WTF

I’m Drawing Four Boxes and Some Tubes
The heart has four chambers (two red, two blue) and a series of arteries (blue) and veins (red). I often depict the tubes in some way differently from the boxes.
Sometimes the tubes are one line while the boxes are two lines at an angle. Or one is diagonal and the other perpendicular to the page. Or one is drawn using a ruler for a smoother line. Or by varying the pressure.

They Pump, They Flutter, They Break, They Beat
I started the project by trying to make them as simple as possible, seeing how simple a drawing could be and still convey a heart. A Cubist strategy is essentially reductionist. Over time they’ve become more crowded and more complicated. 
I’ve experimented with concentrating the energy in the middle, or having a hole in the middle, and having everything swirling around it, sometimes all spread out.
I started layering the marks on top of each other instead of drawing right through the each other, and so one mark is on the top of the stack. The first mark is in the top of a stack.

The Aortic Arch Is My Achilles’ Heel
I have some opening moves that almost always work, about ten of them taped to the wall. These usually involve the aortic arch, the largest blood vessel in the body. It pops out the top of your heart and the curves down behind it with three major arteries branching off it like a crown. It can be awkward to fit them in at the end and have it look balanced, so I tend to draw them first.