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Clinical Skills > EKG > Flashcards

EKG Flashcards

1
Q

What is a normal R-R interval?

A

0.6-1 sec (60-100 bpm)

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2
Q

What is a normal P-R interval? Elongation suggests ________

A

0.12-0.2 sec (1 large box). Longer suggests AV block.

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3
Q

Small box corresponds with ___ sec

A

0.04

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4
Q

Large box corresponds with ___ sec

A

0.20

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5
Q

What is a normal QTc interval? How do you calculate it?

A

QTc ≤ 0.40 sec. QTc=(QT)/SqRoot RR (in seconds)
Quick and dirty rule:
<1/2 of RR

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6
Q

Basic rule for estimating rate by observation:

A

Find an R wave that peaks on/near a thick box. Count thick boxes until you hit the next r wave: 300, 150, 100, 75, 60, 50
Another option is 300/# of large boxes in R-R interval

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7
Q

How do you estimate rate by observation if it is slow?

A

Cycles per 6-second strip x 10= rate (bpm)

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8
Q

SA node inherent rate

A

60-100 bpm

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9
Q

atrial focus inherent rate

A

60-80 bpm

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10
Q

AV junctional focus inherent rate

A

40-60 bpm

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11
Q

Ventricular focus inherent rate

A

20-40 bpm

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12
Q

Sinus tachycardia

A

> 100 bpm

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13
Q

Sinus bradycardia

A

<60 bpm

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14
Q

What is a normal QRS interval? What does elongation suggest? Which leads should you check?

A

<0.12 or less than 3 small boxes).

Bundle branch block is suggested, check leads V1, and V2 (for r BBB) and leads v5 and v6 (for L BBB).

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15
Q

sinus arrhythmia

A

irregular rhythm that varies with respiration. All P waves are identical.

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16
Q

wandering pacemaker

A

Irregular rhythm. P waves change shape as pacemaker location varies (p, p prime)
RATE IS <100

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17
Q

Multifocal atrial tachycardia

A

Irregular rhythm. P waves change shape as pacemaker location varies (p, p prime)
RATE IS >100

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18
Q

Describe how an escape beat would appear and how you can tell where it originates:

A

If an SA node fails to emit a pacing stimulus, a beat may escape from an automaticity focus (atrial, junctional, or ventricular).
There will be a pause. If what follows the pause is an abnormal p-wave followed by a normal QRS, then it is an atrial escape beat.
If what follows is an inverted p-wave, it could be junctional (could also be absent)
If what follows is just a wide QRS, then it’s ventricular.

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19
Q

How can you tell a premature atrial beat from a junctional or ventricular

A

If atrial P1 wave will be different from normal. If Junctional, the p wave will be inverted or absent. Both are followed by normal QRS.

In a PVC, the QRS complex will be wide and morphologically distinct.

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20
Q

What is bigeminy?

A

When a PAB or PVC occurs regularly following a normal PQRS. Can be atrial, junctional, or ventricular

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21
Q

What is trigeminy? Quadrimeginy?

A

Trigeminy PAB, PJB, or PVC after every OTHER normal PQRS. Quadrigeminy is every third.

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22
Q

SVT

A

Term for PAT and PJT together. An irritable focus in the atrial or AV junction is discharging at a rate (atrial obv) of 150-250. If p1 waves are visible, this suggests PAT. Inverted or absent suggests PJT.

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23
Q

Paroxysmal ventricular tachycardia

A

Ventricular focus produces a rapid sequence of PVC-like wide ventricular complexes (rate is 150-250)

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24
Q

Atrial flutter

A

a continuous “saw tooth” rapid sequence of identical p waves which may or may not conduct. Rate is 250-350.

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25
Q

Ventricular flutter

A

A rapid series of smooth sine waves from a single, rapid-firing ventricular focus. Same as Torsades de Pointes. VRate is 250-350.

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26
Q

Atrial fibrillation

A

multiple atrial foci rapidly discharge producing a jagged baseline of tiny spikes. QRS response is irregular. ARate is 350-450.

