I have seen other names, like Portuguese Knotted Stem Stitch, but there is actually no knot in it.
Also I found, in a Swedish embroidery book, Hemmets Handarbetslexikon, the following information:
Anyway, here is my take on the stitch. I used my new stencils to draw both heart and curvy lines.
The first time I used Portuguese Stem Stitch was during the Sumptuous Surface Embroidery course and like that time I used some pulled stitches here for the centre of the heart.