Despite the fact that many authors in the literature defend the need of ontologically well-founded languages for ontology representation, this approach has not yet been broadly adopted. We present in this paper a codification of a well-founded heart-ECG domain ontology in OWL+ SWRL. The lightweight ontology produced is then applied to a web environment for heart electrophysiology reasoning and visualization. We also reflect on this codification process to argue in favor of the view that two classes of languages are needed for ontology engineering:(i) a theoretically well-founded representation language for creating conceptual domain ontologies;(ii) a lightweight representation language for codifying these conceptual ontologies.