Watch the Example 21 online guitar lesson by Brad Carlton from Guitar Lab: Boogie-Woogie

Now it gets stretchy with second intervals occuring between voices 3 and 4. The chords are A add9, Dmaj7/A, A9 no 3rd and Dmaj7/A. Watch your intonation as it is easy to pull the strings either sharp or flat with these close voicings out of A mixolydian.