Twu Bancroft Jr2 Ecg

Front 1

What cells have mechanical function

Back 1

Myocardial cells, they are stimulated, contractile filaments slide together and myocardial cells contract. (ECG, p. 30)

Front 2

What cells have electrical function

Back 2

Pacemaker cells, specialied cells of the heart's electrical system. They are responsible for spontaneously generating and conducting electrical impulses. (ECG, p. 30)

Front 3

automaticity

Back 3

the ability of cardiac pacemaker cells to create an electrical impulse without being stimulated by a nerve (ECG p. 30)

Front 4

how does the SA node prevent other pacemaker cells from assuming the function and pacemaking

Back 4

The SA node depolarizes faster than any other pacemaker cells. (ECG, p. 30)

Front 5

How does K+, Na+ and Ca++ in the blood affect automaticity?

Back 5

Increased levels in the blood, decreases automaticity

Decreased levels in the blood, increases automaticity. (ECG, p. 30)

Front 6

Excitability

Back 6

(irritability) refers to the ability of cardiac muscles cells to respond to an outside stimulus (ECG, p. 30)

Front 7

Conductivity

Back 7

refers to the ability of a cardic cell to receive an electrical impulse and conduct it to an adjoining cardiac cell. (ECG, p. 30)

Front 8

What cells are responsible for the property of cardiac cells?

Back 8

intercalated disks present in the membranes of cardiac cells (ECG,p. 30)

Front 9

Contractillity

Back 9

refers to the ability of myocardial cells to shorten in response to an impulse. (ECG, p. 30)

Front 10

current

Back 10

flow of electrical charge from one point to another.
(ECG, p. 30)

Front 11

voltage

Back 11

the measurement of the potential energy
(ECG, p. 30)

Front 12

electrolytes

Back 12

found in body fluids, elements or compounds that break into charged particles (ions) when melted or dissolved in water or another solvent. EX: Na+, K+, Ca++, & Cl -
(ECG, p. 30)

Front 13

action potential

Back 13

five phased cycle that reflects the difference in the concentration of the charged particles across the cell membrane at any given time.
(ECG, p. 30)

Front 14

What leaks out of a cardiac cell at rest

Back 14

K+

(ECG, p. 31)

Front 15

polarized state

Back 15

when the inside of the cell is more negative than the outside
(ECG, p. 31)

Front 16

membrane potential

Back 16

the voltage (difference in electrical charge) across the cell membrane.
(ECG, p. 31)

Front 17

What must exist for a pacemaker cell to "fire"

Back 17

a flow of electrolytes across the cell membrane must exist. -> Rush of Na+ and K+ INTO the cell, causing it to become POSITIVE.
(ECG, p. 31)

Front 18

depolarization

Back 18

the movement of charged particles across a cell membrane causing the inside of the cell to become more positive. (ECG, p. 31)

Front 19

What must take place before the heart can mechanically contract and pump blood?

Back 19

depolarization, goes from the innermost layer of the heart (endocardium) to the outermost layer (epicardium)

(ECG, p. 31)

Front 20

What appears on the ECG when the atrium contracts?

Back 20

the P wave.
(ECG, p. 32)

Front 21

What does the QRS wave represent?

Back 21

Ventricular depolarization
(ECG, p. 32)

Front 22

What is PEA

Back 22

pulseless electrical activity. You can have the electrical even , but not the mechanical even that normally follows.
(ECG, p. 32)

Front 23

repolarization

Back 23

the movement of charged particles across a cell membrane in which the inside of the cell is restored to its negative charge. (stops the flow of Na+ into the cell and allows K+ to leave.)
(ECG, p. 32)

Front 24

Which direction does repolarization go?

Back 24

epicardium to endocardium.
(ECG, p. 32)

Front 25

What does the ST- segment and the T wave represent?

Back 25

Ventricular repolarization
(ECG, p. 32)

Front 26

What phases of the cardiac action potential are referred to as electrical systole?

