A medical device handle assembly can include a modular extension that allows for the addition of any number of connector ports to an existing handle. In an embodiment, such an extension can comprise a main body portion configured to be coupled with an elongate medical device shaft comprising at least one of an electrical wire and a fluid lumen. The main body portion may comprise a handle port configured to provide access to one or more of a fluid connector fluidly coupled with the fluid lumen and an electromechanical connector electrically coupled with the electrical wire. The handle assembly can further comprise a handle extension portion coupled with the handle port.