The Cardiovascular Interaction (CVI) simulation model was developed by Carl Rothe (1929-2016) as an interactive computer simulation in the form of a tutorial. The original tutorial was based on a five-compartment model (Venous Bed, Right Heart, Lung Bed, Left Heart, and Arterial Bed). This work examines the simulation Dr. Rothe developed based on a six-compartment model (Systemic Veins, Right Ventricle, Pulmonary Arteries, Pulmonary Veins, Left Ventricle, and Systemic Arteries). Both models were originally developed in Visual Basic. Both models have been reimplemented in C# WPF for Windows and in LabVIEW for Windows 10 and Mac OS X.