CV - introduction to the ECG Flashcards

1
Q

the ____________ node is the pacemaker of the heart.

A

sinoatrial (SA)

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2
Q

electrical impulses initiated by the sinoatrial node proceed through ____________ which activate a wave of ____________ in the atrium that converges on the ____________ node.

A

internodal tracts
depolarization
atrioventricular (AV)

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3
Q

there is a brief delay at the atrioventricular node, after which the impulses rapidly flow through the ____________ and activate the ventricles through the ____________.

A

bundle of his

right and left bundles

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4
Q

after traveling through the right and left bundles, the impulses then diverge into ____________ which activate ____________ and ____________.

A

purkinje fibers
ventricular myocardial cell depolarization
contraction

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5
Q

the initial deflection is the ____________ wave.

A

P

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6
Q

the P wave is due to ____________.

A

atrial depolarization

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7
Q

the deflection following the P wave is the ____________.

A

QRS

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8
Q

the QRS is due to ____________.

A

ventricular depolarization

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9
Q

the Q is ____________, the R is ____________ and the S is a ____________ deflection.

A

negative
positive
late negative

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10
Q

the normal duration of the QRS is ____________ seconds.

A

0.06 to 0.10

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11
Q

the ____________ wave is the deflection following QRS.

A

T wave

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12
Q

the T wave is due to ____________.

A

ventricular repolarization

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13
Q

a normal PR interval is ____________ seconds.

A

0.12 to 0.20

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14
Q

the QT interval represents ____________.

A

the total duration of depolarization and repolarization

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15
Q

unipolar leads measure the difference in electrical potential between ____________ and ____________.

A

a point on the body

virtual reference point with zero electrical potential located in the center of the heart

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16
Q

bipolar leads measure the difference in electrical potential between ____________.

A

two different points on the body

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17
Q

depolarization moving towards a limb lead will produce a ____________ deflection.

A

positive

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18
Q

define ischemia

A

ischemia occurs when blood supply is insufficient to meet the oxygen demand in the ventricles

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19
Q

ischemic changes in the EKG alter ____________ and affect the ____________ and ____________ wave.

A

ventricular repolarization
ST segment
T

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20
Q

ischemia due to sudden high oxygen demand in the presence of fixed coronary obstruction causes ____________ of the ST segment.

A

depression

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21
Q

typically, T waves and Q waves go in the ____________ direction.

A

same

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22
Q

an inverted T wave is a sign of ____________.

A

ischemia

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23
Q

ST ____________ is a sign of transmural injury in an acute pericarditis or acute coronary syndrome, usually with a clot due to platelet aggregation obstructing a coronary artery.

A

elevation

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24
Q

Q waves in inferior leads (II, III aVF) are due to ____________.

A

inferior infarcts

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25
Q

Q waves in leads V1-V4 are due to ____________.

A

anterior wall infarcts

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26
Q

Q waves in leads I, aVL and the anterolateral leads (V5, V6) are associated with ____________.

A

lateral wall infarcts

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27
Q

the normal duration of a P wave is ____________ seconds.

A

0.08 to 0.10

28
Q

with a paper speed of 25mm/sec, the light lines of an ECG are spaced by ____________ seconds.

A

0.04

29
Q

with a paper speed of 25mm/sec, the heavy lines of an ECG are spaced by ____________ seconds.

A

0.2

30
Q

typically, the major dominating force in an ECG is what happens in the ____________.

A

left ventricle

31
Q

summary of leads: name the three bipolar limb leads

A

I
II
III

32
Q

lead I is ____________ in the right arm and ____________ in the left arm.

A

positive

negative

33
Q

summary of leads: name the unipolar limb leads:

A

aVR
aVL
aVF

34
Q

what are the three inferior leads?

A

II
III
aVF

35
Q

what are the two lateral leads?

A

I

aVL

36
Q

where do the lateral leads detect damage?

A

high in the left ventricle

37
Q

what are the two left-sided leads?

A

V5

V6

38
Q

what are the two right-sided leads?

