DR RV ANAND SENIOR NEUROLOGIST CHENNAI MEENAKSHI HOSPITAL SYNCOPE can also be due to cardiac causes.it can be both due to fast heart beat and slow heart beat due to disturbances in the electrical system of heart it can also be due to block in the blood flow from the heart as it happens in AORTIC STENOSIS or HYPERTROPHIC CARDIOMYOPATHY it can happen due to postural fall of blood pressure as in conditions like 1 dehydration 2.alcohol consumtion 3.blood loss due to various causes 4.anti hypertensive medivcation especially class of drugs called as alpha blockers