Ch. 2 ECG

Question 1

Basic contractile unit of the heart

Answer 1

myofibril

Question 2

SA Node

Answer 2

@ RA/SVC

• controlled by ANS (symp/para)
• at P wave

Question 3

AV Node

Answer 3

@ interior intra-atrial septum- relays signal from atrium to ventricle
- during P-R= isoelectric line

Question 4

EKG Times

Answer 4

• P wave= 0.8-1.2
• QRS= .8-.1
• T wave= .2
• PR= .12-.2
• ST= .12-.15

Question 5

Elevated vs Depressed S-T

Answer 5

Elevated ST= myocardial injury

Depressed ST= acute MI/ischemic

Question 6

Inverted vs Peaked T wave

Answer 6

Inverted= ischemia
Peaked= high K

Question 7

Deep QRS

Answer 7

necrosis

Question 8

Node BPM

Answer 8

SA= 60-100
AV= 40-60
Perkinje= 20-40

Brady < 60
Tachy >100

Question 9

U wave

Answer 9

due to low K/Ca, or perkinje repol

Question 10

PAC

Answer 10

Premature Atrial Contraction

-early P wave, QRS/Twave= normal

Question 11

Atrial Tachycardia

Answer 11

Pwave overlaps with Wave, rhythm regular with narrow QRS (bpm= 120-150)
-aka paroxysmal supraventricular tachycardia (PSVT)

Question 12

Atrial Flutter

Answer 12

Pwave= bidirectional** and saw-toothed*

2: 1 ratio Atrial:Ventricle
- atrial 250-350 bpm

Question 13

Atrial Fibrillation

Answer 13

irregular ventricular response (AV node)***

• high atrial impulses
• ventricular response
  1) rapid- 100 bpm
  2) mod- 60-100
  3) slow- <60

Question 14

AV Block

Answer 14

1st: P-R > .2 sec
2nd (intermittent)= some signals fail to present QRS
3rd (complete block)= no impulse hit AV nod= no vent depol from AV node- random impulses though the ventricle conduction

Question 15

PVC

Answer 15

Premature Ventricle Contraction= No P wave, wide QRS, followed by pause

1) Bigminy= every sinus beat followed by PVC
2) Trigeminy= every 2 sinus beats followed by PVC
3) Couplet= 2 consecutive PVCs

Question 16

Ventricular Tachycardia

Answer 16

ventricle rate > 20-50 bpm, QRS >100

Question 17

Ventricular Fibrillation

Answer 17

starts with short run of VT

-ventricle quivers= no contration

Question 18

ANS effects on SA node

Answer 18

1) sympathetic= norepinephrine= increase HR, contraction
2) parasympathetic= acetylcholine= decrease HR, CO, perph resistance
- works on prejunctional to lower nori release
- works on post junctional muscarinic receptors= lower beta adrenergic receptors

Question 19

Chemoreceptors and Baroreceptors

Answer 19

@carotid and arctic bodies

• chemo= stimulated by low O2, high CO2, low pH
• baroreceptors= controls HR, BP, and lesser inotrophy

Question 20

Exercise and Hemorrhage do what do ANS

Answer 20

increase sympathetic, lower para

incase BP, HR

Question 21

Adrenergic, muscarinic, and nicotinic receptors

Answer 21

adrenergic= symp (alpha and beta)
muscarinic/nicotinic= para