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Bloc C - Exam 2 COPY > ECG > Flashcards

ECG Flashcards

1
Q

What is the QRS complex?

A

Depolarization of ventricle

Q↓ R↑ S↓ after R

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2
Q

What does the T represents on an ECG?

A

The repolarization

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3
Q

What does the P represents on an ECG? When is it abnormal?

A

The P wave represents depolarization of the right atrium followed quickly by depolarization of the left atrium (superimposed). They are seen in lead II and V1

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4
Q

What is the ST interval ?

A

The line between the QRS complex and the T wave, it is normally isoelectric (at the same level as the “baseline”). It may move up or down when the heart is lacking oxygen:

  • Upward = MI
  • Downward = Ischemia
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5
Q

What is the PR interval ?

A

Time from the start of the P wave to the start of the QRS complex

NORMAL = 0.12-0.20 sec.

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6
Q

What is the QT interval?

A

Time from the start of the QRS complex to the end of the T wave, represents the time for ventricular depolarization and repolarization. This interval changes according to the heart rate and is not constant.

You calculate it with Bazett’s formula (QTc ≤ 0.44 for men and 0.46 for women) or the rapid rule with normal heart rate: if the QT interval is less than ½ the R-R interval, then the QT is within normal range.

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7
Q

What are the 12 leads recorded by an ECG?

A
  • 6 “LIMB LEADS” record the depolarization currents in the FRONTAL PLANE
    ​By overlaying the vectors of the 6 limb leads, an Axial Reference System is established.
  • 6 “PRECORDIAL” LEADS record depolarization currents in the TRANSVERSE PLANE
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8
Q

What are the bipolar leads?

A
  • I : RA (-) to LA (+)
  • II: RA (-) to LL (+)
  • III: LA (-) to LL (+)
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9
Q

What are the unipolar leads?

A
  • aVR: CT (-) to RA (+)
  • aVL: CT (-) to LA (+)
  • aVF: CT (-) to LL
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10
Q

What are the corresponding lead references on the electric circuit of the heart ?

A

Avant P : SA node

P: du SA node au AV node

Après P: AV node

QRS: ventricules

T: repolarization des ventricules

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11
Q

The normal rhythm initiated by depolarization of the sinus node is known as “Sinus rhythm”. Sinus rhythm is presented how on an ECG?

A

Criteria:

  1. Each P wave is followed by a QRS
  2. Rach QRS is preceded by a P wave
  3. The P wave is upright in leads I, II, and III
  4. The PR interval is greater than 0.12 seconds (3 small boxes)
  • Normal sinus rhythm = Heart rate between 60 and 100 beats/min
  • Sinus bradycardia = Sinus rhythm with heart rate < 60 beats/min
  • Sinus tachycardia = Sinus rhythm with heart rate > 100 beats/min
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12
Q

How do we calculate heart rate ?

A
  • Method 1: count number of small boxes between QRS complexes. Very good method for fast heart beat
    1500
    23
  • Method 1: Count-off method from QRS peaks. You memorize the sequence: 300-150-75-60-50
  • Method 3: ECG recording paper often indicates 3-sec time markers N beats x 20.
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13
Q

What is mean axis and its 4 classification?

A

“AXIS” refers to the angle of this average vector in the frontal plane. In a normal individual, the normal axis vector lies between -30° - +90°. The orientation of your heart in your chest will deviate your axis. Axis is classified into one of 4 categories:

  • NORMAL (lead I and II positive)
  • LEFT AXIS DEVIATION (lead I positive lead II negative)
  • RIGHT AXIS DEVIATION (lead I negative lead II positive)
  • EXTREME AXIS DEVIATION (lead I negative lead II negative)
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14
Q

When do we suspect a Right ventricular hypertrophy?

A
  • R > S in V1
  • Right axis deviation
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15
Q

When do we suspect a Left ventricular hypertrophy?

A
  • S in V1 plus R in V5 or V6 > 35 mm
  • R in aVL > 11 mm or R in lead I > 15 mm
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16
Q

Where is the pathological Q wave in an anteroseptal Myocardial Infarction?

A

V1 and V2

17
Q

Where is the pathological Q wave in an Anterolateral Myocardial Infarction?

A

I, aVL, V5, V6

18
Q

Where is the pathological Q wave in an Inferior Myocardial Infarction?

A

II, III, aVF

19
Q

Where is the pathological Q wave in an Anteroapical Myocardial Infarction ?

A

V3, V4

20
Q

Where is the pathological Q wave in an Posterior Myocardial Infarction ?

A

TRICK QUESTION: WE GET TALL R NOT Q WAVE IN V1, V2

21
Q

What do we see in Transient Myocardial Ischemia?

A

T wave inversion or ST depression

22
Q

What do we see in acute MI if the blockage is complete?

A

ST elevation

23
Q

What do we see in acute MI if the blockage in not complete (the thrombus is only partially occlusive)?

A

NO Q waves as typically only the sub-endocardium is involved

24
Q

What are the criteria of a right bundle branch?

A
  • Wide QRS
  • Rabbit ears in V1
  • Big S in V6
25
Q

What are the criteria of a left bundle branch?

A
  • Wide QRS
  • Big R in V6
  • Big S + no R in V1

Bloc C - Exam 2 COPY (7 decks)

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