Back 26

Phase 1, 2, and 3
(ECG, p. 32)

Front 27

What phase of cardiac action potential is referred to as electrical dystole

Back 27

Phase 4
(ECG, p. 32)

Front 28

Phase 0 of Cardiac Action Potential

Back 28

Depolarization

Front 29

Phase 0 of the Cardiac Action Potential

Back 29

Depolarization-> rapid entry of Na+ is biggest reason for cardiac action potential.
(ECG, p. 32)

Front 30

what are other names for Phase 0 of the cardiac action potential

Back 30

upstroke, spike, or overshoot
(ECG, p. 32)

Front 31

What happens in Phase 0 of the cardiac action potenital?

Back 31

1. cell receives impulse
2. Na+ moves IN to cell, K+ OUT, Na++ IN
3. Cell depolarizes, cardiac contraction
QRS Complex
(ECG, p. 32)

Front 32

How do to SA and AV nodes compare to other cells in the heart as far as Na+ channels?

Back 32

they have fewer than other cells
(ECG, p. 32)

Front 33

What is the corresponding effect on heart rate when the flow of Na+ is slowed or blocked?

Back 33

the heart rate slows, cells are less excitable, and speed of contraction is decreased
(ECG, p. 32)

Front 34

What comes after Depolarization

Back 34

immediately followed by repolarization which has 3 phases.
(ECG, p. 33)

Front 35

What events happen during Phase 1: Early Repolarization of the cardiac action potential

Back 35

1. Na+ channels partially close, slowing Na+ entering cell.
2. Cl- enters the cell, K+ leaves (causing sm (-) deflection of action potential
(ECG, p. 33)

Front 36

What events happen during Phase 2: Plateau Phase of the cardiac action potential

Back 36

1. Ca++ slowly entering
2. K+ leaving cell
3. allows cardiac muscle to sustain an increased period of contraction.
(ECG, p. 34)

ST segment on the ECG

Front 37

Which cells have Ca channels

Back 37

cells of the atria, ventricles, and purkinje fibers.
(ECG, p. 34)

Front 38

What decreases the ST segment

Back 38

hypercalcemia and medications like digitalis
(ECG, p. 34)

Front 39

what is the result on cardiac cells if the flow of Ca+ is slowed or blocked

Back 39

the cells of the atria, ventricles, and Purkinje fibers spend less time in phase 2,
(ECG, p. 34)

Front 40

What events take place in Phase 3: Final Repolarization of the cardiac action potential

Back 40

This begins the downslope of action potential
1. repolarization completes as K+ rushes out of cell causing it to be (-).
2. Na+ and Ca++ channels close
3. original sensitivity is restored
4. repolarization is complete by end
T wave (ventricular repolarization) on the ECG
(ECG, p. 34)

Front 41

What events happen during Phase 4: Resting Membrane Potential, cardiac action potential

Back 41

XS Na+ inside, XS K+ outside
1. Na+/K+ pump activated
2. heart is polarized (ready for discharge) and will stay this way until reactivated by another stimulus.
(ECG, p 34)

Front 42

What is the effect on action potential if the potassium channels are blocked in Phase 3?

Back 42

the result is a longer action potential.
(ECG, p. 34)

Front 43

What are some examples of Ca++ blockers

Back 43

1. diltiazem (Cadizem, Dilacor, Tiazac, or Diltiazem)
2. verapamil (Calan, Covera, Idoptin, Verelan)
3. amlodipne (Norvasc)
4. feodipine (Plendil)
5. bepridil (Vascor)
6. nisoldipine (Sular)
7. nicardipine (Cardene)
8. nifedipine (Adalat, Procardia)
(ECG, p. 34)

Front 44

arrhythmia/dysrhythmia

Back 44

abnormal heart rhythm
(ECG, p. 34)

Front 45

what is the desired effected of antiarrythmic medications

Back 45

slow down the heart. classified by effects on the cardiac action potential.
(ECG, p. 34)

Front 46

Refractoriness

Back 46

describes a period of recovery that cells need after being discharged before they are able to respond to a stimulus, in heart, longer than contraction itself.
(ECG, p. 34)

Front 47

absolute refractory period

Back 47

(also know as effective refractory period) cell will not respond to further stimulation no matter how large the stimulus.
(ECG, p 34)

Front 48

How does the absolute refractory period reflect on the ECG

Back 48

corresponds to the onset of the QRS complex to the peak of the T wave.

