Cardiac infections, including infective endocarditis and cardiovascular implantable electronic device infections, are associated with substantial morbidity and mortality and are commonly caused by gram-positive bacteria. Standard management typically requires prolonged courses of intravenous antibiotics and extended hospitalisation, which are costly, burdensome, and associated with complications related to long-term vascular access. People who inject drugs are disproportionately affected and often experience stigma, barriers to care, and poorer outcomes. Long-acting lipoglycopeptides such as oritavancin maintain therapeutic serum concentrations for prolonged periods and may offer an alternative to conventional intravenous antibiotic regimens. Oritavancin is not TGA-registered in Australia and is accessed as an unregistered medicine (for example, via SAS or clinical trials). It is approved in other jurisdictions, including the United States and European Union, for acute bacterial skin and skin structure infections. Prospective data in cardiac infections remain limited, and optimal dosing strategies, including the role of therapeutic drug monitoring, are uncertain. This multicentre, open-label pilot study will assess the feasibility, pharmacokinetics, safety, acceptability, and preliminary efficacy of oritavancin for gram-positive cardiac infections using both standard fixed dosing and TDM-guided dosing strategies. Findings will inform PK/PD modelling, the potential role of TDM, and the design of future larger-scale trials and models of care, including alternatives to prolonged inpatient intravenous therapy.