Unit 6: Atherosclerotic plaque Flashcards
What is the primary carotid disease?
Atherosclerosis
What are some other carotid diseases encountered by vascular technologist?
- Dissection
- Thrombosis
- Fibromuscular dysplasia
- Kinking
- Carotid body tumor
- Aneurysm/pseudoaneurysm
- Subclavian steal
What does atheroma mean?
greek for porridge or gruel.
What are macrophages?
Large white blood cells, eating cells, may be found in tissue or moving through blood flow.
What is a fibrous cap?
It is a protective layer over atheromatous core of lipids or necrotic debris seperating it from the lumen.
What can a plaque be or contain?
- Fibrous
- Fatty
- Calcific
- Necrotic core
What is the dysfunction of endothelial cells?
Atherosclerosis
What are the hemodynamics (forces) associated with athersclerosis?
- Oscillatory flow
- Turbulence (post-stenosis)
- Low shear stress.
What is the difference between typical stress and shear stress?
Typical stress→ arises from the force perpendicular to the material cross section on which it acts.
Shear stress→ it is the force parallel to the cross section. Friction of blood rubbing along the wall as it flows. ( think of friction in a landside.)
Where does plaque usually form?
In areas of low shear stress.
What are some risk factors for athersclerosis?
- Hypertension
- diabetes
- High cholestorol
- Smoking
- Obesity
- Physical inactivity
- Renal failure
What are the 3 arterial layers?
- Intima
- Media
- Adventitia
What is the intima?
It is the single layer of endothelial cells.
What do risk factors do to the endothelial cells?
- It creates dysfunctional endothelial cells which causes monocytes (WBC) to adhere to endothelial cells.
- This combo enables them to move to the intima-media layer
- A NEOINTIMAL layer is formed below the endothelial cells.
- Monocytes become macrophages
- Macrophage become foam cells as they ingest cholestoral and oxidized lipids.
AN early lesion, aka “fatty streak” (type 1) will form:
- Foam cells
- Lipid droplets in smooth muscle
- Appears as a yellowish streak in the wall
- May progress or be reversed through excersise and control of risk factors.
What happens as plaque starts to grow?
The artery dilates to compensate and then the wall remodels to increase lumen size
When does glagovian remodeling occur?
It occurs in response to wall shear stress.
What happens when the artery cannot enlarge any further?
Plaque may grow to narrow the lumen.
What does a atheroma consist of
Lipid core, smooth muscle cell displacement with a matrix.
When would an atheroma cause symptoms?
If a peice break off and move downstream as emboli
When do fiborous plaque occur?
Occurs over the age of 40
What does a fibrous plaque have?
It has a lipid core with a fibrous cap.
What does a fibrous cap do?
It seperates the core and lumen. It can also disrupt and cause thrombosis which may in turn block flow or break off and become emboli.
What is a necrotic core?
It is a region of a plaque that is made up of primarily dead macrophage foam cells.
What are 4 types of complicated lesions?
- Hemorrhage within plaque
- Necrosis
- Thrombosis of lumen
- Ulceration of plaque
What does a dangerous plaque have?
It has a large/lipid/necrotic core close to a thin/disrupted fibrous cap, few smooth muscle cells and many macrophages.
What does a rupture of plaque cause?
It allows emboli to escape from the plaque.
What can happen to a ruptured plaque?
It can heal or enlarge with a thrombus on the surface.
T/F:
You can clearly identify plaque substances on an ultrasound.
False!
You cannot clearly identify plaque substances on ultrasound as fibrous, fatty, hemmorhagic, ulcerated, ect.
How can you clearly identify calcification?
It is a bright area with shadow deep to it.
What is calcification known to be a sign of?
It is a sign of plaque stability.
