i have been experiencing heart beating very fast, when i smoke , i dont smoke weed/marijuana, i a5ft2 and 7.5 stone in weight, i have slight level of cholestrol not known how high, this only occurss mainly when i am smoking , as soon as i light up the cig and pumps away the heart fast, sometimes the beating can last 20-30mins ven after smoking - i have been to the dr, had my blood checked out and ECG was carried out, al they said was i had to much adrenaline and everything was ok. how i feel unease about this, i never had this problem before, i ave been smoking for about 9 years and only experienced this problem for about 2 yrs please help ad what is the cause f this?