What can I do about severe heart palpitation?

Palpitations. Need to diffrentiate underlying etiology. Need to diagnose whether it is from anxiety disorder or cardiac arrythmias. You will get benefit from ekg, holter monitor and/or event monitor. You should see a pcp and eventually a cardiologist.
Palpitation treat. Treatments include not using caffeine, alcohol , street drugs, smoking and other stimulant substances. Try to learn meditation and other calming techniques, cut out herbal substances, cough and cold medicines, nutritional supplements, see your doctor to be sure no direct heart problem and for treatment if the basics above don't help.