How To Model Heart in Inventor ?
Depending on how detailed you need it I would say open a polygon model and extract either the horizontal edges into nurb curves from top to bottom. This would give a nice detailed solid. The other way might be to creat some geometry based on each of the major parts and the Boolean them to create a complete shape. Once you have that you can go back and start the vascular part that wraps the beast.
Another way might be if you can find a ct scan multi-sclice. Then you could trace the walls and extrude it that way.
Or you can go to Turbosquid and pay for a poly and just go with that. It will probably cost less than the time it takes to make.
2D heart :
Draw a square with a vertical diagonal
Draw semicircles on two upper edges
Trim all internal lines, and fillet the corners
Basic : extrude the section by same distance as length of side of square used to draw the 2d, and fillet the edges by half the same distance
i.e if square side = 10, extrude by 10, fillet by 5
Advanced : if you really want this perfect and dont mind working harder.
From your graphic, it is apparent that the edges are not a plain circular fillet, but more elliptical.
Draw the various cross sections, atleast 4, for the upper and lower points, as well as two lobes, and loft the 4 sections using the 2d heart as rail.