Peripheral vascular disease can result in a number of serious infections complicating ischemia. However, infections as primary causes of peripheral vascular disease, although uncommon, are also very important clinically. Overall, the arterial vascular system is relatively resistant to infection, but infections do occur, often with terrible consequences. Although uncommon, arterial infections can be seen with a variety of microbial pathogens. Pyogenic bacterial infections are most frequently recognized, but infections with atypical bacterial pathogens, spirochetes, mycobacteria, fungi, parasites, helminths, and even viruses also occur. Diagnosis can be extremely difficult, and many times the infection is not diagnosed until the time of vascular surgery for arterial rupture or another catastrophic event, or at autopsy. Therapy can be just as challenging. Even with a combined medical and surgical approach, arterial infections can be very difficult to eradicate. These infections are associated with significant morbidity and mortality, even if microbiological cure can be achieved.
Not all the effects of infection on peripheral arteries are direct. In some cases, the infection incites a vasculitis. It is the resulting inflammation, with or without ongoing arterial infection, that leads to arterial disease. Finally, direct infection and indirect effects of chronic infections on the arterial system may be subclinical, but these asymptomatic infections may cause endothelial cell dysfunction or lead to pathologic changes, including accelerated atherosclerosis.
Peripheral arterial infections have been comprehensively reviewed in a number of books, chapters, and other reviews.1,2 This chapter will attempt to review the subject with inclusion of new information and a discussion of contemporary management issues and controversies, as well as discuss the entire breadth of infectious agents that can directly or indirectly affect the peripheral vascular system.
NATURALLY OCCURRING BACTERIAL AND FUNGAL INFECTIONS OF THE ARTERIAL VASCULATURE, I.E., INFECTIOUS ARTERITIS
Classification and Nomenclature
Although the term mycotic aneurysm is often used for any arterial infection, other terminology may be used that gives some insight into the pathogenesis. Wilson et al.3 devised a commonly used classification of arterial infections: Mycotic aneurysms caused by septic embolization from endocarditis, secondarily infected atherosclerotic aneurysms, infectious arteritis without aneurysm formation or necrotizing arteritis, and finally infected pseudoaneurysms from trauma or a vascular procedure. Even this classification is not all encompassing, and does not include arterial infections caused by local spread from an adjacent site of infection.
Incidence and Epidemiology
Infections of the arterial system are relatively rare. In general, the ability of bacteria to bind and cause infection of the arterial endothelial surface is low, but the exact incidence of infectious arteritis is not well defined. Even autopsy data on the frequency of this type of infection is limited, and usually reports only focus on very large vessels, such as the aorta or, in some studies, the femoral arteries. Furthermore, many of the large autopsy studies that reference infectious arteritis ...