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z_MEDSURGE: FINAL REVIEW > Cardiac Conduction Cycle > Flashcards

Cardiac Conduction Cycle Flashcards

1
Q

Describe the pathway of the cardiac conduction system.

A
  • The sino-atrial (SA) node
  • The atrio-ventricular (AV) node
  • The bundle of His
  • The left and right bundle branches
  • The Purkinje fibers
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2
Q

The 3 stages of a single heart beat are:

A
  • Atrial depolarization
  • Ventricular depolarization
  • Atrial and ventricular repolarization
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3
Q

The PQ segment represents…

A

Atrial contraction and repolarization

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4
Q

The QRS segment represents…

A

Ventricular contraction

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5
Q

The T wave represents…

A

Ventricular repolarization

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6
Q

The ST segment is a…

A

Key indicator for both myocardial ischemia and necrosis if it goes up or down

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7
Q

What is Sinus Bradycardia and what does it look like on an EKG strip?

A
  • Sinus Bradycardia: HR = < 60
  • It is a normal heart tracing, just slower
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8
Q

What type of drugs can cause sinus tachycardia?

A

Beta and Calcium Channel blockers

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9
Q

What is Sinus Tachycardia and what does it look like on an EKG strip?

A
  • Sinus Tachycardia: HR = > 100
  • It is a normal heart tracing, just faster
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10
Q

Would hypovolemia cause Brady or Tachycardia?

A

Tachycardia – the heart needs to circulate faster to get blood out and BP up

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11
Q

What is a Sinus Arrythmia?

A
  • Same as Sinus Rhythm, but the rhythm is irregular
  • All waves are present, but the P-P interval shifts by more than 10%
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12
Q

Possible causes of Sinus Arrythmia?

A
  • Respiratory – shifts with inspiration and expiration
  • Non-respiratory – for unknown reasons
  • Sometimes associated w/ Complete Heart Block
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13
Q

How long should the Q-T interval be?

A
  • .35-43sec
  • 1.5 to just over 2 big squares
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14
Q

What is the cause of Atrial Fibrillation and Flutter?

A

Any condition that causes an increase in pressure within the atria can cause AF, but it is mainly linked to enlargement of the left atria (or both) as a result of the increased atrial pressure.

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15
Q

What is Atrial Fibrillation?

A

An irregular quivering of the atria as opposed to normal contractions

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16
Q

What is the rate of stimulation in atrial fibrillation?

A

Around 600 stimuli/min

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17
Q

What does a heart tracing of A-Fib look like?

A

Distinct and irregular R waves with all else being indiscernible and low

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18
Q

What does a heart tracing of A-Flutter look like?

A

Sawtooth waves between pronounced R waves

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19
Q

What are S/S of A-Fib?

A
  • SOB
  • Chest Pain
  • Both SOB and chest pain are due to lack of O2
  • Not always present, but more likely the faster it goes
  • Palpitations
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20
Q

What are the key points to A-Fib regarding cardiac OP?

A
  • Due to rapid contractions of the atria, the ventricles do not have ample time to fill before their contraction leading to a drop in OP to 50% or more
  • This will naturally increase symptoms
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21
Q

What is the order of TX for A-Fib?

A
  • O2 therapy
  • Glyceryl trinitrate (GTN)
  • Adenosine/Digoxin
  • Warfarin/Heparin
  • Electrical (DC) Cardioversion
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22
Q

Why is Glyceryl trinitrate (GTN) used to treat A-Fib?

A

It a vasodilator commonly used for angina pain as it helps to open up the coronary arteries to increase the blood and oxygen supply to the heart muscle.

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23
Q

Why is Adenosine/Digoxin used to treat A-Fib?

A

to slow down the heart and allow the ventricles to work more efficiently

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24
Q

Why is Digoxin specifically used to treat A-Fib?

A
  • Strengthens myocardial contraction and tells the SA/AV nodes to slow down
  • This slowing down often helps the heart re-assert its normal rhythm.
  • If not, we move to Cardioversion
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25
Q

What is Cardioversion?

