Vascular System Chapter 8

Function of the circulatory system with the heart and lymphatics

Transport gases, nutrient materials and other essential substances to the tissues. Transport waste products from the cells to the appropriate sites for excretion.

Flow of blood goes from

Arteries to arteries to capillaries to venules to veins back to the heart

Arteries carry oxygenated blood where?

Away from the heart

Veins carry deoxygenated blood where?

To the heart from the tissues

Arteries and Veins have how many layers?

3 layers

What is the innermost layer of an artery/vein?

Tunica Intima

3 layers of the tunica intima?

• layer of endothelial cells lining the arterial passage (called the lumen)

• Layer of delicate connective tissue

• Elastic layer made up of a network of fibers

What is the second layer of an artery/vein?

Tunica Media

Tunica media is made up of what?

Smooth muscle fibers with elastic and collagenous tissue

What is the third/most outermost layer of a vein/artery?

Tunica Adventitia

Tunica Adventitia Is made up of what?

Loose connective tissue with bundles of smooth muscle fibers and elastic tissue

Vasa Vasorum

Makes up the tiny series and veins that supply the walls of blood vessels

The tunica media is thicker in veins or in arteries?

In arteries, it is what allows veins to be collapsible

The blood in arteries is driven by what?

Heart contraction

Smaller arteries contain ____ elastic tissue and ____ smooth muscles than the larger arteries?

Less elastic tissue and more smooth muscles

Elasticity of larger arteries is important for maintaining what?

Steady blood flow

Does the aorta change in diameter with changes to respiration?

No it does not change

The blood flow in veins is aided by what?

Skeletal muscle contractions and pressure gradients

Why do veins have valves?

To prevent backflow and permit blood to only flow in one direction

Do veins have a smaller or larger total diameter than arteries?

Veins have a large total diameter

Arteries get progressively ____ leaving the heart and veins get progressively ____ as they return to the beart

smaller, larger

Capillaries

walls have one permeable layer that nutrients pass through

Arteriovenous Fistula/Malformation

Abnormal connection between an artery and vein

Fistulas can result from

Trauma or biopsy

Malformations (AVMs)

May be congenital or caused by surgery, malignancy, biopsy or trauma

If a fistula is iatrogenic it is

Caused by us/doctors/not naturally occurring

Five sections of the aorta in order

Aortic root, ascending aorta (aka aortic arch), descending aorta (aka thoracic aorta), abdominal aorta and bifurcation

Ascending Aorta Branches

• Brachiocephalic

• Left common carotid

• Left subclavian

Bifurcation

Right and left common iliac arteries, occurs at the belly button/umbilicus

Branches of the Abdominal Aorta

• Celiac trunk/axis

• Superior mesenteric artery (SMA)

• Renal arteries

• Inferior Mesenteric artery (IMA)

Celiac Trunk/Axis

Seen as the seagull sign in transverse plane.

Arises anterior from the abdominal aorta.

Supplies liver, spleen, stomach and pancreas

Celiac Trunk/Axis Branches

“Right wing” is the common hepatic artery CPA, “left wing” is the splenic artery SA and the third branch is the left gastric artery, this is not commonly seen on ultrasound

Common Hepatic Artery branches into

1. Gastroduodenal artery

2. Proper hepatic artery

Superior Mesenteric Artery SMA

Second abdominal branch

Posterior to body/neck of pancreas

Runs parallel to aorta

Celiac Trunk/Axis supplies

Supplies liver, spleen, stomach and pancreas

Superior Mesenteric Artery SMA Supplies

Small intestines, colon and pancreas

Has high resistance flow when fasting and low resistance flow after eating

Superior Mesenteric Artery SMA Branches

Inferior pancreatic, duodenal, colic, ileocolic and intestinal arteries

SMA Angle of over 15 degrees may indicate

Swollen lymph nodes/lymphadenopathy.

Not going to measure angle in sonography.

Renal Arteries

Third abdominal branch

Arise from anterolateral surface of aorta

What renal artery is longest?

Right renal artery is longest

What renal artery Is the only vessel posterior to the IVC?

Right renal artery is posterior to IVC

Coronal view of the renal arteries shows what sign?

Banana peel sign

Inferior Mesenteric Artery

Has three main branches; the left colic, sigmoid and superior rectal arteries.

Not often seen on ultrasound

Inferior Mesenteric Artery Supplies

Supplies the left transverse colon, descending colon, sigmoid colon and rectum

Common Iliac Arteries

Arise at the bifurcation of the abdominal aorta at the fourth lumbar vertebra/umbilicus

Internal Iliac Artery supplies

Pelvic viscera, peritoneum, buttocks and sacral canal

External Iliac Artery supplies

Lower extremities

Calcifications appear how sonographically?

VERY hyperechoic with posterior shadowing, form along the walls.

Thrombus/blood clots appear how sonographically?

Hypoechoic

How does the aorta appear in the transverse plane?

A circular structure anterior to the spine and slightly to the left of the midline

Measuring the aorta in transverse proximal is done

Just below the level of the diaphragm, superior to the celiac axis

Measuring the aorta in transverse mid is done

Above the renal arteries, at the SMA

Measuring the aorta in transverse distal is done

Inferior to renal arteries, above bifurcation

How does the aorta appear in the longitudinal plane?

