Here are two different sets of Chord Substitutions to the 1938 Hoagy Carmichael (pictured to the left) standard Heart And Soul. The "A" sections of this song are comprised of repeated Standard (I-vi-ii-V7) Progressions. Like the I Got Rhythm example, these substitutions are a great study of Standard Progression substitution.
The "B" section follows the Circle of Fifths through five changes and is usually played as originally written except that "D#7" chord is commonly substituted by an "A7" chord. I suggest that you obtain the original sheet music and closely compare it to each of these possible Chord Substitutions.
