Histological properties of oscillating intracardiac masses associated with cardiac implantable electric devices.

Background: There have been a few cases of echogenic cardiac implantable electric device (CIED) lead-associated oscillating intracardiac masses (ICMs) in leads imaged by echocardiography. The histological properties of ICMs could help clarify the etiological diagnosis. Although there is extensive literature on mass size, the histological properties of such masses have not been characterized.