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Boards: Cardiovascular > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

On a 6 lead ECG (3 standard + augmented leads), which one is inverted?

A

aVR (right arm)

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2
Q

How do Bundle Branch blocks affect the mean electrical axis?

A

LBBB –> deviates to left and up
RBBB –> deviates right

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3
Q

Name 2 differentials for decreased voltage on ECG

A
  • pericardial effusion
  • myocardial damage (infarction or decreased mass)
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4
Q

How does Hypertrophy affect the ECG?

A

deviates MEA towards the hypertrophy
hypertrophy will require longer time for electrical impulse traveling through and more muscle mass will create greater electrical impulse

longer travel time (prolonged conduction) –> prolonged QRS

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5
Q

How does a bundle branch block affect the T wave?

A

LBBB - T wave inverted
RBBB - upright

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6
Q

What are the 2 types of 2nd degree AV block?

A

Mobitz type I (Wenkebach) - PR interval increases with every beat until it finally drops

Mobitz type II - suddenly P without QRS

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7
Q

What is the idioventricular rate?

A

less than 40

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8
Q

Explain Stokes-Adams Syndrome

A

total AV block that comes and goes - when AV node is suddenly blocked ventricular escape needs 5-30 seconds to kick in due to overdrive suppression from previous sinus impulse

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9
Q

How does the T wave change after a VPC?

A

inverted to the polarity of the QRS

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10
Q

What are causes of QT prolongation, what does a prolonged QT interval predispose to?

A

hypocalcemia, hypokalemia, hypomagnesemia

predisposes to torsades de pointes

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11
Q

Describe the difference between atrial fibrillation and atrial flutter

A

atrial fibrillation alway have an irregularly irregular beat, impulses travel uncoordinated from different ectopic niduses

atrial flutter - can be irregular or regular, electrical impulse continues to travel through atrium - circus movement

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12
Q

How can you differentiate an ectopic beat of a VPC coming from the right side or the left side of the heart?

A

L-side - RBBB morphology, deep S wave
R-side - LBBB morphology, upright

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13
Q

What rate is considered VT in cats versus dogs?

A

over 180 (dogs), over 240 (cats)

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14
Q

Name 3 breed-related heart conditions commonly leading to ventricular arrhythmias

A
  • Dobermann Pincher, DCM
  • Boxer, ARVC
  • German Shepherd, IVAGSD
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15
Q

What are the beta-1 and beta-2 effect proportions of atenolol, esmolol, and propranolol

A

atenolol, beta-1 and beta-2 but more beta 1
esmolol, beta-1 selective

propranolol - nonselective beta blockade

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16
Q

Why are class II antiarrhythmics contraindicated in CHF?

A

because of further suppression of systolic function (negative inotropic), can worsen HF

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17
Q

What class effects does Sotalol have?

A

II, III

beta-blocking
K-channel blocking (main effect)

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18
Q

What class effects does amiodarone have?

A

all I, II, III, IV

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19
Q

Why do VPCs have wider QRS complexes than sinus beats?

A

because they don’t use the normal conduction system - sinus beat ventricular depolarization initiated through Purkinje Fibers which have an extremely fast conduction velocity - will be slower to travel through ventricular myocytes

20
Q

Describe the physiologic AV block

A

means that atrial rate is too high and the AV node “purposefully” filters out impulses to slow the ventricular rate, protective

21
Q

What group of tachyarrhythmias are more responsive to vagal maneuvers?

A

SVTs - VT almost never repsond to vagal maneuvers

22
Q

Describe how you would perform a vagal maneuver

A

carotid massage - between mandibular arch and atlas wings - apply pressure from ventrally to the neck for 5-10 seconds

ocular - apply gentle pressure to the closed eye

23
Q

What is the recommended ergency treatment for SVTs?

A

Diltiazem and/or beta-blockers

24
Q

Name 3 oral treatment options for VTs.

A

Sotalol, mexiletin, amiodarone

25
Q

Describe how you would perform an atropine response test

A

give 0.04 mg/kg atropine IV or IM
if IV - recheck ECG 15 min later
if IM - recheck 30 min later

rate should increase by 50-100%??

26
Q

Name long term oral treatment options for atropine-responsive bradyarrhythmias. What are the MOAs of these drugs?

