The megaaortic syndrome: Progression of ascending aortic aneurysm or a disease of distinct origin?
BACKGROUND
Thoracic aortic aneurysm (TAA) is an often asymptomatic disease with fatal outcome, such as dissection or rupture. The megaaortic syndrome (MAS) is an extensive dilatation of the whole aorta with low incidence but high lethal outcome with unknown pathophysiology so far.


RESULTS
We compared aortic tissue of patients with sporadic TAAs and MAS of the ascending aorta with non-aneurysmal control tissues. Specimens of MAS patients showed a significantly reduced thickness of the media but an increased thickness of the intima compared to control tissue and TAAs with moderate dilatation. Advanced media degeneration however was detectable in both, TAAs with enhanced luminal diameter and MAS specimens, accompanied by reduced medial smooth muscle cell-density. Further specimens of MAS were characterized by massive atherosclerotic lesions in contrast to specimens of sporadic TAA patients. Infiltrations of macrophages in atherosclerotic lesions but also in the media adjacent to the adventitia were significantly elevated in tissue of TAAs with dilatation ≤6cm. Of note, atherosclerotic plaque-associated macrophages as well as those in the external media produce huge amounts of MMP-9 which is possibly involved in media degeneration and tissue destruction.


CONCLUSIONS
Taken together these results demonstrate that the pathology of MAS shows similarities with that of TAAs but pathological differences in the ascending aorta, suggesting that MAS might be a disease of different origin.
Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria.
Ulrike
U
Baranyi
Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria.
Christian
C
Stern
Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria.
Birgitta
B
Winter
Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria.
Adrian
A
Türkcan
Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria.
Bernhard
B
Scharinger
Department of Surgery, Cardiac Surgery, Medical University of Vienna, Vienna, Austria.
Marie-Elisabeth
ME
Stelzmüller
Department of Surgery, Cardiac Surgery, Medical University of Vienna, Vienna, Austria.
Thomas
T
Aschacher
Department of Surgery, Cardiac Surgery, Medical University of Vienna, Vienna, Austria.
Martin
M
Andreas
Department of Surgery, Cardiac Surgery, Medical University of Vienna, Vienna, Austria.
Marek
M
Ehrlich
Department of Surgery, Cardiac Surgery, Medical University of Vienna, Vienna, Austria.
Günther
G
Laufer
Cardiac Surgery Research Laboratory Innsbruck, University Clinic for Cardiac Surgery, Innsbruck Medical University, Innsbruck, Austria.
David
D
Bernhard
Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria. Electronic address: Barbara.messner@meduniwien.ac.at.
Barbara
B
Messner
D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta / Q000473:pathology* / Q000601:surgery; D017545:Aortic Aneurysm, Thoracic / Q000473:pathology* / Q000601:surgery; D004108:Dilatation, Pathologic / Q000473:pathology / Q000601:surgery; D018450:Disease Progression; D005260:Female; D006801:Humans; D008264:Macrophages / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013577:Syndrome
Atherosclerosis; MMP-9; Megaaortic syndrome; Thoracic aortic aneurysms