Left arm numbness 4 5 mnths.er visit cbc, cmp, tropononin 1 and ekg, vascular screen all normal.visit to orthopedic doc. nothing abnormal in x-ray.heart?

LUE numbness.: Some relatively common conditions which can cause one sided arm numbness such as entrapment neuropathy and cervical radiculoapthy will not be detected on the tests you've mentioned. You can see a neurologist for an exam and a nerve study and (s)he will determine if additional diagnostic testing such as a cervical spine MRI or brain MRI is indicated. Hope nothing serious and good luck.

Very unlikely: It's an atypical presentation and the prevalence of disease in your age group is low. "common things happen commonly" - i'd look to your shoulder for the probable cause.