Constrictive pericarditis occurs when the pericardium becomes scarred and stiff, preventing the heart from properly expanding and filling with blood. This causes the heart to work harder to pump enough blood, eventually leading to heart failure if left untreated. Symptoms include shortness of breath, chest pain, fatigue, and swelling. Diagnosis involves tests like echocardiograms, CT scans, and cardiac catheterization. Treatment focuses on managing the underlying cause, using diuretics to reduce fluid, and sometimes pericardiectomy surgery to remove the constricted pericardium. Complications can be life-threatening if not addressed.