My 44 Healthy Son Just Had A Stroke. MRI Shown

My 44 healthy son just had a stroke. MRI shown several small one before and medium size - all without symptoms. The last one however was symptomatic - loss of vision, severe headache . 2 wks later still no clear peripheral vision. He is under care of neurologist and cardiologist. Chemistry results are good.
Dr's are testing deeper into gens mutations, autoimmune and coagulation causes.
My question is : what nutrients will strengthen his veins?