Transit Visa for LHR - Heathrow from Dubai to US?

[immigaya]

Please let me know if I need a transit visa for the following.
I have a valid US Visitor Visa.
I am planning to book the following route Dubai (DXB) - LAX layover in LHR (London, Heathrow)
Do I need a transit or DATV visa or am I exempt?

I will be returning to Dubai within 6 months and the return flight also has a layover in Heathrow. Will I not have any problems?


Please let me know.

THank you