A 69-year-old woman presented to the emergency department with a 3-year history of dyspnea on exertion. She had a history of focal pleural plaques that had been attributed to asbestos exposure that occurred during her work at an insulation-manufacturing company. Physical examination was notable for signs of volume overload. A chest radiograph showed circumferential calcification of the pericardium, pleural effusions, and interstitial edema (Panel A, lateral view). Computed tomography of the chest revealed extensive pericardial calcification (Panel B). A transthoracic echocardiogram showed a preserved ejection fraction with a septal bounce in early diastole as well as expiratory diastolic reversal in the hepatic vein. A subsequent simultaneous left and right heart catheterization showed ventricular interdependence and discordance of the pressure tracings. During inspiration, when pressures in the right ventricle were at their highest, left ventricular pressures were at their lowest; this pattern reversed during expiration (Panel C; right ventricular pressure, solid arrow; left ventricular pressure, dotted arrow). A “square root” sign (also called a dip-and-plateau pattern; Panel C, red line), which represents rapid ventricular filling in early diastole before abrupt cessation in late diastole, was seen. A diagnosis of constrictive pericarditis due to asbestosis was made. A pericardiectomy was performed. Analysis of pericardial tissue was negative for tuberculosis. At 2 years of follow-up, the patient was doing well.