This includes phases 0, 1, 2, & 3 of the cardiac action potenial.
(ECG, p. 35)

Front 49

relative refractory period

Back 49

also known as vulnerable period

Some cells have repolarized to threshold potential and can be depolarized with sufficient stimulus.

downslope of T wave on ECG
(ECG, p. 35)

Front 50

supernormal period

Back 50

1. after relative refractory period
2. weaker than normal stimulus can cause depolarization
3. extends from end of phase 3 to beginning of phase 4
4. end of T wave on ECG
(ECG, p. 35)

Front 51

In which of the refractory periods is it most common to have dysrhythmias

Back 51

supernormal period
(ECG, p. 35)

Front 52

conduction system`

Back 52

a system of pathways in which the specialized electrical (pacemaker) cells in the heart are arranged.
(ECG, p. 35)

Front 53

What is the function of the conduction system

Back 53

to make sure that the chamber of the heart contract in a coordinated fashion. (ECG, p, 36)

Front 54

Sinoatrial Node characteristics

Back 54

1. heartbeat begins here
2. 10 - 20 mm long
3. 2 - 3 mm wide
4. Slightly < 50% pacemaker, remainder are conduction
(ECG, p. 36)

Front 55

in what situation would other areas of the heart take over pacemaker responsibility

Back 55

1. the SA node fails to fire
2. the SA node fires too slowly
3. The SA node fails to activate the surrounding atrial myocardium
(ECG, p. 36)

Front 56

where is the SA Node located in the heart

Back 56

upper posterior part of right atrium where superior vena cava and the right atrium meet. It lies 1 mm from the epicardial surface.
(ECG, p. 37)

Front 57

What will stimulation of the vagus nerve do to the heart rate

Back 57

decrease it
(ECG, p. 37)

Front 58

What is the effect on heart rate if the sympathetic nerves are stimulated

Back 58

the heart rate will increase
(ECG, p 37)

Front 59

From where does the SA node receive its blood supply

Back 59

60% of people from right coronary artery

40% of people from circumflex artery
(ECG, p. 37)

Front 60

What are the three internodal pathways that transmit impulses from the SA to AV

Back 60

1. anterior= Bachmann's bundle
2. middle = Wenckebach's bundle
3. posterior = Thorel's pathway
(ECG, p. 37)

Front 61

What is the path of impulses from SA to AV nodes

Back 61

SA node-> rt atrium -> interatrial septum -> lft atrium (they contract at almost the same time (50 millisec apart)-> 1 of 3 internodal pathways -> AV node
(ECG, p. 37)

Front 62

AV junction

Back 62

AV node and nonbranching portion of the Bundle of His

has specialized conduction fibers that links the atria and ventricles
(ECG, p. 37)

Front 63

accessory pathway

Back 63

this is the abnormal route when the AV junction is bypassed by an abnormal pathway. (ECG, p. 37)

Front 64

AV Node Characteristics

Back 64

1. group of cells located in the floor of the right atrium immediately behind the tricuspid valve and near the opening of the coronary sinus.
2. 22 mm long, 10 mm wide, 3 mm thick
3. blood supplied by rt coronary artery in 85-90% of population
(ECG, p. 37)

Front 65

why is there a delay in conduction of the impulse from atria to ventricles

Back 65

1. fibers in AV junction are smaller than those in atrial muscle
2. has fewer gap junctions
3. allows atria to empty blood into ventricles before the next contraction begins
Primarily in AN and N regions
(ECG, p. 37)

Front 66

what are the 3 functional regions of the AV node

Back 66

1. atrionodal (AN) upper region also know as transitional zone
2. nodal (N) midportion,
3. Nodal- His (NH) lower, fibers merge to Bundle of His.
(ECG, p. 37)

Front 67

Bundle of HIs

Back 67

1. also known as the common bundle or the atrioventricular bundle.
2. located in upper portion of the interventricular bundle
3. receives blood from branches of left anterior and posterior descending coronary arteries
(ECG, p. 38)

