Sem1mini3 - ECG MCQ
.JPG "Sem1mini3 - ECG MCQ - Quiz")
- 1.
The following image is an ECG trace from Lead I. Determine if the heart rate and duration of the PR interval and QT interval are within the normal ranges. Heart rate PR interval QT interval
- A.
Normal Normal Normal
- B.
Normal Greater than normal Normal
- C.
Normal Normal Greater than normal
- D.
Bradycardia Normal Less than normal
- E.
Bradycardia Greater than normal Less than normal
- F.
Bradycardia Less than normal Normal
Correct Answer
A. Normal Normal NormalExplanation
The heart rate, PR interval, and QT interval are all within the normal ranges.Rate this question:
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- 2.
The figure below shows a ventricular action potential. Which of the numbered portions of the action potential most closely corresponds to the ST-segment on an ECG trace?
- A.
1
- B.
2
- C.
3
- D.
4
- E.
5
Correct Answer
C. 3Explanation
The ST-segment on an ECG trace represents the plateau phase of the ventricular action potential, which is when the ventricles are contracting and pumping blood. In the given figure, portion 3 closely corresponds to the ST-segment because it represents the plateau phase, where the membrane potential remains stable before repolarization occurs.Rate this question:
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- 3.
What electrical event of the heart is NOT recorded on the standard 12-lead ECG trace?
- A.
Atrial depolarization
- B.
Atrial repolarization
- C.
Phase 2 of the ventricular action potential
- D.
Ventricular repolarization
- E.
Phase 4 of the ventricular action potential
Correct Answer
B. Atrial repolarizationExplanation
Atrial repolarization is not recorded on the standard 12-lead ECG trace. This is because the electrical activity associated with atrial repolarization is masked by the much larger QRS complex, which represents the depolarization of the ventricles. The P wave on the ECG trace represents atrial depolarization, and the T wave represents ventricular repolarization. Phase 2 and phase 4 of the ventricular action potential are also represented on the ECG trace.Rate this question:
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- 4.
The normal direction of the QRS complex in lead aVR results from the
- A.
Repolarization of the ventricular endocardial surface before the epicardial surface.
- B.
Depolarization of the ventricular septum before the left ventricular wall
- C.
Conduction delay caused by the AV-node
- D.
Wave of depolarization moving away from the positive electrode.
- E.
Depolarization of the right ventricle before the left ventricle.
Correct Answer
D. Wave of depolarization moving away from the positive electrode.Explanation
The normal direction of the QRS complex in lead aVR is opposite to the direction of the QRS complex in the other leads. This is because lead aVR is placed on the right arm, which is in a position opposite to the other limb leads. Therefore, the wave of depolarization in lead aVR moves away from the positive electrode, resulting in an inverted QRS complex.Rate this question:
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- 5.
Choose the answer choice below which most closely represents the heart rate of the ECG trace shown.
- A.
300 beats per minute
- B.
150 beats per minute
- C.
100 beats per minute
- D.
75 beats per minute
- E.
60 beats per minute
Correct Answer
B. 150 beats per minuteExplanation
The ECG trace shown indicates a regular and consistent pattern of peaks and valleys. By counting the number of peaks within a minute, we can determine the heart rate. In this case, there are approximately 150 peaks, indicating a heart rate of 150 beats per minute.Rate this question:
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- 6.
If there is a blockage between the AV node and the AV bundle, how will this affect the appearance of the EKG?
- A.
PR interval would be smaller
- B.
QRS interval would be shorter
- C.
There would be more P waves than QRS complexes
- D.
There would be more QRS complexes than P waves
- E.
The T wave would be absent
Correct Answer
C. There would be more P waves than QRS complexesExplanation
If there is a blockage between the AV node and the AV bundle, it means that the electrical signals from the atria are unable to pass through to the ventricles. This would result in the atria continuing to generate their own electrical signals, causing more P waves to appear on the EKG. However, since the signals are not reaching the ventricles, there would be fewer QRS complexes, which represent ventricular depolarization. Therefore, the correct answer is that there would be more P waves than QRS complexes.Rate this question:
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- 7.
The T Wave on an EKG represents:
- A.
Ventricular Depolarization
- B.
Ventricular Repolarization
- C.
Atrial Depolarization
- D.
Atrial Repolarization
- E.
Ventricular Systole
Correct Answer
B. Ventricular RepolarizationExplanation
The T Wave on an EKG represents ventricular repolarization. This is the phase of the cardiac cycle where the ventricles relax and reset their electrical charge in preparation for the next contraction. During ventricular repolarization, the ventricular muscle cells recover from the depolarization phase and regain their resting state. This is reflected as a positive deflection on the EKG tracing.Rate this question:
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.JPG "The normal direction of the QRS complex in lead aVR results from the")
.JPG "Choose the answer choice below which most closely represents the heart rate of the ECG trace shown.")
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Current Version
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Mar 21, 2023Quiz Edited by
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Dec 07, 2011Quiz Created by
BLACKMD
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