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Nursing 230 Cardio Exam #1 > Electrophysiology > Flashcards

Electrophysiology Flashcards

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0
Q

Define Escape

A

Escape - The opposite of “Irritability”, when the normal pacemaker of the heart slows or fails then the site with the next highest highest inherent rate will take over. I.e., if the SA Node fails then the AV Node will take over.

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1
Q

Define Irritability

A

Irritability - The mechanism of an irritable site speeding up an taking over as pacemaker. I.e., if the SA Node is discharging at a rate of 72 bpm while the AV Node is discharging at a rate of 95 bpm, then the AB Node will become the pacemaker.

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2
Q

What part of the heart does the Sympathetic branch innervate? Parasympathetic?

A

1) Sympathetic - Atria, AV node and ventricles

2) Parasympathetic - Ventricles only

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3
Q

What is the normal range of time for a PR Interval? QRS Complex? How are they measured?

A

1) PRI = 0.12 to 0.2 seconds (beginning of the P-wave to the beginning of the QRS complex).
2) QRS = 0.12 seconds or less (beginning of the QRS complex to the end of the QRS complex/J-point).

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4
Q

What are the 4 most common causes of interference/artifacts on an EKG tracing?

A

1) Muscle tremors or shivering
2) Patient moving
3) Loose electrodes
4) Other electrical equipment in the room (aka 60-cycle interference)

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5
Q

Describe the difference between the Absolute Refractory period and the Relative Refractory Period.

A

1) Absolute Refractory Period - When no impulse can cause depolarization.
2) Relative Refractory Period - When strong impulse can cause a premature, abnormal discharge.

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6
Q

Identify the difference between the following as it relates to the QRS Complex:

1) Q
2) R
3) R’
4) S
5) S’

A

1) Q - 1st negative deflection
2) R - 1st positive deflection
3) S - Negative deflection after R wave
4) R’ - Positive deflection after R Wave
5) S’ - Negative deflection after S wave

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7
Q

Way are the 5 properties of ALL Cardiac cells?

A

1) Conductivity - ability to transmit impulse (musculature also have this property but specialized cells are 6x faster).
2) Excitability/Irritability - Ability to respond to an electrical impulse.
3) Automaticity - Ability to to initiate an electrical impulse.
4) Rhythmicity - Regularity of the beat or rhythm.
5) Refractoriness - The inability to respond to another impulse while in the resting phase.

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8
Q

Define Bachman’s Bundle?

A

Bachman’s Bundle is the spread of conduction impulses from the SA Node to the left atrium.

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9
Q

What are the intrinsic rates for the following conduction systems in the heart:

1) SA Node
2) AV Node
3) His-Purkinje Fibers

A

1) SA Node - 60 to 100 beats/min
2) AV Node - 40 to 60 beats/min
3) His-Purkinje Fibers - 20 to 40 beats/min

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10
Q

The atrial and ventricular systems are electrically separate from each other and only connected through the AV node and Bundle of His. What is the significance of the 0.2 sec delay at the AV node?

A

To prevent too many impulses from stimulating the ventricles.

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11
Q

What happens if the AV node is damaged and no impulses go through? What will happen and why? What is this called?

A

The atria and ventricles would beat separately from each other at their own rates; because of automaticity (they would not “dance” with each other.
This is called 3rd degree or complete heart block.

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12
Q

What are the 5 effects of the sympathetic NTs on the heart?

A

1) ⬆ HR
2) ⬆ AV conduction
3) ⬆ Contractility
4) ⬆ Irritability
5) ⬆ MVO2 (myocardial oxygen consumption)

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13
Q

Which electrolyte is responsible for depolarization? What are its normal values in the serum and inside the cell?

A

Sodium - 135-145 mEq in serum and around 10 mEq inside the cell.

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14
Q

Which electrolyte is responsible for repolarization? What are its normal values in the serum and inside the cell?

A

Potassium - 3.5 to 5 mEq in the serum and around 160 mEq inside the cell.

