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The EKG Flashcards

1
Q

The heart contains three types of cells - what are they?

A

Pacemaker Cells
Electrical Conducting Cells
Myocardial Cells

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2
Q

These heart cells depolarize spontaneously over and over; rate
determined by innate characteristics

A

Pacemaker Cells

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3
Q

These heart cells carry current rapidly and efficiently throughout heart

A

Electrical Conducting Cells

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4
Q

These heart cells are a major part of heart tissue, responsible for the heavy labor of contraction

A

Myocardial Cells

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5
Q

The dominant pacemaker
60-100bpm influenced by SAS and vagal

A

SA node

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6
Q

The only conducting path between the atria and ventricles autonomic control also

A

AV node

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7
Q

QRS represents

A

ventricular contraction (depolarization)

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8
Q

depolarization of atria and simultaneous contraction

A

P wave

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9
Q

What is the resting potential of cardiac cells?

A

-90mV

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10
Q

What is the threshold of cardiac cells?

A

-70mV

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11
Q

K+ is also very important in cardiac cells - explain the effects of too low or too high potassium on the cardiac cells

A

High K+: depolarize cardiac cells (cardiac arrest)

Low K+: hyperpolarizes the tissue (harder to stimulate)

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12
Q

Cardiac cells rely on what substance?

A

Na+

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13
Q

In cardiac cells, what is the function of Na+?

A

Cell to cell depolarization

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14
Q

In cardiac cells, what is the function of K+?

A

Repolarization

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15
Q

In cardiac cells, what is the function of Ca2+?

A

Myocyte contraction and AV node conduction

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16
Q

What substances enhance Ca2+ movement= increased action potential = enhanced contraction?

A

Catecholamines

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17
Q

What is the max negative voltage of the pacemaker cells?

A

-60mV

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18
Q

What cells have properties of automaticity and undergo spontaneous depolarization?

A

Pacemaker Cells

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19
Q

A single contraction of cardiac muscle is completed before a second action potential can be generated. Why is this?

A

Designed to take a pause so the heart can get blood to itself

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20
Q

A period where muscle cannot be restimulated

Necessary to allow ventricles sufficient time to empty their contents and refill before next contraction

A

Refractory Periods

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21
Q

Cell is completely unexcitable to a new stimulation

A

Absolute refractory periods

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22
Q

Includes absolute refractory period and extends beyond to include short interval of phase 3

Many anti-arrhythmic drugs alter the ERP

A

Effective refractory period (ERP)

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23
Q

Stimulation triggers an action potential that is conducted, but because cell is stimulated from a voltage less negative than the resting potential, upstroke is less steep and lower amplitude

A

Relative refractor period

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24
Q

On the EKG, the vertical axis measures what?