Front 68

At what rate are AV pacemaker cell capable of firing

Back 68

40-60 beats/min
(ECG, p. 38)

Front 69

At what rate are the SA pacemaker cells capable of firing

Back 69

60 - 100 beats/min
(ECG, p. 36)

Front 70

fascicles

Back 70

small bundles of nerve fibers. the left bundle branch divides into 3.
(ECG, p. 38)

Front 71

Purkinje Fibers

Back 71

Fibers that spread from the interventricular septum into the papillary muscles to apex of heart. Helps ventricle contract in a twisting motion to wring blood out of ventricle
(ECG, p. 38)

Front 72

At what rate are the Purkinje Fibers capable of firing

Back 72

20-40 beats/min
(ECG, p. 38)

Front 73

what is the sequence of activation through the conduction system

Back 73

Figure 2-16, p. 39 ECG
S->A-(AN, N, NH)-> H->BB-> P

Front 74

Where is the speed of conduction the fastest

Back 74

The His-Purkinje system
(ECG, p. 38)

Front 75

Where is the speed of conduction the slowest

Back 75

the SA and AV nodes
(ECG, p. 38)

Front 76

What is Enhanced Automaticity

Back 76

1. cardiac cells that are not normally associated with a pacemaker function begin to depolarize spontaneously
2. a pacemaker site other than the SA node increases ts firing rate beyond that which is considered normal.
(ECG, p. 39

Front 77

What are some causes of Enhanced Automaticity

Back 77

Box 2.2, pg. 40, ECG.
1. Catecholamines, epinephrine
2. Administration of atropine sulfate
3. Digitalis toxicity
4. Acidosis
5. Alkalosis
6.Hypoxia
7. Myocardial ischemia/MI
8. Electrolyte issues, hypokalemia, hyperkalemia or hypocalcemia.

Front 78

Abnormal heart rhythms are usually due to one of what 3 basic mechanism

Back 78

1. enhanced automaticity
2. triggered activity
3. reentry
(ECG, p. 39)

Front 79

Triggered Activity

Back 79

results from abnormal electrical impulses that sometimes occur during repolarization, when cells are normally quiet.
(ECG, p. 39)

Front 80

Why does triggered activity happen

Back 80

when pacemaker cells from a site other than the SA node and myocardial working cells depolarize more than once after being stimulated by a single impulse.
EX: Hypoxia, increased catecholamines, hypomagnesmia
MI, medications that prolong repolarization (like quinidine)
(ECG, p 39-40)

Front 81

extopics

Back 81

impulse originating from a source other than the SA node.
EX: irritable site in the ventricles can produce episodic ventricular beats or a sustained, rapid rhythm such as Ventricular tachycardia
(ECG, p. 40)

Front 82

Reentry

Back 82

the spread of an impulse through tissue already stimulated by the same impulse. Impulse is delayed or blocked then goes.
(ECG, p. 41)

Front 83

Reentry requires what 3 conditions

Back 83

1. a potential conduction circuit or circular conduction pathway
2. A block within the part of the circuit
3. Delayed conduction with the remainder of the circuit
(ECG, p. 41)

Front 84

Escape

Back 84

the term used when the SA node slows down or fails to initiate depolarization, and a lower site spontaneously produces electrical impulses, assuming the pace making of the heart. this is a fail safe mechansim
(ECG, p. 41)

Front 85

What are some common causes of reentry

Back 85

1. Hyperkalemia
2. Myocardia ischemia
3. Some antiarrhythmic medications
(ECG, p. 41)

Front 86

What is an ECG

Back 86

records electrical activity of a large mass of atrial and centrical cells as specific waveforms and complexes.
(ECG, p. 41)

Front 87

What are some reasons for an ECG

Back 87

1. Monitor heart rate
2. evaluate effects of disease or injury
3. Evaluate pacemaker function
4. Evaluate response to meds
5. obtain baseline recording before or after a medical procedure.
(ECG, p. 41)