A

the use of drugs or electric shock to reset the HR back to Sinus

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26
Q

How does Electrical Cardioversion work?

A
  • There is the delivery of a synchronized electric shock at the point in the conduction cycle where the atria is repolarizing.
  • The effect is to literally stop and restart the heart.
  • It is hoped that when the heart restarts, the SA node restarts with normal function.
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27
Q

Which condition is less @risk for embolization: A-Fib or A-Flutter?

A

A-Flutter

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28
Q

The “Flutter” rate for A-Flutter is around…

A

150-300/min

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29
Q

Describe a Premature Atrial Contraction heart tracing.

A
  • PQRST complex is present in general
  • Periodically, the STQ will show as one wave, this is the premature atrial contraction OVER the ST complex.
  • This will be followed by a prolonged T to P segment, then a return to PQRST until the next premature contraction
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30
Q

When is a De-fib used?

A
  • ONLY USED when heart has STOPPED, will kill the flutter pt
  • If person is alive, alert, responsive… DON”T FUCKING DO IT!
  • Must be unconscious – completely
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31
Q

What two chemicals are used for Chemical cardioversion?

A
  • Adenocord
  • Adenosin
32
Q

How is chemical cardioversion administrated?

A
  • If fluids present, take off, need direct access to admin med
  • Administer quickly followed by 10-20mL of NS to get it in system
33
Q

What is the PT teaching re: Chemical cardioversion?

A
  • gonna feel some warmth
  • heart is going to briefly stop (which can be scary for pt, we see it as a flatline) and then,
  • if it works, it will kick back in to sinus.
  • Sometimes it doesn’t work, if so, its tried again, if not again, then another med is used
34
Q

Describe the heart tracing for a First Degree Heart Block.

A
  • This will be tricky as it looks just like a normal sinus rhythm.
  • The only difference is a prolonged P-Q interval
35
Q

What is the intervention for a First Degree Heart Block?

A

Treat the underlying cause and observe for progression to a more advanced heart block

36
Q

Describe a Second Degree AV Block – Type I (Wenckebach)

A
  • P-Q interval gets progressively longer until there is a QRS complex drop
  • Then it resets and does it again
37
Q

What is the Tx for Second Degree AV Block?

A

Treatment is usually not indicated as this rhythm usually produces no symptoms

38
Q

Describe a Second Degree AV Block – Type II

A
  • PQRST waves all present
  • Key characteristic is multiple P waves in a row prior to a QRS complex.
39
Q

What is the Tx for a 2nd degree AV Block -Type II

A

Artificial pacing

40
Q

Describe a Third Degree (Complete) AV Block

A
  • atrial rate is usually normal; faster than the ventricular rate
  • normal with constant P-P intervals, but not “married” to the QRS complexes
  • QRS may be normal or widened depending on where the escape pacemaker is located in the conduction system
  • It is ultimately an irregular rhythm
41
Q

What is the cause of a 3rd degree heart block?

A
  • digitalis toxicity
  • acute infection
  • MI and
  • degeneration of the conductive tissue.
42
Q

Tx for 3rd degree heart block?

A
  • External pacing and atropine for acute, symptomatic episodes and
  • Permanent pacing for chronic complete heart block.
43
Q

Describe a Premature Ventricular Contraction heart tracing

A
  • The P wave is followed by a positively inflected Q wave (now an R wave) rather than negative.
  • This is the ventricular contraction
  • This will be followed by an abnormally large T wave and subsequent negative inflection, then back to the P wave
44
Q

Describe a V-Tach heart tracing.

A
  • ONLY R waves present
  • Just a constant cycle of giant R waves
  • all other conduction is masked
45
Q

Common causes of V-Tach?

A
  • CAD
  • acute MI
  • digitalis toxicity
  • CHF
  • ventricular aneurysms.
46
Q

Tx for V-Tach?

A
  • Electrical countershock is the intervention of choice if the patient is symptomatic and rapidly deteriorating.
  • Some pharmacological interventions include
  • amiodarone and
  • lidocaine.
47
Q

V-Tach can rapidly progress to…

A

V-Fib

48
Q

V-Fib results in the absence of…

A

Cardiac OP

49
Q

Describe a V-Fib heart tracing.

