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VET433: Cardio/Respiratory > ECGs & Arrhythmias > Flashcards

ECGs & Arrhythmias Flashcards

(54 cards)

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1
Q

what is the resting membrane potential of cardiomyocytes

A

-90 mV

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2
Q

steps of cardiac action potential

A

SA node sends impulse –> Na+ entry –> cardiomyocyte depolarization –> Ca influx –> cardiac muscle contraction –> K+ efflux out –> repolarization –> cardiac muscle relaxation

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3
Q

what is the path of electrical activity in the heart

A
  1. SA node
  2. internodal conduction tracts –> R atrium –> L atrium
  3. AV node
  4. bundle of his
  5. purkinje fibers
  6. cardiomyocytes
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4
Q

SA node

A

sinoatrial node

FASTEST pacemaker
located in the RA wall
spreads current RAPIDLY to through the internodal tracts to reach the AV node

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5
Q

superior exit from atrium

A

high in atrial wall
common exit taken by the current with high sympathetic tone (tall P wave)

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6
Q

inferior exit in atrium

A

low in atrial wall
common exit taken by the current with high parasympathetic tone (shorter P wave)

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7
Q

wandering pacemaker

A

variable P wave height due to variable exit pathways based on autonomic input

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8
Q

AV node

A

atrioventricular node

SLOW pacemaker
located in the septum between RA/RV near the center of the heart

gatekeeper - the ONLY conduction pathway between the atria and the ventricles

current spreads slowly through the AV node to allow for atrial depolarization and contraction to finish before sending signal to the ventricles

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9
Q

bundle of his

A

conducts current RAPIDLY to the ventricles via the L and R bundle branches

allows for coordinated contraction across the ventricles

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10
Q

purkinje fibers

A

penetrating fibers that conduct signal through the ventricles to the myocytes

once current reaches myocytes –> cell to cell signaling occurs

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11
Q

how is an ECG generated

A

heart is activated by a depolarizing current that moves as a boundary between resting and activated tissues

electrical field gets generated onto the body surface –> detected by ECG surface electrodes

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12
Q

TP interval

A

time in between depolarizations

time during which the SA node initiates conduction PRIOR to the P wave

(not strong enough to be detected on ECG)

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13
Q

P wave

A

atrial depolarization

SA node –> R atrium –> L atrium
- slight delay between R and L atrial depolarization

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14
Q

PQ interval

A

conduction from SA node –> AV node –> bundle of his

represents the time required to travel through the AV node

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15
Q

QRS wave

A

ventricular depolarization

3 vectors in species with category A conduction

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16
Q

ST interval

A

early ventricular repolarization

duration of ventricular contraction - Ca coming into cells but no electrical activity

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17
Q

T wave

A

ventricular repolarization

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18
Q

QT interval

A

entire time for ventricular depolarization and repolarization

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19
Q

what leads are bipolar

A

leads I, II, III

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20
Q

what leads are unipolar

A

aVR
aVL
aVF

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21
Q

what is the correct positioning for the animal when taking an ECG

A

right lateral recumbency

can be standing or sternal if only looking at rate and rhythm

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22
Q

what are indications for running an ECG

Study These Flashcards
A
  • clinical signs - weakness, collapse, syncope
  • auscultation - abnormal heart rate or rhythm
  • diagnosis of heart disease or a systemic disease that causes arrhythmias
  • monitoring of critically ill patients/anesthesia
23
Q

what are the steps to evaluating an ECG

Study These Flashcards
A
  1. heart rate
  2. heart rhythm
  3. P wave for every QRS
  4. QRS for every P wave
  5. complex morphology
24
Q