Front 88

What information can and ECG provide

Back 88

1. the orientation of the heart in the chest
2. conduction disturbances
3. electrical effects of medication and electrolytes
4. The mass of cardiac muscle
5. the presence of ischemic damage
(ECG, p. 42)

Front 89

What is one important thing the ECG does not provide

Back 89

it does not provide information about the mechanical condition of the myocardium. This must be done with pulse, and blood pressure.
(ECG, p. 42)

Front 90

What exactly is measured on the ECG

Back 90

The structures are too small to produce detectable voltage on the body surface. So the activation and recovery of working cells of the heart are measured.
(ECG, p. 42)

Front 91

electrode

Back 91

paper, plastic, or metal device that contains conductive media and is applied to the patient's skin.
(ECG, p. 42)

Front 92

How can you avoid distortion (artifacting) on the electrodes

Back 92

Be sure there is enough conductive jelly in the electrodes.
(ECG, p. 42)

Front 93

Why is it not recommended to use alcohol before applying ECG electrodes

Back 93

it dries out the skin
(ECG, p. 42)

Front 94

Lead

Back 94

record (tracing) of electrical activity between 2 electrodes
(ECG, p. 42)

Front 95

What are the characteristics of the rhythm that starts at the SA node

Back 95

1. positive P wave before QRS
2, P waves look alike
3. Constant PR interval (0.12 -0.20)
4. Regular atrial and ventricular rhythm
(ECG, p 82)

Front 96

What affects impulses that begin at SA node

Back 96

1. medications
2. Diseases or conditions that cause HR to increase or decrease, or be irregular
3. Diseases or conditions that delay or block the impulses from leaving the SA node
4. Diseases or conditions that prevent an impulse from being generated in the SA node
(ECG, p. 82)

Front 97

Sinus rhythm

Back 97

name given to a normal heart rhythm,
Rhythm starts at SA node, heads down the normal conduction pathway through atria, AV junction, bundle branches, and ventricles resulting in depolarization of Atria and Ventricles
(ECG, p. 82

Front 98

what is the acceptable variation plus or minus and still be regular

Back 98

10%
(ECG, p. 82)

Front 99

What is severe sinus bradycardia

Back 99

HR at 40 beats a min or lower
(ECG, p. 82)

Front 100

What does sinus bradycardia look like

Back 100

HR<60 beats
1. Rate < 60 beats/min
2. Rhythm is regular
3. P Wave is normal
4. PR: 0.12-0.20
5. QRS 0.10 -or less
(handout)

Front 101

What causes sinus bradycardia

Back 101

1. adults at rest, well conditioned athletes
2. some MI
3. prolonged standing or vagus nerve stimulation (vomit, bowel movement, coughing, cold water in face)
4. carotid sinus pressure
(ECG, p 83)

Front 102

What causes sinus tachycardia

Back 102

normal response to body's demand for increased oxygen.
1. execise
2. Fever
3. Pain, fear, anxiety
4. caffeine
5. Nicotine
6. Dehydration
7 CHF, MI, Hypoxia
(ECG, p. 85-6)

Front 103

What does sinus tachycardia look like

Back 103

1. Rate: 101- 180
2. Rhythm: Regular
3. P wave: Normal
4. PR Interval 0.12 - 0.20
5. QRS 0.10 or less
(Handout)

Front 104

Sinus Arrhythmia

Back 104

SA node-> normal pathway, but just fires irregularly
(ECG, p. 86)

Front 105

What does a sinus arrhythmia look like on ECG

Back 105

1. Rate: 60 - 100 beats/min
2. Rhythm: irregular
3. P wave normal
4. PR interval 0.12 - 0.20
5. QRS 0.10 or less
(ECG, p. 86)

Front 106

What causes sinus arrhythmia

Back 106

1. respirations, HR increases w/ inspiration, decreases w/ expiration
2. older individuals
3. heart disease
4. medications, digitalis and morphine
5. carotid sinus pressure
(ECG, p. 86)

Front 107

What is done for sinus arrhythmia

Back 107

nothing unless is accompanied by slow heart rate and causes hemodynamic compromise. = give atropine
(ECG, p. 86)

