Is Periaortic Fat Pad Only Adipose Tissue?

Introduction: The histology of periaortic tissue was examined by electron-microscope to assessthe hypothesis whether resection of tissue to be effective in the development of postoperativeatrial fibrillation.Patients and Methods: The study consisted of 20 male patients who were scheduled for coronaryartery bypass grafting (CABG) with a mean age of 56.4 ± 7.3 years. The periaortic tissue samples were collected through arterial cannulation, aortic root, cardioplegia needle and aorta-saphenous vein anastomosis areas intosaline-filled tubes. Electron-microscobic examination was revealed after preparation of the samples.Results: The histology of tissue samples consists of myelinated and unmyelinated nerve fibers, glial cells and synaptic terminals. All thesegments of tissue include nerve cells. Transient atrial fibrillation was developed in 6 (33%) patients and returned to normal sinus rhythmwith medical therapy.Conclusion: Periaortic adipose tissue is rich in nerve cells. The resection of this tissue may cause the reduction of parasympathetic innervationof the heart by damaging the periaortic nerve cells. Although the causal mechanisms for development of atrial fibrillation is stillunclear, avoiding from resection of periaortic mass could be more appropriate unless there are compelling.