A
  • Looks like a mini V-Tach
  • Low conduction scribble line w/ no QRS
50
Q

Tx for V-Fib

A

Immediate defibrillation and ACLS protocols.

51
Q

Describe A-Systole heart tracing

A

Flatline

52
Q

A-systole interventions?

A
  • CPR, 100% oxygen,
  • IV
  • intubation
  • transcutaneous pacing
  • epinephrine 1.0 mg., IV push, q3-5 minutes
  • atropine
53
Q

What is a Sinus Node Dysfunction (SND)

A

SND refers to abnormalities in sinus node impulse formation and propagation, and includes sinus bradycardia, sinus pause/arrest, and sinoatrial exit block.

54
Q

Although SND may occur at any age, it is primarily a disease of the _____.

A

Elderly

55
Q

What is the Tx for chronic, symptomatic SND?

A

Pacemaker therapy

56
Q

True or False

Asymptomatic SND Pts do not require pacemaker therapy

A

True

57
Q

As SND becomes more severe, patients may develop symptoms due to organ _____ and pulse _____.

A
  • Hypoperfusion
  • Irregularity
58
Q

Traditional pacemakers are used to treat…

A

slow heart rhythms.

59
Q

Pacemakers regulate the _____ atrium and ventricle to maintain a good heart rate and keep the atrium and ventricle working together.

A

Right

60
Q

A biventricular pacemaker is a special pacemaker used for cardiac _____ therapy designed to treat a delay in heart ventricle contractions.

A

Resynchronization

61
Q

The two main types of programming for pacemakers are:

A
  • Demand pacing
  • Rate-responsive pacing
62
Q

Explain “demand pacing” pacemaker programming.

A
  • monitors your heart rhythm.
  • It only sends electrical pulses to your heart if your heart is beating too slow or if it misses a beat.
63
Q

Explain “Rate-responsive” pacemaker programming.

A
  • Pacemaker monitors your sinus node rate, breathing, blood temperature, and other factors to determine your activity level.
  • It will then speed up or slow down your heart rate depending on how active you are.
64
Q

How long should the PR interval be?

A
  • 0.12-0.20 or
  • 3-5 small squares
65
Q

How long should the QRS interval be?

A

0.06-0.12 or

< than 3 small squares

66
Q

How do you calculate the HR w/ a 6 second strip?

A
  • # of R waves in 6 seconds x10
  • Rhythm must be regular
67
Q

How do you calculate an irregular rhythm on a strip?

A

300 divided by the number of boxes between R waves

68
Q

Characteristics of a 1st degree heart block…

A

partial block Consistent prolonged PR interval

69
Q

Characteristics of a 2nd degree, type 1 heart block…

A
  • progressive block
  • Progressively long PR interval
  • Eventual QRS drop and cycle repeats
  • “long, long, drop”
70
Q

Characteristics of a 2nd degree, type 2 heart block…

A
  • intermittent block
  • No progressive PR
  • interval Normal EKG rhythm with occasional QRS drops
  • “normal, normal, drop”
71
Q

Characteristics of a 3rd degree heart block…

A
  • complete block
  • P waves and QRS waves are not coordinated
  • Each will have their own regular, unrelated tempos
72
Q

What type of drugs end in “pril” and what do they do?

A
  • Ace Inhibitors
  • Prevents fluid retention
  • Reduces blood pressure
73
Q

What type of drugs end in “olol” and what do they do?

A
  • Beta blockers
  • Slow heart
  • Reduce BP
74
Q

What type of drugs end in “ipine” and what do they do?

A
  • Calcium channel blockers
  • Reduce SVR, BP, contractility, conduction
  • Diltiazem & Veropamil are also calcium channel blockers
75
Q

What type of drugs end in “ides” and what do they do?

A
  • Diuretics
  • Reduces fluid volume
76
Q

What are normal potassium levels?

A

3.6 to 5.2

z_MEDSURGE: FINAL REVIEW (15 decks)

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