350 QUESTIONS AND ANSWERS
1. Q: What does ECG stand for? ANSWER Electrocardiogram - a recording
of the electrical activity of the heart.
2. Q: What is the normal heart rate range for adults? ANSWER 60-100
beats per minute.
3. Q: How many leads are in a standard 12-lead ECG? ANSWER 12 leads
(6 limb leads and 6 precordial leads).
4. Q: What does the P wave represent? ANSWER Atrial depolarization.
5. Q: What does the QRS complex represent? ANSWER Ventricular
depolarization.
6. Q: What does the T wave represent? ANSWER Ventricular repolarization.
7. Q: What is the normal duration of the PR interval? ANSWER 0.12-0.20
seconds (120-200 milliseconds).
8. Q: What is the normal duration of the QRS complex? ANSWER Less
than 0.12 seconds (120 milliseconds).
9. Q: What is the normal QT interval? ANSWER 0.36-0.44 seconds (varies
with heart rate).
10. Q: What does the ST segment represent? ANSWER The period between
ventricular depolarization and repolarization.
11. Q: What is the standard paper speed for ECG recording? ANSWER 25
mm/second.
12. Q: How much time does each small square represent on ECG paper?
ANSWER 0.04 seconds (40 milliseconds).
13. Q: How much time does each large square represent on ECG paper?
ANSWER 0.20 seconds (200 milliseconds).
,14. Q: What is the standard voltage calibration for ECG? ANSWER 10
mm = 1 mV.
15. Q: Which leads are considered inferior leads? ANSWER II, III, and
aVF.
16. Q: Which leads are considered lateral leads? ANSWER I, aVL, V5, and
V6.
17. Q: Which leads are considered anterior leads? ANSWER V1, V2, V3,
and V4.
18. Q: What is the normal axis range for the heart? ANSWER -30° to +90°.
19. Q: What does left axis deviation indicate? ANSWER Axis between -30°
and -90°.
20. Q: What does right axis deviation indicate? ANSWER Axis between
+90° and +180°.
21. Q: Where is the V1 electrode placed? ANSWER Fourth intercostal space,
right sternal border.
22. Q: Where is the V2 electrode placed? ANSWER Fourth intercostal space,
left sternal border.
23. Q: Where is the V4 electrode placed? ANSWER Fifth intercostal space,
midclavicular line.
24. Q: What is the isoelectric line? ANSWER The baseline of the ECG where
no electrical activity is recorded.
25. Q: What is sinus rhythm? ANSWER Normal heart rhythm originating
from the sinoatrial node.
26. Q: What are the criteria for sinus rhythm? ANSWER Regular rhythm,
rate 60-100 bpm, P wave before each QRS, normal PR interval.
27. Q: What is bradycardia? ANSWER Heart rate less than 60 beats per
minute.
28. Q: What is tachycardia? ANSWER Heart rate greater than 100 beats per
minute.
29. Q: What is the refractory period? ANSWER The period during which
cardiac tissue cannot be stimulated to depolarize.
, 30. Q: What is depolarization? ANSWER The process of electrical activation
of cardiac muscle.
31. Q: What is repolarization? ANSWER The process of electrical recovery
of cardiac muscle.
32. Q: What is the SA node? ANSWER The sinoatrial node, the heart's
natural pacemaker.
33. Q: What is the AV node? ANSWER The atrioventricular node, which
delays impulses between atria and ventricles.
34. Q: What is the bundle of His? ANSWER The conducting pathway that
carries impulses from the AV node to the ventricles.
35. Q: What are Purkinje fibers? ANSWER Terminal branches of the
conduction system that activate ventricular muscle.
36. Q: What is meant by electrical axis? ANSWER The overall direction of
electrical activity during ventricular depolarization.
37. Q: What is a premature beat? ANSWER An early heartbeat that occurs
before the next expected beat.
38. Q: What is an escape beat? ANSWER A late heartbeat that occurs when
the normal pacemaker fails.
39. Q: What is heart rate variability? ANSWER Normal variation in time
between heartbeats.
40. Q: What is the difference between bipolar and unipolar leads?
ANSWER Bipolar leads measure voltage between two electrodes; unipolar
leads measure voltage at one electrode relative to a reference.
41. Q: What are the standard limb leads? ANSWER I, II, and III.
42. Q: What are the augmented limb leads? ANSWER aVR, aVL, and aVF.
43. Q: What is Einthoven's triangle? ANSWER The theoretical triangle
formed by the limb leads I, II, and III.
44. Q: What is the normal P wave duration? ANSWER Less than 0.12
seconds (120 milliseconds).
45. Q: What is the normal P wave amplitude? ANSWER Less than 2.5 mm
in limb leads, less than 1.5 mm in precordial leads.
