Rita had annual echocardiograms to evaluate ongoing cardiac valve dysfunction. one year the technologist had difficulty getting proper images of the structures. the radiologist reading the tests referred rita to a pulmonary specialist, who arranged for a biopsy of the left lung by a thoracic surgeon. what is a thoracic surgeon?

A thoracic surgeon refers to a surgeon exhibiting a special training in operating organs within the chest, like the lungs and the heart.  

Thoracic surgery also called cardiothoracic surgery refers to the branch of medicine that deals with the surgical treatment of organs present within the thorax, that is, the chest. Usually, the treatment of the conditions associated with lungs and heart comes under thoracic surgery and is performed by a specialist thoracic surgeon.  

not sure if this is what you'r looking for eubacteria and archaebacteria