Hi Monteforte, Thank you for your query, Bicuspid Aortic valve without any leakage(regurgitation) or stenosis(narrowing) of valve occurs in approximate 0.5% normal population. The smoking pot or marijuana in small quantity and never as cocktail of drink + smoking (Nothing is better then not taking drugs at all) or never progress to taking drugs intravenously can be positively harmful both for Nervous System (previous episode of loss consciousness could have been stoned out a severe potentially damaging neurological illness) and cardiovascular system, with bicuspid aortic valve your son stands a higher risk of infection of the valve(in case of i/v use). Otherwise side effects of pot smoking on heart include and not limited to as follows: If the smoking is less it is correct that there are no catastrophic effects in young age, nonetheless, taking drug as cocktail with alcohol or taking too much of it neutralizes the benefit of young age and you still can have following: Marijuana increases heart rate by 20-100 percent shortly after smoking; this effect can last up to 3 hours. In one study, it was estimated that marijuana users have a 4.8-fold increase in the risk of heart attack in the first hour after smoking the drug. This may be due to increased heart rate as well as the effects of marijuana on heart rhythms, causing palpitations and arrhythmias. This risk may be greater in aging populations or in those with cardiac vulnerabilities. Bicuspid aortic valve comes under vulvnerability . Dr Anil Grover, Medical Specialist and Cardiologist.