The sequence 1D-1S-2H is still a reverse, and promises extra strength (17+ is typical, but not universal). The reason why such a rebid normally promises extra strength is that it commits the partnership to the three level, should partner have a minimum hand and a preference for your first suit. This may be something you don't want to do.
So if you have 2443 shape and minimum strength (12-14), your proper rebid after 1D-1S is 1NT:
- You have a balanced hand, so the NT rebid gets the message across.
- You have a minimum opener, so you don't want to go higher without encouragement from partner.
- And finally, if you belong in hearts, partner is still there. If they ahve extra strength, the bidding won't stop here.
Having said all that, a few problematic hand types do come to mind. If partner has 5 spades, 4 hearts and a weak(ish) hand, you might belong in hearts. There are various gadgets seeking to solve such problems such as Reverse Flannery and, of course, all forms of checkback, or new minor forcing. Discuss with partner before agreeing to use them. My experience with BBO suggested to me that nearly everybody in the US plays new minor forcing, but here I was told that's not the case. Caution!
Having such holes in the system is somewhat unavoidable, there simply is not enough room to tell everything you would like to, and you need to select bids least likely to leave your partnership in an awkward contract.