refresh datagrid items without losing selected row - XAML

I have two datagrid's ( Master/detaiL). I refresh my window using DispatcherTimer for every 5 secs. when I select any row on my Master grid, the focus on the selected row stays only for those 5 secs, after that the selection focus moves to the top most row.

how to overcome this issue in XAML?

kindly help.

Thanks