ECG Part I

Question 1

what is phase 0 of the cardiac action potential?

Answer 1

upstroke

Question 2

what is phase 1 of the cardiac action potential?

Answer 2

early fast repolarization

Question 3

what is phase 2 of the cardiac action potential?

Answer 3

the plateau

Question 4

what are the outward potassium currents for repolarization?

Answer 4

Ito1
ikr
iks

Question 5

what normally controls the heart rate?

Answer 5

sinus node

Question 6

what is automaticity a property of?

Answer 6

spontaneous depolarization

Question 7

altered slope to phase 4 changes ___________________

Answer 7

heart rate

Question 8

which myocardial tissues have automaticity?

Answer 8

sinoatrial node
internodal pathways
atrioventricular junctional tissue
purkinje fibers in the ventricle

Question 9

what are some cardiac structures that do not possess excitability?

Answer 9

pericardium
cardiac valves

Question 10

what is the absolute refractory period?

Answer 10

no stimulus can cause depolarization of the cell

Question 11

what species have type A ventricular activation?

Answer 11

dog
cat
man

Question 12

what leads to rapid ventricular activation in type B species?

Answer 12

extensive purkinje fiber network

Question 13

what is escape depolarization?

Answer 13

comes after a pause

Question 14

what is ectopic?

Answer 14

impulse originates from focus other than SA node

Question 15

what is a conduction block?

Answer 15

a pathologic delay or interruption of conduction

Question 16

what is atrioventricular dissociation?

Answer 16

independent depolarization of the atrial and ventricles

Question 17

what is paroxysmal tachycardia?

Answer 17

sudden onset and abrupt end
“burst” of tachycardia

Question 18

what is fibrillation?

Answer 18

totally chaotic activation of atria or ventricles

Question 19

what can you measure on a dog and cat electrocardiogram?

Answer 19

P wave height
P wave duration
PR interval
R wave height
QRS duration
QT interval

Question 20

what is the ECG “standard calibration”?

Answer 20

1 cm/mV

Question 21

at 25mm/sec, how long does one little box represent?

Answer 21

0.04 sec

Question 22

what are the normal heart rate values for dogs?

Answer 22

60-160 beats/min for adults
up to 180 beats/min for toy breeds
up to 220 beats/min for puppies

Question 23

what is normal P wave duration for dogs in lead II?

Answer 23

<= 0.04 sec

Question 24

what is normal P wave height for dogs in lead II?

Answer 24

<= 0.4 mV

Question 25

what is the range of normal cat heart rate (in the hospital)?

Answer 25

160-240 beats/min

Question 26

what are the normal cat rhythms on an ECG?

Answer 26

normal sinus rhythm sinus tachycardia

Question 27

what is the normal P-R interval in a cat on an ECG?

Answer 27

0.05 to 0.09 seconds

Question 28

what is a hummingbird heart rate while perching?

Answer 28

500 bpm

Question 29

what is method 1 to obtain heart rate using an ECG?

Answer 29

50 mm/sec or 25 mm/sec count number of QRS in 3 seconds multiply by 20

Question 30

the first negative wave is a ______ wave

Answer 30

Q

Question 31

which wave is always positive?

Answer 31

R wave

Question 32

what are the limb leads?

Answer 32

I II III aVF aVR

Question 33

in whom do we use the base-apex lead system?

Answer 33

horses and ruminants

Question 34

how many leads in chest leads may be used?

Answer 34

4-6

Question 35

why are base-apex leads used in horses and ruminants?

Answer 35

extensive purkinje sustem burst activation of ventricle cannot use ECG to identify cardiac enlargement

Question 36

what is ECG used mostly for in horses and ruminants?

Answer 36

rate and heart rhythm

Question 37

does cardiac hyperplasia occur in the adult?

Answer 37

no

Question 38

what can cause cellular hypertrophy?

Answer 38

physiologic: exercise, anemia pathologic: systemic hypertension, mitral valve reegurgitation

Question 39

what is hypertrophy triggered by?

Answer 39

load on myocytes autocrine, paracrine, and endocrine factors

Question 40

what are some inadequate responses with cardiac hypertrophy?

Answer 40

cell overload myocyte failure/death CHF

Question 41

what is a concentric hypertrophy pattern caused by?

Answer 41

pressure overload: systemic hypertension, aortic stenosis

Question 42

what can cardiac hypertrophy be stimulated by?

Answer 42

increasing wall stress catecholamines angiotensin II aldosterone hypoxia or ischemia cytokines, or other signaling factors

Question 43

does cardiac hypertrophy trigger ECG changes?

Answer 43

it can

Question 44

what is phase 3 of the cardiac action potential?

Answer 44

repolarization to diastolic potential

Question 45

what is phase 4 of the cardiac action potential?

Answer 45

resting membrane potential

Question 46

does atropine speed or slow the heart rate?

Answer 46

speeds

Question 47

what does altered slope to phase 4 do?

Answer 47

changes heart rate

Question 48

what is the supernormal period?

Answer 48

less than normal stimulus might cause depolarization

Question 49

there are ________ of the 1mm boxes in 1 second at 50mm/sec

Answer 49

50

Question 50

what is a normal P-R interval for a dog?

Answer 50

0.06-0.13sec

Question 51

what is a normal QRS duration for most dogs?

Answer 51

<=0.05 seconds 0.06 seconds giant breeds

Question 52

what is a normal R wave height for dogs?

Answer 52

<=2.5 mV <3.0 mV giant breeds

Question 53

what is a normal P-R interval for a cat?

Answer 53

0.05-0.09 seconds

Question 54

what is a normal QRS duration for a cat?

Answer 54

<=0.04 seconds

Question 55

what is a normal R wave height for a cat?

Answer 55

<=0.9 to 1.0 mV

Question 56

what is the second method to obtain heart rate?

Answer 56

count number of boxes between R waves, divide into 3000 for 50mm/sec or 1500 for 25mm/sec

Question 57

what is an advantage of chest leads?

Answer 57

search for P waves when not evident in frontal plane leads

Question 58

does cardiac hyperplasia occur in the adult?

Answer 58

no

Question 59

when is cardiac hypertrophy an adequate response?

Answer 59

compensated hypertrophy

Question 60

what causes eccentric hypertrophy?

Answer 60

volume overload: mitral regurgitation, ventricular septal defect, anemia