EKG (Middlekauff)

Question 1

Little box and big box measurements

Answer 1

Little box: 1mm = 40ms = .04s

Big box = 5mm = 200ms = .2s

Question 2

How do you measure rate?

Answer 2

Find a QRS wave on a heavy line.

Start counting at NEXT heavy line: 300, 150, 100, 75, 60, 50, 40, 37, 35, 30.

Then estimate HR between heavy lines.

Question 3

Is this sinus rhythm?

Answer 3

Identifiable P waves

P waves before each QRS

Rate between 60 and 100

Question 4

What leads do you look at to determine rhythm?

Answer 4

II and V1

(Because P wave easy to see)

Question 5

Limb leads and chest leads

Answer 5

Limb leads: I, II, III, aVR, aVL, aVF

Chest leads: V1, V2, V3, V4, V5, V6

Question 6

How do you determine axis of the heart?

Answer 6

Look at lead I and aVF

Left axis deviation (LAD): I positive and aVF negative

Normal: I positive and aVF positive

Right axis deviation (RAD): I negative and aVF positive

Right axis deviation extreme: I negative and aVF negative

Question 7

PR interval

Answer 7

Beginning of P to beginning of QRS

Time to depolarize atria AND pass through AV node

Conduction delay through AV node

Normally < 200ms

Question 8

QRS interval

Answer 8

Beginning of Q to end of S

Time to depolarize ventricles

Normally < 120ms

(If conduction delay, bundle branch block, then this is prolonged)

Question 9

QT interval

Answer 9

Beginning of QRS to end of T

Electrical depolarization and repolarization of ventricle

Mechanical contraction of the ventricles (still contracting as they’re repolarizing!)

Normally < 400ms

Question 10

P wave

Answer 10

Atrial depolarization

Question 11

T wave

Answer 11

Ventricular repolarization

T wave inversion indicates recent MI

Question 12

ST segment

Answer 12

Isoelectric, ventricles depolarized

Question 13

Order for classifying EKG

Answer 13

1) Sinus rhythm? (P then QRS, look in II or V1)
2) Rate (300, 150, 100, 75, 60)
3) Axis (I and aVF)
4) Are intervals normal?

Question 14

What is a Q, an R, and an S?

Answer 14

Q: if QRS begins with negative deflection, it is Q

R: anything positive is R

S: only if you have a negative after a positive is S

Question 15

What determines the height of a deflection on an EKG?

Answer 15

Muscle mass

Athlete or person with heart failure who has hypertrophy will have larger voltage

Or, you could have normal muscle mass but small voltage if you’re obese (fat in the way) or if you have emphysema (air in the way)

Question 16

Third degree/complete heart block

Answer 16

Signal from SA node does not travel to ventricles

P wave fires but not connected to QRS wave

Question 17

Which leads roughly respresent activity in what areas of the heart?

Answer 17

V1: RA (P wave) and RV (QRS complex)

II: RA or LA (P wave; bi-humped P wave indicates enlargement of both)

II: LV (QRS complex)

V2 - V6: LV (QRS complex)