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SAM I > Arrhythmias Part 2 (diagnosis) > Flashcards

Arrhythmias Part 2 (diagnosis) Flashcards

1
Q

Why do arrhythmias occur?

A
  1. Heart is diseased

2. Extra-cardiac disease is affecting the heart’s electrical activity and/or cardiac blood supply (i.e. GDV)

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2
Q

What are the mechanisms of arrhythmias?

A
  1. Disturbances of impulse formation (excitability)
  2. Disturbances of impulse transmission (conduction)
  3. Complex: disorders involving both
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3
Q

If cardiac excitability is increased and intermittent it will create what kind of impulse formation?

A

premature heart beats

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4
Q

If cardiac excitability is increased and sustained it will create what kind of impulse formation?

A

tachycardia

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5
Q

If cardiac excitability is intermittenly decreased it will create what?

A

lack of sinus complexes (sinus pause)

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6
Q

If cardiac excitability is decreased and sustained it will create what kind of impulse formation?

A

bradycardia or asystole

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7
Q

What is a sinus bradycardia?

A

Sinus rhythm with an abnormally low heart rate (prolonged R-R interval)

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8
Q

What is a primary cause of sinus bradycardia?

A

Sinus node dysfunction

Sick Sinus syndrome

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9
Q

What is a secondary cause of sinus bradycardia?

A

increased/high vagal (parasympathetic) tone

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10
Q

Which is more common in both sinus bradycardia/tachycardia?

A. Primary cause
B. Secondary cause

A

B. Secondary cause

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11
Q

What are pathological causes of high vagal tone?

A
  • respiratory/ intrathoracic disease
  • GI disease
  • neurologic disease (increased ICP)
  • opthalmic disease (increased IOP)
  • drugs/deep anesthesia/ toxins
  • hypothermia
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12
Q

What are non-pathologic causes of high vagal tone?

A
  • sleep/rest
  • athleticism
  • brachycephalics
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13
Q

What is sinus tachycardia?

A

A sinus rhythm with an abnormally high heart rate (shortened R-R intervals)

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14
Q

What are primary causes of sinus tachycardia?

A

Sinus node dysfunction

Sick Sinus Syndrome

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15
Q

What are secondary causes of sinus tachycardia?

A

Increased/high sympathetic tone

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16
Q

What are causes of high sympathetic tone?

A 
Hypotension 
Hypoxia 
Anemia 
Pain/excitment 
Drugs/toxins
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17
Q

What is a supraventricular premature complex (SVPC)?

A

Premature depolarization generated by an ectopic impulse located above the ventricles

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18
Q

Where is the most common ectopic impulse located for a SVPC?

A

Atrial

Others: AV node/junction, SA node

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19
Q

In SVPC, what would you see in an ECG?

A
  • Premature P-QRS-T (P’ might not be visable)
  • narrow QRS
  • QRS associated with a P’
  • often followed by a pause
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20
Q

What are causes of SVPC?

A
  • atrial dilation
  • atrial tumor
  • various systemic and metabolic diseases
  • drugs
  • old age
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21
Q

What is supraventricular tachycardia (SVT)?

A

Any pathological tachycardia originating above the ventricle (atria, AV node/junction, SA node)

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22
Q

What are the different types of SVT?

A
  • Atrial
  • AV nodal
  • Junctional
  • SA nodal
  • Bypass tract
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23
Q

In SVT, what will you see on the ECG?

A
  • 3 or more SVPCs with abnormally high rate (tachycardia!)
  • P’ waves instead of P waves
  • can be sustained (continuous) or paroxysmal (intermittent)
  • usually a regular rhythm
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24
Q

What is atrial fibrillation (AF)?

A

Chaotic and very rapid atrial impulses (400-1200/min) and a large surface area is required

