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234342 > ECG interpretation > Flashcards

ECG interpretation Flashcards

1
Q

ECG strips are divided into boxes. How many small boxes in a large box

size in mm of the small boxes

A

25

1mm x 1mm

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2
Q

rate of ECG recording and therefore

how much time does a large box and a small box show

A

• ECG records ast 25mm/s  5 large squares covered each sec

one large square = 0.2sec; one small square = 0.04sec

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3
Q

t or f

100% of the time the electrical impulse stimulates muscle ontraction

A

f sometimes there are rare disorders that make this incoordinated

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4
Q

what is the ony time during cardiac cycle that L ventricle is perfused and why does tachycardia affect this

A

• Left ventricular muscle perfused only during diastole. As such, tachycardia = less perfusion to LV. If demand exceeds supply  LV ischemia (+ poss infarc)

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5
Q

what does asystole or isoelectric line indicate

A

• Isoelectric line: no electrical signal on ECG; indicates asystole (systole absent in pt, has cardiac arrest)

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6
Q

if there is a rise in the line on the ECG (up from the isoelecric line what does this indicate

A

• Rise in line on ECG: positive deflection – means electrical act is following the same direction of flow as bipolar lead or traveling toward unipolar lead

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7
Q

what is an artefact

what could cause this

A

artefact (= anything appearing on ECG trace that is not from cardiac origin)
often looks like jagged line

could be from any electrical activity eg shivering

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8
Q

how can you identify artefacts/distinguish them from being cardiac in origiin

A

• Artefact can usually be ID’d by incongruity w other info (eg: with AFib would see jagged isoelectric line, but the QRS complex would appear normal. With artefact, see jaggedness in QRS as well)

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9
Q

the strenght of the plateau or absolute refractory period in the cardiac cycle is d/t what ion

A

o Strength of contraction d/t amount of intracellular Ca2+ and so length of plateau influences contractile strength

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10
Q

value of resting voltage in mv

A

-90mv

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11
Q

where are the electrodes placed for lead II

A

• Lead II (2) is normally being shown if not specified. Goes from R arm to L foot

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12
Q

how s amplitude meas or shown in the strip

A

Vertically(AMPLITUDE): each small box is 0.1mV, or 1mm, adding up to 0.5mV or 5mm **this will come in handy later when we discuss MIs

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13
Q

can you note the atria contracting partway through the P wave

A

no! the ECG only detects electrical activity

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14
Q

what to look at in P wave

A

in my notes from med surg and elsewhere it says it should be less than 0.11 secs on her slides it says 0.6-0.12
Represents atrial depolarization
When evaluating a P wave, look closely at its characteristics, especially its location, configuration, and deflection

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15
Q

how are dysrhythmias named

A

o Dysrhtymias are named according to site of origin of impulse and mechanism of formation or conduction involvd eg impulse that originates in SA node and at slow rate is sinus bradycardia

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16
Q

what aspect do you focus on with the PR interval

what does the PR interval reflect

duration

A

When evaluating a PR interval, look especially at its duration
From the beginning of the P wave to the beginning of the QRS complex.
The PR interval tracks the atrial impulse from the atria through the AV node, bundle of His, and right and left bundle branches. When evaluating a PR interval, look especially at its duration.

Duration: 0.12 to 0.20 second

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17
Q

what do changes in the PR interval reflect

A

Changes in the PR interval indicate an altered impulse formation or a conduction delay, as seen in AV block.

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18
Q

what char does a normal QRS comple have

how high can it be

what does it come after

how long is it and what can you compare its length to

A

Follows the PR interval
5 to 30 mm high but differs for each lead used
0.06 to 0.10 second, or half of the PR interval

Duration is measured from the beginning of the Q wave to the end of the S wave (or from the beginning of the R wave if the Q wave is absent)
consists of the Q wave (the first negative deflection after the P wave), the R wave (the first positive deflection after the P wave or the Q wave), and the S wave (the first negative deflection after the R wave

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19
Q

ST segment what to pay extra attn to

what does it look like
what does abn indicate

A 
Pay special attention to the deflection of the ST segment. 
A normal ST segment has the following characteristics:
Extends from the S wave to the beginning of the T wave 
Usually isoelectric (neither positive or negative

A change in the ST segment may indicate myocardial damage. An ST segment may become either elevated or depressed.

20
Q

what is the point that marks the end of the QRS complex and start of the ST segment known as

A

The point that marks the end of the QRS complex and the beginning of the ST segment is known as the J point.

21
Q

what to evaluate with a t wave

is duration significant

A

When evaluating a T wave, look at the amplitude, configuration, and deflection.

Duration is not measured

22
Q

what are normal T wave char

what does it come after
how high is it and what shape

A

Normal T waves have the following characteristics:
Follows the S wave
0.5 mm in lead II configuration—typically round and smooth
deflection—usually upright in lead II

23
Q

what does T wave represent

A

The T wave represents ventricular recovery or repolarization.

