What is an Endovascular Infection?
An endovascular infection is a microbial infection (primarily bacterial) of blood vessels or implanted vascular devices, including native arteries and veins, vascular grafts, endografts, and intravascular catheters. 1, 2
Key Anatomic Sites
Endovascular infections can occur in:
- Arterial system: Native vessels (mycotic aneurysms), vascular grafts, and endografts following procedures like EVAR
- Venous system: Septic thrombophlebitis of deep veins, internal jugular vein, and intracranial venous sinuses
- Cardiac structures: While technically endovascular, cardiac endocarditis is typically classified separately 2
The term encompasses infections beyond the heart, distinguishing these from the more extensively studied cardiac endocarditis 2.
Pathogenic Mechanisms
Four primary mechanisms lead to endovascular infection 1:
- Septic emboli to the vasa vasorum or vessel branch points, with bacteria extending inward through the vessel wall
- Direct extension from contiguous infected tissue (e.g., vertebral osteomyelitis, gastroenteritis)
- Hematogenous seeding during bacteremia, particularly targeting atherosclerotic plaques or pre-existing aneurysms
- Direct contamination from surgical procedures, intravascular catheterization, IV drug use, or penetrating trauma
Common Microbiology
The bacterial spectrum varies by location and mechanism 1:
- Staphylococci (S. aureus and coagulase-negative): 50-60% of cases, now the most common pathogens
- Gram-negative bacilli: 30-40% of cases, particularly nontyphoidal Salmonella species (S. enteritidis, S. choleraesuis) which have special predilection for vascular tissue
- Other organisms: Listeria, anaerobes, Candida, and rarely Mycobacterium tuberculosis
Critical caveat: In endograft infections specifically, culture-negative infections occur in up to 45% of cases, making diagnosis challenging 3.
Clinical Significance
These infections carry high morbidity and mortality 2, 4. The incidence after vascular procedures is relatively low but devastating:
- Post-EVAR: 0.36 per 100 person-years
- Post-open surgery: 0.60 per 100 person-years 3
Management requires multidisciplinary involvement from the outset and typically necessitates source control (device/tissue removal) combined with prolonged antimicrobial therapy 2, 4.