Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HMS Homeostasis I > The Electrocardiogram > Flashcards

The Electrocardiogram Flashcards

1
Q

Lead I

A

Placed on the left hand.

If current travels towards Lead I, the deflection is upward.

If it travels away from Lead I, the deflection is downward.

If it travels perpindicular, there is no deflection.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

P wave

A

Atrial deflection. When the SA node fires and sends its signal to the AV node, also resulting in contraction of the atria.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

QRS complex

A

Represents firing of AV node, depolarization of septa, and depolarization of the ventricles (left dominant)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why does depolarization of the left ventricle dominate the ventricular electrical signal?

A

Because there is more muscle in the left ventricle! So consequently, there is more electrical activity, since all of those muscles are firing at once. In effect, the right ventricle signal is being hidden and the net vector is left.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

T wave

A

Repolarization of the ventricles. Also left dominant.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

P QRS T diagram

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why is Q negative on Lead I?

A

Because Q represents depolarization of the interventricular septum, which is to the right of the left ventricle (especially given the bulge due to higher left ventricular hydrostatic pressure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

x and y axis on an ECG

A

x = time

y = voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Ca2+ resting potential

A

+123 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Na+ resting potential

A

+67 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

K+ resting potential

A

-92 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Depolarization potential

A

Usually -70 mV

(The potential necessary for fast sodium channels to open)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Gating potential for voltage-gated potassium channels

A

+20 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Depolarization stages

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

V1 location

A

Right 4th intercostal space, on the sternal border

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

V2 location

A

Left 4th intercostal space, on sternal border

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

V4 location

A

Left 5th intercostal space, on midclavicular line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

V3 location

A

Halfway between V2 and V4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

V5 location

A

Left anterior axillary line, in the same axial plane as V4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

V6 location

A

Left midaxillary line, same axial plane as V4

Underneath the armpit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Appendage leads

A

Two on the arms, in the same axial plane as V4 when the patient is supine, should be ~2/3 down the brachium

Two on the legs, same axial plane as one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Upward deflections are always going towards the ___ electrode.

A

Upward deflections are always going towards the + electrode.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

myocardial action potential durations are more prolonged in cells near the ___ than ___

A

myocardial action potential durations are more prolonged in cells near the inner endocardium (the first cells stimulated by Purkinje fibers) than in myocytes near the outer epicardium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The cells close to the endocardium are the ____

A

The cells close to the endocardium are the first to depolarize but are the last to repolarize

25
Q

ECG placement diagram

A
26
Q

The right-leg electrode

A

The right-leg electrode is not used for measurement but serves as an electrical ground.

27
Q

aVR

A

Right arm + with respsect to other electrodes

unipolar lead

28
Q

Unipolar leads

A

There is no single (−) pole; rather, the other limb electrodes are averaged to create a composite (−) reference.

Ex: aVR, aVL, aVF

29
Q

aVF

A

Recorded by setting the left leg as the (+) pole, such that a positive deflection is recorded when forces are directed toward the feet.

30
Q

aVL

A

Lead aVL is selected when the left-arm electrode is made the (+) pole and it records an upward deflection when electrical activity is aimed in that direction

31
Q

Bipolar leads

A

Bipolar indicates that one limb electrode is the (+) pole and another single electrode provides the (−) reference.

32
Q

Limb lead diagram

A
33
Q

Axial reference system for limb leads

A
34
Q

The magnitude of the deflection, either upward or downward, relative to other deflections reflects . . .

A

The magnitude of the deflection, either upward or downward, relative to other deflections reflects how parallel the electrical force is to the axis of the lead being examined

35
Q

Precordial leads in relation to ventricles

A
36
Q

The first region to depolarize is . . .

A

The first region to depolarize is the midportion of the interventricular septum on the left side

37
Q

Current vectors of a standard myocardial depolarization

A
38
Q

Standard depolarization as seen from different precordial leads

A
39
Q

Horizontal axis of an ECG

A

The horizontal axis represents time. Because the standard recording speed is 25 mm/sec, each 1 mm division represents 0.04 sec and each heavy line (5 mm) represents 0.2 sec.

40
Q
A
41
Q

ECG machines routinely inscribe a ____ at the beginning or end of each 12-lead tracing to document the voltage calibration of the machine.

A

ECG machines routinely inscribe a 1.0-mV vertical signal at the beginning or end of each 12-lead tracing to document the voltage calibration of the machine.

42
Q

Each 1-mm vertical box on the ECG paper represents ___

A

each 1-mm vertical box on the ECG paper represents 0.1 mV

So the calibration signal records a 10-mm deflection

43
Q

Sinus rhythm

A

Normal cardiac rhythm:

  1. every P wave is followed by a QRS
  2. every 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 sec
44
Q

normal sinus rhythm

A

If the heart rate in sinus rhythm is between 60 and 100 bpm and the rhythm is sinus

45
Q

sinus bradycardia

A

If the heart rate is less than 60 bpm and rhythm is sinus

46
Q

sinus tachycardia

A

If the heart rate is greater than 100 bpm and the rhythm is sinus

47
Q

Calculating HR from an ECG

A
48
Q

When measuring irregular heart rates on ECG, it is most convenient to . . .

A

. . . count the # of QRS complexes between the first and third markers on the strip (6 seconds) and multiply by 10.

49
Q

When measuring regular heart rates on ECG, it is most accurate to . . .

A

. . . divide 1,500 over the number of mm between beats

(1,500 comes from 25 mm/sec and 60 sec/min)

1500 / (mm between QRS)

50
Q

corrected QT interval

A

Since QT varies with HR, this should be corrected for by dividing the measured QT by the square root of the R—R interval.

51
Q

Angle of a normal QRS

A
52
Q

Leads __ and __ are best used to classify a normal vs abnormal current vector

A

Leads I and II are best used to classify a normal vs abnormal current vector

53
Q

isoelectric complex

A

When the upward and downard deflections of QRS are of equal magnitude

When an ECG limb lead inscribes an isoelectric QRS complex, it indicates that the mean electrical axis of the ventricles is perpendicular to that particular lead.

54
Q

How to calculate QRS axis

A
  1. Inspect limb leads I and II. If the QRS is primarily upward in both, then the axis is normal and you are done. If not, then proceed to the next step
  2. Inspect the six limb leads and determine which one contains the QRS that is most isoelectric. The mean axis is perpendicular to that lead.
  3. Inspect the lead that is perpendicular to the lead containing the isoelectric complex. If the QRS in that perpendicular lead is primarily upward, then the mean axis points to the (+) pole of that lead. If primarily negative, then the mean QRS points to the (−) pole of that lead.
55
Q

Bundle Branch Block summary

A
56
Q

Normal vs path Q waves

A
57
Q

Left lateral wall infarction on ECG

A
58
Q

Conditions detectable on ECG

A

HMS Homeostasis I (62 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions