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Periphere arterielle Verschlusskrankheit I: Einführung
Die periphere arterielle Verschlusskrankheit (pAVK) ist überwiegend auf Arteriosklerose zurückzuführen. Dabei bilden sich Fettablagerungen (Plaques) i…
Die periphere arterielle Verschlusskrankheit (pAVK) ist eine atherosklerotische Erkrankung, die zu einer fortschreitenden Verengung der Arterien in den oberen und unteren Extremitäten führt. Es betrifft häufig die Bauchaorta, das Beckenmark und die Oberschenkelarterien.
Die Hauptursache für pAVK ist Arteriosklerose. Es kann jedoch auch aus vaskulären Entzündungen, Strahlenbelastung, Diabetes, Rauchen, Fettleibigkeit, Bluthochdruck und Hypercholesterinämie resultieren.
Diese Faktoren tragen zur endothelialen Dysfunktion bei, erhöhen die Durchlässigkeit des Endothels und ermöglichen es dem Lipoprotein niedriger Dichte (LDL), in die Intima einzudringen.
Sobald es sich im Inneren befindet, oxidiert LDL zu entzündlichem oxidiertem LDL und zieht Makrophagen an. Diese Makrophagen verschlingen oxidiertes LDL und bilden Schaumzellen.
Diese Zellen sammeln sich an und bilden Fettstreifen, die frühe Anzeichen von Arteriosklerose sind.
Wenn sich Schaumzellen ansammeln und die Entzündung anhält, entwickelt sich atherosklerotische Plaque, die aus Cholesterin, Schaumzellen, Kalzium und einer fibrösen Kappe besteht.
Im Laufe der Zeit können instabile Plaques mit dünnen Kappen und großen nekrotischen Kernen reißen, thrombogenes Material freilegen, die Bildung von Gerinnseln auslösen und möglicherweise eine akute Ischämie der Gliedmaßen verursachen.
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Q1: What is peripheral artery disease and which arteries does it typically affect?
Peripheral artery disease (PAD) is an atherosclerotic disease causing progressive narrowing of arteries in the upper and lower extremities. It commonly affects the abdominal aorta, iliac, and femoral arteries, significantly reducing blood flow to the legs and, in rare cases, the arms.
Q2: How does atherosclerosis develop in peripheral artery disease?
Atherosclerosis begins with endothelial dysfunction, allowing low-density lipoprotein (LDL) to penetrate the arterial intima. LDL oxidizes into inflammatory oxidized LDL, attracting macrophages that engulf it and form foam cells. These accumulate into fatty streaks and eventually develop into atherosclerotic plaques comprising cholesterol, foam cells, calcium, and a fibrous cap.
Q3: What are the primary risk factors that contribute to peripheral artery disease?
Key risk factors include smoking, diabetes, high blood pressure, high cholesterol, obesity, aging, and family history. Smoking damages the arterial lining through oxidative stress and inflammation. Diabetes causes hyperglycemia-related vessel damage. These factors independently accelerate atherosclerosis and exacerbate PAD progression and severity.
Q4: What happens when atherosclerotic plaques rupture in peripheral artery disease?
When unstable plaques with thin caps and large necrotic cores rupture, they expose thrombogenic material, triggering clot formation. This can acutely block the artery, causing sudden, severe ischemia and potentially tissue death. However, the body may compensate by developing collateral circulation—new blood vessels forming around blockages to improve blood flow.
Q5: How does narrowing of arteries lead to symptoms in peripheral artery disease?
As atherosclerotic plaques enlarge and harden, they narrow the arterial lumen in a process called stenosis. This reduces blood flow and causes ischemia, where tissues receive insufficient oxygen. Initially, this may cause claudication—pain or cramping in the legs during exercise—as oxygen demand exceeds supply during activity.
Q6: What role do foam cells play in the development of atherosclerotic plaques?
Foam cells form when macrophages engulf oxidized LDL and accumulate within the arterial wall. These foam cells, along with accumulated lipids and migrating smooth muscle cells, contribute to plaque formation. The accumulation of foam cells represents an early sign of atherosclerosis and drives the progression toward stable or unstable plaque development.
Q7: How do smoking and diabetes specifically damage blood vessels in peripheral artery disease?
Smoking introduces harmful chemicals that cause oxidative stress and inflammation, weakening endothelial cells and damaging the arterial lining. Diabetes causes hyperglycemia, which directly damages blood vessels. Both conditions contribute to endothelial dysfunction, increasing permeability and allowing LDL penetration into the arterial intima, initiating atherosclerotic disease.