Pathogenesis of aortoenteric fistula. An experimental study

Area of Science:

• Vascular Surgery
• Surgical Pathology
• Experimental Medicine

Background:

• Aortoenteric fistulas are rare but life-threatening complications following aortic reconstruction.
• Understanding the precise mechanisms of their formation is crucial for prevention and treatment.

Purpose of the Study:

• To investigate the role of mechanical factors and bacterial infection in the pathogenesis of aortoenteric fistulas.
• To evaluate the efficacy of methicillin in preventing fistula formation.

Main Methods:

• Aortoenteric fistula model created in 23 dogs using dacron grafts and duodenal wall.
• Four experimental groups were established to test different conditions: pseudoaneurysm with bacteremia, pseudoaneurysm with bacteremia and methicillin, intact anastomosis with bacteremia, and intact anastomosis without bacteremia.
• Staphylococcal bacteremia was induced, and methicillin was administered in specific groups.

Main Results:

• 100% fistula formation in the pseudoaneurysm with bacteremia group (Group I).
• 80% fistula formation in the pseudoaneurysm with bacteremia and methicillin group (Group II).
• 14% fistula formation in the intact anastomosis with bacteremia group (Group III).
• 0% fistula formation in the intact anastomosis without bacteremia group (Group IV).

Conclusions:

• Mechanical factors, specifically the creation of a pseudoaneurysm, play a decisive role in the development of aortoenteric fistulas.
• Bacterial infection exacerbates fistula formation, but mechanical stress is the primary driver.
• Preventing pseudoaneurysm formation is critical in reducing the incidence of aortoenteric fistulas.