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Arrhythmias Flashcards

1
Q

Sinus arrhythmia

A
  • P for every QRS but R-R varies
    • All PQRS complexes look the same–rate is just what is varying
  • SA node rate varies w/ respiration
    • HR increases w/ inspiration, decreases w/ exhalation
  • Vagal tone–fit, brachycephalic, chronic bronchitis
  • Eye/abdominal surgery
    • Atropine
  • No treatment required
  • Not normal in cats–only dogs
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2
Q

Wandering atrial pacemaker

A
  • P waves from outside SA node
  • Variable morphology/amplitude of P wave
    • Usually goes in nice wave pattern (+, -, +, etc.)
  • Variable P-R interval
  • Increased vagal tone usually
  • No hemodynamic consequences–no treatment
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3
Q

Sinus bradycardia

A
  • Rate
  • Outside the heart–drugs, lytes, thyroid, vagal tone–eye/gut, respiratory, lesions, idiopathic (atropine test)
    • Atropine test: kills vagal tone–> HR goes up
    • Drugs: digoxin (causes any arrhythmia), xylazine, beta blockers, lidocaine
  • Inside the heart–fibrosis, infect, trauma, neoplasia, idio
    • Signs if > 6-8 s
  • Exercise animal to make sure HR goes up (could just have a normally slow HR)
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4
Q

Treatment for sinus bradycardia?

A
  • Remove the cause
    • Correct the drug dose/use
    • Lower the K
    • Treat the hypothyroid
  • Atropine or glycopyrrolate test
      • = look for vagal problems
        • Terbutaline/isoproterenol/isopropamide/ probanthine
        • Need to counteract PNS–can’t block it so increase SNS instead
      • = pacemaker if clinical
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5
Q

Pacemaker

A
  • Pulse generator
  • Pacing leads endo/epicardial
    • Transvenous (through jugular vein–> bottom of right heart)
    • Epicardial
    • Transdiaphragmatic
  • Demand; exercise
  • Infection; scarring; twitching; arrhythmias; effusion
  • Cannot re-use human pacemakers
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6
Q

Sinus arrest

A
  • Failure of SA node–1/more beats
  • Drugs/lytes/vagal tone, etc. as before
  • > 6 s = signs
  • Atropine test, check lytes; treat as you would for sinus arrhythmia
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7
Q

Junctional (nodal)/ventricular escape beats

A
  • Keeps circulation going to brain (keeping animal alive) when the sinus beat fails to materialize
  • Normal QRS but no P wave = junctional
  • Abnormal QRS + no P wave = ventricular
  • Junctional escape will occur first, then ventricular (often if junctional doesn’t work)
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8
Q

Which monitor can be used to record junctional/ventricular escape beats?

A
  • Holter/cardiac event monitor–continuous recording, only remembers last 30-60 sec; hit button to record last minute to permanent memory
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9
Q

What is the treatment of junctional/ventricular escape beats?

A

Positive chronotropes/pacemaker

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10
Q

Hyperkalemia

A
  • Renal failure; ATE; hyperadrenocorticism; crush
  • Raises resting membrane potential–> heart fibrillates
  • Bradycardia
    • T waves tall
    • P waves disappear
    • Prolonged QRS
    • Sinusoidal shape
  • Bicarb/glucose, Ca glutonate for treatment
    • Give fluids that don’t contain K
    • Boluses of glu better than insulin–glu raises insulin levels
    • Bicarb works if underlying cause is acidemia
    • Ca effusion to lower resting membrane potential
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11
Q

AV block

A
  • Delay or failure of transmission at the AV node
  • Outside heart–drugs, lytes, thyroid, vagus
  • Inside–ischemia, -itis, neo, trauma, genes, idio
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12
Q

1st degree AV block

A
  • PR > 0.13s/0.09s
    • Usually drugs or vagal tone
  • No treatment–monitor
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13
Q