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25
In A Fib, what will you see on the ECG?
- irregularly irregular R-R intervals - No P waves - Fibrillation waves - QRS is usually narrow - HR usually fast but can be normal or slow - usually a sustained (continuous) rhythm
26
In dogs and cats, atrial fibrillation is usually secondary to atrial dilation associated with a structural heart disease. A. True B. False
A. True
27
What are causes of A Fib?
- general anesthesia - GI disease - hypothyroidism - post-pericardiaocentesis
28
What is a lone (primary) atrial fibrillation? And what breeds do you see it most commonly in?
- no structural heart disease | - giant and large breed dogs
29
What is atrial flutter?
- organized and rapid atrial impulse (280-400/min)
30
In Atrial flutter, what do you usually see in the ECG?
- No P waves - Flutter waves (look like saw tooth) - QRS usually narrow - No return back to baseline (isoelectric) - heart rate is often fast but can be normal or low - usually a sustained (continuous) rhythm
31
How can you tell the difference between ST, SVT or Atrial flutter?
- ST rarely exceed 220 bpm in dogs/ 280 bpm in cats | - vagal maneuver can be performed so you can visualize a P, P' or flutter wave
32
What is a ventricular premature complex (VPC)?
Premature depolarization generated by an ectopic focus located in the ventricular tissue (i.e. beyond the bundle branches and Purkinje fibers)
33
What is a common cardiac cause of VPC?
cardiomyopathies
34
What are non-cardiac causes of VPCs?
- abdominal tumors (splenic/hepatic) - GDV - hypokalemia - acidosis - anemia - hypoxemia - trauma - sepsis - hypovolemia - drugs/toxins
35
In VPC, what will you see on ECG?
- premature QRS - wide QRS - VPC often followed by a pause - VPC can be + (upright), - (downward) or biphasic
36
VPC from the left ventricle will be... A. positive deflection B. negative deflection
B. negative deflection
37
VPC from the right ventricle will be... A. positive deflection B. negative deflection
A. positive deflection
38
What is a ventricular tachycardia (VT)?
Tachycardia originating from the ventricle
39
In VT, what can you see on ECG?
- 3 or more consecutive VPCs with abnormally high heart rate - VT can be sustained or paroxysmal - VT usually is a regular rhythm - Wide QRS - regular rhythm
40
What is Ventricular fibrillation?
Chaotic/disorganized and rapid ventricular impulses (ventricles are quivering not contraction so no CO or BP)
41
What is concerning about VF compared to all other arrhythmias?
Fatal rhythm (1 cause of cardiac arrest)
42
What is accelerated idioventricular rhythm (AIVR)?
- looks like a VT without the T - usually due to non- cardiac disease - don't treat with anti-arrhythmic drugs - treat the cause treat the arrhythmia
43
What are the disorders of impulse conduction?
- AV blocks - bundle branch blocks - atrial standstill
44
What is a first degree AV block?
Conduction in the AV node is delayed
45
What will you see on ECG in first degree AV block?
- Prolonged PR interval - Consistent PR interval - QRS normal
46
What causes first degree AV block?
- high vagal tone (most common) - drugs/toxins (digoxin) *Not hemodynamically significant
47
What is a second degree AV block?
Conduction through the AV node is stopped BUT only intermittenly
48
In a second degree AV block what will you see on ECG?
- Some P waves do not have a QRS after them - QRS normal - Rhythm can be regular or irregular
49
In second degree AV block, what is Mobitz type I?
leading up to the block the PR interval gradually increases (prolongation)
50
In second degree AV block what is Mobitz type II (low grade)?
- no prolongation of the PR interval prior to the block | - most of the impulses are getting down the ventricles
51
In second degree AV block what is Mobitz type II (high grade)?
- no prolongation of the PR interval prior to the block - there are more impulses not getting through than there are impulses getting through (more Ps less QRS) - causes a bradycardia!!
52
What is a third degree AV block?
Conduction through the AV node is stopped permanently
53
In third degree AV block what will you see on ECG?
- Ps without QRS - PR interval is not consisten (AV disassociation) - before a QRS there is a pause (escape complex) - bradycardia - rhythm is usually regular
54
What is a typical cause of first degree AV block and second degree AV block Mobitz type I?
- high vagal tone (most common) | - drugs (digoxin + alpha 2 agonist)
55
What are typical causes of second degree AV block Mobitz type II and third degree AV block?
- structural disease of AV node most common - hyperkalemia - drugs (digoxin)
56
What are bundle branch blocks?
Delays in conduction or lack of conduction in the left and/or right bundle branch
57
In bundle branch blocks what will you see on ECG?
- wide QRS complex (>70ms dogs, >40ms cats)
58
In a right bundle branch block, on ECG (lead II) the QRS will deflect... A. positively B. negatively
B. negatively
59
In a left bundle branch block, on ECG (lead II) the QRS will deflect... A. positively B. negatively
A. positively
60
What is an atrial standstill?
Absence of atrial depolarization
61
In atrial standstill, what will you see on ECG?
- no P waves - No fibrillation/flutter waves - QRS normal
62
What can cause atrial standstill?
- hyperkalemia (urinary obstruction, Addison's) | - atrial myopathy (springer spaniel nueromyopathy)
63
What can you see with Sick Sinus syndrome?
- sinus bradycardia and/or sinus arrest (sinus pause) - SVPC, VPC, SVT, VT - first or second degree AV block
64
What are predisposed breeds to Sick sinus syndrome?
- miniature schnauzer - Westie - Dachshund - cocker spaniel
65
What will you see with hypokalemia?
- prolong repolarization (VPC/APC) | - lowers the resting membrane potention
66
What will you see with MILD hyperkalemia?
shortened repolarization and tented T waves *** NAVLE
67
What do you see with MODERATE hyperkalemia?
prolonged transmission velocity (WIDE QRS complexes)
68
What do you see with SEVERE hyperkalemia?
- prolonged PR interval or absent P waves - ventricular fibrillation - pulseless electrical activity/electromechanical dissociation

SAM I (2 decks)

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