Atherosclerosis

Atherosclerosis Most common form of vascular disease Narrowing of the lumen Caused by a build up plaque in the tunica intima

Lumen: the inside space of a tubular structure (ex. blood vessel) Plaque: build up of cholesterol and other substances in the tunica intima

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Atherosclerosis ©http://www. nlm. nih

Atherosclerosis of the Coronary Artery ©http://www. uphs. upenn

Atherosclerosis with Thrombus (Blood Clot) ©http://www. uwcvb

http://path.upmc.edu/cases/case158/images/micro4.jpg

How does this occur? Fat enters the area of the endothelial cells of the tunica intima What type of lipid or fat causes this plaque build up? Cholesterol

Cholesterol Produced by the liver and is found in saturated fats Some cholesterol is needed for good health It is the basis for many hormones Forms cell membranes

It becomes a problem when there is too much cholesterol in the bloodstream Hypercholesterolemia

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Cholesterol is carried through the bloodstream by lipoproteins There are two types of lipoprotein carriers: HDL LDL

HDL: high density lipoprotein “Good” type of cholesterol Does not build up on the walls of arteries

Thought to protect from heart disease by removing plaque and taking it back to the liver where it can be passed from the body This is now being questioned in the scientific community

LDL: Low density lipoprotein “Bad” cholesterol Accumulates in the arteries causing a build up A clot (THROMBUS) can form near the plaque and block blood flow

©http://www.liponex.ca/images/charts/bad_good.jpg

Cholesterol Can be measured with a blood test

What Causes Plaque to Build Up on the Walls of Arteries? Inflammation of the tunica intima occurs May be caused by excessive irritation or a bacteria

Macrophages move in to remove the misplaced fat LDL deposits cholesterol into the inflamed or injured areas of the tunica intima Macrophages move in to remove the misplaced fat Attempt to engulf the fat-laden cells

As macrophages engulf lipids, they look like foam Hence the name FOAM CELLS

Foam Cells

Foam cells die and remain in the blood vessel Smooth muscle cells and endothelial cells continue to proliferate creating a fibrous cap over the lesion

Processes continues and the lumen is narrowed

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In observing the atheroma, you may see cholesterol clefts Cholesterol cleft: a space caused by the dissolving of cholesterol crystals in an atheroma

Foam Cells and a Cholesterol Cleft Seen in Atheromatous Plaque ©http://www.es.oersted.dtu.dk/~jw/eksamensprojekter/cv010.jpg

http://path.upmc.edu/cases/case158/images/micro4.jpg

Narrowing of an Artery ©http://d. yimg. com/origin1. lifestyles. yahoo

Atheroma ©http://www.heartzine.com/thumbs/atherosclerosis.jpg

Plaque that builds up deeper in the artery, between the intima and the media is called VULNERABLE PLAQUE The film covering the plaque may rupture and cause a clot that could occlude the artery

Vulnerable Plaque ©http://www. texasheartinstitute

Vulnerable Plaque ©http://www. texasheartinstitute

Vulnerable plaque may be even more dangerous than a build up in the intima

Factors that Contribute to the Rate of Atherosclerosis Diet Fat intake Saturated fats, trans-fats, and dietary cholesterol are all problematic

The liver produces enough cholesterol for cellular structures and functions Any additional intake of fat can create problems

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Heredity Genetics are the biggest factor Ex. Your genetic makeup may cause your liver to produce too much cholesterol

Hypertension High blood pressure (the silent killer) Increased pressure on your artery walls damage your arteries, which can speed up the accumulation of fatty deposits

Hypertension ©http://www. medmarketplace. com/images/HighBloodPressure

Diabetes High blood sugar contributes to high LDL cholesterol and low HDL cholesterol High blood sugar also damages the lining of your arteries

Lack of exercise Regular cardio is beneficial, but not a huge gain

Smoking Nicotine is a potent vasoconstrictor Increases heart rate Damages the walls of your blood vessels, making them likely to accumulate fatty deposits

Gender Estrogen regulates the amount of cholesterol the liver produces Lowers LDL and increases HDL

Treatment for Atherosclerosis Coronary by-pass operation Surgery reroutes or bypasses the clogged artery to improve blood flow and oxygen

Surgeons take a vessel from somewhere else in the body and make a detour around the occluded vessel Gortex is also used

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Coronary Artery Bypass ©http://www. taxus-stent

Balloon angioplasty with stent Stent: cage-like wire that holds the lumen open

Stent ©http://heart.image-animation.com/ANGIOPLASTY-STENT-1.jpg

Stent ©http://heart.image-animation.com/ANGIOPLASTY-STENT-3.jpg

Stent ©http://www.taxus-stent.com/images/045g_StentV1_EN_150.jpg

https://www.youtube.com/watch?v=S9AqBd4RExk

Problem? Body tends to scar over the stent: restenosis This is more than just a covering of endothelial cells—actual scaring that narrows the lumen

Solution Drug coated stent Same type of stent, but coated with an anti-mitotic drug Lasts 3-31/2 weeks by inhibiting the mitotic ability After 3 weeks, endothelial cells cover stent without the scaring: fibroblast Keeps lumen open

What is the problem with this? New study shows that if we prevent the growth of scar tissue over the metal, people have a higher incidence of blood clots How does it cause clots? Platelets hit and tear on bare metal releasing enzymes that create clots

Patients are also given an anti-coagulant to prevent blood clots

Beta-Catheter Once used to clear plaque build up with beta particles Problem? Eradication of normal tissue and formation of scar tissue cutting off the blood supply

Now used (sparingly) to clear the overgrowth of normal tissue from a stent after angioplasty

Basic fibroblast growth factor AND Percutaneous myocardial revascularization Used together and only done in extreme situations

Cardiologist uses a laser catheter to bore channels inside the heart Catheter is sent through the femoral artery and into the left ventricle to the ischemic tissue (“oxygen starved”) The hurt muscle (around the channel) sends out a signal to make new capillaries

The fibroblast growth factor is administered to stimulate blood vessel differentiation

Percutaneous myocardial Revascularization ©http://images. google

Blood Vessel Layers

Healthy Artery

Atherosclerosis ©http://www. chelationtherapyonline

Atheroma with Thrombus

Atherosclerotic Plaque https://secure. health. utas. edu

Atherosclerotic Plaque

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Cholesterol Clefts in an Atheroma