27
Q

What is the “method” for interpreting EKGs?

A
  1. Rhythm- Is there a p for each QRS? A QRS for each P? If so, it’s sinus!
  2. Rate- 300/#lg boxes (or other rules)
  3. Axis- is it deviated? Use the thumb rule and the circle.
  4. Waves- P waves- do they all match? Is amplitude >2mm (If so, think hypertrophy); QRS- do they match (otherwise PVC); T waves peaked? Any U waves?
  5. Intervals (QRS, P-R, Q-T)
  6. Hypertrophy (Add V1 + V6 or V5). If it is >35mm=ventricular hypertrophy
  7. Infarction- look for ST segment changes.
28
Q

What do peaked T waves suggest? Flat T waves?

A

Peaked~ hyper-K

Flat~ hypo-K

29
Q

What SHORTENS the QT interval?

A

QT<0.3 sec. Suggests hyper-Mg or hyper-Ca

30
Q

What can cause LONG QT?

A

Tricyclic antidepressants, hypo-Ca, hypo-Mg, MI…

31
Q

What physiologic changes will cause ST depression?

A

Ischemia, posterior MI, Digoxin, PE (accompanied by sinus tach), LBBB

32
Q

What physiologic changes will cause ST elevation?

A

Acute MI (only in SOME leads), pericarditis (ALL leads)

33
Q

Which leads are “inferior”?

A

II (bottom left->up); AvF (straight up); III (bottom-right->up)

34
Q

Which leads are considered “lateral”?

A

I and AVL (left side).

35
Q

Rule for distinguishing between 2nd degree AV blocks:

A

Long, longer, drop, you’ve got a Wenckebach. Otherwise, it’s Mobitz.

36
Q

1st degree AV block

A

prolonged PR interval (>0.2 sec or 1 lg square). All p’s are followed by QRS.

37
Q

2nd degree block

A

Only some P’s are followed by QRS’s. Differentiate between Wenckebach and Mobitz.

38
Q

3rd degree heart block

A

P waves and QRS complexes are completely independent of one another.

39
Q

Right bundle branch block

A

QRS will be shorter than 3 small boxes. “Rabbit ears” in V1 or V2.

40
Q

Left bundle branch block

A

QRS appearance between R and R1 causes a “plateaued” appearance in V5 or V6

41
Q

A couple quick and dirty ways to determine axis deviation, frontal and horizontal planes.

A
  1. FRONTAL: Two thumbs, two leads: I (R) and AVF (L), drive the car.
  2. HORIZONTAL: Find the isoelectric CHEST lead. Should be V3 or V4. If it’s V1 or V2, then there’s a Right deviation. If it’s V5 or V6, then it’s a LEFT deviation.
  3. FRONTAL: If you have an axis wheel you can estimate quantitatively. Find the limb lead that is most isoelectric. Using the wheel, find the lead that is 90 degrees from this. Check your strip to see if this lead is + or -, then read the axis. Normal is 0- +90.
42
Q

How to check for atrial enlargement/hypertrophy? How to tell R from L?

A

Look at lead V1. In atrial enlargement, the V1 p-wave will be diphasic (+ and -). In R atrial enlargement, the initial phase will be larger and often peaked (OR just larger than 2.5mm without diphasic appearance). In L atrial enlargement, the diphasic appearance will be more clear in V1, with the terminal component being larger.

43
Q

Ventricular hypertrophy- what does it look like and how to differentiate L from R:

A

Normally the overall QRS deflection in V1 should be negative, with S a much larger magnitude than R.

In Right ventricular hypertrophy, V1 will have a mainly positive deflection (R larger than S), and R will appear gradually smaller as you move from V1-V2-V3-V4. This will also be accompanied by R axis deviation and R rightward rotation in the horizontal plane.

In L ventricular hypertrophy, S in V1 will have very large magnitude, as will R in V5. If the sum of S from V1 and R from V5 is >35mm, then there is LVH. This will usually be accompanied by L axis deviation. LVH may also be accompanied by T-wave inversion and assymetry (long gradual down, fast up).

44
Q

What are “strain signs”?

