Haemodynamic monitoring — measurement of cardiac output, filling pressures, and vascular resistance — forms the foundation of advanced heart failure and critical care cardiology. The pulmonary artery catheter (PAC/Swan-Ganz catheter), introduced by Swan and Ganz in 1970, remains the gold standard for invasive haemodynamic profiling. The Forrester classification (1977) used PCWP and cardiac index to define four haemodynamic profiles in acute MI, which evolved into the Stevenson clinical profiles (warm-dry, warm-wet, cold-dry, cold-wet) used today for ADHF management. Non-invasive estimates using echocardiography (LVOT VTI, IVC collapsibility) have largely replaced PAC in many settings.