Figure 23j

Eisenmenger's Syndrome.
In patients with Eisenmenger's syndrome, in response to substantial left-to-right shunting, morphplogic alterations occur in the small pulmonary aretries and arterioles(inset), leading to pulmonary hypertension and the resulant reversal of the intracardiac shunt(arrow). In the small pulmonary arteries and arterioles, medial hypertrohy,intimal cellular proliferation,and fibrosis lead to narrowing or closure of the vessel lumen.With sustained pulmonary hypertension, extensive atherosclerosis and calcification often develop in the large pulmonary aretries. Eisenmenger's syndrome may occur in association with a ventricular defect(as shown), but it also may occur in association with an atrial septal defect or a patent ductus arteriosus.