Ultrasound for Aorta

 Ultrasound of the aorta

The anatomy of the abdominal aorta runs from the aortic hiritis to the bifurcation it has three major anterior branches the celiac axis at t12 the sma at l1 the ima at l2 it has multiple paired branches of which the most significant is the renal arteries at t2 the gonadal arteries and there are four paired lumber arteries this these are the gonadal arteries the celiac artery and the sma arise from the anterior aspect of the proximal aorta, this is the select axis and this is the sma in one to three percent of patients the celiac artery and the sma arise from a common trunk this is the common trunk coming off here and giving off the celiac.

 Aorta technique

The abdominal aorta technique measures the aorta and common iliac arteries from the outer diameter in the ap and transverse planes.

Doppler tips

Doppler tips aliasing is a marker of stenosis the doppler spectrum should be obtained from the site of aliasing or turbulent flow in this case from the origin of the celiac axis where an area of aliasing is seen indicating stenosis at the celiac axis elevated velocities are seen within the stenosis.

Normal Aorta

The normal aorta is larger in males than in females it increases with age at the aortic hiatus

the normal male aorta measures 2.7 centimeters in females, it measures 2.3 centimeters at the bifurcation the aorta measures 2.1 centimeters in the females, it measures 1.7 centimeters at the normal common iliac artery should be less than 1.5 centimeters in size.

The appropriate way to measure the aorta in the transverse plane the Doppler waveform of the normal aorta is triphasic with early diastolic reversal of flow lower resistance i.e more diastolic flow is seen in the proximal aorta before the takeoff of the renal arteries than in the distal aorta peak systolic velocity in the normal aorta is 110 centimeters per second when young with increasing age this decreases to 70 to 100 centimeters per second.

Abdominal Aortic Aneurysm

Risk factors for abdominal aortic aneurysm 

Hypertension smoking family history

Age connective tissue disease

Infection and is called a mycotic aneurysm

Inflammation and trauma

Abdominal aortic aneurysms increase in size with time there is high variability in growth rates

The abdominal aortic aneurysm has been called the silent killer because it is asymptomatic and can rupture suddenly resulting in high mortality.

 Laplace's law describes the relationship between the diameter of the aorta and the pressure on the wall essentially the larger the aneurysm the greater the pressure on the wall of the aorta and the greater the risk of rupture incidence of rupture rises therefore with aortic diameter it is for aortas that are three to five centimeters in diameter it is one percent per year when the aneurysm increases to greater than 5.5 centimeters it is 10 per year the rupture rate is increased in active smokers these are two famous people who died of ruptured aortic aneurysm.

Measurement for Aorta In US

 Measurements of the abdominal aorta should be obtained in the longitudinal and a transverse plane perpendicular to the long axis measurements should be performed from the outer wall to the outer wall and the length of the aneurysm should be measured additionally the location of the measurements should be recorded most abdominal aortic aneurysms occur inferior to the origin of the renal arteries but a few occur suprarenal or juxta renal.

A diagnosis of abdominal aortic aneurysm Ultrasound

 When the diameter of the order exceeds three centimeters or increases to 1.5 times greater than that of the adjacent normal aorta a common iliac artery aneurysm is diagnosed when the diameter exceeds 1.5 centimeters when an aneurysm has been diagnosed the policy is to follow up a three to four-centimeter aneurysm annually a four to four-point five-centimeter aneurysm every six months for aneurysms greater than five centimeters.

The correct way the measurement caliper has been placed on the outer surface of the aorta and the correct distance is from the outer surface of the aorta here to the outer surface of the aorta.

Measurement technique patients should fast for 8 to 10 hours a 2.5 megahertz curvilinear transducer should be used compression may be applied to eliminate bile gas another useful maneuver to eliminate biogas is to place the patient in the left lateral decubitus position long-axis views of the kidneys should be obtained measurements should be obtained from the proximal mid and distal aorta the common iliac artery should be measured at the bifurcation for screening purposes a single transverse measurement will suffice it is important to obtain the measurements perpendicular to the plane of the vessel the aorta can be a very torture.