A

For right ventricular strain, look in V1. The ST segment will be slightly depressed and humped in the middle.

For L ventricular strain, look at the ST segment in V5. It will be slightly depressed and humped in the middle.

45
Q

Ischemia is suggested by…

A

T wave inversion on CHEST leads (esp V2-V6) (it’s not weird to see on limb leads). Marked inversion on V2 and V3 indicates Wellens syndrome- stenosis of the anterior descending coronary artery.

46
Q

EKG findings of pericarditis…

A

ST elevation, where the segment is flat or concave. Often this elevation runs into and elevates the entire T wave. It will be seen in leads where the QRS is usually mainly positive (lateral and inferior limb leads).

47
Q

Subendocardial infarction presentation on EKG:

A

This small infarct will appear as flat ST depression on the leads where QRS is positive (lateral and inferior limb leads). The segment will be either horizontal or slightly downward sloping (but always flat). Be sure to check V1 and V2 to make sure this isn’t actually a posterior MI!

48
Q

When is a q wave considered “significant” (Q)?

A

When it is >0.04 sec in duration (1 sm square) or 1/3 of the total QRS amplitude in the leads where the QRS complex is usually positive.

49
Q

Necrosis of a MI is indicated by…

A

significant Q waves. Check all leads except AVR.

50
Q

In an anterior (LV) infarct, significant Q waves will occur in leads…

A

V1-V4 (depolarization is moving away from leads and unopposed because of dead myocardium anteriorly). ST elevation will occur in the SAME leads if the infarction is acute.

51
Q

In a lateral infarction, significant Q waves will be present in leads…

A

I and AVL (the lateral leads). (Lateral Infarct = LI = I and avL).

52
Q

In an inferior infarct, we expect suspect significant Q waves in which leads?

A

Inferior leads (Inferior infarct= “II” = most “I’s”= II + III (and AVF is obv inferior).

53
Q

What do we expect to see on EKG in a posterior infarction?

A

Basically the opposite of what we would see in an anterior infarct on the chest leads (there are no posterior leads). So there will be a significant R wave (an upside-down positive Q)in leads V1 and V2 followed by ST depression! R waves in V1 and V2 are usually VERY small (with deep S waves).

If you aren’t sure, try a mirror or transillumination test. Invert the tracing then hold the back (blank side) facing you either with a light behind or into a mirror. Look at V1 and V2 for classic “Q wave and ST elevation” of posterior MI.

54
Q

When is an EKG diagnosis of MI invalid?

A

If LBBB is present.

55
Q

an “anterior” infarct is truly happening where?

A

LAD branch of LCA

56
Q

a “lateral” infarct is truly occurring where?

A

circumflex branch of LCA

57
Q

an “posterior” infarct is truly happening where?

A

Right coronary artery (RCA).

58
Q

An “inferior” infarct is truly located where?

A

A branch of either left or right coronary artery. Can’t be sure.

59
Q

Anterior hemiblock…what does it look like? Which vessel supplies the branch?

A

Q1S3. Q wave in I, deep/wide S wave in III. Accompanied by left axis deviation (but so is inferior MI). Supplied by LAD and can be caused by anterior infarct.

60
Q

Posterior hemiblock:

A

S1Q3. Deep/wide S in I and significant Q in III. Supplied by L and R coronary arteries. Will cause right axis deviation.

61
Q

COPD produces _______ on EKG

A

low amplitude QRS complexes in all leads, right axis deviation, and possibly MAT.

62
Q

PE produces ________ on EKG

A

Large S wave in lead I; ST depression in lead II; large Q wave in lead III (w/ T-wave inversion). May also see T wave inversion in V1-V4, RBBB (in right chest leads- V1,2).

63
Q

Digitalis effect:

A

a curved ST segment that is slightly depressed at it’s lowest point. Looks like Dali’s mustache in a lead with no demonstrable S wave.

64
Q

What is a normal axis?

A

0 - +90
LAD: -90 - 0
RAD: +90 - +`80
eRAD: -90 - -180

Clinical Skills (2 decks)

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