EKG

Question 1

Rules of electrocardiography

Answer 1

1. wave of depol travels towards + pole gives a + voltage deflection
   2) size of deflection : mass of tissue

Question 2

SA wave

Answer 2

too small for a signal, not seen

Question 3

P-wave

Answer 3

atria depolarization

Question 4

PR-segment

Answer 4

depol wave moving through AV node

period between P-wave and Q-wave

Question 5

Q-wave

Answer 5

left side of septum depolarizing
(wave travels from L to R away from + node)
His/Purkinje
often too small to be detected in lead I

Question 6

R-wave

Answer 6

ventricle depole (endocardium -> epicardium)
mass on L > R = positive deflection
large mass = large peak

Question 7

S-wave

Answer 7

last part of ventricle depol near the atrium

Question 8

QRS complex

Answer 8

reflects ventricular depolarization

Question 9

ST -segment

Answer 9

interval bet depol and repol

Question 10

T-wave

Answer 10

repolarization of ventricle

epicardium -> endocardium

Question 11

interval between P waves

Answer 11

sinus rhythm
heart rate
Fast = tachycardia
slow = bradycardia

Question 12

measuring PR interval

Answer 12

amt of time it takes for the impulse to get rhough the AV node and His/Purk system (mostly AV bc it is slower)
PR longer than normal = abnormality in conduction pathway

Question 13

widening of QRS complex

Answer 13

ventricle depolarizing more slowly than normal

ie bundle branch block

Question 14

mean electrical axis

Answer 14

summation of all electrical activity

normally; between -30 aVl and +90 aVf

Question 15

right axis deviation (towards aVr)

beyond 100

Answer 15

right ventricular hypertrophy, increase mass -> smaller than normal QRS in lead 1, positive deflection in aVr

Question 16

left axis deviation

aVf more negative than -30

Answer 16

left ventricle hypertrophy

Question 17

first degree AV block

Answer 17

PR-interval longer
every P wave followed by QRS
(conduction through AV node is slowed)

Question 18

second degree AV block

Answer 18

PR-interval longer
some P waves NOT followed by QRS
(more severe block)

Question 19

third degree AV block

Answer 19

dissociate of P and QRS

slower bc QRS is driven by the His/Purk system

Question 20

atrial flutter

Answer 20

not every P wave followed by QRS

atrial rate faster than needed to get proper propagation through the AV node

Question 21

atrial fibrillation

Answer 21

atria not driven by SA node, but by local currents = uncoordinated firing NO P-waves

Question 22

ventricular tachycardia

Answer 22

ventricular rate > atrial rate

100-200 beats per min

Question 23

ventricular flutter

Answer 23

> 200 beats per minute

Question 24

ventricular fibrillation

Answer 24

electrical activity (and pumping) is completely uncoordinated) - lethal

Question 25

alterations in ST waves

Answer 25

ventricular repol very sensitive to myocardial perfusion, pertubation of perfusion can lead to alterations in ST waves
Myocardial Infarction - recent w/in days after

Question 26

ST depression

Answer 26

mild to moderate deprivation of flow

subendocardial layers of myocardium effected

Question 27

ST elevation

Answer 27

severe transmural deprivation of flow

subepicardial and subendocardial layers

Question 28

fast conduction

Answer 28

contracting regions, His/Purkinje

Question 29

slow conduction

Answer 29

pacemaking, and slow conduction (AV node)