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Small Animal Medicine II > Atrial Arrhythmias > Flashcards

Atrial Arrhythmias Flashcards

1
Q

What is ectopy? Single/couplet/triplet?

A

abnormal impulse formation not initiated by the SA node and rather from the atria, junctional, or ventricles

  • SINGLE = 1 abnormal beat
  • COUPLET = 2 abnormal beats
  • TRIPLET = 3 abnormal beats
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2
Q

What are more than 3 abnormal beats in a row?

A

paroxysm

(aka: salvo, burst, run)

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3
Q

What is the difference between bigeminy and trigeminy?

A

BIGEMINY = normal beat followed by one abnormal beat (repetitive pattern)

TRIGEMINY = 2 normal beats then one abnormal beat (repetitive pattern)

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4
Q

Where does atrial/supraventricular ectopy come from? How does this affect the ECG?

A

above the ventricles - atrial myocardium or AV node

  • P waves = abnormal morphology
  • QRS = narrow (conduction still passes through AV node to bundle of His and Purkinje fibers)
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5
Q

What is the difference between atrial premature complexes (APCs) and atrial/supraventricular tachycardia (SVT)?

A

APC = one abnormal complex

SVT = multiple abnormal complexes

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6
Q

What are atrial premature complexes (APCs)? What are 4 signs on an ECG?

A

supraventricular premature beats usually occuring with normal sinus rhythm

  1. premature P and QRS +/- abnormal P wave abnormalities
  2. narrow, upright QRS complex resembling sinus beats
  3. short TP interval before QRS complex, which may bury previous T wave
  4. variable PR interval
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7
Q

What are APCs frequently associated with? Is treatment necessary?

A

atrial enlargement (not always pathologic)

treat underlying disorder

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8
Q

What is occurring in this ECG:

A

2 APCs

  • premature P waves with abnormal morphology with non-compensatory pause
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9
Q

APCs vs. normal rhythm:

A

P wave came in too soon + pause for reset

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10
Q

APCs:

A

early P waves with abnormal morphology

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11
Q

What is occurring in this ECG?

A

APC @ 6th beat

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12
Q

What is atrial/supraventricular tachycardia?

A

rapid rhythm that originates above the ventricles, but not at the SA node —> ectopic focus = abnormal P waves, but hard to see during fast rates

  • often starts with an APC (>3 is considered tachycardic)
  • DOGS = >180 bpm
  • CATS = >240 bpm
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13
Q

What is a paroxysmal atrial/supraventricular tachycardia?

A

abrupt stop and start to signs on ECG

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14
Q

What treatment is used for atrial/supraventricular tachycardia? In what patient is this most commonly seen?

A

slow HR to maintain cardiac output - vagal maneuvers, medication

dogs or cats with severe heart disease (LA enlargement)

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15
Q

What is the difference between supraventricular tachycardia and sinus tachycardia? How are each treated?

A

SVT = PATHOLOGICAL fast HR >200 bpm in dogs (rare in cats), where an APC initiates it and it has an abrupt start and stop; treat rhythm

ST = physiologic increase in SA nodal rate with upright P waves with HR usually <200 bpm in dogs and <240 bpm in cats; treat underlying cause

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16
Q

What is occurring in this ECG?

A

SVT

  • APC initiates with abrupt start
  • HR > 200 bpm
  • cannot see P waves, but RR intervals are consistent
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17
Q

What is occurring in this ECG?

A

SVT —> sinus tachycardia

  • 11 beats in 3 s = 220 bpm, then 8 beats in 3 s = 160 bpm
  • look for underlying heart disease possibly causing SVT
18
Q

What is occurring in this ECG?

A

sinus tachycardia

  • upright P waves
  • HR < 200 bpm
  • consistent - no APC to start it off
19
Q

When do signs of SVT occur? What are 3 options for treatment?

A

if cardiac output falls —> weakness, syncope

  1. correct underlying problem
  2. vagal maneuvers to increase vagal tone to slow conduction through AV node - ocular pressure, carotic sinus massage, diving reflex (sudden immersion of head in cold water)
  3. thump on chest, cardioversion
20
Q

What are the main 2 acute pharmacologic therapies for SVT? Chronic therapy?

A
  1. calcium channel blockers (Diltiazem, Verapamil, Mexiltine) - minimal effect on vascular tone and inotropic state
  2. beta-blockers (Atenolol, Sotolol) - second option where vagal maneuvers and calcium channel blockers fail

Digoxin + beta-blockers + calcium channel blockers

21
Q

What are 5 signs on ECG in cases of atrial fibrillation?

A
  1. rapid HR (~200-240 bpm)
  2. irregularly, irregular rhythm
  3. inconsistent RR intervals
  4. absent P waves
  5. F waves - chaotic electrical activity in atria with no discernable P waves
22
Q

What is seen on physical exam in cases of atrial fibrillation? How does this affect cardiac output?

