6- electrocardiography

Question 1

phase 0 of cardiac AP

Answer 1

upstroke, Na+ intracellular shift

Question 2

phase 1 cardiac AP

Answer 2

early fast repolarization, Ca2+ intracellular/K+ extracellular shift

Question 3

phase 2 cardiac AP

Answer 3

plateau, K+ extracellular shift

Question 4

phase 3 cardiac AP

Answer 4

repolarization to diastolic potential, K+ extracellular shift

Question 5

phase 4 cardiac AP

Answer 5

resting membrane potential

Question 6

absolute refractory preiod

Answer 6

no stimulus, no matter how strong, can initiate a new AP

Question 7

relative refractory period

Answer 7

a stronger than normal stimulus can initiate a new AP

Question 8

supranormal period

Answer 8

small stimuli which normally wouldn’t trigger depolarization can initiate a new AP

Question 9

SA node

Answer 9

pacemaker of heart, located in RA, initiate electrical impulse

Question 10

atrial conduction pathway

Answer 10

impulse spread through atrial muscle, causes atrial contraction

Question 11

AV node

Answer 11

located in junction between atria and ventricles, delays the impulse to allow ventricles to fill

Question 12

bundle of his

Answer 12

conducts impulse from AV node to ventricles

Question 13

right and left bundle branches

Answer 13

carry impulses down the interventricular septum

Question 14

purkinje fibers

Answer 14

throughout ventricular walls, trigger ventricular contraction

Question 15

what does the ecg machine detect?

Answer 15

electrical changes in heart muscle resulting from depolarization and repolarization

Question 16

describe each ecg wave

Answer 16

P wave: depolarization of atria in response to SA node triggering
PR interval: delay of AV node to allow ventricles to fill
QRS complex: depolarization of ventricles
ST segment: beginning of ventricular repolarization
T wave: ventricular repolarization

Question 17

ECG measurement: each small box is ____, 5 small boxes is _____, 10 small boxes is _____

Answer 17

1mm, 5mm, 1 cm

Question 18

how many 1mm boxes in 1 sec at the 25 mm/sec? how many in 1 sec at 50 mm/sec?

Answer 18

25, 50

Question 19

how to calculate HR at paper speed 25 mm/s

Answer 19

count R waves in 3 sec (15 boxes) x 20
OR count R waves in 6 sec (30 boxes) x 10

Question 20

how to calculate HR at paper speed of 50 mm/s

Answer 20

count number of R waves in a 6 sec strip (60 large squares) and x 10 to get BPM OR count # of R waves in 30 sec (30 boxes) and x 20

Question 21

how to calculate instantaneous HR

Answer 21

50 mm/sec: count # of boxes between R waves and divide by 3000
25 mm/sec: count # of boxes between R waves and divide by 1500

Question 22

normal dog ECG values and rhythms

Answer 22

HR: 60-160 bpm in adults, up to 180 bpm for toy breeds, up to 220 bpm for puppies
normal rhythm: sinus rhythm, sinus arrhythmia, wandering SA pacemaker

Question 23

normal cat ECG values

Answer 23

HR: 160-240 bpm
cardiac rhythms: normal sinus rhythm, sinus tachy

Question 24

basic ECG interpretation

Answer 24

determine predominant rhythm, analyze complexes, determine mean electrical axis, identify arrhythmias

Question 25

describe premature beats

Answer 25

extra beats that start too early

Question 26

describe Afib

Answer 26

irregular, fast beating of upper chambers

Question 27

describe VFib

Answer 27

chaotic quivering of the lower chambers (emergency)

Question 28

describe SVT

Answer 28

fast rhythm above the ventricles

Question 29

describe heart block

Answer 29

signal delay or block between atria and ventricles

Question 30

right atrial enlargement ecg finding and common causes

Answer 30

tall P waves, pulmonary hypertension, lung disease, tricuspid stenosis

Question 31

left atrial enlargement ECG findings and common causes

Answer 31

wide, notched P waves; mitral stenosis or regurgitation, hypertension, aortic valve disease

Question 32

RV hyperrtrophy ecg and common cuases

Answer 32

tall R wave, prolonged QRS; pulmonary HTN, chronic lung disease, congenital heart disease

Question 33

LV hypertrophy ecg and common causes

Answer 33

Tall R wave, deep S waves; long standing HTN, aortic stenosis

Question 34

premature depolarization

Answer 34

heartbeat that starts too early, before heart is ready

Question 35

escape depolarization

Answer 35

backup heartbeat that kicks in when the normal pacemaker of the heart pauses or fails to fire; comes after a pause

