Myocardial perfusion changes in patients irradiated for left-sided breast cancer and correlation with coronary artery distribution

Prone versus supine positioning for whole and partial-breast radiotherapy: A comparison of non-target tissue dosimetry

“…The majority of these deaths are cardiovascular in origin (2) and irradiation of the left-anteriordescending coronary-artery (LAD) is implicated in pathogenesis (3)(4)(5). Irradiation of lung, chestwall and other tissues also contributes to late mortality and morbidity (1,2).…”

Cardiovascular effects of radiotherapy on the patient with cancer

“…This can affect the coronary ostia. 14,16,20,24,25 as they occupy the region with greatest risk of being included in the irradiation fields. 20 Under microscopy it is possible to observe fibrointimal thickening, fibroproliferative lesions, fibrocalcific and also fibrolipid plaques in the areas of coronary stenosis.…”

“…However, sub-clinical lesions have been identified within six months of the end of treatment. 25,28 Myocardial damage has been identified early through scintigraphic studies with images of myocardial perfusion performed six months after RT in patients treated for left breast CA. Currently, RT techniques with tangential photon beams are used with prior planning using three-dimensional computed tomography in order to minimize such damage.…”

“…However, any dose of radiation always affects the heart, mainly in the anterior wall of the left ventricle. 25,28 Perfusion defects are found in approximately 40% of patients 6 to 24 months after RT for left breast CA and these defects are more prevalent in patients with a higher heart volume within the radiation field. 28 Perfusion defects after irradiation of a small fraction of the myocardium are caused by damage to the microvasculature.…”

“…28 Perfusion defects after irradiation of a small fraction of the myocardium are caused by damage to the microvasculature. Ionizing radiation causes damage to the endothelial cells of the capillaries with consequent capillary edema, obstruction of the lumen of the vessel and subsequent myocardial fibrosis, 25 as a result this leads to sub-clinical functional abnormality of the left ventricle. 28 In addition to the microvascular damage, there is also direct damage from the radiation over the cardiomyocytes.…”