Guidelines for Complications of Cancer Treatment Vol VIII Part B

without calcification. Inflammation and other cellularcomponents are absent. Left-sided valves are more commonlyaffected and show regurgitant changes. Valves are normallydevoid of vascular structures in any of the three layers and theetiology is unlikely ischemic in origin. Accelerated changescaused by radiation to preexisting abnormalities or damagemay be an important factor in the evolution of clinical valvulardysfunction and may be the high pressures in the left-sidedchambers that cause persistent stress-related injury to damagedvalves and chemotherapy have synergistic effect.Conduction disturbances are classified as early and late inonset. Early electrical alterations are common but transient.Late conduction abnormalities occur months to years aftertreatment and include infranodal blocks, atrioventricular nodalbradycardia, and all types of heart block, including completeheart block.The clinical presentation of coronary artery damage is similarto atherosclerotic coronary disease. The morphologic featuresin radiation-induced arteriosclerosis (RIAS) are similar tothose seen in classic atherosclerotic coronary disease. Subtledifferences include the increased proximal location often withinvolvement of the coronary ostia in RIAS. A variety ofmicroscopic patterns are seen, including fibrous, fibrocalcific,and fibro fatty lesions with abundant cholesterol and lipid.Focal or multiple patchy foci of medial and adventitial fibrosisis suggestive of healed arteritis and favors a radiation etiology.Late alterations in the large elastic arteries such as thepulmonary arteries and aorta have not been thoroughly studied.Cases of acute rupture have been reported and most cases occurin the setting of other local complications such as infection orfistula formation. Fajardo and Lee reported two cases of denovo aortic rupture that demonstrated aortic adventitialnecrosis or severe necrosis of the elastic layer.301