I can hear rush of blood and my heart beating loudly in my left ear. notice heart beat sounds stop or greatly diminish when lifting legs. what is this? why getting louder and is affected by body movements?

Pulsatile tinniitus: Negative pressure or fluid in the middle ear(Eustachian tube dysfunction), tumors and vascular anomalies of the middle ear can cause this symptom. Intracranial vascular anomalies or normal pressure hydrocephalus are other considerations. This has an extensive list of possibilities. You need a good ENT history, exam, and hearing test. Imaging is usually done. This is important to check.