Explain how constrictive pericarditis produces reduced exercise capacity and systemic congestion.

A thickened, scarred, and often calcified pericardium prevents the heart from expanding normally. Reduced ventricular filling limits the amount of blood available for each cardiac cycle and compromises cardiac output. Patients may therefore develop exercise intolerance, and longstanding disease can contribute to cachexia and muscle wasting. At the same time, impaired forward flow and elevated venous pressures produce jugular venous distension, hepatic congestion, ascites, and peripheral oedema. **Key takeaway:** Constriction causes both low-output symptoms and systemic venous congestion through restricted diastolic filling. **Glossary:** **Cachexia**: severe wasting associated with chronic illness. **Systemic venous pressure**: pressure in veins returning blood from the body to the heart.