I've recently bought a hoe which has a sort of heart shaped head. It is sharp on all edges and does a superb job. It's only about 4" wide but I'm finding it much faster in use than any other hoe I've used. No name on it but purchased at our local garden centre.
Looks similar to this one http://www.rutlands.co.uk/sp+gardening-garden-tools-hoes-cultivators-short-handle-hoes-heart-shape-hoe-140mm-480mm-ash-handle+gd1009