Aorta appears as a long, pulsatile tubular structure anterior to the left of the spine

Longitudinal Plane aorta landmarks

Left lobe of the liver and gastroesophageal junction (anterior to aorta)

What should change with the aortic lumen measurement as it proceeds distally in the abdomen?

It should taper

Clinical indications for sonographic evaluation

Pulsatile abdominal mass, abdominal pain radiating to the back, abdominal bruit (sound heard with a stethoscope associated with stenosis), and hemodynamic compromise in the lower legs

Arterial system may be affected by 

atheroma (plaque), aneurysm, connective tissue disorder, rupture, thrombosis or infections

Most Common pathology of aorta

• Atherosclerosis

• Abdominal aortic aneurysm

• Pseudoaneurysm

• Aortic rupture

• Aortic dissection

Arteriosclerosis

hardening of the arteries occurs when arterial vascular system becomes thick and stiff, leading to restriction of blood flow to the organs and tissues

Atherosclerosis

specific form of arteriosclerosis, build-up of fats and cholesterol (plaque) that can restrict blood flow

Treatment for atherosclerosis

Stent

Definition of aneurysm

permanent dilation of an artery, with an increase of diameter greater than 1.5 times its normal diameter

Abdominal Aortic Aneurysm diagnostic criteria

when the diameter exceeds 3cm

Aortic ectasia

diagnosed when the diameter is less than 3cm but does not taper

How many layers are involved in a true aneurysm?

All 3 layers

2 types of aneurysms

Fusiform and saccular

Normal diameter of vessel

Less than 3cm

95% of AAAs occur 

infrarenal, remaining 5% occur suprarenal or pararenal

Common to co-occur with aneurysms

Mural thrombus (blood clot on the vessel wall)

Surgery is considered when an aneurysm is

> 5cm

Myotic aneurysm

aneurysm that is the result of an infection

Fusiform AAA

wider in the middle, tapers near the end. Uniformly fat, uniform weaking of the walls

Saccular AAA

focused weakening, sudden dilation of a vessel. Sac-like appearance

AAA Risk Factors

Tobacco use, hypertension, vascular disease, COPD, family hx and connective tissue disorder.

AAA Causes

Atherosclerosis, trauma, birth defects, syphilis, mycosis, increased valve pressure, inflammation of media and adventitia and abnormal volume load

AAA Clinical Signs and Symptoms

Palpable/pulsatile abd mass, abd bruit, back/abd pain, lower extremity pain and a drop in hematocrit.

Can also be asymptomatic

2 treatments of AAA

Open Surgery or EVAR

EVAR

graft placed via common femoral artery.

Can be straight, bifurcated or uni-iliac graft

Pseudoaneurysm

Involves 1-2 layers of the vessel wall

caused by trauma/injury to the vessel

Pseudoaneurysm Sonographic Appearance

perivascular hematoma, ying-yang sign (turbulent flow IN the mass on PW) and connecting neck (to-fro flow in connecting neck on PW)

Rupture/leak of AAA symptoms

excruciating abd/back pain, shock, expanding pulsatile mass, hypotension and decreased hematocrit.

AAA Mortality rate

50% upon diagnosis, aneurysms over 5cm have a 25% incidence to rupture over 8 years

Aortic Dissection

separation of the layers of the arterial wall, most likely the intima. Must have visible true and false lumen to be diagnosed.

Aortic Dissection Symptoms

intense chest pain, hypertension, abd/lower back pain and neurologic symptoms

IVC is formed by

union of common iliac veins and median sacral vein

Diameter of IVC

<2.5cm, but enlarged does not mean aneurysm

Anterior IVC tributaries 

Hepatic veins - draining blood from liver to IVC

Lateral IVC tributaries

Renal veins (drain blood from kidneys to IVC) and right gonadal vein (drain blood from right ovary/testicle to IVC)

IVC should appear how with color?

Filled wall to wall

Hepatic Veins

Largest visceral tributaries of IVC. Has a right, middle and left. Drain posteriorly into IVC at the diaphragm.

Return unoxygenated blood from the liver

Hepatic Veins make what sign in transverse?

Playboy bunny or reindeer

Hepatic veins have what kind of waveform?

Triphasic waveform, appears almost like a W

Renal veins

Courses anteriorly to left renal artery, courses between the SMA and the aorta. 

Which renal vein is longer?

Left renal vein is longer

Gonadal Veins

right drains directly into the IVC, left drains into the left renal vein and is always longer

Abnormalities of IVC

IVC dilation (enlarged), IVC tumor (within IVC) and IVC thrombosis (within IVC). Uncommon abnormalities include double IVC and infrahepatic interruption of IVC.

Dilation (enlargement) of IVC can be associated with 

right sided heart failure

How to identify IVC tumor vs thrombus?

Thrombus will not have internal color with color doppler, tumor will

IVC Tumor Invasion

commonly seen with kidney cancer, more common on R kidney due to RRV being closer/shorter to IVC than L kidney.