The aorta is the main artery of the chest and abdomen that carries blood from the heart to all the body’s vital organs and also to the lower limbs via the iliac arteries. Atherosclerosis can occur in these arteries resulting in narrowing or occlusion of these arteries. This can result in the patient experiencing claudication (leg cramp and pain with exercise). Examination of these arteries with ultrasound can determine whether they are narrowed or occluded and estimation made on the degree of narrowing.
Ultrasound can also be used to examine the renal arteries which are the arteries that connect the kidneys to the aorta. Stenosis of the renal arteries can cause hypertension and reduced blood flowto the kidneys. The renal arteries and veins are scanned to assess for stenosis and the kidney perfusion examined.
The superior and inferior mesenteric arteries and the coeliac, hepatic and splenic arteries can also be examined with ultrasound to determine patency and presence of stenosis. Stenosis or occlusion of the SMA, IMA and coeliac arteries can cause bowel ischemia.
All of these arteries can become dilated or enlarged with this enlargement termed an aneurysm. An ultrasound can also determine if there is an aneurysm and provide measurements to determine size and location of the aneurysm and whether there is thrombus present. Thrombus in an aneurysm can sometimes embolise and occluded arteries more distal to the aneurysm. Enlargement of the abdominal aorta is called and abdominal aortic aneurysm (AAA). The aorta is considered aneurysmal if it exceeds 3cm in diameter with treatment of the aneurysm considered if it exceeds 5cm in diameter. Patients who have an AAA or aneurysm of the iliac or visceral arteries may have the scan repeated many times over the years to determine if it is growing and the rate of this growth.
Treatment of narrowing or occlusion of the abdominal arteries can consist of ballooning the narrowed segment via a balloon catheter. At times a stent may also need to be placed within the artery to keep the artery open. A synthetic bypass graft can be used to bypass the occluded artery or to repair the aneurysmal artery. This can be performed via a tradition open operation or via a catheter inserted via the groin arteries.
PATIENT PREPARATION AND EXAMINATION TECHNIQUE:
Patients need to fast for 6 hours prior to the examination to minimize bowel gas interference. Clear fluids and medications may be taken as required. The examination is non-invasive with no needles used.
The patient will be examined in a quiet, darkened room with privacy assured. The patient will be examined lying on their back and they may need to roll onto their sides at times. Gel will be applied to the abdomen and the arteries in question examined with B-mode and Doppler to assess the patency of these arteries and if any atherosclerosis is present. The arteries will be examined for stenosis and if aneurysmal dilatation is present. The sites of stenosis and size of the aneurysms will be recorded and a formal report prepared.
The examination takes approximately 30 minutes.
Degree of stenosis in the aorto-iliac arteries is classified as <50%, >50%, >75% and occlusion.
Degree of stenosis in the renal arteries is classified as <60% and >60%.
Degree of stenosis in the SMA and coeliac artery is classified as <50% and >50%.
Sites of stenosis or occlusion are recorded and length of occlusion measured.
For aneurysms – aneurysm size, location and the presence or absence of mural thrombus is noted.