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15
Q

What is the significance if Hypokalemia in heart patients?

A

Hypokalemia can lead to irritability and excitation (the opposite of polarized/resting).

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16
Q

What is the significance of Calcium and Magnesium on heart patients? What are there normal serum levels?

A

1) Calcium (9 to 11 mEq per liter) - Responsible for cell membrane permeability, muscular activity, nerve impulses, vascular tone, cardiac contractility, and blood clotting.
2) Magnesium (1.5 to 2.3 mEq per liter) - Activates enzymes involved in the breakdown of ATP for energy, which is responsible for neuromuscular function and myocardial contraction/irritability.

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17
Q

What is the significance of Phosphorous on heart patients?

A

Phosphorous is essential for ATP/ADP, which are responsible for energy inside the cell.
Hypophosphatemia can cause muscular weakness, including respiratory and cardiac arrest.

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18
Q

Explain the difference between the waves on an EKG vs the isoelectric line. What do the represent?

A

The movement of ions (in or out across the cell membrane) creates the typical wave patterns.
The isoelectric line represents the resting state or no movement of ions.

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19
Q

Define Pulseless Electrical Activity (PEA)

A

PEA - When the heart has electrical activity (an EKG pattern on the monitor), but the no mechanical activity (no beating).

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20
Q

What are the 5 effects of aging on the conduction system?

A

1) Fewer pacemaker cells
2) Fewer conduction cells: 50% ⬇ in His bundle fibers
3) Atherosclerosis ⬇ SA node ability to respond to the ANS
4) Ventricular arrhythmias are common, i.e., PVCs
5) Atrial arrhythmias are common, i.e., a-fib

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21
Q

What are the 8 general causes of Dysrhythmias?

A

1) Hypoxia - Respiratory arrest or depression
2) Ischemia - ⬇ O2 to myocardium
3) Sympathetic Stimulation
4) Medications
5) Illicit Drugs
6) Cardiac Hypertrophy
7) Electrolyte Disturbances
8) Cardiac Diseases

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22
Q

What are the common clinical manifestations of Dysrhythmias?

A

1) Nothing (its common for PTs to feels nothing)
2) Palpitations/skipped heart beat or fluttering in chest
3) Lightheadedness/dizziness/syncope
4) Fatigue
5) Angina

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23
Q

What is the proper EKG lead placement for a 2-lead EKG?

A

The negative lead is placed above the nipple line, usually on the right arm/shoulder and the positive lead is usually placed below the nipple line, on the left leg/hip.

24
Q

What is the difference between Lead-2 and MCL1 lead placements?

A

1) Lead-2 represents the normal vector of the heart and the QRS and P waves are positive (above the isometric line).
2) MCL1 - Negative lead is above the heart but on the left arm/shoulder, while the positive lead is below the heart but on the right side of the body. The QRS is normally negative in this type of lead (below the isoelectric line).

25
Q

How much time does each little box on the EKG strip represent? Each big box?

A

1) Little box = 0.04 secs

2) Big box = 0.2 secs

26
Q

How much voltage is represented by one little box on an EKG strip? One big box?

A

1) Little box = 0.1 mV

2) Big box = 0.5 mV

27
Q

What are the 3 formulas used to calculate rate?

A

1) 1,500 divided by number of small boxes between two R-waves (used for regular rhythms).
2) 300 divided by number of large boxes between two R-waves (used for regular rhythms).
3) 10 multiplied by the number of R’s in 6 seconds (used for irregular rhythms).

28
Q

Should you count the “extra beats” like PVCs in the rate calculation?

A

Yes, they take the place of a normal beat, so count them into the rate calculation.

29
Q

Why is the P-wave smaller (less voltage) than the QRS?

A

Less myocardium mass

30
Q

What does the ST segment on an EKG represent?

A

ST Segment - The period between the completion of ventricular depolarization to the beginning of ventricular repolarization.
Measured from the J-point (or end of the S-wave/end of the QRS) to the beginning of the T-wave.