1. Q: What does ECG stand for? ANSWER Electrocardiogram - a recording
of the electrical activity of the heart.
2. Q: What is the normal heart rate range for adults? ANSWER 60-100
beats per minute.
3. Q: How many leads are in a standard 12-lead ECG? ANSWER 12 leads
(6 limb leads and 6 precordial leads).
4. Q: What does the P wave represent? ANSWER Atrial depolarization.
5. Q: What does the QRS complex represent? ANSWER Ventricular
depolarization.
6. Q: What does the T wave represent? ANSWER Ventricular repolarization.
7. Q: What is the normal duration of the PR interval? ANSWER 0.12-0.20
seconds (120-200 milliseconds).
8. Q: What is the normal duration of the QRS complex? ANSWER Less
than 0.12 seconds (120 milliseconds).
9. Q: What is the normal QT interval? ANSWER 0.36-0.44 seconds (varies
with heart rate).
10. Q: What does the ST segment represent? ANSWER The period between
ventricular depolarization and repolarization.
11. Q: What is the standard paper speed for ECG recording? ANSWER 25
mm/second.
12. Q: How much time does each small square represent on ECG paper?
ANSWER 0.04 seconds (40 milliseconds).
13. Q: How much time does each large square represent on ECG paper?
ANSWER 0.20 seconds (200 milliseconds).
,14. Q: What is the standard voltage calibration for ECG? ANSWER 10
mm = 1 mV.
15. Q: Which leads are considered inferior leads? ANSWER II, III, and
aVF.
16. Q: Which leads are considered lateral leads? ANSWER I, aVL, V5, and
V6.
17. Q: Which leads are considered anterior leads? ANSWER V1, V2, V3,
and V4.
18. Q: What is the normal axis range for the heart? ANSWER -30° to +90°.
19. Q: What does left axis deviation indicate? ANSWER Axis between -30°
and -90°.
20. Q: What does right axis deviation indicate? ANSWER Axis between
+90° and +180°.
21. Q: Where is the V1 electrode placed? ANSWER Fourth intercostal space,
right sternal border.
22. Q: Where is the V2 electrode placed? ANSWER Fourth intercostal space,
left sternal border.
23. Q: Where is the V4 electrode placed? ANSWER Fifth intercostal space,
midclavicular line.
24. Q: What is the isoelectric line? ANSWER The baseline of the ECG where
no electrical activity is recorded.
25. Q: What is sinus rhythm? ANSWER Normal heart rhythm originating
from the sinoatrial node.
26. Q: What are the criteria for sinus rhythm? ANSWER Regular rhythm,
rate 60-100 bpm, P wave before each QRS, normal PR interval.
27. Q: What is bradycardia? ANSWER Heart rate less than 60 beats per
minute.
28. Q: What is tachycardia? ANSWER Heart rate greater than 100 beats per
minute.
29. Q: What is the refractory period? ANSWER The period during which
cardiac tissue cannot be stimulated to depolarize.
, 30. Q: What is depolarization? ANSWER The process of electrical activation
of cardiac muscle.
31. Q: What is repolarization? ANSWER The process of electrical recovery
of cardiac muscle.
32. Q: What is the SA node? ANSWER The sinoatrial node, the heart's
natural pacemaker.
33. Q: What is the AV node? ANSWER The atrioventricular node, which
delays impulses between atria and ventricles.
34. Q: What is the bundle of His? ANSWER The conducting pathway that
carries impulses from the AV node to the ventricles.
35. Q: What are Purkinje fibers? ANSWER Terminal branches of the
conduction system that activate ventricular muscle.
36. Q: What is meant by electrical axis? ANSWER The overall direction of
electrical activity during ventricular depolarization.
37. Q: What is a premature beat? ANSWER An early heartbeat that occurs
before the next expected beat.
38. Q: What is an escape beat? ANSWER A late heartbeat that occurs when
the normal pacemaker fails.
39. Q: What is heart rate variability? ANSWER Normal variation in time
between heartbeats.
40. Q: What is the difference between bipolar and unipolar leads?
ANSWER Bipolar leads measure voltage between two electrodes; unipolar
leads measure voltage at one electrode relative to a reference.
41. Q: What are the standard limb leads? ANSWER I, II, and III.
42. Q: What are the augmented limb leads? ANSWER aVR, aVL, and aVF.
43. Q: What is Einthoven's triangle? ANSWER The theoretical triangle
formed by the limb leads I, II, and III.
44. Q: What is the normal P wave duration? ANSWER Less than 0.12
seconds (120 milliseconds).
45. Q: What is the normal P wave amplitude? ANSWER Less than 2.5 mm
in limb leads, less than 1.5 mm in precordial leads.
