Circulation Terms in Plain English

Vascular reports and clinic letters are written for other clinicians. This is what the words mean in ordinary English, grouped by where you are likely to meet them.

The basic plumbing

Term What it means
Artery A vessel carrying blood away from the heart, under pressure, delivering oxygen
Vein A vessel carrying blood back to the heart, at low pressure, with one-way valves to stop it falling backward
Capillary The microscopic vessels where oxygen and nutrients actually cross into tissue
Lymphatic system A separate drainage network that clears the fluid and protein tissues leave behind
Perfusion How much blood is actually reaching a tissue. Good perfusion means well supplied
Calf muscle pump The calf squeezing leg veins as you walk. It is the main engine pushing venous blood uphill
Distal / proximal Further from the body (toes) / closer to it (thigh)
Bilateral / unilateral Both sides / one side

How the three systems differ.

Artery words

Term What it means
Atherosclerosis Fatty, fibrous plaque building up in the artery wall and narrowing it. The underlying process in most PAD
Peripheral artery disease (PAD) Atherosclerosis narrowing the arteries to the limbs, usually the legs
Stenosis A narrowing
Occlusion A complete blockage
Ischemia Tissue not getting enough blood for what it is being asked to do
Claudication Cramping or aching in the leg muscles brought on by walking a fairly predictable distance and relieved by standing still
Rest pain Pain in the forefoot and toes when lying flat, relieved by hanging the leg down. A serious sign
Chronic limb-threatening ischemia (CLTI) Advanced PAD with rest pain, a non-healing wound, or tissue loss. Formerly called critical limb ischemia
Acute limb ischemia Blood supply cut off suddenly, over minutes to hours. An emergency
Collateral vessels Small side-branches that enlarge over time to carry blood around a blockage. Part of why walking helps
Gangrene Tissue that has died from lack of blood supply
Dependent rubor A dusky red color in a foot that is hanging down. Paired with pallor on raising, it suggests poor arterial supply
Embolus A fragment of clot or plaque that travels and lodges further downstream

The PAD guide and rest pain explained.

Vein words

Term What it means
Chronic venous insufficiency Leg vein valves no longer closing properly, so blood falls back and pressure stays high
Reflux Blood flowing backward through a failed valve. What the ultrasound is looking for
Venous stasis Blood pooling and moving sluggishly in the leg veins
Varicose veins Superficial veins that have stretched and become twisted and visible
Deep vein thrombosis (DVT) A clot in one of the deep veins, usually of the leg
Pulmonary embolism A clot that has traveled to the lungs. An emergency
Superficial thrombophlebitis Clot and inflammation in a surface vein — a tender, firm, red cord you can feel
Post-thrombotic syndrome Long-term swelling, aching and skin changes after a DVT has damaged the valves
Hemosiderin staining The rusty brown discoloration around the ankle, from iron left behind by leaked red cells
Lipodermatosclerosis Hardened, tight, narrowed skin and tissue above the ankle from long-standing venous pressure
Ablation Closing a leaking vein from the inside, usually with heat or glue via a catheter
Sclerotherapy Injecting a solution that seals a vein shut

The veins section.

Swelling and lymph words

Term What it means
Edema Excess fluid in the tissues. The medical word for swelling
Pitting edema Swelling that holds a dent for a while after you press it
Non-pitting edema Swelling that does not dent. Points more toward lymphatic causes or thyroid disease
Lymphedema Swelling from a lymphatic drainage problem rather than a blood-flow one
Lipedema A symmetrical build-up of fat tissue in the legs, usually sparing the feet. Not the same as lymphedema
Stemmer sign Not being able to pinch a fold of skin at the base of the second toe. Suggests lymphedema
Cellulitis Bacterial infection of the skin and tissue beneath it — spreading redness, warmth, tenderness

The swelling section.

Tests and numbers

Term What it means
Ankle-brachial index (ABI) Ankle blood pressure divided by arm blood pressure. Roughly 1.0 to 1.4 is normal; below 0.9 suggests PAD; above 1.4 usually means stiff, incompressible arteries rather than a good result
Toe-brachial index (TBI) The same idea using the toe. Used when ankle arteries are too stiff to compress, which is common with diabetes and kidney disease
Duplex ultrasound Ultrasound that shows both the picture of the vessel and the flow inside it
Segmental pressures Cuffs at several levels of the leg, to locate roughly where a blockage sits
Pulse volume recording A waveform tracing of the pulse at each level. Useful when pressures are unreliable
Angiography Imaging the inside of the arteries with contrast, by CT, MRI, or catheter
Transcutaneous oxygen (TcPO2) Oxygen measured at the skin surface. Estimates whether a wound has enough supply to heal
D-dimer A blood test used in assessing possible clot. Useful for ruling out, poor for ruling in
Monofilament test A thin nylon strand pressed on the foot to check protective sensation
Triphasic / biphasic / monophasic Descriptions of an arterial waveform on ultrasound. Triphasic is normal; monophasic suggests significant disease upstream

What each test involves.

Treatment words

Term What it means
Revascularization Restoring blood flow past a blockage, by any method
Endovascular Treatment done from inside the vessel through a catheter, rather than by open surgery
Angioplasty Opening a narrowed segment with a balloon
Stent A mesh tube left in place to hold a vessel open
Bypass graft A new route around a blockage, using one of your own veins or a synthetic tube
Restenosis A treated segment narrowing again
Antiplatelet Medicine that makes platelets less likely to clump — aspirin and clopidogrel among others
Anticoagulant Medicine that slows clot formation. Often loosely called a blood thinner
Statin Cholesterol-lowering medicine that also stabilizes plaque. Standard treatment in PAD regardless of cholesterol level
Supervised exercise therapy A structured, monitored walking program. First-line treatment for claudication
Debridement Removing dead or unhealthy tissue from a wound so it can heal
Offloading Taking pressure off a wound, with footwear, padding or a cast
Compression therapy Graduated external pressure — bandages or stockings — to counteract high venous pressure

Common questions

My report says my ABI is 1.5. Is that better than 1.0?

No. A value above about 1.4 usually means the ankle arteries are too stiff to be squeezed by the cuff, which happens with diabetes and kidney disease, so the number is falsely high rather than reassuring. The next step is a toe-brachial index or a waveform study. More.

What is the difference between venous insufficiency and PAD?

They are opposite plumbing problems. PAD is not enough blood arriving through the arteries; venous insufficiency is blood not leaving properly through the veins. They cause different symptoms, different wounds in different places, and treatments that can work against each other — which is why the difference matters. The full comparison.

My letter says monophasic flow. Should I be worried?

It means the pulse waveform has lost its normal shape, which generally points to a significant narrowing further up the leg. It is a finding to follow up rather than an emergency in itself, and it is usually interpreted alongside pressures and symptoms. Ask what the plan is rather than what the word means alone.

Sources

  1. National Heart, Lung, and Blood Institute. Peripheral Artery Disease.
  2. Society for Vascular Surgery. Vascular Conditions.
  3. MedlinePlus, National Library of Medicine. Medical Dictionary.
  4. Centers for Disease Control and Prevention. About Blood Clots.

Written by Tom Biernacki, DPM, FACFAS. Published 21 September 2026. General education, not medical advice.