Syncope Flashcards
(17 cards)
What is syncope?
Global hypoperfusion of the brain causes transient loss of consciousness.
What causes reflex syncope?
Vagal output from the brain releases acetylcholine to the heart, causing a cardioinhibitory effect, reducing heart rate, cardiac output, and systolic blood pressure.
What is the effect of reflex syncope on the vascular system?
It causes a vasodepressor effect which leads to vasodilation, reducing diastolic blood pressure and cerebral perfusion.
What are some reasons for reflex syncope?
1) Vasovagal: increased pain, phobia, standing for a long time,
2) Situational: triggers, coughing, micturition
3) carotid sinus hypersensitivity, carotid sinus massage, tight collar, head turn.
What is orthostatic syncope?
It occurs in patients with reduced venous return, leading to reduced preload, stroke volume, cardiac output, and blood pressure.
What causes orthostatic syncope?
1) Hypovolemia- vomiting/diarrhea, polyuria, burns, profuse sweating, bleeding
2) vasodilators- calcium channel blockers, alpha 1 blockers
3) ANS neuropathy- sympathetic nerves that release adrenaline/noradrenaline to vasoconstrictor the vessels, lose their ability to do so due to a neuropathy, this leads to reduced systemic vascular resistance, and therefore reduced venous return
What is cardiogenic syncope?
It is caused by reduced cardiac output, leading to reduced blood pressure and cerebral perfusion.
What are some causes of cardiogenic syncope?
1) Arrhythmias- tachycardia- increased HR- reduced diastolic filling- reduced SV- reduced CO. eg. VT/VF
- bradycardia- heart blocks
2) mechanical causes, reduced contractility (MI, HR with RReF), reduced filling (tension pneumothorax, cardiac tamponade), increased afterload (Hypertrophic cardiomyopathy, Aortic stenosis, PE)
What should be considered when taking histories for reflex syncope?
Ask about triggers, pain, visual triggers, and straining.
What should be considered when taking histories for orthostatic syncope?
Ask about positional changes.
What should be considered when taking histories for cardiogenic syncope?
Ask about sudden onset, arrhythmias, palpitations, chest pain, and other cardiac symptoms.
What is a diagnostic approach for orthostatic syncope?
Check orthostatic blood pressure; a difference of more than 20mmHg in systolic or diastolic BP, or an increase in HR greater than 10 when sitting and standing is diagnostic.
What is the role of ECG in diagnosing syncope?
Get an ECG to check for arrhythmias.
How can you differentiate between syncope and seizures?
Syncope involves loss of consciousness without jerky movements, aura, tongue biting, or incontinence, with rapid return of consciousness. Seizures involve tonic-clonic activity, aura, tongue biting, incontinence, and post-ictal confusion.
What is the treatment for reflex syncope?
Treat the cause.
What is the treatment for orthostatic syncope?
Fluids and stopping vasodilators.
What is the treatment for cardiogenic syncope?
Treat the cause.