2nd degree AV block–Mobitz type I

A
  • Intermittent failure of conduction
  • Mobitz type I
    • PR interval increases until QRS dropped–Wenkebach
    • Vagal tone/drugs
  • P wave consistent = sinus perfectly fine
    • QRS not responding consistently = intermittent AV block
  • Can hear clinically–watch chest to differentiate from sinus arrhythmia
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14
Q

2nd degree AV block–Mobitz type II

A
  • No PR changes before dropped QRS
  • Node disease
  • Ratio– P : QRS
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15
Q

2nd degree AV block–high grade node disease

A
  • Can’t tell if it’s Mobitz type I or II
  • Only 1 normal beat before dropped beat
  • High grades more likely to develop into type III down the road (= BAD) –> poor prognosis
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16
Q

3rd degree AV block

A
  • No AV conduction
  • P waves and escape beats
    • AV/junctional (40-60 bpm)
    • Ventricular < 40 – bizarre-looking
    • Completely independent of each other
  • Give atropine test, check lytes
    • Usually ends up being disease of AV node
    • Damaged–> replaced by fibrous tissue
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17
Q

What is the treatment for AV block?

A
  • Treat the cause–stop dig, treat itis
  • If symptomatic try drugs if responsive to atropine test
  • Emergency isoproterenol/dopamine IV (if responsive to atropine)
  • If not atropine responsive:
    • Pacemaker–inc. survival over 6 months
      • Need for grade III
  • Won’t always show clinical signs (ex: old dogs who don’t exercise)
    • Pay attention to dogs with low heart rates during physical exams–normally nervous/excited
18
Q

Sick sinus syndrome

A
  • Abnormal sinus node and AV system
    • Sinus bradycardia
    • Intermittent sinus arrest/AV block
    • Paroxysms of tachycardia
  • Intermittent weakness/syncope
    • Send home w/ monitor
  • Drugs??–ventricular demand pacemaker
    • Can’t use drugs to treat both–one will make the other worse
  • Pacemaker to treat sinus arrest, then drugs to control tachycardia
19
Q

Sinus tachycardia

A
  • Increased HR– > 160-180bpm/240bpm
  • Normal P QRST
    • ​No arrhythmia, HR just too fast
  • Physiological–fear, pain
  • Pathological–fever, anemia, thyroid
    • Anemia–heart beat is stronger–heart must pump fewer # of RBCs harder/faster to effectively reach tissues; “waterhandle” pulses
    • Common in cats with hyperthyroidism
20
Q

SPD’s and sinus tachycardia

A
  • Premature
    • Part of the atrium depolarizes spontaneously–> can become pacemaker–> premature depolarization
  • Variable P
  • May be buried in T wave
  • Normal QRS
  • Lab/boxer–8y–66% heart disease
    • Cardiomyopathy
    • Neoplasia
    • Re-entry
21
Q

Diagnosis?

A

Supraventricular premature depolarization

22
Q

What are the signs/treatment of sinus tachycardia?

A
  • Signs occur if CO falls
    • Weakness, syncope
  • Treat the underlying cause
  • Slow the heart
    • Emergency–esmolol/diltiazam (slow; BP)
      • Thump on chest, vagal maneuvers, cardioversions
    • Maintenance–sotalol (oral, BID)/diltiazem
    • Pathway ablation
23
Q

Ventricular premature depolarizations (contractions)

A
  • Ectopic focus–ventricle
  • Hypertrophy, inflammation, trauma, hypoxia, drugs, systemic conditions, anesth., etc.
  • QRS–premature + no P wave
    • Wide and bizarre
  • Junctional escape beats–premature = occurs after very short beat
24
Q

Triplets and fusion beats–what do they look like?

A
  • Mix of P wave and ectopic focus
  • Might look like multiple lesions–>look for P wave to ensure fusion beat
25
Q

What is this an example of?

26
Q

What is this?

27
Q

What are the VPD signs?

A
  • Dropped heart sounds
  • Irregular pulse
  • Dropped pulses
  • Rarely–weakness/syncope
  • Commoner–sudden death
    • Not no’s
    • Runs R-on-T
28
Q

VPD treatment?