24
Q

what is most imp about QT interval

A

duration

25
Q

where does Qt interval start and stop and how long should it be

A

Location—extends from the beginning of the QRS complex to the end of the T wave
Duration—varies according to age, sex, and heart rate; usually lasts from 0.36 to 0.44 seconds; shouldn’t be greater than half the distance between consecutive R waves when the rhythm is regular.

26
Q

what normal process will affect QT interval duration

A

heart rate will shorten it if increasing

27
Q

what does QT interval meas

A

The QT interval measures ventricular depolarization and repolarization. The length of the QT interval varies according to heart rate. The faster the heart rate, the shorter the QT interval.

The QT interval shows the time needed for the ventricular depolarization-repolarization cycle.

28
Q

what would short or long QT interval indicate

A

An abnormality in duration may indicate myocardial problems. Prolonged QT intervals indicate that the relative refractory period is longer.

Prolonged QT syndrome is a congenital conduction- system defect present in certain families. Prolonged QT intervals indicate that the relative refractory period is longer.
Short QT intervals may result from digoxin toxicity or hypercalcemia.

29
Q

what is a U wave
are they always there
what is most significant about them

A

The U wave may not appear on an ECG
Represents the recovery period of the Purkinje or ventricular conduction fibers
The configuration is the most important characteristic of the U wave.

30
Q

char of U wave

what can cause them

A

Location—follows the T wave
Typically upright and rounded

A prominent U wave may be due to hypercalcemia, hypokalemia, or digoxin toxicity

31
Q

what are the 8 steps to ECG interpretation (just the names of the steps

A
  1. Determine the rhythm-
  2. Determine the rate-cant just look at VS monitor. Do p wave and R wave. If the pt has irreg heart rhythm make sure you have 6 second strip.
  3. Eval the P wave-
  4. meas PR interval-make sure they are all the same.
  5. meas QRS
  6. eval T wave
  7. QT interval-can be alt by brady or tachy eg from exercise. QT represents the entire ventricle cycle
  8. Note any abn and conclude your analysis
32
Q

step 1 of ECG interpretation

how is this done
what tool do you need

A

1)Determine the atrial and ventricular rhythm:
Measure from P-P and R-R
Are they regular or irregularly spaced?
Using either calipers or the paper method

33
Q

what is the paper method for determining the rhythm

A

not as easy as caliper method

take paper and meas R-R and make notes on your paper then move those little noted areas to the next R and compare and so on

then do for P-P

34
Q

how to determine the rate from an ECG

this is best for regular rhythm

A

Various methods to determine the rate….
Most accurate is dividing by 1500, this works well for regular rhythms:
Count the small squares between two consecutive P waves and then divide 1,500 by that number to get the atrial rate. To obtain the ventricular rate, use the same method with two consecutive R waves. ie: 1500/20 = 75 BPM

35
Q

determining rate for irreg rhythm how long of a strip will you need

A

you need 6 sec strip

36
Q

det rate of irreg rhythm method

A

The 10 times method is helpful for irregular rhythms:
Print a 6 second strip (ECG paper is marked at 3 second intervals)
Count the number of P waves and multiply by 10, and repeat for the R waves

37
Q

how many lg boxes is in between the vertical hash marks (the black lines)
how many seconds is this

A

15lg boxes

3 seconds

38
Q

what do you look at when evaluating the P wave

A

Are there P waves?
How do they look? Normal? Upright? Rounded? Are they all a similar size and shape?
Is there one P wave per QRS complex?

39
Q

what do you look at when eval the PR interval

how long should it be?

A

Count the small squares between the P wave and the beginning of the QRS complex, multiply by 0.04
Normal range = 0.12 – 0.20 seconds
Are the PRIs constant?

40
Q

what do you look at when eval the QRS

what is normal range

A

Measure from the end of the PR interval to the end of the S wave
Count the number of small squares and multiply by 0.04
Normal range = 0.06 -0.10 seconds
Is each QRS the same? If not, measure and record each one separately
Does each QRS follow a P wave?

41
Q

do you meas the legnth of T waves

what do we need to look at with them

A

Are there T waves?
Are they upright in lead II?
Are they all the same shape?
Does each T wave follow a QRS complex?

42
Q

what kind of relationship does QT interval have with heart rate

A

inverse relationship

As the heart rate increases, the QT interval decreases;
as the heart rate decreases, the QT interval increases.

43
Q

what to eval when looking at QT interval

A

Count the number of small squares between the beginning of the QRS complex and the end of the T wave, where the T wave returns to the baseline and multiply by 0.04
Normal range = 0.36 – 0.44 seconds

44
Q

what is step 8 of ECG analysis and what do you do

A

Note any abnormalities and conclude your analysis

Are there any ectopic beats?
Anything else unusual?
Is the ST segment isoelectric? Elevated? Depressed?
Record and document your findings

45
Q

how to document your analyss

A

1-The origin of the rate (sinus node, atria, AV node, or ventricles)
2-The rate (bradycardic, tachycardic)
3-Rhythm abnormalities (flutter, fibrillation, heart block, escape rhythm, or other arrhythmias)

234342 (11 decks)

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