Question 36

conduction block

Answer 36

pathologic conduction delay or interruption

Question 37

AV dissociation

Answer 37

independent depolarization of atria and ventricles

Question 38

Paroxysmal tachycardia

Answer 38

burst of tachycardia with sudden onset and abrupt end

Question 39

Fibrillation

Answer 39

totally chaotic activation of atria or ventricles

Question 40

sinus tachycardia: describe, cause, treat

Answer 40

>160 bpm in dogs, >240 bpm in cats; caused by increase sympathetic tone; no treatment

Question 41

sinus bradycardia: describe, cause, treat

Answer 41

<60 bpm in dogs, <160 bpm in cats; caused by decrease SNS or increased vagal tone

Question 42

sinus arrhythmia: describe, cause, treat

Answer 42

cyclic slowing and speeding of sinus rate, associated with respiration; normal in dogs; incidental finding, no treatment

Question 43

atrial premature contractions: define, cause, treat

Answer 43

early abnormal beats that arise from atria, caused by structural heart disease, congenital accessory conduction pathway, extra-cardiac illness; no treatment, investigate cause

Question 44

supraventricular tachycardia: define, cause, treat

Answer 44

pathologic rhythm disturbance characterized by rapid, regular, tachycardia initiated within or above AV node; caused by conditions that cause atrial enlargement, metabolic disease; treat if symptomatic

Question 45

AFib: define, cause, treat

Answer 45

irregularly, irregular rhythm, F waves; caused by atrial dilation secondary to heart disease; tx: rhythm control (cardiovert) and rate control

Question 46

Ventricular premature complexes: define, cause, treat

Answer 46

premature ventricular beats, wide and bizarre QRS, no P waves: caused by cardiac or non cardiac causes; treat: none for isolated, treat when couplets or triplets

Question 47

Compensatory v non compensatory pause

Answer 47

compensatory: pause during premature beat is equal to 2x the normal R-R interval (VPC usually) non-compensatory: pause during premature beat is less than 2x normal R-R interval (APC usually

Question 48

compensatory pause

Answer 48

non compensatory pause

Question 49

ventricular tachycardia: define, cause, treat

Answer 49

abnormal electrical impulse within ventricles, caused by cardiac, abn electrolytes, GI disease; 4 or more VPCs in succession with rapid rate; tx with lidocaine

Question 50

VFib: define, cause, treat

Answer 50

chaotic, irregular baseline, no rhythm; medical emergency; tx CPR

Question 51

electrical alternans: define, cause, treat

Answer 51

sinus rhythm with alternating QRS amplitudes, most commonly due to pericardial effusion

Question 52

AV block 1st degree

Answer 52

slowed conduction

Question 53

AV block 2nd degree

Answer 53

sometime doesn't conduct type 1: gradual prolongation before block type 2: consistent PR interval before block

Question 54

AV block 3rd degree

Answer 54

never conducts

Question 55

1st degree AV block ecg, cause, tx

Answer 55

PR interval prolonged; increased vagal tone, B blockers, electrolyte imbalance; no tx

Question 56

2nd degree AV block- Mobitz type 1: ecg, cause, tx

Answer 56

progressive PR lengthening until a beat is dropped, caused by medications, benign, may observe

Question 57

2nd degree AV block - mobitz type 2: ecg, cause, treat

Answer 57

sudden dropped QRS with constant PR intervals; lyme disease, pacemaker required

Question 58

3rd degree AV block: ecg, cause, treat

Answer 58

P waves and QRS dissociated, ischemic heart disease, immediate pacing

Question 59

sinus arrest

Answer 59

failure of sinus node to discharge for >2 times normal PP interval

Question 60

sick sinus syndrome: signalment, cause, treatment

Answer 60

mini shnauzers, idiopathic fibrosis of sinus node; period of sinus arrest followed by SVT, tx: atropine response test

Question 61

atrial standstill

Answer 61

no P waves, due to severe hyperkalemia - peaked T wave, bradycardia

Question 62

Bundle branch blocks - Right

Answer 62

QRS too wide, can be normal, intermittent, or associated with RV disease

Question 63

Left BBB

Answer 63

QRS too wide, associated with significant left heart disease

Question 64

Left anterior fascicular block

Answer 64

associated with various forms of heart disease in cats, especially HCM