Unit 4 - EKGs

Question 1

what are EKGs compromised of?

Answer 1

vector sums

Question 2

what are EKGs assessed for?

Answer 2

rate, rhythm, axis, and injury

Question 3

what is rate calculated by?

Answer 3

counting number of large boxes (200 ms) from R-R

-300-150-100-75-60-50-37.5

Question 4

what is normal:

• PR interval
• QRS
• QT

Answer 4

• PRI: 0.12 - 0.20 sec
• QRS: 0.06 - 0.10 sec
• QT: 0.36 - 0.44 sec

Question 5

what is bradycardia, normal, and tachycardia?

Answer 5

brady < 50
normal = 50 - 100
tachy > 100

Question 6

what is expected in normal sinus rhythem?

Answer 6

• every QRS is preceded by a P-wave
• 1:1 concordance between P-waves and QRS
• PR interval is constant or approximately constant

Question 7

what leads are used to measure axis?

Answer 7

I and aVF

• both upright: normal
• I upright, aVF downward: left axis
• I downward, aVF upward: right axis
• both downright: extreme right axis

Question 8

what does ST depression VS elevation mean (usually)?

Answer 8

depression: myocardial injury
elevation: myocardial infarction

Question 9

what are inferior wall leads?

Answer 9

II, III, aVF

Question 10

what are lateral wall leads?

Answer 10

I, aVL, V4-6

Question 11

what are anterior wall leads?

Answer 11

V2-4

Question 12

what are septum leads?

Answer 12

V1-2

Question 13

what are posterior wall leads?

Answer 13

(depression in) anterior-septal leads (V1-4)

Question 14

what does atrial tachycardia show?

Answer 14

preserved rhythm, but abnormal rate

Question 15

what does atrial fibrillation show?

Answer 15

rapidly occurring abnormal waves replacing normal P wave

Question 16

what does atrial flutter show?

Answer 16

saw-toothed waves replacing P wave

-ventricular depolarization occurs after several atrial waves

Question 17

what does atrioventricular block show?

Answer 17

PR interval gradually prolonged until QRS complex completely disappears

Question 18

what does premature ventriclar contraction show?

Answer 18

occurs at random, disrupting normal rhythm (downward wave)

Question 19

what does ventricular tachycardia show?

Answer 19

rapidly widened QRS complexes of irregular shape

Question 20

what does ventricular fibrillation show?

Answer 20

fibrillatory waves are small and irregular, or large and bizzarely shaped

Question 21

what are the bipolar leads? where do they go?

Answer 21

I - left arm to right arm (lateral)
II - left leg to right arm (inferior)
III - left leg to left arm (inferior)

Question 22

what are the unipolar leads? where do they go?

Answer 22

aVL - left arm to indifferent electrode (right arm + right leg) = lateral
aVR - right arm to indifferent electrode (left arm and left leg) = lateral
aVF - left leg to indifferent electrode (left arm and right arm) = inferior

Question 23

what are the precordial chest leads? where do they go?

Answer 23

V1 - right sternal margin, 4th intercostal space (anterior/septal)
V2 - left sternal margin, 4th intercostal space (anterior/septal)
V3 - halfway between V2 and V4 (anterior)
V4 - 5th intercostal space in left mid-clavicular line (anterior/lateral)
V5 - 5th intercostal space in anterior axillary line (lateral)
V6 - 5th intercostal space in midaxillary line (lateral)

Question 24

what does P-wave correspond with?

Answer 24

depolarization of atrium

Question 25

what does PR interval correspond with?

Answer 25

time needed for impulse to pass thru AV node

-0.12 to 0.20 seconds

Question 26

what does QRS complex correspond with?

Answer 26

depolarization of ventricles

-<0.1 second

Question 27

what does ST segment correspond with?

Answer 27

little electrical activity in heart

Question 28

what does T wave correspond with?

Answer 28

repolarization of ventricles