Normal EKG Flashcards

1
Q

What is the function of the SA node?

A
  • Initial depolarization of the myocardium.
  • Sets the heart rate at 60-100 bpm.
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2
Q

What does the AV node do?

A

Delays the electrical signal, allowing the ventricles time to fill with blood, with an inherent rate of 40-60 bpm.

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3
Q

What is the function of the Bundle of His?

A

Transmits impulses from the AV node to the ventricles.

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4
Q

What are the Purkinje fibers responsible for?

A

Spread the impulse through the ventricles, causing them to contract.

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5
Q

Conduction Principles

  • Automaticity = ?
  • Rhythmicity = ?
  • Conductivity = ?
A
  • Automaticity: The heart’s ability to contract on its own without external stimuli.
  • Rhythmicity: The heart’s ability to contract in a regular, rhythmic manner.
  • Conductivity: The heart’s ability to transmit impulses throughout the myocardium.
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6
Q

What are the main components of the cardiac cycle?

A
  • Starts at the end of systole
  • Includes closing of semilunar valves
  • Opening of mitral valves for ventricular filling.
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7
Q

What information does a 12-lead ECG provide?

A

Rate, rhythm, impulse conduction, myocardial pathology, and physiologic status.

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8
Q

How many electrodes are used in a 12-lead ECG?

A

10 electrodes.

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9
Q

Name the 6 limb leads in a 12-lead ECG.

A
  • Lead I
  • Lead II
  • Lead III
  • aVR
  • aVL
  • aVF
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10
Q

What is the ‘Rule of L’s’ in ECG?

A
  • Lead I (Right to Left Arm)
  • Lead II (Right Arm to Left Leg)
  • Lead III (Left Arm to Left Leg)
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11
Q

What does the QRS complex represent?

A
  • Depolarization of the ventricles
  • Initiation of ventricular systole
  • 0.06-0.10 sec
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12
Q

What is the significance of the ST segment?

A
  • Represents early ventricular repolarization
  • Abnormalities may indicate heart disease
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13
Q

What does the T-wave represent?

A
  • ventricular repolarization
  • beginning ventricular filling
  • 0.16 sec
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14
Q

What is the normal duration of the PR interval?

A
  • 0.12-0.20 seconds
  • 3-5 small boxes
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15
Q

What does the P-wave represent?

A
  • Depolarization of the atria
  • 0.08-0.11
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16
Q

What does a normal sinus rhythm look like?

A
  • P waves are upright and precede every QRS complex
  • PR interval 0.12-0.20 seconds
  • QRS complex is identical and 0.06-0.10 seconds
  • HR 60-100 bpm
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17
Q

Define

  • sinus bradycardia = ?
  • sinus tachycardia = ?
A

Sinus Bradycardia: A sinus rhythm with a heart rate of less than 60 bpm.

Sinus Tachycardia: A sinus rhythm with a heart rate of more than 100 bpm.

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18
Q

Define sinus tachycardia.

A

A sinus rhythm with a heart rate of more than 100 bpm.

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19
Q

What is sinus arrhythmia?

A

An irregular sinus rhythm, often associated with breathing cycles.

20
Q

What does a 5-lead ECG typically assess?

A

Heart rate and rhythm in clinical settings.

21
Q

How is heart rate calculated using the 1500 method?

A

1500 divided by the number of small boxes between two R-waves.

22
Q

How is heart rate calculated using the 6-second method?

A
  • Count the number of R-waves in a 6-second strip and multiply by 10.

  • Use if abnormal
23
Q

What does the PR segment represent?

A

Transmission of the electrical impulse from the atria to the ventricles.

24
Q

What is the normal duration of the QRS complex?

A

0.06-0.10 seconds.

25
Q

What does the R-R interval measure?

A

The regularity of the heart rate.

26
Q

What might cause an abnormal QRS complex?

A

Conditions like ventricular hypertrophy or conduction block.

27
Q

What is the role of the Purkinje fibers in the ECG?

A

They cause the ventricles to contract, represented by the QRS complex.

28
Q

What does the QT interval represent?

A

The total time for ventricular depolarization and repolarization.

29
Q

What does an elevated ST segment indicate?

A

Possible myocardial infarction (STEMI).

30
Q

What does the P-R interval indicate in terms of conduction?

A

The time it takes for the electrical impulse to travel from the SA node through the AV node.

31
Q

Why is the T-wave important?

A

It indicates ventricular repolarization, and abnormalities can indicate electrolyte imbalances or ischemia.

32
Q

What does sinus arrest mean?

A

A pause in the heart’s activity when the SA node fails to initiate an impulse.

33
Q

How do you calculate the heart rate using the Box Counting Method?

A

Count the number of large boxes between two R-waves and divide 300 by this number.

34
Q

What is the significance of a biphasic P-wave?

A

It may indicate atrial enlargement.

35
Q

What is the ‘sawtooth’ pattern on an ECG indicative of?

A

Atrial flutter.

36
Q

What might a wide QRS complex suggest?

A

Ventricular conduction delays or bundle branch blocks.

37
Q

What is the significance of the P-R segment being isoelectric?

A

It indicates that the atria have depolarized and the impulse is traveling to the ventricles.

38
Q

What does a notched P-wave indicate?

A

Possible left atrial enlargement.

39
Q

How does the 6-second method differ for figuring out heart rhythm?

A

It’s the only method suitable for calculating heart rate in irregular rhythms.

40
Q

What is the normal duration of a T-wave?

A

Approximately 0.16 seconds.

41
Q

How can electrode misplacement affect an ECG reading?

A

It can lead to incorrect interpretation of heart rhythms and conditions.

42
Q

What does a normal T-wave look like?

A

Upright and same direction as the P-wave, with a duration of about 0.16 seconds.

43
Q

What is the purpose of a caliper in ECG analysis?

A

To measure the R-R interval and check for regularity of the rhythm.

44
Q

.

A

.

45
Q

What does the term ‘sinus rhythm’ imply?

A

A heart rhythm originating from the SA node.

46
Q

What are the characteristics of sinus tachycardia?

A

Normal P, PR, and QRS but with a heart rate over 100 bpm.

47
Q

What is the main feature of sinus bradycardia?

A

Normal P, PR, and QRS but with a heart rate under 60 bpm.