Dorothy,   Thanks for your question.  Your symptoms may just be palpitations from early heart beats from the small chamber, called premature atrial beats (PACs), or from the ventricle, called premature ventricular contractions (PVCs).  However, with your history, recurrent supraventricular tachycardia (SVT) must be considered and ruled out.  Mitral Valve Prolapse (MVP) can be associated with several different types of cardiac arrhythmias, so this must be taken into consideration also.   You need to contact your physician for an appointment in the next couple of days to have an electrocardiogram as well as a physical examination.  He/she might request further testing such as a 24 hour monitor of your heart rhythm if your electrocardiogram is non-diagnostic.  Because of the chest tightness, a stress test may also be requested.   If you do get these symptoms that are continuous, then another trip to the emergency room is in order.  But try to see your doctor soon, rather than wait for this to happen.   Best wishes.   Martin Cane, M.D.