EKG (All lectures)

Question 1

How is the heart’s current measured?

Answer 1

An electrical current causes the heart to contract & the current spreads in the surrounding tissues. Some of this current goes to the surface of the body, which is measured by the electrodes placed on the body.

Question 2

Look @ my EKG diagram, isoelectric diagram, & EKG Illnesses sheet.

Answer 2

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Question 3

The QRS complex is produced by the ____ of all the ventricular action potentials.

The plateau phase (phase 2) corresponds to the _____ segment of the ECG.

The ___ wave is produced by ventricular repolarization (phase 3).

The ____ segment corresponds to ventricular diastole, at the end of which atrial depolarization produces the P wave of the ECG.

Answer 3

The QRS complex is produced by the sodium upstrokes (phase 0) of all the ventricular action potentials.

The plateau phase (phase 2) corresponds to the ST segment of the ECG.

The T wave is produced by ventricular repolarization (phase 3).

The TP segment corresponds to ventricular diastole, at the end of which atrial depolarization produces the P wave of the ECG.

See pg. 120 of notes 3

Question 4

Diastole begins at the dichrotic notch (drop in pressure & flow reversal) when the _____ valve closes.

The trampoline effect & flow reversal of the aortic valve @ the dichronic notch is what perfuses the _______ located @ the base of the aorta.

Answer 4

Diastole begins at the dichrotic notch (drop in pressure & flow reversal) when the aortic valve closes.

The trampoline effect & flow reversal of the aortic valve @ the dichronic notch is what perfuses the coronary arteries located @ the base of the aorta.

Question 5

Does atrial contraction cause the blood to go into the ventricles?

Answer 5

No, the atrial contraction does not put any blood into the heart. This is why people with atrial arrhythmias do not lose any signifiant CO since CO is due to the action to the left ventricle.

The atrium does not contract until the ventricle is full, it contracts @ the very end.

Question 6

First heart sound S1 is closure of the ____ (lub), & the second heart sound S2 is the closure of the _____ valves (dub).

S3 ________ & S4 ________.

Answer 6

First heart sound is closure of the AV valves (lub), & the second heart sound is the closure of the aortic & pulmonary valves (dub).

S3 diastolic filling of ventricles (evident in children) & S4 atrial contraction (pathologic).

Question 7

P wave & Q wave _____ atrial & ventricular contraction respectively because depolarizations occur ______ contractions.

Answer 7

P wave & Q wave precede atrial & ventricular contraction respectively because depolarizations occur before contractions.

Question 8

Jugular pulse follows _______ atrial pressure.

A wave follows _____ contraction

C wave follows closure of the ______

V wave is _____ filling & emptying

Answer 8

Jugular pulse follows right atrial pressure.

A wave follows atrial contraction

C wave follows closure of the tricuspid valve

V wave is atrial filling & emptying

Question 9

Right atrium contracts _____ left atrium (due to proximity to SA node where wave starts), although they contract very close to one another.

Left ventricle contracts _____ right ventricle since AP starts @ SA but the current goes diagonally from upper right to lower left.

Answer 9

Right atrium contracts before left atrium (due to proximity to SA node where wave starts), although they contract very close to one another.

Left ventricle contracts before right ventricle since AP starts @ SA but the current goes diagonally from upper right to lower left.

Question 10

Valve openings are right side _____ left side for the atrium & left side _____ right side for the ventricles.

Pressure in the pulmonary system (pulmonary artery) is _____ than in the systemic system (aorta) so the aortic valve closes ______ the pulmonary valve.

Answer 10

Valve openings are right side before left side for the atrium & left before right for the ventricles.

Pressure in the pulmonary system (pulmonary artery) is less than in the systemic system (aorta) so the aortic valve closes before the pulmonary valve.

Left ventricular contraction is before right ventricular contraction. Hence mitral valve closes before tricuspid valve closes. But pulmonary artery pressure is less than aortic pressure. Hence, pulmonic valve opens before aortic valve opens.

Aortic pressure is higher than pulmonary artery pressure. Hence, aortic valve closes before
pulmonary valve closes. Also, the drop in pressure in the left ventricle is larger and takes longer
than in the right ventricle. Hence the tricuspid valve opens before the mitral valve opens.

Question 11

Analyze the Wiggers diagram on pg. 124 & watch YouTube video on Wiggers diagram.

Answer 11

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Question 12

Watch the pressure volume loop from handwritten tutorials & watch the 3 ECG/ EKG video from handwritten tutorials!

Answer 12

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Question 13

Describe the basic ECG features necessary for the recognition of cardiac arrhythmias.

