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A Brief on ECG

ECG or Electrocardiograph is a test that is used to assess the muscular and electrical functionalities of the heart. It is a painless test which can be conducted in a few minutes and results can also be read instantly. An electrocardiograph is basically a graph of voltage plotted against time of electrical activity of the heart.

The electrical activity of the heart - The electrical system is the power source that makes the working of the heart possible in a nutshell. The electrical impulses trigger the heartbeat that travels down a pathway through the heart. These pathways are conduction pathways and they are responsible for causing ventricles of the heart to contract and pump out blood. The human heart has a natural pacemaker which produces these electrical impulses all by itself. These electrical impulses generate an electrical current that spreads over our body. An electrocardiogram measures these currents in the form of wave graphs on a paper.

The electrodes of the electrocardiogram are placed on the skin to note the normal working conditions of the heart. These electrodes detect the electrical impulses occurring during each heartbeat. The impulses are picked up from the changes in an electrical path on the skin. These changes arise from the heart muscles and the electrophysiologic patterns of the depolarizing.

Let’s have a look at some solved Multiple-choice questions on ECG

MCQs on Electrocardiography or ECG

1. Who developed an Electrocardiogram?

  1. Wilhelm His

  2. Steward

  3. Hubert Mann

  4. Willem Einthoven

Answer: (d)

2.In case of a normal Heartbeat, Depolarization stimulus arises in which of the following?

  1. Epicardium

  2. Sinoatrial Node (SA node) 

  3. Atrioventricular Node (AV node)

  4. His bundle

Answer: (b)

3. What does the P wave represent?

  1. Depolarization of the atria

  2. Depolarization of the ventricles

  3. Represents the repolarization of the ventricles

  4. Depolarization of the atria and ventricles

Answer: (a)

4. Which of these cannot be detected by an Electrocardiogram?

  1. The rate and rhythm of Heartbeats

  2. The size and position of the Heart chambers

  3. The function of implanted Pacemakers

  4. Presence of asymptomatic blockages in the atria of the Heart

Answer: (d)

5. Which of the following indicates Ventricular Muscle Depolarization?

  1. P wave

  2. QRS complex

  3. T wave

  4. PR interval

Answer: (b)

6. What does the T wave represent in an ECG?

  1. Atrial diastole

  2. Atrial systole

  3. Ventricular diastole

  4. Joint diastole

Answer: (c)

7. What does the Depolarization of Ventricles initiate?

  1. Atrial diastole

  2. Atrial systole

  3. Ventricular systole

  4. Joint diastole

Answer: (c)

8. Counting the number of QRS complexes, which of the following can be interpreted?

  1. Rate of heart beat

  2. Rate of breathing

  3. Cardiac output

  4. Stroke volume

Answer: (a)

9. What do Depolarization and Repolarization initiate in different chambers of the Heart?

  1. Contraction and relaxation

  2. Relaxation and contraction

  3. Thickening and thinning

  4. Contraction and thickening

Answer: (a)

10. Which of the following waves of ECG represent Repolarization?

  1. P wave

  2. QRS complex

  3. RS wave

  4. T wave

Answer: (d)

11. In a single circulation the Heart Pumps?

  1. Oxygenated blood

  2. Deoxygenated blood

  3. Mixed blood

  4. Only blood nutrients

Answer: (b)

12. The Depolarization Stimulus for the normal Heartbeat originates in the

  1.  Epicardium

  2.  His-bundle areas

  3. Atrioventricular (AV) nodal

  4.  Sinoatrial (SA) node

Answer: (d)

13. A shortened PR interval, slurring (called a delta wave) of the initial QRS deflection, and prolonged QRS duration are characteristics of

  1. Wolff-Parkinson-White (WPW) syndrome

  2. B. Atrial tachycardia

  3. C.  Left bundle branch block

  4. D. Myocardial ischemia

Answer: (a)

14. The classic ECG changes in Myocardial Infarction (MI) are

  1. T-wave inversion

  2. ST-segment elevation

  3. Development of an abnormal Q wave

  4. All of the above

Answer: (d)

15. ECG depicts the Depolarisation and Repolarisation processes during the Cardiac Cycle. In the ECG of a normal healthy individual one of the following waves is not represented, which one is that?

  1. Depolarization of atria

  2. Repolarization of atria

  3. Depolarization of ventricles

  4. Repolarization of ventricles

Answer: (b)

16. Which of the following correctly explains a phase/ event in cardiac cycle in a standard Electrocardiogram?

  1. QRS complex indicates atrial contraction.

  2. QRS complex indicates ventricular contraction.

  3. Time between S and T represents atrial systole.

  4. P-wave indicates beginning of ventricular contraction.

Answer: (b)

17. In a normal individual, the heart rate can be determined by the ___________ in an ECG

  1. Interval between two QRS complexes

  2. Number of P waves

  3. Interval between the P and T waves

  4. Number of T waves

Answer: (a)

18. This is the classic ECG change in MI (Myocardial Infarction)

  1.  ST-segment elevation

  2. T-wave inversion

  3. Development of an abnormal Q wave

  4. All of these

Answer: (d)

19. In which of these conditions can widened QRS and Tall-tented T waves be observed

  1. Hyponatremia

  2. Hyperkalemia

  3. Hyperglycemia

  4. Hyperphosphatemia

Answer: (b)

20. A particular ECG change observed in Hypokalemia is

  1. ST segment elevation

  2. U wave, which is a position deflection after the T wave

  3. Tall peaked T waves

  4. Widening of the QRS complex and increased amplitude

Answer: (b)

21. ECG identified by the PR interval tends to become longer with every succeeding ECG complex until there is a P wave not followed by a QRS is observed in

  1. Third-Degree Atrioventricular Block

  2. Second-Degree Atrioventricular Block, Type II

  3. Second-Degree Atrioventricular Block, Type I

  4. First-Degree Atrioventricular Block, Type II

Answer: (c)