EKG (POM only)

Question 1

How do we name arrhythmia’s?

Answer 1

60-100 B/min = normal

100 = tachycardia

Sinus Bradycardia < 60

Question 2

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 2

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 3

On an EKG, how do we calculate heart rate?

Answer 3

1) 1500/ # small boxes between R-R interval **EASIEST METHOD
2) Use the following numbers to indicate what the heart rate is between two successive R waves : 300, 150, 100, 75, 60, 50, 43, 37, 33, 30

Question 4

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 4

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 5

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 5

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 6

Discuss first second & third degree heart or AV block.

Answer 6

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 7

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 7

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 8

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

Answer 8

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 9

Where are the leads placed?

Answer 9

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 10

Right bundle branch block looks like

Answer 10

Bipeak or kind of isoelectric rSR’ in V1

Wide QRS, greater than 3 little boxes

Question 11

Left bundle branch block looks like

Answer 11

Left bundle branch block = bunny ears in V6 & negative deflection in V1

Wide QRS, greater than 3 little boxes

Question 12

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

Answer 12

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

Amplitude (y axis) is 10mm/1mV

Time is x axis

Question 13

Describe lead reversal

Answer 13

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 14

Describe normal sinus rhythm

Answer 14

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

Sinus Bradycardia < 60

Sinus Tachycardia >100

Question 15

Concave up ST segment elevation = _____ MI

Concave down ST segment elevation = ____ MI

Answer 15

Concave up ST segment elevation = non MI

Concave down ST segment elevation = acute MI

Mnemonic: Frown when concave down

Question 16

Describe how an STEMI is an injury current.

Answer 16

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 17

Give the EKG events of an acute MI in order:

Answer 17

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 18

Anterior wall/ Septal leads =

Answer 18

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 19

Inferior wall leads =

Answer 19

Inferior wall leads: II, III, AVF

Question 20

Lateral wall leads =

Answer 20

Lateral wall leads: I, AVL, V5, V6

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

Question 21

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

Answer 21

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