Answer 13

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Question 14

Explain and classify the various forms of heart block.

Answer 14

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Question 15

Describe the diagnostic features of premature beats and the tachyarrhythmias.

Answer 15

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Question 16

What are the 3 things you look for in every EKG?

Answer 16

Rhythm

Conduction

Wave form

Question 17

Where can rhythym originate & what is normal, fast, & slow? How do we name arrhythmia’s?

Answer 17

It can originate in SA, AV node-AV & AV junction, or ventricles.

60-100 B/min = normal
100 = tachycardia

So there is sinus bradycardia, AV node tachy, all we do is combine the top origin & the rate = arrhythmia etc.

Question 18

1) What is the standard paper speed on an EKG?
2) How is EKG paper organized?
3) Each large square is ___ sec, so 1 sec is _____ squares?
4) Each small box is ___ sec & there are _____ in 1 min. There are ___ small boxes width wise in 1 large box.

Answer 18

1) 25mm/sec
2) Large (dark) & small (light) squares. In each big box, there are 5 smaller boxes.
3) 1/5 sec = .2 sec, so 1 second is 5 large squares
4) .2/5 = .04 sec. There are 1500 small boxes in 1 min. There are 5 small boxes width wise in 1 large box.

Question 19

On an EKG, how do we calculate heart rate?

Answer 19

1) (# beats in 6 sec) x 10 = beat/min
2) 1500/ # small boxes between R-R interval **EASIEST METHOD

Typically, the HR is given on the top of the EKG.

see pg. 163

Question 20

1) How do we measure AV conduction? What does it measure? Normal PR interval time?
2) How do we measure I-V conduction? What does it measure? Normal QRS complex time?
3) How do we measure QT interval? What does it measure? Normal QT interval time?
4) Which measurements are most important of arrhythmias?

Answer 20

1) PR interval is the time it takes for the current to get from the atrium into the ventricle. Normal is ≤ .2 sec (1 big box). Measures from onset of P wave to onset of QRS.
2) IV conduction is the time it takes for the ventricle to depolarize it is the duration of the QRS complex. Normal is ≤ .1 sec.
3) Onset of QRS to end of T wave (it has nothing to do with arrhythmias). It is the time it takes for depolarization & depolarization of the ventricles. It varies with HR so corrected form is QTc = square root of R-R interval. Normal ≤ .45 sec. “c” means corrected.
4) AV & IV conduction

Question 21

1) What is the time of the PR interval on pg. 165?

2) What about QRS?

Answer 21

1) .2 - .04 = .16 sec

2) .08 sec = 2x(.04)

Question 22

What doesn’t show up on EKG?

Answer 22

SA, AV node, bundle of his, bundle branches, purkinje volatages are so low that they do not show up on EKG. QRS complex covers up atrial repolarization.

Question 23

Leads 1, 2, & 3 will show positive displacement on the ____ wave. This means that there is normal _____ rhythm & that the current comes from the ____node.

Answer 23

Leads 1, 2, & 3 will show positive displacement (upright) on the P wave. This means that there is normal sinus rhythm & that the current comes from the SA node.

You will always see an upright P wave in lead 2, if this is not occurring & it is inverted, then the current cannot be coming from the SA node & coming from somewhere else in a lower direction.

See pg. 166

Question 24

Discuss normal conduction of the heart

Answer 24

SA node–>Atrium–>AV node–>AV junction–>His bundle–>Purkinje system–> Ventricles

Question 25

Discuss the bundle branch block

Answer 25

When there is a blockade in one of one of the ventricles (right side–see pg 167), the right sided purkinje fibers are interrupted, the left ventricle is activated normally. However, the right ventricle is activated by cell-cell transmission through the myocardium.

Purkinje system = rapid conduction, so without this rapid conduction the cell-cell myocardial (muscle) transmission is slower & the QRS is increased & late activation coming toward the right.

see pg 167-169

Question 26

Analyze slides rest of slides in the lecture starting from pg. 159

Answer 26

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Question 27

Discuss first second & third degree heart or AV block.

Answer 27

First degree AV block: Prolonged PR interval

Second degree AV block:
-Mobits type 1: PR interval increases more & more in beats 1, 2, & 3, until a P wave is not conducted @ beat 4 & there is a pause. The P wave that follows has a shorter PR interval.

-Mobits type 2: Sudden drop in P wave with no change in PR interval.

Third degree AV block: No P waves conducted.

Note that:

Conduction ratio = #P waves/ # QRS waves

See pg. 173

Question 28

When the heart is beating in a normal rhythm and another unanticipated extra beat, beats before the normal beat, we have ________ beats. They can arise in the ________, ________, or________.

