12. Peri-operative arrhythmias

Question 1

causes of sinus bradycardia

Answer 1

• vagal reflex (associated with hypotension) tx: atropine
• opioids/alpha 2s
• sudden onset hypertension
• Cushing’s response (BP high, compensatory mechanism for brain PP) tx:mannitol

(hypoglycemia, hypoxemia
hypothyroidism
hyperkalemia)

Question 2

causes of sinus tachycardia

Answer 2

• inc. adrenergic tone
• hypovolemia
• pheochromocytoma

Question 3

sequela of sinus tach

Answer 3

hypertension, hypotension

myocardial ischemia triggered arrhythmias

Question 4

sinus means?

Answer 4

one QRS for every P wave

Question 5

sinus arrhythmia in cats usually means vs. dogs?

Answer 5

upper respiratory obstruction

more common in normal dogs

Question 6

APCs common with?

hemodynamic consequences?

Answer 6

L atrial enlargement

- usually none, may have smaller pulse associate with the APC

Question 7

irregularly irregular rate associated with what arrhythmia?

breeds?

Answer 7

atrial fibrillation (no P wave) 
giant dog breeds, horses

Question 8

causes of atrial fibrillation

Answer 8

increased parasympathetic tone - triggered by opioids, GI/resp/neuro disease

Question 9

hemodynamic consequences of A fib

Answer 9

decreased CO

Question 10

second degree AV block

Answer 10

• prolonged or normal PQ followed by non conducted p wave

Question 11

all brady arrhythmias may be _______ response

Answer 11

Cushing

Question 12

mobitz type I vs. II

Answer 12

Second Degree AV block:

I - prolonged interval before nonconducted P wave
II - PQ constant before nonconducted P
II Hight grade - 2 consecutive nonconducted p waves

Question 13

treatment second degree av block

Answer 13

• anticholinergic may help
• pacemaker if chronic high grade
• dobutamine acts on beta adrenergic which increases HR

Question 14

before giving anticholinergic need to check what?

Answer 14

• blood pressure
  only treat if abnormal
• low dose ace, inc. inhalant to cause vasodilation if super low HR with normal BP

Question 15

Third degree AV block

Answer 15

complete dissociation between atria and ventricles - two independent rates

• junctional escape (40-60 bpm)
• ventricular escape (20-40 bpm)

Question 16

causes of third degree AV block?

Answer 16

very rarely vagally mediated

- idiopathic, neoplastic, hyperkalemia

Question 17

treatment third degree AV block

Answer 17

pacemaker
may respond to anticholinergic (if not a myocardial issue)
fix hyperkalemia..
(isoproterenol)

Question 18

sick sinus syndrome

why is it dangerous?
treatment?

Answer 18

idiopathic disease of sinus node

• WHWT, schnauzers, cockers
• periods of tachy, brady, long pauses in sinus (arrest) followed by escape rhythm
• may sound normal
• *when anesthetized pauses may become severely prolonged
• pacemaker!!

Question 19

Which drugs should you avoid in patients with life-threatening bradyarrhythmias?

Answer 19

opioids

alpha twos

Question 20

bundle branch block

ECG?
L vs. R?

Answer 20

impulse takes longer to get to ventricles

• p wave always associated with qrs.
• L block:severe disease vs. R block: may be incidental
• R BBB: deep s wave
• L BBB: wide, regular s

Question 21

treatment for VPCs

Answer 21

rarely necessary
lidocaine

if frequent, multifocal, frequent runs or impacts CO

Question 22

causes of VPCs

Answer 22

primary cardiac disease
trauma, shock, hypoxemia
electrolyte/AB imbalance
GDV
hemangiosarcoma

Question 23

ventricular escape rhythm

treatment?

Answer 23

ventricle beats because nothing else is, happens after a pause
- atropine not lidocaine!

Question 24

Idioventricular rhythm

causes?
tx?

Answer 24

Accelerated IR if rate >100
- FB, sepsis, GDV, hemoabdomen
- treat underlying cause
NOT LIDOCAINE may cause asystole; atropine if necessary

Question 25

VTach

two types?
treatment?

Answer 25

polymorphic - needs defibrillator, call for help
monomorphic - can not need

treatment - lidocaine in dogs

Question 26

ventricular fibrillation or PVT

time phases?

Answer 26

shockable

• electrical phase <2 min: shock first
• circulatory (4-6 min): 2 min chest compressions then defibrillate
• metabolic (>6min): irreversible damage

Question 27

treatment for asystole or PEA

Answer 27

low dose epi (.01 mg/kg) every other cycle (2 minute cycles, 120/min)
+/- atropine e/o cycle

Question 28

Causes of all the different AV blocks?

Answer 28

type 1 - vagal
type 2I: vagal/ opioids, alpha 2/ Cushing
type 2II: pathologic (not vagal)
type 3: idiopathic/pathologic