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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
What is this an example of?
Bigeminy
26
What is this?
Doublets
27
What are the VPD signs?
* Dropped heart sounds * Irregular pulse * Dropped pulses * Rarely--weakness/syncope * Commoner--sudden death * Not no's * Runs R-on-T
28
VPD treatment?
* 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
Drugs for VPD?
* **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
What is the treatment for VPD in cats?
* 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
Ventricular tachycardia
* 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
Treatment for VT?
* Treatment as for VPDs * Won't stop all VPDs or all deaths
33
Accelerated idioventricular rhythm/idioventricular tachycardia
* Spontaneous ventricular depolarizations at 60-180bpm * Capture and fusion beats * Asymptomatic mostly
34
Treatment for accelerated idioventricular rhythm/tachycardia?
* Correct underlying electrolyte/acid base imbalances or systemic conditions * **Monitor--VT may be coming**
35
Ventricular fibrillation
* Usually terminal * Irregular and disorganized ventricular activity * No CO/coronary flow * Coarse or fine * Arises from ectopic foci/reentry/'R on T'
36
Treatment for ventricular fibrillation?
* Electrical cardioversion--int/ext * Epinephrine * CPR
37
Atrial fibrillation
* 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
Atrial fibrillation--physical exam findings?
* Chaotic heart sounds * Variable and dropped pulses * (Sinal tachycardia--animal would be extremely afraid, in shock, pain, heart failure, etc.)
39
Treatment for atrial fibrillation?
* 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
Atrial fibrillation--cats?
* Usually with hypertrophic cardiomyopathy * Treat HCM w/ beta blocker and will treat atrial fib as well 1. Propranolol 2. Diltiazem 3. Digoxin contraindicated
41
Differential diagnoses for atrial fibrillation?
* 60 Hz interference * Atrial flutter

SAM 1 (20 decks)

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