A

V1

V2

39
Q

the right-sided leads V1 and V2 are able to describe which two structures of the heart?

A

right ventricle

septum

40
Q

in ventricular hypertrophy, more muscle = ____________ volts = ____________ amplitude of the QRS segment of an ECG.

A

more

greater

41
Q

in what two ways can ischemia manifest itself? what are the respective ECG findings associated with these manifestations?

A

1 ischemia due to sudden high oxygen demand, potentially in the presence of fixed coronary obstruction - depression of ST segment
2 ischemia due to acute artery obstruction that causes insufficient oxygen supply even during periods of low oxygen demand - T wave inversion

42
Q

what are the unipolar precordial leads?

A

V1-V6

43
Q

what are the bipolar precordial leads?

A

there are none!

44
Q

how is left ventricular hypertrophy ready by left-sided leads on ECG?

A

big R waves in left-sided leads (I, aVL, V5, V6)

45
Q

how is right ventricular hypertrophy read by right-sided leads on ECG?

A

big R waves in right-sided leads (V1, V2)

46
Q

absence of normal transmural vector produces a ____________ deflection in leads over infarcted myocardium (____________).

A

negative

Q wave

47
Q

abnormal Q wave appearance indicates ____________.

A

necrosis/infarction

48
Q

what are the three criteria necessary to define a “significant” Q wave?

A

1 is >/= one fourth the amplitude of the R wave
2 is >/= one small box (0.04 seconds) wide
3 must be in at least 2 leads reflecting the same region of the left ventricle (i.e. at least two inferior leads must display the Q wave)

49
Q

what is the sequence of stages of an evolving transmural myocardial infarct?

A

peaked T wave (hyper acute stages)
T wave inversion (early stage)
ST elevation (most common in transmural infarcts)
Q wave, ST elevation, T wave inversion (common in transmural infarct, late stage)

50
Q

define transmural myocardial infarction

A

ischemic necrosis of the full thickness of the infected myocardial segment, extending from the endocardium through the epicardium

51
Q

define subendocardial myocardial infarction

A

infarction involves only the layer of muscle subjacent to the endocardium

52
Q

what are the ECG findings typical of transmural myocardial infarction?

A

ST elevation with Q waves

53
Q

what are the ECG findings typical of subendocardial myocardial infarctions?

A

ST depression with no Q wave

54
Q

V1 and V2 leads are typically involved when there is a ____________ infarct.

A

anteroseptal

55
Q

V3 and V4 leads are typically involved when there is an infarct of the ____________ wall, septal or lateral.

A

anterior

56
Q

V5 and V6 leads are typically involved when there is an ____________ infarct.

A

anterolateral

57
Q

II, III and aVF leads are typically involved when there is an infarct of the ____________ wall.

A

inferior

58
Q

anterior infarcts are generally ____________ and ____________ than inferior infarcts.

A

larger

more serious

59
Q

I and aVL leads are typically involved when there is an infarct of the ____________ wall.

A

high lateral

60
Q

what are the causes of a long QT interval? (4)

A
electrolyte abnormalities (hypocalcemia, hypokalemia, hypomagnesemia)
drug therapy (class Ia, Ic or III anti arrhythmic drugs)
hypothermia
congenital long QT syndrome
61
Q

hypercalcemia causes a ____________ QT interval, while hypocalcemia causes a ____________ QT interval.

A

short

long

62
Q

a ____________ T wave is indicative of hypokalemia, and the presence of a ____________ wave is unique to hypokalemia, though is not seen in all hypokalemeias.

A

flattened

U

63
Q

the commonest finding unique to mild hyperkalemia is the presence of a ____________ T wave on ECG.

A

tall, peaked & symmetrical

64
Q

in moderate hyperkalemia, P and R waves ____________, QRS and T waves ____________, and big ____________ waves develop.

A

flatten
broaden
S

65
Q

in severe hyperkalemia, P and R waves ____________, S and T waves ____________ in a ____________ pattern.

A

disappear
broaden
sine wave