SEARCH RESULTS FOR: AAA-Pathogenesis

AAA-Pathogenesis

Abdominal Aortic Aneurysm (AAA): Pathogenesis Different parts of the aorta have different embryologic origins Atherosclerosis Hypertension Age > 65 Progressive deterioration of aorta structural integrity over life span Connective Tissue Disease Structurally abnormal protein or protein organization in aorta Autoimmunity Infection (e.g Chlamydia, Mycoplasma pneumoniae, Helicobacter pylori, human cytomegalovirus, herpes simplex virus) Antigens (substance that causes immune response) on virus or bacteria resemble local proteins in abdominal aorta Antibodies produced in response to infection inappropriately target host cells in the aorta Antibodies tag cells in the abdominal aorta for destruction by T-lymphocytes Immune-mediated destruction of aorta Smoking Genetics Unclear mechanisms Subacute (not clinically detectable) inflammation of aortic tissue Inflammatory cytokines are released and immune cells are recruited ↑ pressure on aorta and other vessel walls Infiltration of vessel wall by lymphocytes and macrophages Production of enzymes that break down elastin & collagen proteins (which provide most tensile strength to aorta) Aorta susceptible to damage Degradation of aortic connective tissue Biomechanical stress on vessels Authors: Olivia Genereux Davis Maclean Reviewers: Jason Waechter* Amy Bromley* Yan Yu* *MD at time of publication The exact mechanisms are complex, debatable, and an area of intensive research – the 3 mechanisms and associated pathophysiology presented here are generally thought to be the main causes of abdominal aortic aneurysms Infrarenal aorta has poorly developed vaso vasorum (dedicated blood supply to vessel wall) Infrarenal aorta relies solely on nutrient diffusion from aortic blood that crosses abdominal aorta Infrarenal aortic wall has fewer “lamellar” units (fibromuscular units) than other regions of the aorta Infrarenal aorta is less elastic & less able to distribute stress Loss of smooth muscle cells & thinning of tunica media Destruction of elastin in tunica media Normal layers of the aortic wall ↓ aortic tensile strength (ability to withstand stretching) Aorta expands and dilates due to internal pressure Tunica Intima (inner-most tissue layer of aorta) Tunica Media (layers of elastic tissue (elastin) and muscle fibers) Adventitia (thin outermost collagenous layer) (longitudinal section) Aortic aneurysms are usually infrarenal (85%) Abdominal Aortic Aneurysm Infrarenal aorta more prone to ischemia and has impaired repair potential Abnormal, irreversible dilation of a focal area of abdominal aorta (area of aorta between diaphragm & aortic bifurcation) to twice the diameter of adjacent normal artery segment Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published February 27, 2021 on www.thecalgaryguide.com

Tętniak aorty brzusznej: Patogeneza

Tętniak aorty brzusznej: Patogeneza