Purvottanasana (Intense stretch of the the East/Front side of the body) is a back bending posture. One that we probably couldn't stay in for much longer than 30 seconds so let's all thank B.K.S. Iyengar for coming up with the supported version!
If you don't have all the equipment shown, don't give up. We all have a bed or a coffee table that can easily be used instead of the chairs. If you don't have a bolster or bolsters, then simply roll or stack thick blankets.
As in yesterdays supported Savasana for the heart, the upper chest region should feel both supported and spacious. If you have a heart problem or other issue affecting your health in the chest area, use support for the arms so the chest can be wide and deep (vs. just going for a "good" stretch).