Hello! Welcome and thank you for asking on HCM! I understand your concern and would explain that these episoded of fainting could be related to different causes. A low blood pressure could be the cause, as the blood pressure that you refer is low. Anyway a careful check up from his GP is needed to exclude other causes like a possible cardiac arrhythmia or epilepsy seizures. I would recommend performing some tests to exclude the above mentioned disorders: - resting ECG - chest x ray study (aorta) - head up tilt test (for orthostatic hypotension) - an EEG (for possible epilepsy) - some blood lab tests (complete blood count, fasting glucose, kidney and liver function tests, blood electrolytes, etc). Meanwhile, the best thing to do is to give him plenty of fluids and monitor his blood pressure. Hope to have been helpful! Best regards, Dr. Iliri