Venous Properties LE
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Which layer is the thickest in the venous system?
Tunica intima, media, or adventitia?
Where do valves originate?
Which layer is the thinest? -
Tunica Adventitia is the thickest in the venous system.
Valves are extensions of the intima.
Media is thin, almost absent in venous system -
Where does multiphasic arterial flow become monophasic venous flow?
How do you adjust the equiptment to reflect this change? -
At the level of the arterioles. Pulsatile flow is abolished:
Muscle contracts, vessel constricts, luminal diameter decreases, resistance increases, flow diminishes.
Equiptment must be sensitised. Velocities range from .25-.4 m/sec. Decrease the scale by 1/2 from arterial setting, decrease sample volume. - What are capillaries and why are they significant?
- Capillaries are one cell thick, semipermiable vessels. Exchange of substances occur here by osmosis. Flow within them is forwar, slow and steady.
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Veins receive blood from where?
How much blood can the venous system store?
What enables the venous system to store blood? -
Veins receive blood only from capillaries.
Veins store 60-75% of blood.
Veins are in a semi collapsed state. They are thin walled and flexible (when empty) and stiff (when full.) If the vessel becomes too full, edema will occur. - How much blood is in our bodies?
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9 pts.
5 or so liters - How do valves work?
- Valves are bicuspid. They close in diastole to prevent blood from falling backwards down the legs. Valves will coapt (close well) or flutter and be incompetent if they don't coapt well. This will cause reflux.
- Is the venous system high or low resistant?
- Veins carry low resistant flow in a high resistant system. Due to the veins being in a semi-collapsed state.
- What is the difference between paring and duplication of veins?
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Below the knee, normal anatomy is 2 veins and 1 artery. "paired or vena cominantes"
Duplications occur in 50% of the population. Always expect to find a dupliation, thrombosis can occur here as well. In Trans, look to see if the vein and artery appear to be the same size, duplication is common. (Vein should be larger than artery without a duplication present.) Also look to see if they are near one another or far apart. If they are far apart, duplication is likely. - What is Hunter's canal?
- Medial above the knee where veins will dive deep to go posteriorly behind the knee.
- Which direction do veins carry blood?
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Veins carry blood toward the heart.
Pulmonary veins carry O2 blood from lungs to Lt. atrium. -
Which vessels make up the deep system in the lower extremeties?
Which vessels make up the superficial system in the lower extremeties? -
The lower extremity deep venous system is made up of the IVC, common iliac, external iliac, common femoral, (superficial) femoral, Profunda Femoris, Popliteal, Posterior Tibial, Anterior Tibial, Dorsalis Pedalis, Peroneal. (PT, AT, DP, Paroneal are all paired)(Deep veins run along the artery, have spontaneous flow and are deeper into the tissue.)
Superficial veins of the lower extremeties include, LSV and GSV. (do not run with artery, are shallow and do not have spontaneous flow unless collateralized.) - What are perforators?
- Perforators are 1 bicuspid valved conduits that connect the superficial and deep system. Varicosities can result when valves are damaged. They run through facial planes.
- When is a superficial thrombosis worrysome?
- When it is high in the GSV near the Femoral Junction.
- What physical effect do valves have on luminal size?
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In superficial veins, the lumen will be larger at the area of a valve.
There are 2 times more valves below the knee to promote forward flow. - What things influence normal venous flow?
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Val Salva- Pressure changes
Breathing- Phasicity
Augmentation -
What is the longest Vein in the body?
What is it commonly used for? -
The Greater Saphenous.
It is often used for the Cabg proceedure. - Should there be spontaneous flow in the superficial system?
- No, if you note spontaneous flow in the superficial system, you should be suspicious of colateral flow due to thrombosis.
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To demonstrate spontaneous flow in a vessel in which it is not filling the color box, what should you ask the pt to do?
What can you do to help? -
Dorsiflexion will force blood up the leg and cause the color flow to fill the vessel.
Keep pt warm or reposition. -
Veins should be larger than arteries, if the vein is equal or smaller size, what should we look for?
If the vein is much larger than the artery what should we look for? -
Look for duplication in veins that are equal or lesser in size than the artery.
Look for thrombosis if the vein is much larger than the artery. -
At what level in the venous system do we use the Val Salva?
When should the Val Salva be avoided? -
Val Salva is done at the CFV.
It should not be done on heart patients.