I would not be worried about sending energy past my heart, because I don't presume to understand how the qi actually works. If it was gamma or xray energy I would be concerned. However, I am asking the universe to the send energy here and I'm using a visualization to make the request more powerful.
I don't worry about harming my home when I do thunder palm or sword finger meditations, because the intent is the important part. The visualization is only supportive.
However, some other ideas I might personally try are: visualizing a sun around the blockage and ... whatever you want, or seeing myself before me and workin on myself from behind, or the one I would most probably do is call on Master Lin and visualize him behind me and working on me.
Remember to be thankful and confident the blockage is completely cleared.
You are perfection.
Iam2 
