electrocardiography

[MCQs] Electrocardiography- Part 1

I. Start the exam by click the “Start” button

Electrocardiography- Part 1

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