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RUSVM SAM 1 > Arrhythmias 1 > Flashcards

Arrhythmias 1 Flashcards

1
Q

Why do arrhythmias occur?

A

The heart is diseased

  • atria or ventricular myocardium
  • conducting system
  • cardiac blood supply

Extra-cardiac Disease affecting hearts electrical activity or cardiac blood supply

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2
Q

What are the mechanisms of arrhythmias?

A

Disturbances of impulse formation (excitability)

Disorders of impulse transmission (conduction)

Complex: disorders of both impulse formation and conduction

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3
Q

What ions are responsible for impulses in the heart?

A

Potassium
Calcium
Sodium
Magnesium

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4
Q

What happens is excitability is increase and intermittent?

A

Premature heart beats

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5
Q

What occurs if cardiac excitability is increased and sustained?

A

Tachycardia

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6
Q

What occurs is excitability is intermittently decreased?

A

Sinus pause (lack of sinus compels)

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7
Q

What occurs is there is a decreased and sustained excitability ?

A

Bradycardia or asystole

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8
Q

What are the 3 classifications of disturbances of impulse formation?

A
  1. Sinus
  2. Supraventricular (atria/AV node/junction / SA node)
  3. Ventricular
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9
Q

What do you call a sinus rhythm with an abnormally low heart rate?

A

Sinus bradycardia

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10
Q

What are the causes of sinus bradycardia ?

A

Primary - sinus node dysfunction / sick sinus syndrome

Secondary - increased vagal (PSNS) tone

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11
Q

What are pathologic causes of high vagal tone?

A

Respiratory/intrathoracic disease

GI disease

Neurological disease (Increase ICP)

Ophthalmic disease (increase IOP)

Drugs/deep anestheric plane

Toxins

Hypothermia

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12
Q

What are non-pathologic causes of high vagal tone?

A

Sleep/rest
Athleticism
Brachycephalic

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13
Q

What do you call a sinus rhythm with abnormally high heart rate ?

A

Sinus tachycardia

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14
Q

What are causes of sinus tachycardia?

A

Primary- sinus node dysfunction/ sick sinus syndrome

Secondary - increased sympathetic tone

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15
Q

What are causes of high sympathetic tone?

A 
Hypotension 
Hypoxia 
Anemia 
Pain 
Fear/excitement 
Drugs/toxins
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16
Q

What is a supraventricular premature complex?

A

Premature depolarization generated by an ectopic impulse located ABOVE the ventricles

  • atrial -most common
  • AV node/junction
  • SA node
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17
Q

ECG

RR interval between sinus beats is regular, with shortened RR intervals.
There is a P before evert QRS
P between the short RR intervals has a different morphology than the sinus beats
QRS are narrow and same morphology as sinus beats

Interpretation??

A

Supreventricular premature complexes

-the short RR intervals are due to ectopic beats with P’ having different appearance than the P for the sinus beat

QRS have same morphology because there is normal conduction following the AV node

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18
Q

What are causes of a supraventricular premature complex?

A

Atrial dilation associated with structural heart disease
Atrial tumor
Various systemic and metabolic diseases
Drugs

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19
Q

What is a supraventricular tachycardia?

A

Any pathologic tachycardia originating above the ventricles

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20
Q

What are the types of SVT?

A 
Atrial 
AV nodal 
Junctional 
SA nodal 
Bypass tract
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21
Q

ECG

> 3 consecutive SVPC with abnormally high rate
P’ instead of Pwaves

Interpretation?

A

Supraventricular tachycardia

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22
Q

T/F: supraventricular tachycardias usually have an irregular rhythm

A

False

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23
Q

What is atrial fibrillation?

A

Chaotic and rapid impulses from the atria

-large surface area is required for AF

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24
Q

ECG

Irregularly irregular RR intervals
No Pwaves
Fibrillation waves
QRS are narrow

Interpretation ??

A

Atrial fibrillation

-fibrillation waves are just partial depolarizations of the atria, not a full wave

