Complete Atrioventricular Block Following Mediastinal Irradiation: A Report of Six Cases

Abstract

Complete atrioventricular block (AVB) following radiotherapy has been reported rarely, usually after high dose mediastinal irradiation for Hodgkin's disease or lung or breast carcinoma. We report six new cases of episodic complete infranodal AVB, requiring permanent pacemaker implantation. The mean age was 48-years old (ranging from 25-60) at the first Adams Stokes attack, mean delay was 12 years after irradiation (10-18), and mean radiation dose was 5,200 rads (4,000-6,500). All patients had abnormal interval electrocardiograms (right bundle branch block in two, left bundle branch block in three, alternating left and right bundle branch block in one). Electrocardiograms during the episode of AVB or Holter recordings were consistent with infranodal block in all patients; electrophysiological study performed in five patients confirmed infranodal AVB in four, and one was normal. Pericardial disease was constant, which included pericardial constriction in four patients. Two patients died after failure of pericardiectomy to improve congestive heart failure, due to epicardial, myocardial, and endocardial involvement. Noncardiac mediastinal lesions were present in four cases. Since this delayed complication may occur in patients of such age that the relation between the AVB and the chest irradiation is questionable, we propose the following etiologic criteria; high radiation dose (over 4,000 rads); delay of 10 years or more; abnormal interval tracings; pericardial involvement; and associated cardiac or mediastinal radiation-induced lesions.

Radiation-Induced Heart Disease: A Clinical Update

“…Injury to bundle may occur either directly from radiation or indirectly from associated myocardial fibrosis and ischemia. One of the common serious manifestations is complete atrioventricular (AV) block [69]. Dual chamber pacing has been found to be somewhat more efficacious in symptom improvement in such patients [70].…”

Atrioventricular Node Ablation in Langendorff-Perfused Porcine Hearts Using Carbon Ion Particle Therapy

“…[16][17][18][19] Autopsy findings showed that damage was largely mediated through vascular injury. 19,20 The vascular endothelium of different organs has been shown to be susceptible to ionizing irradiation.…”

Post-operative radiotherapy (PORT) or chemoradiotherapy (CPORT) following resection of stages II and IIIA non-small cell lung cancer (NSCLC) does not increase the expected risk of death from intercurrent disease (DID) in Eastern Cooperative Oncology Group (ECOG) trial E3590

“…Other multivariate analysis of radiation induced cardiac disease has demonstrated that increasing age, male gender and pretreatment cardiac medical history were significantly associated with post-treatment ischemic heart disease [34]. Conduction abnormalities have also been reported related to radiation including fibrosis of the conduction system [35].…”