Greetings, welcome to the Forums.
This is the trouble with common names. Even though many Philodendron have leaves that are more-or-less cordate (heart-shaped),
the name Heart-leaf Philodendron is usually reserved for Philodendron hederaceum (formerly P. scandens). Your plant is not that.
Your plant is a contorted cultivar (or hybrid) of Thaumatophyllum bipinnatifidum (formerly Philodendron bipinnatifidum), that should probably be labelled as Thaumatophyllum bipinnatifidum 'Atom' or 'Super Atom', but is usually called Philodendron 'Atom' or Philodendron 'Super Atom'. These might be two different cultivars but they are similar and often confused.
Your plant will want care similar to Thaumatophyllum bipinnatifidum, which is often called Hardy Philodendron, though as it is a contorted cultivar it may be somewhat fussier. Give your plant bright, indirect light, and regular water with good drainage.
Make certain that the soil and pot drain well. The pot must have drainage holes and the plant should not be kept in sodden, saturated soil. Let the soil partly dry before the next irrigation. Fertilize occasionally with a complete liquid fertilizer.
Thaumatophyllum bipinnatifidum can be grown outdoors in Adelaide, so you might even try this cultivar outdoors, at least during the warmer months. Summering house plants outdoors is often a great restorative.