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EMER 110 CARDIAC AND RESPIRATORY THEORY > LO2 3 Lead ECGs > Flashcards

LO2 3 Lead ECGs Flashcards

1
Q

Sodium (Na+)

A

goes into cell and initiates depolarization

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2
Q

Potassium (K+):

A

flows out of the cell to initiate repolarization

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3
Q

Hypokalemia

Hyperkalemia

A

Hypokalemia: increased myocardial irritability

Hyperkalemia: decreased automaticity/conduction

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4
Q

Calcium (Ca)

A

has major role in the depolarization of pacemaker cells (maintain depolarization) and in myocardial contractility

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5
Q

Hypocalcemia

Hypercalcemia

A

Hypocalcemia: decreased contractility and increased myocardial irritability

Hypercalcemia: increased contractility

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6
Q

Magnesium (Mg)

A

stabilizes the cell membrane: acts in concert with potassium and opposes the actions of calcium

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7
Q

Hypomagnesemia

Hypermagnesemia

A

Hypomagnesemia: decreased conduction

Hypermagnesemia: increased myocardial irritability

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8
Q

Absolute Refractory Period

A

the cardiac muscle cell is completely insensitive to further stimulation

Start of the QRS and ends at middle of T wave

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9
Q

Relative Refractory Period

A

During the relative refractory period, the muscle cell is more difficult than normal to excite, but it can still be stimulated.

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10
Q

Nervous system controlling heart rate

A

Two nerves link the cardiovascular center in the medulla oblongata of brain with the SA node of the heart

  1. Accelerator nerve (sympathetic NS)
  2. Vagus nerve (parasympathetic NS):
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11
Q

Accelerator nerve (sympathetic NS)

A

when stimulated, releases neurotransmitter at the SA node to increase heart rate

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12
Q

Vagus nerve (parasympathetic NS)

A

when stimulated, releases neurotransmitter at the SA node to decrease heart rate

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13
Q

Electrical Conduction System

A
  • Automaticity
  • Generates its own electrical impulses without stimulation from nerves
  • Unique feature of the heart
  • Specialized conduction tissue
  • Pacemaker
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14
Q

The Sinoatrial (SA)Node

A

• The Primary Pacemaker

  • Theoretically, any cell can act as a pacemaker.
  • Located in the right atrium, near the inlet of the superior vena cava
  • Receives blood from the Right Coronary Artery in 50-60% of population
  • Fastest pacemaker in the heart
  • Inherent rate of 60 to 100 beats per minute(bpm)
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15
Q

Secondary Pacemakers

A

If the SA becomes damaged or is suppressed

  • AV node inherent rate 40-60 bpm (RCA blood flow in 85-90% of population).
  • Purkinje fibers 20-40 bpm
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16
Q

ECGs

A
  • The ECG is a graphic representation of the heart’s electrical activity.
  • It does not provide information regarding mechanical events.
  • Valuable diagnostic tool for identifying cardiac abnormalities.
  • For good blood flow the electrical signal must send and the heart must respond
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17
Q

Indications for ECG Monitoring

A
  • Patients at risk for dysrhythmias shall receive continuous ECG monitoring
  • Known or suspected cardiac patients
  • Suspected Overdose
  • Electrical Injuries
  • Syncope
  • Elderly patients “feeling unwell”
  • Issues concerning the Sympathetic System
18
Q

Voltage
Positive:

Negative:

A

positive
- Seen as an upward deflection on the ECG tracing.

negative

  • Seen as a downward deflection on the ECG tracing.
  • Flowing backwards

isoelectric

  • No electrical current detected.
  • Seen as a straight baseline on the ECG.
19
Q

ECG Leads

  • Bipolar lead*:
  • Unipolar lead:
A
  • Bipolar lead*:
    o Two electrodes of opposite polarity.
  • Unipolar lead:
    o Single positive electrode and reference point.
20
Q

Lead Placement

A
  • White (upper right), black (upper left), green (lower right), red (lower left)
  • Between ribs, does not conduct well on bone
  • Positive always at the bottom
21
Q

lead triangle

A

GO LOOK AT IT

  • double positive is on the bottom
  • top right (patients right) double negative
  • top left (patients left) negative and positive
22
Q

ECG Graph Paper

A
  • Each Little square is 1mm x 1mm 0.04sec

- Each Large square is 5mm x 5mm 0.20 sec

23
Q

Calibration

A
  • The sensitivity of the 12-lead ECG machine is standardized
  • When properly calibrated, a 1-mV electrical signal produces a 10-mm deflection (two large squares) on the ECG tracing
24
Q

Time Interval

A
  • Denoted by short vertical lines on the ECG graph paper.

- At standard speed, the distance between each short vertical line is 75 mm (3 seconds).

25
Q
  • Depolarization
A

The sinoatrial (SA) node on the wall of the right atrium initiates depolarization in the right and left atria, causing contraction, which corresponds to the P wave on an electrocardiogram

o Discharge of the impulse

26
Q
  • Repolarization
A

resets charge

27
Q
  • P wave
A

depolarization of the atriums

o Impulse being sent to AV node

o Positive deflection because its going towards positive

28
Q
  • Q wave
A

polarization of right ventricle (may not have)

o Bigger the Q wave the bigger the injury

o If you can fill it with water its important

29
Q
  • R wave
A

left ventricle contracting

30
Q

-QRS

A

ventricular depolarization

31
Q
  • T
A

ventricular repolarization

o Reset

32
Q

PRI Interval

QRS interval

R-R Interval

A
  • PRI should me 0.12-0.20 sec
    how long it takes impulse to get from sa node to av node
  • QRS less than 0.12 sec
  • R to R interval: top of R wave to next
33
Q

Artifact Common causes

A 
o	Improper grounding of the ECG machine 
o	Patient movement 
o	Loss of electrode contact with the patient's skin 
o	Patient shivering or tremors 
o	External chest compressions
34
Q

Rhythm Interpretation 5 Steps

A 
Regularity 
rate
p waves
P-R interval 
QRS complex
35
Q

Regularity

A
  • Is the rhythm regular?
  • To analyze ventricular rhythm, compare R-R intervals (time between each contraction) systematically from left to right
  • Certain rhythms will never be regular
  • Sinus tach will rarely be over
36
Q

Rate

A
  • SVT has no p waves ever
  • Anytime its wide means its going slow

o Should be less than 0.4 (1.2)

Six Second method: Count number of QRS complexes in a 6-second interval and multiply number by 10

37
Q

P waves significance

A
  • Are P waves present?
    o If there are no p waves it means SA node is not working
  • Are the P waves regular?
  • Is there one P wave for each QRS complex, and is there a QRS complex following each P wave?
  • Are they upright or inverted?
  • Do they all look alike?
38
Q

PRI

A
  • Represents the amount of time it takes for the atria to depolarize and for the impulse to travel through AV node.
  • It includes the slight delay that normally occurs when the impulse is slowed AV node.
  • This delay allows for ventricular filling Normal PRI is 0.12-0.20 sec
  • Normal PR Interval (PRI)
  • 0.12sec – 0.20sec (3-5 little boxes long)
39
Q

QRS Complex

A
  • Is there a QRS complex for every P Wave?
  • IS it Narrow?
  • a normal QRS complex is less than .12
40
Q

shockable rhythms

A

v fib

pulseless v tach

41
Q

starlings law

A

the greater the stretch the greater the contractions

EMER 110 CARDIAC AND RESPIRATORY THEORY (8 decks)

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