A case of constrictive pericarditis complicating disseminated lupus erythematosus is reported in a 58-year-old man. Hemodynamic studies documented the diagnosis and also confirmed the clinical suspicion of coexistent atrial septal defect. Measurement of left ventricular volume by a thermodilution technic augmented information available from routine studies. Pericardiectomy and closure of the atrial septal defect relieved the mechanical lesion.The case is also unique in its documentation of the coexistence of three different forms of heart disease—congenital atrial septal defect, pericardial constriction from lupus erythematosus, and rheumatic valvular disease.