A
  • irregularly feeling pulse (ventricular filling times vary)
  • auscultation sounds like sneakers in a dryer

atrial muscle fibers are not coordinated and the atria no longer contribute to ventricular filling so there is decreased output

23
Q

What is the most common cause of atrial fibrillation?

A
  • pathologic, severe atrial enlargement —> common in dogs with DCM and cats with HCM
  • cats may have one instance of Afib where there is no underlying disease
24
Q

How are QRS complexes affected by atrial fibrillation?

A
  • ventricular rate will be high, but the complexes are normal
  • irregular rhythm due to AV activation of AV node randomly
25
Q

What effect does atrial fibrillation have on the heart? What 3 things are seen with chronic cases?

A

increased myocardial oxygen consumption —> myocardial hypoxia due to little time for diastolic perfusion

  1. additional arrhythmias
  2. cardiac remodeling
  3. turbulent flow can lead to blood clots (need anticoagulants in these patients)
26
Q

What is occurring in this ECG?

A

atrial fibrillation

  • irregularly irregular QRS/HR
  • absent P waves
  • F waves
27
Q

What is occurring in these ECGs?

A

atrial fibrillation

  • irregularly irregular QRS!
28
Q

What causes atrial flutter?

A

severe atrial enlargement causes rapid depolarization of atria (350-600/min) much faster than the ventricles causing up to 4 atrial beats (P) to every ventricular beat (QRS)

  • types of SVT
29
Q

What are 5 signs of atrial flutter on ECGs?

A
  1. rapid HR
  2. irregularly irregular rhythm
  3. inconsistent RR intervals
  4. absent P waves - F waves present (saw tooth pattern)
  5. multiple atrial beats to one ventricular beat
30
Q

What is seen in this ECG?

A

atrial flutter

  • inconsistent RR intervals
  • very fast F waves, but not all are conducted
  • several F waves for QRS complexes
31
Q

What is seen in this ECG?

A

atrial flutter

  • ~ 3 atrial beats per ventricular beat
32
Q

What are the 3 key features for treating atrial fibrillation/flutter?

A
  1. lowering ventricular response
  2. slow conduction through AV node
  3. get the lowest HR possible without cardiovascular compromise (140-160 bpm)
33
Q

What are 6 options for treating atrial fibrillation/flutter? When is treatment not necessarily needed?

A
  1. calcium channel blockers (Diltiazem)
  2. Digoxin + Diltiazem - better control of ventricular response rate, but more side effects
  3. beta-blockers (Atenolol, Sotalol) - use cautiously if systolic dysfunction is present
  4. Amiodarone - rate control, conversion of a lone AF to a sinus rhythm
  5. electrical cardioversion
  6. anticoagulants - prone to thromboemboli due to turbulent flow

normal HR and no structural disease —> optimal control is <150 bpm in hospital and 70-120 bpm at home

34
Q

What is the goal of treating SVT? What are 5 options?

A

help AV node to slow the rate

  1. Amiodarone (potassiun channel blocker) - conversion in early disease
  2. Beta-blockers
  3. Calcium channel blockers (Diltiazem)
  4. Digoxin (Vagomimetic)
  5. Electrocardioversion under anesthesia
35
Q

Atrial tachycardias:

A
36
Q

What is atrial bradyarrhytmia? What are the most common primary and secondary causes?

A

atrial standstill resulting from failure of the atria to depolarize despite normal sinus node discharge (dogs > cats) = no P waves + regular junctional escape rhythm ~40 bpm

  1. primary atrial myopathy - muscular dystrophy in English Springer Spaniels
  2. secondary myopathy - sinoventricular rhythm from hyperkalemia
37
Q

What are some causes of hyperkalemia? How does this affect the ECG?

A
  • urinary obstruction
  • iatrogenic (fluids, supplements)
  • Addisonian crisis
  • reperfusion injury

SINOVENTRICULAR RHYTHM - relatively normal QRS complexes lacking P waves —> 40 bpm —> treating hyperkalemia may bring back P waves

38
Q

What are 5 signs of sinoventricular rhythm on ECGs?

A
  1. bradycardia
  2. tall T waves (spiked)
  3. small P waves (typically disappear)
  4. prolonged QRS complexes with reduced R waves (seems sinusoidal)
  5. eventual cardiac arrest if hyperkalemia is not reversed
39
Q

Sinoventricular rhythm, hyperkalemia:

A
40
Q

Hyperkalemia:

A

sinoventricular rhythm

  • higher K = wider, more bizarre QRS complex
41
Q

What treatments are indicated with sinoventricular rhythm?

A

decrease K

  • unblock cat
  • treat Addisons
  • calcium gluconate - cardioprotective
  • fluids with insulin - move K into cells
  • Lasix - K excretion

Small Animal Medicine II (57 decks)

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