Syncope

Question 1

pre-syncope

Answer 1

episodic weakness, intermittent profound hypotension resulting in reduced blood flow to the brain
arrhythmia and tachycardia but less profound than in syncope

Question 2

syncope

Answer 2

intermittent profound hypotension resulting in marked reduction in blood flow to the brain

Question 3

collapse

Answer 3

falling down

Question 4

cardiogenic causes of collapse

Answer 4

bradycardia -
dogs <60bpm
cats <100bpm
can be drug induced - ACP, opioids, alpha 2s
sinus bradycardia - doesn’t lead to syncope

tachycardia -
dogs >160bpm
cats >200bpm
supraventricular tachycardia - usually atrial defibrillation
ventricular tachycardia - boxers - CO drops rapidly, can lead to sudden death

Question 5

neurocardiogenic causes of collapse

Answer 5

vasovagal syncope

combination of bradyarrythmia and vasodilation
exacerbated by structural heart disease or concurrent GIT disease

c-fibre signal to brain –> sympathetic withdrawal and increased vagal tone –> vasodilation and bradycardia –> collapse

fight or flight
DCM
genetics
high preload
situational syncope - easily identified trigger - eg cough, common in small, middle age or old dogs

Question 6

other causes of collapse

Answer 6

HCM in cats
pulmonary hypertension
impaired right side inflow
hypoxia and hypoglycemia - insulinoma
severe anemia with exertion
exercise induced

Question 7

non-syncopal collapse

Answer 7

neurological conditions
profound
hypoxemia
metabolic - hypoadrenocorticism, hypoglycemia

Question 8

ddx cardiac syncope and pre-syncope

Answer 8

hypotension inducing arrythmia - sinus arrest, ventricular tachycardia, atrioventricular block

combination of structural heart disease and less hypotensive inducing arrhythmia, with or without exertion

Question 9

presentations associated with cardiac syncope/pre-syncope

Answer 9

cyanosis
jugular pulsation/distension
heart mumurs
arrhythmias
wheezes/crackles
asynchronous femoral pulses
tachypnoea
bradycardia
rebound tachycardia
flaccid limb and body tone, loss of bladder/bowel control - during syncope

Question 10

tests for investigating causes of syncope and pre-syncope

Answer 10

blood tests -
complete blood count
biochem and electrolytes
cardaic troponin 1
NT-proBNP

blood pressure

ECG

thoracic and abdominal imaging - ultrasound and radiography

halter monitor - monitor up to 7 days while doing normal activity