Abdomen Ultrasound II- Discussion 9

Abdominal Vasculature Pathology

What is the largest artery in the body?

aorta

Where does the aorta originate?

Left ventricle of the heart

Where is the aorta positioned?

Anterior to the spine, just left of midline

Arteries become thick and stiff restricting blood flow to your organs and tissue

arteriosclerosis

The buildup of plaque, which can restrict blood flow.

Atherosclerosis

Full occlusions of the abdominal aorta tend to occur in the __________ portion of the aorta and/or _____________________ with thrombus spreading upward.

lower; common iliac

Ultrasound features of atherosclerotic plaque: 

• Luminal irregularities – plaques

• Aortic wall calcifications- sharp, hyperechoic, can display acoustic shadowing

• Tortuosity (twisting)– mild or markedly

Causes of atherosclerosis: 

HTN, high cholesterol, high triglycerides, smoking, insulin resistance or diabetes, inflammation from diseases or infections

Treatments for atheroscelrosis: 

Lifestyle changes, such as eating a healthy diet and exercising, are often the most appropriate treatment for atherosclerosis. Medication or surgical procedures such as angioplasty and stent placement. 

What is the most frequent cause of embolism?

plaque breaking loose and traveling distally until it lodges in a small vessel

Clinical findings of aneurysm:

Pulsatile abdominal mass, abdominal bruit, back pain, abdominal pain, lower extremity pain

What is the measurement for an AAA?

>3 cm

The _____________ the dilation, the more risk there is for potential rupture.

larger

Present when there are areas of dilation less than 3 cm or when there are irregular margins and a non-tapering profile

ectasia

Most aortic aneurysms are _____________.

fusiform

How is the aorta measured?

outer to outer

Risk factors for AAA:

Atherosclerosis, tobacco use, hypertension, trauma, chronic obstructive pulmonary disease and positive family history for AAA, Marfan syndrome, inflammation of media and adventitia

Inherited, degenerative disorder of the connective tissue, which gives shape and structure to tissues in the body and holds them in place

Marfan’s syndrome

Symmetric and gradual dilatation of vessel wall with proximal and distal tapering. Due to chronic degenerative change in arterial wall (makes it slow growing) 

Fusiform aneurysm

Focal, eccentric dilatation of vessel wall. Suggests possible inflammatory or infectious etiology

Saccular aneurysm

Not full thickness of vessel wall. Usually related to prior instrumentation including prior aneurysm repair

Pseudoaneurysm

Blood enters the media of the aorta and splits the aortic wall

Dissecting aneurysm

Fusiform aneurysm

Saccular aneurysm

Pseudoaneurysm

Pseudoaneurysm sonographic findings: 

A perivascular hematoma that contains swirling blood and has a neck connecting it to the vessel, color Doppler demonstrates turbulent flow within the mass, the spectral waveform obtained from the neck of pseudoaneurysm typically displays a high velocity, bidirectional or “to-and-fro” signal (ying-yang)

What is the most common type of splanchnic artery aneurysm? 

splenic artery

Second most common type of splanchnic vessel aneurysms

encountered.

75% extrahepatic in origin.

25% occur intrahepatically.

Right hepatic arterial branch more often affected than the left.

Rare and tend to male preponderance.

Hepatic artery aneurysm

Rarest splanchnic artery aneurysms.

Branch superior mesenteric arterial aneurysms are also rare.

SMA aneurysm

aneurysm caused by infection are termed mycotic aneurysms

Mycotic aneurysm

small saccular aneurysm commonly located in the cerebrum (brain vessels)

brain aneurysm

More commonly seen in very large aneurysms. Usually eccentric in location. Causes narrowing of vessel lumen.

Fresh clots (acute) are hard to see, less echogenic; while chronic clots more echogenic. 

Thrombi-blood clots

The most serious complication of AAA is ________ of the aorta into the retroperitoneum

rupture

Risk of rupture increases with aneurysms larger than ____.

7 cm

Mortality rate for untreated rupture is virtually _______.

100%

With surgery, mortality rate for rupture ranges from 

40-60%

Ruptures aortic aneurysm symptoms: 

severe abdominal pain, hypotension, shock, decreased hematocrit, and an expanding abdominal mass

Sonographic appearance of ruptures aortic aneurysm:

• Varies

• Appears anywhere from completely cystic to complex collection in the abdomen

• It is difficult to identify the exact location of a rupture with ultrasound

• CT is the imaging modality of choice with suspected AAA rupture

Surgical intervention is considered when the aneurysm reaches _____ or greater.