A

measures voltage

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25
On the EKG, the horizontal axis represents what?
represents time
26
How long is a normal PR interval?
0.12-0.2 seconds (3-5 small boxes)
27
How long is a normal QRS interval?
<0.12 seconds (3 small boxes)
28
List some conditions that the EKG detects
Heart rhythm abnormalities Myocardial ischemia and infarction Electrolyte imbalances Effect of certain medications Anatomical orientation of the heart Size of atria/ventricles Path taken by action potentials (did it go the proper way)
29
What can you NOT determine from an EKG?
cannot tell you how well the heart is pumping/squeezing
30
The 12-lead EKG includes what components?
3 limb leads (bipolar) - I, II, III 3 augmented leads (unipolar) - aVR, aVL, aVF 6 precordial leads - V1-V6
31
Which EKG lead is described below? Left arm positive and right arm negative Looks at left lateral side of heart
Lead I
32
Which EKG lead is described below? Left leg positive and right arm negative Looks at bottom part of the heart
Lead II
33
Which EKG lead is described below? Left leg positive and left arm negative Looks at the bottom part of the heart
Lead III
34
Which EKG lead is described below? no man’s land (we don’t care about this one)
aVR
35
Which EKG lead is described below? Left hand positive Looking at left lateral side of heart
aVL
36
Which EKG lead is described below? Positive in the heart
aVF
37
Which EKG leads are described below? called precordial leads Looking at conduction
Chest Leads - V1-V6
38
If the R wave progression is altered in leads V1-V6, what is your next step?
check lead placement or ask patient about previous MI (dead or damaged tissue can alter this)
39
These are the anterior leads
V1, V2, V3, V4
40
These are the inferior leads
II, III, aVF
41
These are the left lateral leads
I, aVL, V5, V6
42
EKG precordial lead placement: 4th intercostal (right)
V1
43
EKG precordial lead placement: 4th intercostal (left)
V2
44
EKG precordial lead placement: Between leads V2 and V4
V3
45
EKG precordial lead placement: Midclavicular (mid collarbone)
V4
46
EKG precordial lead placement: 5th intercostal space (anterior axillary line)
V5
47
EKG precordial lead placement: 5th intercostal space (midaxillary line)
V6
48
Right coronary artery is assessed by which EKG leads?
Leads II, III, aVF
49
The LAD is assessed by which EKG leads?
Leads V1-V4 V1-V2: septal V3-V4: anterior
50
The CCA is assessed by which EKG leads?
Leads I, aVL
51
The LAD and CCA are assessed by which EKG leads?
V5-V6
52
P wave equals what?
atrial contraction of both atrial 🡪 atrial depolarization
53
AV nodal delay: allows the atria to top off the ventricle measured from the end of the P wave to the beginning of the QRS complex
PR Segment
54
Atrial depolarization plus AV nodal delay (Pulse to get to AV node and have a delay) Measured from the beginning of the P wave to the beginning of the QRS complex Represents the amount of time the action potential takes to travel from SA node through AV node
PR Interval
55
Ventricular depolarization (Depolarization of both ventricles; beginning of ventricular contraction) Also atrial repolariztion How long did it take the pulse to travel to ventricles – interval of time the action potential takes to travel from AV node through ventricles
QRS Complex
56
What is a normal QRS Complex duration?
Normal: .05 to .10 seconds; 25mm to 30mm
57
What is a normal PR Interval duration?
Normal: .12 to .20 seconds
58
What is a normal P wave duration?
Normal: <.11 seconds; <2.5mm tall
59
Plateau phase of ventricular repolarization
ST Segment
60
Duration of ventricular systole QRS complex to end of T wave Proportionate to the heart rate About 40% of the normal cardiac cycle
QT Interval
61
Peak of S to end of T Ventricular repolarization (end of S to end of T) Plateua phase: ST segment Rapid phase: T wave
ST Interval
62
Rapid phase of ventricular repolarization K+ leaving the cell (Where you’ll see K+ abnormalities)
T Wave
63
Q waves represent what?
Q waves show that an area of the heart is infarcted (dead)
64
What conditions need to be present for Q waves to be significant?
They need to be greater than 1 box wide Deeper than 1/3 height of the QRS complex Present in 2 or more consecutive leads
65
Measured from the beginning of the QRS to the end of the T wave Normal is dependent on age, gender, heart rate (Female: 0.43; Male: 0.42) Considered prolonged if this is greater than ½ RR interval
QT Interval
66
Inverted T wave represents what?
ischemia
67
Hyperacute T wave represents what?
ischemia
68
Peaked T wave represents what?
hyperkalemia
69
An U Wave represents what?
hypokalemia
70
If SA node fails, one of other potential pacemakers takes over. What is the pace you'd see with the following backup potential pacemakers: Atria AV junction Ventricles
Atria: 60-80 bpm AV junction: 40-60 bpm Ventricles: 20-40 bpm
71
How do you determine the exact rate on an EKG?
1500 divided by the number of small boxes between two R waves
72
Diffuse ST elevation
pericarditis
73
Marked T wave inversion in leads V2 and V3 is the hallmark for what?
Wellen’s Syndrome (stenosis of left anterior descending artery)
74
ST Depression
Ischemia
75
ST Elevation
Infarction
76
Shortened QT interval
Hypercalcemia
77
Prolonged QT interval (may trigger Torsades de Pointes) Early: T wave flattening ST segment starts to depress and can invert the T wave Late: severe characteristic U wave
Hypocalcemia
78
Peaked T waves: earliest and most common finding P waves may be flattened or absent Severe: QRS widening and fuses with T wave (sine waves)
Hyperkalemia

Cardiology (13 decks)

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