Lecture 13+14 Flashcards

1
Q

Waves, segments, and intervals

A

waves: are deflections
P, QRS, T, and U

segments: baseline between two waves
PR segment
ST segment
TP segment

intervals: include wave and segments 
PR interval 
QT interval 
RR interval (one heart beat)
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2
Q

Phase 4 on the ECG?

A

TP segment

no dipole (RMP)

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3
Q

Phase 2 on the ECG

A

ST segment

no dipole (completely depolarized)

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4
Q

depolarization on the ECG?

depolarization on ECG if perpendicular?

A

the vector points toward the + electrode
positive deflection

perpendicular: no net deflection
QRS (up and down deflection)

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5
Q

Repolarization on the ECG

A

The vector points away from the + electrode

positive deflection

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6
Q

Eithoven’s triangle

A

Lead I: RA to LA ( - to +) positive deflection

Lead II: RA to LL ( - to +) positive deflection

Lead III: LA to LL ( - to +) no net deflection

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7
Q

meaning of the different waves on the ECG

A

P-wave = arterial depolarization

PR segment = AV node and Bundle of His

QRS complex = ventricular depolarization

ST segment: ventricles are depolarized

T- wave = ventricular repolarization

TP segment = RMP

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8
Q

P-wave time

A

0.08 to 0.10 seconds

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9
Q

PR interval time

A

0.12 to 0.20 seconds

more than 0.20 seconds indicates AV block

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10
Q

QRS complex time

A

0.06 to 0.10 seconds

more than 0.12s means a intraventricular block

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11
Q

ST segment depression/ elevation means?

A

ischemia

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12
Q

T-wave inversion?

A

ischemia or MI

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13
Q

QT interval time

A

0.20 to 0.40s

greater than 0.44s may indicate high risk for arrhythmias

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14
Q

acute ischemia (hours, 24 hours, days)

A

within hours: peaked T-waves and ST changes

24 hours: T-wave inversion and ST segment resolution

few days: pathologic Q waves
more than 0.40 s and less amplitude

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15
Q

ECG leads (12)

A

bipolar limb leads: I, II, and III

augmented (unipolar) limb leads: aVL, aVR, and aVL

precordial chest leads: V1 to V6

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16
Q

aVR

A

The mean QRS vector is in the opposite direction to lead aVR, thus QRS complex is largely negative

augmented, indifferent electrode
+ electrode is right arm

17
Q

aVL

A

the vector goes towards the left arm
usually a positive deflection (QRS)

augmented and indifferent electrode
+ electrode is left arm

18
Q

aVF

A

The vector goes down towards the feet
QRS is largely upward

augmented and indifferent electrode
+ electrode is left foot

19
Q

precordial chest leads

A

V 1/2 = RV

V 3/4 = septum

V 5/6 = LV

QRS complex

V 1/2 = downward
V 3 = equiphasic
V 4/6 = upward

20
Q

What leads to right and left axis deviation

A

RV hypertrophy = right axis deviation

LV hypertrophy = left axis deviation

21
Q

bradyarrhythmia and tachyarrhythmia

A

abnormal heart rhythm

brady = slow abnormal heart rhythm

tach = fast abnormal heart rhythm

22
Q

causes of arrhythmias?

A

altered automaticity (SA node, AV node, new pacemakers)

altered conduction (blocks)

23
Q

sinus tachycardia

A

faster pace than normal (below 100)
increased depolarization of phase 4 of the SA node potential

occurs during exercise, stress, fright, fever

24
Q

atrial fibrillation

A

rhythm irregular
P wave is not distinguishable
P-R interval is not measurable
QRS is normal

common in elderly
blood can pool in the atria causing clots

25
Q

ventricular tachycardia

A

rate: 150-300bpm

p wave is not seen
QRS is wide, tall, and bizarre (prolonged)

poor CO, this can be deadly

26
Q

ventricular fibrillation

A

Rate: 300 or more beats per minute

irregular and deadly

rhythm does not generate a pulse
QRS is disorganized
all waves are fibrillary

CO and MAP are decreased; most likely unconscious

defibrillation and CPR is needed (emergency)

may be due to MI

27
Q

1st degree heart block (prolonged P-R interval)

A

rate is normal
QRS normal
PR is longer (AV conduction is slowed)

causes:
age, athletic training, surgery, electrolyte disturbance

28
Q

2nd degree block (1+2)

A

Mobitz type 1 (wenckeback):

defect at the AV node 
PR interval gets progressively longer 
sometimes QRS and T waves dont occur 
benign condition (children, athletes, vagal tone increase) 
Mobitz type II:
rate can be 30-100 bpm 
almost every P wave is followed by QRS no T wave 
sometimes it just the P wave 
Need a pacemaker
29
Q

3rd degree heart block

A

QRS will look odd and wide
dissociation of P and QRS relationship

Need pacemaker!

CO and BP is compromised

30
Q

right and left bundle branch block

A

right- will see “bunny ears” wide QRS

left: just a wide QRS and flatter top

contractions of the heart are weaker