12. Peri-operative arrhythmias Flashcards
causes of sinus bradycardia
- 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)
causes of sinus tachycardia
- inc. adrenergic tone
- hypovolemia
- pheochromocytoma
sequela of sinus tach
hypertension, hypotension
myocardial ischemia triggered arrhythmias
sinus means?
one QRS for every P wave
sinus arrhythmia in cats usually means vs. dogs?
upper respiratory obstruction
more common in normal dogs
APCs common with?
hemodynamic consequences?
L atrial enlargement
- usually none, may have smaller pulse associate with the APC
irregularly irregular rate associated with what arrhythmia?
breeds?
atrial fibrillation (no P wave) giant dog breeds, horses
causes of atrial fibrillation
increased parasympathetic tone - triggered by opioids, GI/resp/neuro disease
hemodynamic consequences of A fib
decreased CO
second degree AV block
- prolonged or normal PQ followed by non conducted p wave
all brady arrhythmias may be _______ response
Cushing
mobitz type I vs. II
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
treatment second degree av block
- anticholinergic may help
- pacemaker if chronic high grade
- dobutamine acts on beta adrenergic which increases HR
before giving anticholinergic need to check what?
- blood pressure
only treat if abnormal - low dose ace, inc. inhalant to cause vasodilation if super low HR with normal BP
Third degree AV block
complete dissociation between atria and ventricles - two independent rates
- junctional escape (40-60 bpm)
- ventricular escape (20-40 bpm)
causes of third degree AV block?
very rarely vagally mediated
- idiopathic, neoplastic, hyperkalemia
treatment third degree AV block
pacemaker
may respond to anticholinergic (if not a myocardial issue)
fix hyperkalemia..
(isoproterenol)
sick sinus syndrome
why is it dangerous?
treatment?
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!!
Which drugs should you avoid in patients with life-threatening bradyarrhythmias?
opioids
alpha twos
bundle branch block
ECG?
L vs. R?
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
treatment for VPCs
rarely necessary
lidocaine
if frequent, multifocal, frequent runs or impacts CO
causes of VPCs
primary cardiac disease trauma, shock, hypoxemia electrolyte/AB imbalance GDV hemangiosarcoma
ventricular escape rhythm
treatment?
ventricle beats because nothing else is, happens after a pause
- atropine not lidocaine!
Idioventricular rhythm
causes?
tx?
Accelerated IR if rate >100
- FB, sepsis, GDV, hemoabdomen
- treat underlying cause
NOT LIDOCAINE may cause asystole; atropine if necessary
VTach
two types?
treatment?
polymorphic - needs defibrillator, call for help
monomorphic - can not need
treatment - lidocaine in dogs
ventricular fibrillation or PVT
time phases?
shockable
- electrical phase <2 min: shock first
- circulatory (4-6 min): 2 min chest compressions then defibrillate
- metabolic (>6min): irreversible damage
treatment for asystole or PEA
low dose epi (.01 mg/kg) every other cycle (2 minute cycles, 120/min)
+/- atropine e/o cycle
Causes of all the different AV blocks?
type 1 - vagal
type 2I: vagal/ opioids, alpha 2/ Cushing
type 2II: pathologic (not vagal)
type 3: idiopathic/pathologic