Front 108

Sinoatrial Block

Back 108

SA node creates the impulse but it is not conducted passed SA node. The result is missing PQRST complexes.
(ECG, p. 87)

Front 109

What does the ECG of sinoatrial block look like on ECG

Back 109

1. Rate: 60- 100 (may be +/_)
2. Rhythm: irregular
3. P waves normal
4. PR interval 0.12 - 0.20
5. QRS duration 0.10 or less
(ECG, p. 88)

Front 110

What are some causes of SA block

Back 110

1. Acute MI
2. Coronary Artery Disease
3. Myocarditis
4. CHF
5. Carotid Sinus Sensitivity
6. Increased vagal tone
7. Medications, digitalis, quinidine, salicylates, or procainamide

(ECG, 89)

Front 111

Sinus Arrest

Back 111

Property of automaticity- pacemaker cells of the SA node fail to initiate an electrical impulse for 1 or more beats. AV should take over, if not, missing PQRST complexes.
(ECG, p. 89)

Front 112

What are some causes of sinus arrest

Back 112

1. Hypoxia
2. MI
3. digitalis toxicity
4. reaction to meds, ie beta blockers and Ca channel blockers
5. carotid sinus sensitivity
6. increased vagal tone
(ECG, p. 89)

Front 113

What does sinus arrest look like on the ECG

Back 113

1. Rate: usually normal
2. Rhythm: irregular
3. P waves + , upright, present, b4 QRS
4. PR interval: 0.12 -0.20
5. QRS duration 0.10 sec or less
some missing PQRST complexes
(ECG, p. 90)

Front 114

What are signs and symptoms of hemodynamic compromise

Back 114

1. Changes in mental status
2. Low BP
3. Chest Pain
4. SOB
5. Signs of Shock
6. CHF
7. Pulmonary congestion
8. Fall in urine output
9. Cold, clammy skin
(ECG, p. 84)

Front 115

Which segment of the ECG gives the strongest ECG evidence for the early recognition of MI

Back 115

ST segment
~depression of more than 0.5mm Myocardial ischemia
~elevation of more than 1mm myocardial injury
(ECG, p. 62-3)

Front 116

waveform

Back 116

movement away from the baseline in either a positive or negative direction
(ECG, p. 55-6)

Front 117

Baseline (isoelectric line)

Back 117

a straight line recorded when electrical activity is not detected
(ECG, p. 56)

Front 118

Segment

Back 118

A line between waveforms, named by the waveform that precedes or follows it.
(ECG, p. 56)

Front 119

Interval

Back 119

A waveform and a segment
(ECG, p. 56)

Front 120

Complex

Back 120

several waveforms
(ECG, p. 56)

Front 121

P wave normal characteristics

Back 121

1. smooth and round
2. No more than 2.5 mm in height
3. No more than 0.11 seconds long
4. Positive leads I, II, aVF, and V2 through V6
(ECG, p56-7)

Front 122

What does the P wave represent

Back 122

The first half reflects stimulation of the right atrium, The downslope of the P wave reflects stimulation of the left atrium
(ECG, p. 57)

Front 123

What causes taller than normal P waves

Back 123

enlargement of right atrium
(ECG, p.57)

Front 124

What determines which side of baseline the P wave appears

Back 124

the site where it begins
SA node-positive
AV node-negative
(ECG, p. 5)

Front 125

What does the QRS Complex represent on the ECG

Back 125

the spread of the electrical impulses through the ventricles (depolarization) which normally triggers contraction of ventricular tissue.
(ECG, p. 57)

Front 126

Which waves are always negative

Back 126

Q and S waves
(ECG, p 57-8)

Front 127

Which waves are always positive

Back 127

The R wave
(ECG, p. 58)

Front 128

What does the T wave represent on the ECG

Back 128

It represents ventricular repolarization
(ECG, p. 59)

Front 129

What are the normal characteristics of the T wave

Back 129

1. Slightly asymmetric
2. Usually 5 mm or less in height in any limb lead or 10 mm or less in any chest lead
3. Usually 0.5 mm or more in height in leads I and II
(ECG, p. 59)