5 cm

Correction of pseudo aneurysm may be accomplished by:

Surgical repair, prolonged compression repair, ultrasound guided thrombin injection repair

Aortic dissection almost always begin in the _______ aorta and extend down into the abdominal aorta.

thoracic

Aortic dissection sonographic appearance: 

• Identify 2 channels of flow, using 2D or Color flow Doppler

• A linear intimal flap, may be noted within the aortic lumen. This flap may be visualized swaying in the current of the passing blood

• Determine extent of dissection in either direction

• Determine the velocity of flow and existence of turbulent flow

Type A aortic dissection: 

Tear in the ascending aorta, which may extend into the abdominal aorta -- More common and dangerous type

Type B aortic dissection

Tear in the descending aorta which may also extend into the abdominal aorta

Aortic dissection causes and risk factors: 

• Occurs in a weakened area of the aortic wall

• Chronic HTN may stress the aortic wall making it more susceptible to tearing

• Conditions associated with a weakened and enlarged aorta, such as Marfan syndrome can also increase the chances of occurrence

Aortic dissection most commonly occurs in:

Men during the 6th-7th decade of life (>40 years)

Treatments for Type A aortic dissection:

Requires open heart surgery

Treatments for Type B aortic dissection: 

Can be treated with graft repair

Type A aortic dissection symptoms: 

Sudden, sharp, stabbing pain in the chestType B aortic dissection symptoms: sudden, sharp, 

Type B aortic dissection symptoms:

sudden, sharp, stabbing pain in the back

Aortic dissection

caused by obstruction of the terminal aorta. It usually occurs in males

Leriche syndrome

Leriche syndrome symptoms: 

• fatigue in the hips, thighs, or calves on exercising

• absence of pulsation in the femoral arteries

• Impotence

• coldness/pallor of the lower limbs

Characterized by compression of the third (transverse) portion of the duodenum against the aorta by the superior mesenteric artery

SMA syndrome

The superior mesenteric artery usually forms an angle of approximately ___ with the abdominal aorta. 

45°

Median Arcuate Ligament Syndrome (MALS)

• In some people, the MAL passes anteriorly to the celiac artery and may cause celiac artery compression during expiration due to upward motion of the diaphragm.

• Increased velocities are noted in the celiac artery during compression by the median arcuate artery

• There is an immediate decrease in PSV with Deep Inspiration

What is the largest veining the body?

IVC

IVC measurement

Measure less than 2.5 cm and should be measured during suspended respiration

What is the normal response of the IVC when blood flow is obstructed?

To increase in diameter behind the point of obstruction

What is the most common cause of IVC obstruction that leads to enlargement?

Right-sided heart failure

Metastatic tumors of the IVC most often occur from __________________. 

renal cell carcinoma

How can you tell the difference between a blood clot and a tumor? 

A tumor will demonstrate blood flow

IVC thrombosis/DVT clinical signs: 

Leg edema, low back pain, pelvic pain, gastrointestinal complaints

Gelatinous clump composed of fibrin and blood cells due to blood coagulation

Blood clot

What is fibrin? 

A fibrous mesh that forms during the clotting of blood

T/F An IVC thrombus, or any DVT, is life threatening. 

true

A DVT that dislodges from the vessel wall becomes:

An embolus

An embolus that travels to the lungs is referred to as a: 

pulmonary embolism (PE)

What is the most common vascular problem affecting the IVC? 

thrombosis

The most common findings of IVC thrombosis are: 

IVC enlargement, absence of flow, and thrombus noted within the IVC lumen

Acute thrombus may be completely ___________ or ___________ and a free-floating thrombus tail may be seen in the very acute phase

Anechoic; hypoechoic 

With time, thrombus will become more ___________ and may even calcify and produce acoustic shadowing

echogenic

Thrombosis treatment: 

Focus on preventing a new clot and reducing risk of embolization, medications, IVC filter

Budd-Chiari Syndrome most common cause: 

Blood clots that completely or partially blood flow from the liver

Compression or invasion of the hepatic veins and/or the inferior vena cava by a lesion that originates outside of the vein (for example, a malignancy –hepatocellular carcinoma or adrenal or renal carcinoma)

Secondary Budd-Chiari syndrome

When 2 hepatic veins get occluded, it causes _____________________ that stretches the liver capsule. The fluid starts passing through the liver capsule leading to ascites, portal hypertension and decreased flow into the liver from the portal vein

venous congestion

A vascular compression disorder when the aorta and SMA compress or pinch the left renal vein

Nutcracker syndrome

Nutcracker syndrome symptoms: 

Flank pain, hematuria, oliguria, typically asymptomatic

An abnormal connection between an artery and a vein…essentially bypassing capillary beds and diminishing blood supply to surrounding tissues in the affected area

Arteriovenous fistulas (AVF)

Acquired AVF is normally due to:

injury