Chapter 4 The Aorta

Right renal artery (RRA)

located a few centimeters within the origin of the SMA, it courses anterior to the spine and posterior to the inferior vena cava in route to the right kidney

Superior mesenteric artery (SMA)

just inferior to the CA, divides into several small arteries that supply the ascending portion of the colon and largest portion of the small intestine

Retroperitoneum

portion of abdominopelvic cavity posterior to the peritoneal sac

Thoracic Artery

posterior to the diaphragm

The long axis of the aorta is visualized best in a

sagittal or coronal scanning plane

The biggest risk factor for rupture of an abdominal aorta aneurysm

size

The lie of the aorta within the body is

superior and inferior

Intima

the innermost layer of the artery, which is in contact with blood flow

Axial views of the SMA are seen in a

transverse scanning plane

Longitudinal views of the renal arteries are seen in a

transverse scanning plane

Longitudinal views of the splenic artery and common hepatic artery are seen in a

transverse scanning planes

Transducer Frequency

• 3.0 MHz or 3.5 MHz. • 5.0 MHz for thin patients.

Breathing Technique

• Normal respiration. • Deep, held respiration. Note Different breathing techniques should be used whenever the suggested technique does not give the desired results.

Normal Variants

• Normal variations of the abdominal aorta are rare but include: • Markedly tortuous • May lie on the right side of the inferior vena cava • May include an anterior pulmonary branch close to the CA trunk

Patient Position

• Supine. • Right lateral decubitus, left lateral decubitus, left posterior oblique, right posterior oblique, or sitting semierect to erect as needed. 55 Note Different patient positions should be used whenever the suggested position does not give the desired results.

Patient Prep

• The patient should fast for at least 6 to 8 hours before the ultrasound study. • If the patient has eaten, still attempt the examination.

What is the size of the aorta?

Size is normal up to 3 cm in diameter, gradually tapering toward the bifurcation

Physiology of the aorta

Supplies the organs, bones, and connective structures of the body with oxygen and nutrient-rich blood.

proximal aorta

(closest to origin) portion of the abdominal aorta is described as the area seen inferior to the diaphragm and superior to the CA trunk; it lies anterior to the spine and posterior to the esophageal gastric junction and liver.

Distal aorta

(farthest from origin) portion of the abdominal aorta is described as inferior to the SMA and superior to the bifurcation; it lies anterior to the spine and posterior to the bowel.

The size of the aorta is normal up to

3 cm

Sonographic Appearance

Because the aorta is vertically orientated in the body, longitudinal and long axis views are seen in coronal scanning planes and sagittal scanning planes as demonstrated in the following image. The aorta appears like a large long tube, anechoic with bright walls, immediately anterior to the spine, and immediately posterior to 53the esophageal gastric junction, crus of the diaphragm, SMA, and splenic artery.

Mid Aorta

The mid portion of the abdominal aorta is seen from the CA trunk running along the length of the SMA; it lies anterior to the spine and posterior to the CA, SMA, splenic artery, splenic vein, body of the pancreas, a portion of the stomach, and the liver.

Abdominal Aorta

abdominal cavity; The abdominal aorta is vertically orientated in the body. It descends, anterior to the spine, just to the left of the midline then bifurcates into the common iliac arteries anterior to the body of the fourth lumbar vertebra.

Celiac artery Trunk

also known as "celiac axis," branches into the left gastric artery, common hepatic artery, and splenic artery

Beginning posteriorly, and in correct order by the location in the body, the abdominal aorta is

anterior and just left of the spine posterior to the gastroesophageal junction, CA, SMA, splenic vein, body of the pancreas, portion of the stomach, left lobe of the liver.

common iliac arteries

are two large arteries that originate from the aortic bifurcation at the level of the fourth lumbar vertebra. They end in front of the sacroiliac joint, one on either side, and each bifurcates into the external and internal iliac arteries

The proximal abdominal aorta is the portion

between the diaphragm and CA trunk

Which of the following is not a direct branch of the abdominal aorta?

external iliac artery

Inferior mesenteric artery (IMA

inferior to the SMA and renal arteries, divides into several small arteries that supply the transverse and descending portions of the colon and the rectum

The distal abdominal aorta is the portion

inferior to the SMA trunk and superior to the bifurcation

The mid portion of the abdominal aorta is

inferior to the celiac trunk and along the length of the SMA

What is the most common location of an adominal aorta aneurysm>

infrarnel

A (n) ________________________section of the RRA is seen ________________________________________.

longitudinal; in a transverse scanning plane posterior to an axial section of the inferior vena cava and longitudinal section of the right renal vein.

tortuous

marked by twists, turns, or bends)

Media

middle

Left renal artery (LRA):

ocated a few centimeters within the origin of the SMA, it courses left lateral to the spine and posterior to the tail of the pancreas in route to the left kidney

Aorta

originates at the left ventricle of the heart then ascends posterior to the pulmonary artery

Adventitia

outermost

The aorta is posterior to all of the following except the

pancreas head