Causes

Common causes of syncope include vasovagal syncope and arrhythmias

cause	medical referral b	emergency department b	elderly in a long-term care facility b	young c
cardiovascular cause	25%	21%		3%
- arrhythmia			7%
-- any tachyarrhythmia		7%
-- ventricular tachycardia	11%
-- supraventricular tachycardia	2%
-- bradycardia, 2nd or 3rd degree heart block	3%	11%
-- sick-sinus syndrome	3%
- aortic stenosis	2%	1%	5%
- carotid sinus syndrome		2%-24%
- pulmonary embolism		1%
neurological cause		14%
- seizure disorder	2%	3% to 9%	3%
- transient ischaemic attacks	2%	11%
non-cardiovascular cause	33%	35%
- vasovagal syncope	8%	30% to 70%		12%
- situational syncope	8%	3.5%		3%
-- micturition		2%
-- defecation			5%
-- post-prandial			8%
- orthostatic hypotension	10%	6% to 37%	6%	2%
-- drug-induced syncope	2%		11%	0%
-- volume depletion		3%	4%
- hypoglycaemic		0.5% to 2%
- psychiatric	0.7%	0.6% to 6%		39%
- unknown	41%	14% to 38%	26%	33%