What is an escape rhythm?

Answer 28

When the heart is beating in a normal rhythm and another unanticipated extra beat, beats before the normal beat, we have premature beats. They can arise in the atrium, AV junction, or ventricle.

escape rhythm a heart rhythm initiated by lower centers when the sinoatrial node fails to initiate impulses, when its rhythmicity is depressed, or when its impulses are completely blocked.

See pgs. 180

Question 29

The ________ leads (V?——V?) are placed directly on the _____. 4 more leads are placed on?

Answer 29

The precordial leads (V1, V2, V3, V4, V5 and V6) are placed directly on the chest. 4 more leads are placed on right arm & leg & left arm & leg.

Question 30

Where are the leads placed?

Answer 30

Arm & legs give 4 “limb” leads: RA, LA, RL, LL.

1 = LA -RA

2 = LL - RA

3 = LL - LA

aVR = right arm

aVL = left arm

aVF = left leg

V1 = V6 are the precordia leads

V1 (left) & V2 (right) are 4th intercostal space

V3 = 5th rib

V4 = 5th intercostal space, mid clavicular line

V5 & V6 = 6th rib & V6 is more lateral

See EKG 1 POM lecture slides 10-11

Question 31

Right bundle branch block looks like

Answer 31

Bipeak or kind of isoelectric rSR’ in V1

Wide QRS, greater than 3 little boxes

Question 32

Left bundle branch block looks like

Answer 32

Left bundle branch block = bunny ears & negative deflection in V1

Wide QRS, greater than 3 little boxes

Question 33

Standard ECG recorded at __ mm/sec and __mm/__mV

Answer 33

Standard ECG recorded at 25 mm/sec and 10mm/1mV

Amplitude (y axis) is 10mm/1mV

Time is x axis

Question 34

Describe lead reversal

Answer 34

We have to know that this is lead reversal since all of the leads in lead 1 are upside down

If the limb leads are flat line then that also means the leads were put on incorrectly

Question 35

Describe normal sinus rhythm

Answer 35

Normal sinus rhythm means P waves occur regularly, upright in leads 1 & 2, & rate is 60-100

Sinus Bradycardia < 60

Sinus Tachycardia >100

Question 36

Concave up ST segment elevation = _____ MI

Concave down ST segment elevation = ____ MI

Answer 36

Concave up ST segment elevation = non MI

Concave down ST segment elevation = acute MI

Mnemonic: Frown when concave down

Question 37

Describe how an STEMI is an injury current.

Answer 37

An infracting or ischaemic myocyte will be actively loosing potassium from the cell membrane & since its ATPase’s doesn’t work right due to no O2, so they are depolarized (resting membrane potential is lower).

So the resting membrane potential of an infarcting myocyte is depolarized (less negative than normal) & its upshoot is not as fast, & its recovery time is shortened.

Normal myocyte is more hyperpolarized or has a higher resting potential

Therefore, there is an electrical difference between infracting & non infracting cells due to differences in membrane potential = injury current = ST elevation.

THIS WILL BE A TEST QUESTION

See slide 17 of EKG 2

Question 38

Give the EKG events of an acute MI in order:

Answer 38

First thing to occur is hyperacute T wave (minutes–>hours)

Second is ST segment elevation (hours)

Third is Q waves (1 day)

Memorize slide 29 of EKG 2 (will be a test question)

Question 39

Anterior wall/ Septal leads =

Answer 39

Anterior wall leads: V3 & V4

Septal leads = V1 & V2

Also called V leads (anterior & septal are contiguous with each other).

TEST QUESTION–Which leads reflect which part of the heart?

Question 40

Inferior wall leads =

Answer 40

Inferior wall leads: II, III, AVF

Question 41

Lateral wall leads =

Answer 41

Lateral wall leads: I, AVL, V5, V6

See pg. 19 & look @ where the leads are on the EKG

Question 42

State how aVF & lead 1 are in normal, left axis dev, right axis dev, & extreme axis.

Answer 42

This indicates a normal heart axis. Usually, these two leads are enough to diagnose a normal heart axis! A normal heart axis is between -30 and +90 degrees with positive in lead 1 & aVF.

A left heart axis is present when the QRS in lead I is positive and negative in II and AVF. (between -30 and -90 degrees)

A right heart axis is present when lead I is negative and AVF positive. (between +90 and +180)

An extreme heart axis is present when both I and AVF are negative. (axis between +180 and -90 degrees). This is a rare finding.

http://en.ecgpedia.org/wiki/Heart_Axis