Smoked weed once,probably a bit too much.started showing symptoms of heart valve disease.ecg,blood test, said nothing.im never gonna smoke again.what do i do cos im really worried.especially cos of the random palpitations that stop me in my tracks?

Using cannabis "once" will not cause the cardiac abnormalities cited in your question. Generally, overuse of cannabis may just uncover cardiac defects not obvious previously. Get a referral to a cardiologist for a complete workup as soon as possible.

It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water. Wish you good health!