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25
T/F: in Afib, heart rate is often fast, but can be normal or slow
True
26
Atrial fibrillation in dogs and cats is usually secondary to ???
atrial dilation associated with structural heart disease
27
What dogs can get a lone (primary) Afib, where there is no structural heart disease
Giant and large-breed dogs
28
What is atrial flutter?
Organized and rapid atrial impulse - not as fast as Afib - waves are uniform
29
ECG No P waves, instead waves have uniform and “saw tooth” appearance No return to baseline QRS are narrow RR can be regular/irregular Interpretation?
Atrial flutter
30
T/F: atrial flutter and Atrial fibrillation usually have sustained (continuous) rhythms
True
31
How can you differentiate a sinus tachycardia from a SVT/A flutter?
ST is rarely >220bpm in dog, or >280bpm in cats Any medial reason to have ST? -history, PE, BP, minimum database Vagal maneuver to slow rate —> visualization of P/P’/flutter waves SVT and A flutter and due to pathological abnormalities in the heart ST is a normal physiological response to something external to the heart
32
What is ventricular premature complex?
Premature depolarization generated by an ectopic focus located in the ventricular tissue (ie past the bundle branches)
33
What is the most common cause of ventricular premature complexes?
Cardiomyopathies
34
What are the non-cardiac causes of ventricular premature complex?
Abdominal tumors (splenic or hepatic) Gastric dilatation-volvulus Hypokalemia Acidosis Anemia Hypoxemia Trauma Semis Hypovolemia Drugs/toxins
35
ECG Premature QRS Wide QRS, can be positive, negative, or biphasic QRS is not associated with a P wave Followed by a pause
Ventricular premature complex
36
Where are QRS complexes in VPC wide?
Impulse travels by muscle, no conduction system —> takes more time —> wide QRS
37
What is a ventricular tachycardia?
Tachycardia originating from the ventricle
38
ECG >3 consecutive VPCs with an abnormally high rate Regular, fast, wide QRS
Ventricular tachycardia
39
What conditions can make a wide and fast QRS but that is not ventricular tachycardia ?? How can you tell them apart from VT?
ST + ventricular enlargement /BBB SVT + ventricular enlargement / BBB Not VT because PR interval is normal and consistent —> AV associated VT—> AV disassociation
40
What is ventricular fibrillaiton?
Chaotic/disorganized and rapid ventricular impulses | —> ventricles quiver instead of contract ==> no CO or BP
41
ECG Erratic waves of variable morphology No pattern Incomplete waves
Ventricular fibrillation —>fatal rhythm —>ventricular tachycardia can deteriorate into VF
42
What is an accelerated idioventricular rhythm ?
Has all the same features of a ventricular tachycardia but it is not fast Usually a stable rhythm that does not require therapy
43
What are the three types of disorders of impulse conduction?
AV block Bundle branch block Atrial standstill
44
What is first degree AV block?
Conduction in the AV node is delayed
45
ECG Prolonged PR interval PR interval is consistent QRS is normal
First degree AV block
46
What are causes of first degree AV block?
High vagal tone (most common) Drugs/toxin (digoxin)
47
T/F: first degree AV block is not hemodynamically significant
True
48
What is second degree AV block?
Conduction through AV node is stopped but only transiently
49
ECG Some P waves do not have a QRS after them QRS have a normal appearance
Second degree AV block
50
What is a Mobitz type I AV block
Prolongation of the PR interval prior to the block
51
What is a Mobitz type II AV block
No prolongation of PR interval prior to block Low grade —> more waves are conducted than not High grade —> more waves are block than are conduction —> bradycardia
52
What is third-degree AV block ?
Conduction through the AV node is stopped permanently An impulse from the atria never makes it to ventricle —> QRS are junctional escape complexes
53
ECG P occurs without QRS PR intervals are not consisted ORS are preceded by a pause Heart rate is low
Third degree AV block
54
What are causes of first degree and Mobitz type I second degree AV block?
High vagal tone! Drugs (digoxin, A2 agonsits)
55
What are causes of Mobitz type II second degree AV block and third degree>
Structural disease of AV node (most common) Eg. Degeneration, fibrosis inflammation, or neoplasia Hyperkalemia Drugs
56
What is a bundle branch block?
Delays in the conduction/lack of conduction in the left and/or right bundle branch
57
What is the appearance of QRS in BBB?
Wide Dog > 70ms Cat >40ms
58
Is a right BBB, the QRS is __________ in lead II
Negative
59
In the left BBB, QRS is _________ in lead II
Positive
60
T/F: Bundle branch blocks have AV association, where ventricular rhythms do not
True
61
What is the cause of a left BBB?
Structural heart disease (cardiomyopathy )
62
What is the cause of a right bundle branch block?
Idiopathic in some dogs | Structural heart disease
63
Transient BBB’s can occur with??
Fast sinus tachycardia or SVT
64
What is atrial standstill?
Absence of atrial depolarization
65
ECG No P waves (no flutter or fibrillation ) QRS is normal Bradycardia Regular rhythm
Atrial standstill —> escape rhythm depolarizes ventricles
66
What are causes of atrial standstill?
Hyperkalemia Atrial myopathy Neuromyopathy (springer spaniel)
67
What is sick sinus syndrome?
Complex disturbance of conductive tissues resulting in - sinus bradycardia / sinus arrest - supraventricular or ventricular premature complexes (or SVT/VT) - first or second degree AV block
68
What causes sick sinus syndrome ?
SA node cells are replaced by fibrous/fibrofatty tissue- idiopathic
69
What breeds are predisposed to SSS?
Miniature schnauzer West Highland White terrier Dashunds Cocker Spaniel
70
What abnormalities will you see with hypokalemia?
Prolong repolarization -VPC/APC Lowers the resting membrane potential
71
What abnormalities would you see with MILD hyperkalemia ??
Shortened repolarization (Twave abnormalities are insensitive and non-specific)
72
What abnormalities would you see with a MODERATE hyperkalemia ?
Prolonged transmission velocity (wide QRS complexes)
73
What abnormalities do you see with SEVERE hyperkalemia ?
Prolonged PR interval or absent P wave Ventricular fibrillation Pulseless electrical activity/electromechanical dissociation (PEA/EMD)
74
What electrolyte in a major regulator in enzymatic reactions of potassium?
Mg

RUSVM SAM 1 (26 decks)

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