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Glossary

      

Antegrade:  Forward.

Aorta:  The large elastic artery which receives blood from the heart and distributes it to the rest of the body.

Arteriovenous graft: A connection via an artificial vessel, between an artery and a vein. Artificial grafts are typically made of Dacron.

Atherogenesis:  The development of an atherosclerotic plaque.

Cardiac cycle:  The combination of systole in which the heart contracts and blood is ejected from the heart, and diastole, when the heart refills with blood.

Carotid artery:  The major artery of the neck, which supplies blood to the brain.

Coronary artery:  The arteries which supply blood to the heart.

Cytopathic:  The property of being toxic to a cell.

Deep venous thrombosis:  A thrombus which forms in the deep veins of the legs.  If these dislodge, they can go to your lungs and cause sudden death.

Diastole:  The portion of the cardiac cycle when the heart refills with blood.

Diffuse intimal thickening:  A natural thickening of the arterial intima with aging.  Oxidized LDL and cholesterol accumulate within the thickened intima without causing harm.

Endothelium:  The inner lining of a blood vessel composed of cells, which produce antithrombotic molecules, such as nitric oxide and prostacyclin, when exposed to flowing blood.

Erythrocyte:  The red blood cell, which carries oxygen in the blood.

Fibrinolytic:  The property of breaking down fibrin; one of the constituents of a thrombus or blood clot.

Fistula (pl. fistulae):  An abnormal connection between two spaces.  For our purposes, the fistula is between an artery and vein.

HDL:  High-density lipoprotein or the good cholesterol.

Hematocrit:  The portion of blood consisting of erythrocytes.

Intima:  The inner lining of a blood vessel composed of endothelial cells.

LDL:  Low-density lipoprotein or bad cholesterol.  According to mainstream atherogenesis theory, when oxidized, this particle is cytotoxic.

Non-Newtonian fluid:  A fluid whose viscosity changes with shear or flow.  Think of ketchup.  It’s thick, but gets thinner and easier to pour when you shake it.

Organization:  The process in which new blood vessels grow into a thrombus or dead tissue, which allows influx of fibroblasts, which produce collagen, the main constituent of a scar.

Ostium:  The opening to a blood vessel.

Oxidized:  A chemical modification similar to changing iron into rust.  According to mainstream thought, this change causes LDL to be harmful or cytotoxic.

Platelet:  The particles in the blood which help form a thrombus.  When activated, as by highshear, platelets become sticky and adhere to a vessel wall and each other, beginning thrombus formation.

Retrograde:  Backwards.

Reynolds number:  The number which describes the propensity of a flowing fluid to deviate from orderly or laminar flow to form eddies when encountering an obstruction.  The higher Reynolds number, the more likely is eddy formation.  At a high enough Reynolds number, flow is turbulent.

Shear: The fancy name to describe flow of a liquid.

Shear rate:  The velocity gradient of parallel fluid layers or the rate at which layers of fluid slide over each other.  Calculated as the first derivative of flow velocity with respect to distance from the vessel wall; think of the ratio between blood flow velocity and vessel diameter as shear rate.

Shear stress:  Friction that blood flow causes against the inside of arteries or the tangential frictional force per unit area applied by blood flow upon the endothelial wall.  It is calculated as shear rate multiplied by blood viscosity.

Smooth muscle actin:  A protein in the smooth muscle cell which allows it to contract. 

Stenosis:  A narrowing of an artery.

Stroke volume:  The amount of blood expelled during systole.

Systole:  The portion of the cardiac cycle when the heart contracts, expelling blood.

Thrombosis:  The formation of a blood clot within a vessel.

Thrombus:  A blood clot within a vessel.

Tunica media:  The layer of an artery composed of smooth muscle cells.  

Virchow:  A famous German pathologist of the 19th century.  He postulated Virchow’s triad, three elements which allow formation of a thrombus:  stasis of blood, abnormalities of the vessel wall, and hypercoagulability or increased propensity of blood to clot.  Small pockets of blood stasis outside of the main flow occur if Reynolds number is sufficient.  Decreased blood flow decreases endothelial production of protective molecules, constituting a vessel wall abnormality.  Hypercholesterolemia makes blood hypercoagulable by increasing the formation of erythrocyte aggregates and viscosity at low shear.

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