A

theophylline - methylanthine bronchodilator
terbutaline - beta-2 agonist (bronchodilator)

27
Q

List 4 drug classes that may induce bradycardia

A

sedative
opioids
antiarrhythmics
anesthetics

28
Q

What classifies a second-degree AV block as high degree?

A

if there are more lone Ps than conducted QRS

or consecutive non-conducted atrial impulses

29
Q

What are typical escape rates in dogs and cats

A

20-60 dogs
80-140 cats

30
Q

Explain overdrive suppression in SSS

A

ventricles are overdriven by the previous sinus rhythm (often tachycardia if tachycardia-bradycardia syndrome) - when the sinus block/arrest happens ventricular escape can not “kick in” as fast because of the overdrive - long pause and often syncope

31
Q

Explain the steps of temporary transvenous pacing

A

femoral or left jugular vein (R jug preserved for potential permanent pacemaker insertion)

depending on patient temperament with or without sedation (e.g., opioid + parasympatholytic), sterile prep of the left neck, insertion of introducer catheter large enough to fit electrode –> advanced into the right ventricle, apex
optional: balloon at end inflate once RA, deflate once past the

confirm correct placement via fluoroscopy or echocardiogram

set desired heart rate
gradually increase pacing output (mA) until capture is noted on ECG
pacing: VVI (ventricle paced, ventricle sensed, pacing inhibited during sensed event)
starting sensitivity 2-4 mV

32
Q

What are typical sensitivity settings for temporary pacing?

A

2-4 mV

33
Q

How long do pauses in heart beat usually last before causing syncope (e.g., in SSS or sinus arrest)

A

longer than 6-8 seconds

34
Q

How do you differentiate sinus block and sinus arrest?

A

often difficult to differentiate, some references say block is one beat and arrest is longer
other references: sinus arrest - no sinus impulse initiated, sinus block: electrical impulse happens but can’t leave the SA node because not conducted

35
Q

What is a wandering pacemaker?

A

changes in P wave amplitude corresponding to breathing cycles, when vagally mediated bradycardia

higher P waves during higher HR during inspiration

36
Q

Explain the Bezold-Jarish reflex

A

increased activity/excitement/coughing/vomiting –> tachycardia and hypercontractile ventricle –> intraventricular receptors (C vagal fibers) –> causes reflex simiar to vasovagal reflex

vagal afferent nerves –> medulla –> vagal efferent nerve –> slowing HR suddenly after tachycardia

37
Q

At what PR interval length is the interval considered prolonged in dogs or cats?

A

dog > 130 ms
cat > 90 ms

38
Q

How can you use an atropine response test to differentiate Mobitz type 1 from type 2 AV block?

A

mobitz 2 will not respond or get worse

39
Q

What are the adverse effects of parasympatholytics/

A

dry mouth, constipation, mydriasis, urinary retention, neurologic signs

40
Q

What is the most likely diagnosis in a young/middle-aged dog with paroxysmal SVT that is not systemically ill?

A

Atrioventricular accessory pathway - congenital muscular bundles penetrating the normal fibrous skeleton between atria and ventricles

more often concealed to only move retrograde from ventricle to atria

41
Q

Name 3 proposed mechanisms of myocardial dysfunction from sustained SVTs

A
  • increased HR - increased work –> impaired myocardial energy utilization + energy depletion
  • increased HR –> impaired coronary blood flow –> ischemia
  • abnormal Ca handling
42
Q

List differentials for SVTs with an irregular rhythm

A
  • atrial fibrillation
  • atrial flutter (can be regular too)
  • multifocal atrial tachycardia
43
Q

SVTs usually have QRS durations of less than XXXX in dogs and YYYYY in cats

A

70 ms (dogs), 40 ms (cats)

44
Q

List ways to differentiate SVTs and VTs

A
  • wide QRS VT, narrow QRS SVT (exception SVT with BBB)
  • irregular SVT (both VT and SVT can be regular)
  • atrioventricular dissociation VT
  • abnormal mean electrical axis VT
  • fusion beat VT
  • VT opposite direction T wave, SVT either positive or negative
  • distinct J point SVT
  • response to vagal maneuver SVT
  • response to lidocaine VT
45
Q

What is the in-hospital goal for rate control of the ventricular repsonse rate in afib?

A

160-180

46
Q

Define ventricular tachycardia

A

ventricular rhythm with HR >180

47
Q

Define sustained versus nonsustained VT

A

sustained > 30 seconds

Boards: Cardiovascular (19 decks)

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