Patient selection: complete atrioventricular block in a patient with a history of mediastinal irradiation
Conditions treated with mediastinal irradiation may include:
(1) malignant lymphoma (Hodgkin's or non-Hodgkin's)
(2) breast cancer
(3) lung cancer
(4) mediastinal tumors
Criteria implicating radiation therapy as the cause:
(1) high radiation dose (>= 4,000 rads)
(2) onset >= 10 years after the radiation
(3) abnormal ECG tracings in the interval between radiation and onset of the complete block (often left or right bundle branch block)
(4) radiation-induced pericardial lesion (constrictive pericarditis, other)
(5) radiation-induce lesions in heart or mediastinum
The risk of this complication can be reduced by:
(1) proper use of shielding
(2) proper planning of the radiation doses and routes
The patient usually has placement of a permanent pacemaker.