31
Q

What is the clinical significance of ST segment elevation? ST segment depression?

A

1) ST Segment Elevation - Signifies damage to the cardiac muscle that causes early repolarization or premature ending of systole (i.e., MI).
2) ST Segment Depression - Signifies ischemia.

32
Q

What is the clinical significance of an inverted T-wave?

A

Inverted T-waves signifies ischemia

33
Q

Explain the significance of the following refractory periods and identify where they are on an EKG cardiac cycle:

1) Absolute Refractory Period
2) Relative Refractory Period
3) Non-Refractory Period

A

1) Absolute Refractory Period - (beginning of the QRS complex to the beginning of the downward slope of the T-wave) represents the time when no electrical impulse can cause depolarization.
2) Relative Refractory Period - (beginning of the downward slope of the T-wave to the end of the T-wave) represents when a throng electrical impulse can cause a premature depolarization).
3) Non-Refractory Period - (from the end of the T-wave to the beginning of the QRS complex) represents when the heart is completely capable of responding to another impulse.

34
Q

What does the QT interval represent and what’s the normal range?

A

The QT interval represents the total time for ventricular depolarization and repolarization, and is measured form the beginning of the QRS complex to the end of the T-wave.
The normal range is 0.36 to 0.44 seconds.

35
Q

What is the clinical significance of a prolonged QT interval?

A

A prolonged QT interval ( > 0.46 seconds) is associated with a serious risk for lethal arrhythmias (i.e., Torsades de Pointes/multifocal, VT and VF).
Many meds and electrolyte imbalances can prolong the QT interval.

36
Q

What does the TP segment represent, how is it measured on the EKG, and which 2 significant things happen during this segment?

A

The TP segment represents diastole. It is measured from the end of the T-wave to the beginning of the P-wave. Two significant things that happen during this segment are:

1) Ventricular diastolic filling
2) Coronary artery filling

37
Q

What are the 4 (mentioned) examples of med classes that can prolong a QT interval?

A

1) Asthma Inhalers - Albuterol and Salmeterol)
2) Antihistamines - Benadryl
3) Antiarrhythmics - Qunindine
4) Antipsychotics - Amitryptyline and perphenazine

38
Q

What are the 6 mentioned causes of Sinus Bradycardia?

A

1) Damage to the SA node (i.e., inferior wall MI)
2) Parasympathetic stimulation (i.e., Vagal)
3) Hypoxemia (i.e., during suction)
4) Athletic hearts
5) Pacemaker failure
6) Meds (Beta blockers)

39
Q

Explain the difference between Premature Ventricular Contractions (PVCs) and Bradycardia with Ventricular Escape Beats.

A

1) Premature Ventricular Contractions - When the ventricles contract first, before the atria have optimally filled up. The heart beat is initiated by the Purkinje Fibers.
2) Bradycardia with Ventricular Escape Beats - Happens when the ventricles initiate a heart beat because the SA node’s rate is too slow.

40
Q

Which class of med should be administered to patients experiencing Bradycardia with Ventricular Escape Beats?

A

Atropine - Stimulates the sympathetic NS

41
Q

What are the 3 features of Bradycardia with Ventricular Escape Beats?

A

1) Underlying rhythm is slow
2) Escape beats appear late in the cardiac cycle
3) Escape beat may have a wide QRS if from the ventricle

42
Q

What are the 3 features of Sinus Arrhythmia?

A

1) An irregular R-R interval
2) ⬆ Rate with inspiration
3) ⬇ Rate with expiration

43
Q

Define Paroxysmal Atrial Tachycardia (PAT).

A

PAT - An acute onset of atrial tachycardia.

44
Q

Explain the “Re-entry. Mechanism”.

A

Re-entry Mechanism - Happens when the impulse is transmitted through one pathway but blocked in another. The blocked tissue becomes repolarized and allows retrograde/backwards transmission of the re-entering pulse, which is transmitted to the tissue above the re-entered circuit. The tissue above the blocked area is now repolarized and sends the abnormal/re-entering pulse back down the normal pathway: around and around, with a faster rate.

