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Physiology > Lecture 10 EKG / Lab 10 EKG > Flashcards

Lecture 10 EKG / Lab 10 EKG Flashcards

1
Q

flow of AP / conduction through the heart and matching heart contraction

A

SA node generates AP –> spreads through myocardial cells through gap junctions and both atria contract –> conduction of electrical activity through AV bundles, RBB, LBB and Purkinje fibers –> ventricles contract as atria repolarize –> ventricles repolarize

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2
Q

why SA node is the dominant node

A

rate is faster than that of other pacemaker cells in AV node or Purkinje fibers

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3
Q

ecotopic beat

A

when heart rate is not by SA node by other pacemaker cells possibly in AV node or Purkinje

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4
Q

3 waves of EKG and their cause

A
  • P wave = atria contract
  • QRS complex = ventricles contract (and to a lesser degree atria repolarize)
  • T wave = ventricles repolarize
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5
Q

causes of positive and negative deflection in EKG reading

A
  • positive = AP in heart goes in direction of positive pole and summates
  • negative = AP towards negative pole (summation leads to subtraction in this case)
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6
Q

explain stone thrown in pond analogy to how EKG works

A
  • throwing rock in pond creates concentric circles of waves that can be disrupted by a rock in the middle of the pond
  • electrical current generated by leads are disrupted by electrical activity of the heart
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7
Q

bipolar limb leads and list all 3 and direction

A
  • both poles are on the body
  • lead 1 = right arm –> left arm
  • lead 2 = right arm –> left leg
  • lead 3 = left arm –> left leg
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8
Q

unipolar limb leads, where is the ground, list all 3

A
  • AVR, AVL, and AVF standing for right, left, and foot

- the machine is the ground

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9
Q

unipolar chest leads, how many electrodes on body, how many total

A
  • 6 total, only 1 pole on body, machine serves as the ground
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10
Q

leads and which planes they are on

A
  • coronal plane has bipolar limb leads and unipolar limb leads
  • transverse plane (parallel to ground) has
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11
Q

why longer recording of lead 2

A
  • lead 2 is parallel to heart axis / midline and usually has best recording
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12
Q

standard conversion of paper number of squares to time

A
  • 5 large squares = 1 second

- 1 large square = 200 ms

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13
Q

PR interval, normal length, and what heart activities

A
  • PR interval = start of P wave to beginning of QRS
  • normal = < 200 ms = 1 large square
  • SA node fires, atria contract, all of atria and AV node are depolarized
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14
Q

ST segment

A

between QRS and T wave, flat

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15
Q

QRS complex, average length

A
  • < 120 ms otherwise it is considered broad or elongated and abnormal
  • elongation indicates ectopic beat
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16
Q

how to calculate heart rate

A
  • atria = 300 / number of squares between P waves

- ventricular = 300 / number of squares between QRS complex

17
Q

first degree AV block - cause, EKG reading

A
  • long PR interval > 200ms

- caused by delay in conduction of electricity down AV bundle

18
Q

second degree AV block,ventricular vs atria heart rate, 2 types

A
  • Mobitz 1 = progressive elongation of PR Interval

- Mobitz 2 = QRS complex after every 2-3 P wave making atrial rate much faster than ventricle rate

19
Q

3rd degree aka complete AV block - EKG

A
  • atria and ventricle beat separately and ventricle is controlled by ectopic pacemaker
  • QRS complex is elongated due to ectopic origin, lots of PVC
  • ventricle rate is slow and atria rate is faster than usualy as sympathetic system tries to compensate for decreased cardiac output
20
Q

NSR and 2 questions

A
  • normal sinus rhythm

- is there a P wave and is it immediately followed by QRS?

21
Q

rhythm vs rate

A
  • rhythm = is P wave present and quickly followed by QRS

- rate = frequency of QRS and P waves

22
Q

sinus bradycardia - why sinus, why bradycardia, causes

A
  • sinus = normal rhythm, P wave followed by QRS
  • bradycardia = slow rate, <40
  • can be athletes or pathological
23
Q

sinus tachycardia - why sinus, why tachycardia, causes

A
  • sinus = normal rhythm, P wave followed by QRS
  • tachycardia because fast rate > 100 bpm
  • caused by exercise or sympathetic system
24
Q

ventricular tachycardia - why each name, characteristic EKG signs

A
  • name because ventricle beats very quickly

- elongated QRS due to PVC and ectopic pacemakers in the ventricles

25
Q

ventricular fibrillation - treatment, cause

A
  • irregular activity in the heart
  • caused by many areas of ischemia and many circus rhythms in the ventricles which cause ventricles to shake/spasm
  • electrical defibrillation depolarizes all cells at the same time in attempts to restore sinus rhythm but doesn’t solve underlying problem of ischemia,
26
Q

flutter vs fibrillation

A
  • flutter = fast heart rate

- fibrilation = irregular heart activity

27
Q

cardiac output formula

A
  • cardiac output = heart rate * stroke volume = volume pumped / minute
28
Q

why is it only safe to exercise at 80-90% of maximum heart rate

A
  • if heart rate is too high, diastole is too short for ventricles to fill up with blood and cardiac output decreases
29
Q

calculate maximum heart rate based on age

A

220 - age

- exercise to 80-90% of max heart rate only

30
Q

2 examples of conditions wiht ectopic beats

A
  • 3rd degree AV node block

- VTach

31
Q

ST segment depression and cause

A
  • dip in ST segment

- caused by ischemia of heart cells (not enough oxygen)

32
Q

ST segment elevation cause

A
  • caused by myocardial infarction
33
Q

T wave inversion and cause

A

sign of ischemia

34
Q

PVC and cause (in term of pacemaker location)

A
  • PVC = premature ventricular contraction

- caused by ectopic pace maker

35
Q

PVC, ischemia, and circus rhythm

A
  • ischemia causes circus rhythms in the heart which acts as ectopic pace maker and cause PVC and elongated QRS
36
Q

VTach, VFib, and number of circus rhythms

A
  • VTach = a few or many PVC due to a few circus rhythms

- VFib = many circus rhythms and irregular, random heart electrical activity

37
Q

biphasic QRS in chest lead cause

A
  • chest leads are not along the axis/midline of the heart

Physiology (25 decks)

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