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CP Exam 2 > Lecture 3: Normal ECG Part I and II > Flashcards

Lecture 3: Normal ECG Part I and II Flashcards

1
Q

Important things to consider when interpreting ECG

A

1. Rate

2. Rhythm

3. Axis

  1. PR duration
  2. QRS duration
  3. QRS height
  4. ST segment
  5. T wave
  6. U wave
  7. QT interval
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2
Q

Conduction of the heart

A

SA node–> AV node–> pause –> common bundle of His–> L/R bundle branch–> purkinje fibers

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3
Q

Is SA node fails, what happens?

A

AV node can be our back up

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4
Q

What happens in AV node fails?

A

Ventricular muscles can be backup

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5
Q

P wave

What does it represent?

When is it: upright, inverted, variable?

A

P wave:

  1. Atrial depolarization
  2. Normally upright in: 1, 2, V4, V5, V6 and AVF
  3. Inverted in: AVR
  4. Variable- everything else
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6
Q

PR interval

When does it occur?

What does it represent?

Duration?

A

PR Interval–> from begining of the P wave to the begining of the QRS complex.

It is the time from the SA node–> ventricular muscle fibers

Time: .12-.20 seconds

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7
Q

QRS complex

What does it represent?

Duration?

What should the Q waves look like?

A
  • QRS complex–> ventricular depolarization
  • Duration: .05- .10 seconds
  • The Q wave should not be more that .03 seconds in width; thus, they should be narrow and small.
    • In 1, AVL, AVF, V5 and V6, 1-2 mm is normal.
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8
Q

A QRS complex > .12 seconds means what?

A

bundle branch block

or

hypertrophy

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9
Q

How do we examine the ST segment?

A

The ST segment should be compared to the isoelectric line (where it should be). Thus, look to see if its elevated or depressed and the shape.

  • Normally not elevate more than 1 mm in standard leads (1, 2, 3, aVL, aVF and aVR) and no more than 2mm in chest leads
  • Normally not depressed more than 1/2mm
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10
Q

If we had a ST depression, what would that represent?

A

subendocardial infarction

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11
Q

If we had a ST elevation, what would that signify?

A

Subepicardial/transmural ischemia

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12
Q

What is the T wave and how do we examine it?

Upright-

Inverted-

Variable-

A

T wave–> ventricular repolarization.

  • Upright- 1, 2, V3, V4, V5, V6.
  • Inverted- aVR
  • Variable in the rest

It is slightly rounded and assymetrical height.

Not greater than 5mm in standard leads and not greater than 10mm in precordial leads.

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13
Q

QT duration--> length of _____________. Thus, what can it tell us?

A

Ventricular systole.

Thus, it can tell us abnormalities in

  1. Myocardial ischemia
  2. Myocardial injury
  3. Myocardial infarction
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14
Q

Ischemic patterns are assx with what kind of T waves?

A

Inverted.

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15
Q

What can be indicative of patterns of necrosis or infarction?

A

A QRS complex >.1 seconds.

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16
Q

What wave can be indicative of hyperkalemia?

A

T waves.

17
Q

African americans and athletes may have an exaggerated _______

A

T wave

and elevated ST segment

18
Q

A short PR interval can be indivative of what?

A

Junctional/nodal rhythms

19
Q

Short PR intervals can be indicative of what?

A
  1. Hypertensive patients
  2. AV junctional and low atrial rhythms
  3. Wolf-Parkinson White syndrome
  4. Lown Ganong levine syndrome
  5. Glycogen storing dz
20
Q

Prolonged PR intervals can be indicative of what?

A
  1. AV block due to coronary dz
  2. Hyperthyroidism
21
Q

What are the rules of thumbs for the determining Q R and S in the QRS complex?

A

Q wave- first deflection downwards

R wave- first upright deflection, whether or not it is preceded by Q

S wave- first negative deflection after R wave

22
Q

T/F: Look at all 12 leads to make a diagnosis for T waves because they will all be varient.

A

True

23
Q

LO: How do we determine normal sinus rhythm?

A
  1. Is there a P wave before every QRS complex and vice versa?
  2. P-R <.2 seconds? If yes, no AV block
  3. QRS complex <0.12 seconds. If yes, no bundle branch block!
24
Q

What leads are the best for reading P waves?

A

Lead II and V1

25
Q

What is the first and second half of the P wave?

What is the PR interval?

PR segment?

A

1st half of the P wave–> R atria depolarization

2nd half of the P wave–> L atria depolarization

PR interval–> how long it takes to go from the SA–> AV node (atrial myocardium to the ventricular myocardium)

PR segment--> how long it takes to travel from AV node–> ventricles

26
Q

What is considered tachycardia?

A

A HR>100.

27
Q

What is considered bradycardia?

A

HR<60mV

28
Q

How do we determine the rate?

A
  1. Find the heart rate by finding a R-wave that falls on a black line and count until the next R wave.

300-150-100-75-60

Anything else below is 60 bradycardia.

OR: 300/number of large boxes

29
Q

What is rhythm?

A
  • P wave precedes QRS.
  • P:QRS ratio is 1.
30
Q

Are there other sinus rhythms? If yes, name them?

A

1. Ectopic atrial rhythm

2. Multifocial atrial tachycardia (MAT)

3. Wandering atrial pacemaker

31
Q

In what situations what a P wave occur AFTER a QRS?

A

-Present is side of the pacemaker is changed

Seen in a SVT (AV nodal re-entry tachycardia)

and junctional rhythm

32
Q

In what situations do we see no P waves? (5)

A

A-fib

Atrial flutter

Junctional or ventricular escape rhythms

Junctional tachycardia

VT

33
Q

What is axis?

Normal axis?

How do we determine?

A

The direction the vector is taking during depolarization.

A normal axis will be in between 0-90.

To determine, we look at the NET QRS VOLTAGE (upward- downward QRS deflection)

34
Q

How do we create the 6 intersecting leads that lie in the frontal plane of the patients chest?

A

Combine the bipolar limb leads with the augmented limb leads.

35
Q

What is a normal axis ?

A

Positive defelction in leads I and aVF.

36
Q

Left axis deviation

A

+ deflection in lead 1

  • deflection in aVF
37
Q

Right axis deviation

A
  • deflection in lead 1

+ deflection in aVF

38
Q
A

CP Exam 2 (27 decks)

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