A
  • Underlying disorders
  • Specific therapy
    • If symptomatic**
    • If heart disease
      • Boxer cardiomyopathy
      • Doberman w/ DCM
      • Aortic stenosis
      • Hypertrophic cardiomyopathy
        • High rate, R-on-T, too many
29
Q

Drugs for VPD?

A
  • In emergencies–parenteral
    • Lidocaine
      • Boluses–CRI–K and Mg?
      • Procainamide–IV, IM, SC
      • Esmolol IV then sotalol/propranolol
      • Magnesium
      • Amiadarone?
  • Non-emergency/when stable
    • Sotalol–contractility? (Boxers w/ ARVC)
    • Mexiletine (+ beta blocker) (Dobies w/ DCM)
    • Sotalol and mexiletine, beta blocker–contractility? SAS Procainamide
30
Q

What is the treatment for VPD in cats?

A
  • Correct underlying causes
  • Initial control–propranolol/atenolol
  • 2nd = lidocaine–low dose boluses–CRI
  • Procainamide/quinidine
  • Sotalol? Amiodarone?
  • Maintenance
    • Oral propranolol/atenolol
    • Procainamide, quinidine
    • Mexiletine
31
Q

Ventricular tachycardia

A
  • Serious–maybe pre-fibrillatory–same causes as VPD
  • Runs at > 3VPDs at > 160-180 bpm
  • Sustained > 30s
  • Non-sustained–dec. ectopic focus firing/capture beats
  • Signs: 300 bpm for > 6-8s (heart fx)
32
Q

Treatment for VT?

A
  • Treatment as for VPDs
  • Won’t stop all VPDs or all deaths
33
Q

Accelerated idioventricular rhythm/idioventricular tachycardia

A
  • Spontaneous ventricular depolarizations at 60-180bpm
  • Capture and fusion beats
  • Asymptomatic mostly
34
Q

Treatment for accelerated idioventricular rhythm/tachycardia?

A
  • Correct underlying electrolyte/acid base imbalances or systemic conditions
  • Monitor–VT may be coming
35
Q

Ventricular fibrillation

A
  • Usually terminal
  • Irregular and disorganized ventricular activity
  • No CO/coronary flow
  • Coarse or fine
  • Arises from ectopic foci/reentry/’R on T’
36
Q

Treatment for ventricular fibrillation?

A
  • Electrical cardioversion–int/ext
  • Epinephrine
  • CPR
37
Q

Atrial fibrillation

A
  • Common–DCM + lone AF
  • Chaotic activity
    • Multiple ectopic foci
  • No P waves
  • Normal QRS
  • R-R random
  • No “atrial push”
  • Tachycardia–Inc. myocardial O2 demand but dec. CO and dec. cardiac perfusion (coronary flow down 60%)
38
Q

Atrial fibrillation–physical exam findings?

A
  • Chaotic heart sounds
  • Variable and dropped pulses
  • (Sinal tachycardia–animal would be extremely afraid, in shock, pain, heart failure, etc.)
39
Q

Treatment for atrial fibrillation?

A
  • If heart function and rate normal
    • No treatment/cardioversion
    • Monitor with echo/Holter
  • If heart function normal but rate up (> 150bpm)
    • Slow ventricular response rate
      • Can’t get rid of atrial fib at this stage
      • Diltiazam (Ca channel blocker)
      • Beta blocker–stops SNS from affecting heart–+ ionotropic effect (caution–can push into failure)
      • Cardioversion
  • If heart function decreased and rate up
    • Slow ventricular response rate
      • Digoxin and diltiazem/beta blocker until < 150bpm
      • Amiodarone/cardioversion (?)
40
Q

Atrial fibrillation–cats?

A
  • Usually with hypertrophic cardiomyopathy
    • Treat HCM w/ beta blocker and will treat atrial fib as well
  1. Propranolol
  2. Diltiazem
  3. Digoxin contraindicated
41
Q

Differential diagnoses for atrial fibrillation?

A
  • 60 Hz interference
  • Atrial flutter

SAM 1 (20 decks)

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