45
Q

What are the 3 mentioned clinical significances of PAT?

A

1) Coronary arteries are unable to fill due to short diastolic filling time
2) Shortened ejection time with decreased cardiac output; may n progress to heart failure, shock or death
3) Increased HR cause increased MVO2, especially with MI

46
Q

What is MVO2 and how is it calculated?

A

MVO2 - Myocardial Volume Oxygen Consumption

MVO2 = SBP x HR

47
Q

What is the standard Tx for the following types of patients experiencing Atrial Tachycardia:

1) Stable PT
2) Symptomatic PT
3) Life-threatening/Unstable PT

A

1) Stable PT - Vagotonic maneuvers (Valsalva maneuver, carotid sinus massage, dig, pacemaker override.
2) Symptomatic PT - Adenosine (may cause brief arrest), Verapamil (titrate and give slowly).
3) Life-threatening/Unstable PT - Synchronized cardioversion.

48
Q

Describe Ablative Therapy used for Atrial Tachycardia

A

Ablative Therapy - A special catheter is placed against the area of the heart responsible for the problem. Radio-frequency energy is then passed to the tip of the catheter, so that it heats up and destroys the target area. Considered a non-surgical procedure.

49
Q

What are the 2 causes of Atrial Flutter?

A

1) An irritable focus in the Atrium initiating 250-350 bpm.

2) Intermittent conduction through the AV node.

50
Q

What are the 4 features of Atrial Flutter?

A

1) Atrial rate regular (F-F consistent), but the R-R may be variable
2) Atrial rate 250-350 bpm (count one inside the QRS)
3) Flutter wave usually has sawtooth or shark tooth appearance
4) No T-wave present (usually)

51
Q

What are the 6 mentioned causes of Atrial Fluttter?

A

1) Damage to the SA node or atrium
2) ⬆ Sympathetic tone
3) Hypoxia
4) Heart failure
5) Valvular disease
6) Hyperthyroidism

52
Q

What is the difference between Controlled and Uncontrolled Atrial Fibrillation?

A

1) Controlled - Ventricular rate of 100 or less

2) Uncontrolled - Ventricular rate greater than 100

53
Q

Describe the difference between Atrial Flutter and Atrial Fibrillation.

A

1) Atrial Flutter - A fast and regular rhythm caused by a small and tight circle of electrical activity.
2 Atrial Fibrillation - A fast and irregular rhythm caused by a barrage of uncontrolled electrical signals that trigger cells in the atria to contract independently of each other. The atria themselves do not actually contract because the individual heart muscles aren’t synchronized.

54
Q

What are the 4 mentioned features of Atrial Fibrillation?

A

1) Grossly irregular, but starts to look regular at faster rates
2) Mo discernible P-waves (F-waves instead): bumpy baseline of may appear flat.
3) T-waves may or may not be present
4) No discernible PRI

55
Q

What is the connection between Atrial Fibrillation and Microemboli?

A

Microemboli tend to form on the ventricular wall of patients with Afib due to stasis.

56
Q

How does a patient with A.fib usually present?

A

Weak, short of breath and syncope ins common - all are as a result of lack of cardiac output.

57
Q

What are the 6 mentioned Tx for Acute Atrial Fibrillation and Atrial Flutter?

A

1) Diltiazem - IV bolus then drip (calcium channel blocker)
2) Procainamide or Ibutilide Drip - Antiarrhythmics
3) Elective cardioversion
4) Ablation therapy
5) Echocardiogram of heart chambers first to r/o any mural thrombi that could be dislodged and cause a CVA
6) Anticoagulants

58
Q

What are the 4 mentioned Tx for Chronic Atrial Fibrillation and Atrial Flutter?

A

1) Diltazem (oral) - Calcium channel blocker
2) Procainamide or Amiodarone (oral) - Antiarrhytmics
3) Digoxin
4) Anticoagulants

Nursing 230 Cardio Exam #1 (4 decks)

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