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Flashcards in EKG Deck (45):
1

What occurs in phase 0 of cardiac action potential?

phase 0 = depolarization
- Na+ channels open and there is a rapid influx of Na+
- Na+ channels are rapid opening and rapid closing
- resting membrane potential is -90mV
- Ca2+ channels are also opened, but slower at opening and closing than Na+

2

What is the cardiac cell muscle permeable to during rest?

K+ ions only

3

What occurs in phase 1 of cardiac action potential

phase 1 = repolarization begins
- some K+ channels remain open while others are closed resulting in outflow of K+
- Ca2+ channels still open

4

Why does cardiac m have a prolonged AP in comparison to skeletal m?

Ca2+ channels open slower and have an extended opening

5

What occurs in phase 2 of cardiac action potential?

phase 2 = plateau
- outward flow of K+ is balanced by inward flow of CA2+
- delayed resting membrane potential

6

What occurs in phase 3 of cardiac action potential?

phase 3 = completion of repolarization
- closure of Ca2+ channels accompanied by opening of additional K+ channels, causing rapid outflow of K+
- negative resting membrane potential is restored

7

What occurs in phase 4 of cardiac action potential?

phase 4 = resting phase
- Na+ and Ca2+ are actively pumped out of the cell and K+ is pumped into the cell

8

Why is intrinsic atrial rhythm more rapid than intrinsic ventricular rhythm?

the refractory period of atrial cells is significantly shorter than that of the ventricular cells

9

What are the standard limb leads?

I = diff btwn L arm and R arm
II = diff btwn L leg and R arm
III = diff brown L leg and L arm
- bipolar leads

10

What are the augmented limb leads?

aVR, aVL, and aVF
- unipolar leads

11

Where are the precordial leads?

V1 = 2nd ICS, to R of sternum
V2 = 2nd ICS, to L of sternum
V3 = midway between V2 and V4
V4 = 5th ICS, L midclavicular line
V5 = 5th ICS, L anterior axillary line
V6 = 5th ICS, L mid axillary line

12

What are the "big box" intervals for HR?

300, 150, 100, 75, 60, 50, 42

13

What is the conduction of normal nerve impulse?

SA node --> AV node --> Bundle of his --> BB --> Purkinje --> depolarization of myocardial cells

14

What is a normal PR interval and QRS?

PR

15

Arrhythmia related to discharge from atrial foci; characterized by waves of different shapes

Wandering pacemaker

16

Arrythmia with no clear p wave, quivering baseline; occasional impulse gets through to stimulated ventricles; determine rate with 3 second marks

Atrial fibrilation

17

originates in ventricular ectopic foci; giant ventricular complex after the pause; 20-40 bpm

ventricular escape

18

What are the HRs for paroxysmal tachy, flutter, and fibrillation?

Paroxysmal = 150-250
flutter = 250--350
fibrillation = 350-450

19

What does paroxysmal tachy look like for atrial? jxn'l? ventricular?

Atrial = P waves look different
jxn'l = inverted or no p-wave
ventricular = rapid PVC's

20

What does flutter look like for atrial? ventricular?

atrial = saw-tooth appearance
ventricular = smooth wave appearance

21

What does fibrillation look like for atrial? ventricular?

atrial = no p waves, irregular baseline, QRS irregular
ventricular = "bag of worms", no repetition is recognizable

22

What's 1* AV block criteria?

PR interval > 5 boxes (.2s)

23

What's 2* AV block, Mobitz 1, criteria?

PR interval becomes gradually longer cycle to cycle

24

What's 2* AV block, mobitz 2, criteria?

QRS dropped without lengthening PR interval

25

What's 3* AV block criteria?

No associated P wave and QRS complex; going to their own beat

26

What are the criteria for axis?

Normal: I = +, aVF = +
LAD: I = +, aVF = -
RAD: I = -, aVF = +
Extreme RAD: I = -, aVF = -
- impulse goes toward hypertrophy and away from infarct

27

What are the criteria for atrial hypertrophy?

Diphasic p wave
initial portion larger = RAH
terminal portion larger = LAH

28

What symptoms would you see with hypertrophy upon examination?

increased PMI and BP

29

What are the criteria for ventricular hypertrophy

RVH = S persists in V5 and V6
LVH = S1 + R5 > 35mm

30

What are the criteria for ischemia?

- Jpoint > 1mm below baseline
- inverted T wave

31

What are the criteria for injury?

- ST elevated > 4mm
- big tombstones = acute infarction

32

What are the criteria for infarct?

significant Q waves
- width > 1mm
- amplitude ⅓ of QRS
(not significant in aVR and V1

33

What chest leads indicate anterior infarct?

V1-V4

34

What chest leads indicate lateral infarct?

I, aVL

35

What chest leads indicate inferior infarct?

II, III, aVF

36

Symptoms of bradycardia?

- sx of hemodynamic compromise
1. hypotension
2. dizziness
3. lightheadedness
4. syncope

37

symptoms of SVT?

Pts perceive a racing heart; also have sx of hemodynamic compromise
1. dizziness
2. lightheadedness
3. syncope

38

What is afib often associated with clinically?

embolic cardiac events

39

symtoms of V-tach?

-pt may be asymptomatic if it is a brief run
- if sustained, pt may be asymptomatic, symptomatic, or unconscious and pulseless

40

symptoms of V-fib?

immediate loss of consciousness and loss of circulation

41

what conditions refer the myocardium vulnerable to v fib?

1. v-tach
2. myocardial ischemia or infarction
3. dilation of the heart
4. hyperkalemia
5. electric shock

42

Posterior infarction: larg R with ST depression in V1 and V2; what artery is compromised?

R coronary artery

43

Lateral infarction: Qs in lateral leads I and aVL; what artery is compromised?

Lateral circumflex coronary artery

44

Inferior infarction: Q's in inferior leads II, III, and aVF; what artery is compromised?

R or L coronary artery

45

Anterior infarction Q's in V1-V4; what artery is compromised?

anterior descending coronary artery