how to calculate average HR if paper speed is 25 mm/s

Study These Flashcards
A

number of beats per 30 big boxes x 10

25
how to calculate average HR if the paper speed is 50 mm/s
number of beats per 30 big boxes x 20
26
how to calculate instantaneous HR if the paper speed is 25 mm/s
1500 / number of small boxes in the R-R interval
27
how to calculate instantaneous HR if the paper speed is 50 mm/s
3000 / number of small boxes in the R-R interval
28
what are the supraventricular rhythms
APCs atrial fibrillation supraventricular tachycardia
29
what are the ventricular arrhythmias
VPCs ventricular tachycardia ventricular escape beats ventricular fibrillation
30
what are the conduction disturbance arrhythmias
AV blocks bundle branch blocks
31
what causes sinus arrhythmia
high resting vagal tone normal in dogs abnormal for cats in the clinic (normal at home) faster during inspiration slower during expiration
32
sick sinus syndrome (SSS)
sinus node dysfunction causing sinus arrest AND clinical signs of collapse/syncope (must have both clinical signs and ECG findings)
33
sinus arrest
period of >2 seconds or >2 P-P intervals without sinus node function often followed by a ventricular escape beat
34
supraventricular arrhythmias
irregular heartbeats that originate above the ventricles
35
atrial premature complexes (APCs)
abnormal early depolarization of the atria that gets normally conducted to the ventricles - NARROW QRS that comes before the next sinus beat is expected - can often hide the T wave of the previous beat
36
supraventricular tachycardia
tachycardia caused by rapid signaling from above the ventricles - tachycardia (dogs > 160-180; cats > 260) - regular rhythm - P waves are present but can be difficult to find due to tachycardia
37
atrial fibrillation
areas of the atria continuously depolarizing/repolarizing and bombarding the AV node over and over again AV node can help slow down rhythm but patient is still tachycardic - irregular R-R interval - NO P waves - tachycardia - variable R amplitude - narrow QRS complex - irregular rhythm - undulating baseline
38
ventricular arrhythmias
abnormal heart rhythms that occur due to irregular ventricular beats complexes are WIDE and BIZARRE looking do not have a P wave initiating the complex
39
ventricular premature complexes (VPCs)
ventricles depolarize before the atria (comes in early) - wide QRS coming in where a sinus beat should be
40
ventricular escape beat
SA node fails to fire so the slow AV node takes over (comes in late) bradycardia - dogs: 40-60 - cats: 100-140 - wide QRS complexes coming in after a prolonged TP interval
41
accelerated idioventricular rhythm
rhythm in which ventricular ectopic beats exceed the rate of SA node firing (take over) dogs: 60-160 bpm cats: within 10% of sinus
42
ventricular fibrillation
disorganized ventricular rhythm due to random depolarization of areas of the ventricles unable to have a coordinated contraction - short, wide QRS complexes - disorganized, varying heights
43
ventricular tachycardia
rapid heart rate generated from the ventricles - wide QRS complexes - regular rhythm - lack of P wave association - tachycardia (dogs < 160; cats > 220) can be paraoxysmal, sustained, monomorphic, or polymorphic
44
hyperkalemia (sinoventricular rhythm)
high potassium --> increases resting membrane potential --> harder to depolarize the atria before the ventricles impulse is still generated in the SA node, but it reaches the AV node and ventricles before the atria can depolarize - tall, tented T wave - NO P waves - bradycardia - wide QRS
45
AV block
delayed or absent conduction through the AV node - long PQ interval - P waves without QRS
46
first degree AV block
prolonged PQ interval but ALL P waves are conducted caused by high vagal tone tx with atropine
47
second degree AV block
some P waves are conducted, some are not low grade: roughly every other P wave is conducted high grade: more than every other P wave is blocked
48
second degree mobitz type I AV block
PQ interval gradually prolongs until one P wave is blocked caused by high vagal tone tx with atropine (normal in horses)
49
second degree mobitz type II AV block
consistent PQ interval but P waves are randomly blocked caused secondary to heart disease NOT responsive to atropine
50
third degree AV block
no P waves are conducted QRS is entirely dissociated from P waves - no consistent PQ interval - SA node consistently fires at its own rhythm - AV node fires junctional escape beats randomly throughout caused by AV node disease tx with pacemaker
51
P pulmonale
tall P wave cause: RA enlargement
52
P mitrale
wide P wave cause: LA enlargement
53
tall R wave
LV enlargement
54
R cranial deviation
RV enlargement

VET433: Cardio/Respiratory (17 decks)

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