Peripheral Venous and Arterial Ultrasound – Instrument Based Diagnostic Techniques

00:00 Other tests can be done to look for peripheral vein and peripheral artery abnormalities.

00:09 Here we use ultrasound. This is similar to the ultrasound used in pregnant women to look at the fetus except here we’re looking at the veins and the arteries. This technique is very commonly used for detection of internal carotid artery atherosclerotic plaques and obstruction. And as you see in the little cartoon, there’s obstruction there. And then in the next slide you can see that one can actually estimate the degree of stenosis because the picture shows us the internal lumen or channel of the carotid artery with an obstructive atherosclerotic plaque. It has been shown in many studies that the worst the narrowing in the carotid arteries the greater the risk for stroke for that person.

00:56 And then one needs to do something about it. Of course there’s medical and surgical and catheter therapies for this. And that’s the subject of a later discussion.

01:08 Black and white imaging is done as you saw on the last slide. And you can usually tell if the plaque is greater than 50%, approximately 50% or less or whether in fact the artery is completely blocked.

01:24 When we use it in the venous system, it also shows us whether there’s normal blood or whether there’s an obstruction in the flow of blood in the veins. In other words a blood clot.

01:37 This is a colour Doppler flow map of a vein. The different colours show you the velocity of flow, the red being high-velocity flow. So here we see a very normal vein with lots of blood flowing, turbulent blood at one point probably because there’s a bifurcation or a bridging of two veins that come together in a place which creates a little turbulent flow. What we can see when there’s a clot there is that the flow stops. And you can see clearly in this picture, you can see blood flow up to a certain point in the vein and then suddenly none and then beyond it downstream no blood flow. We also can actually look at patterns of the blood flow. And there are abnormal wave forms versus normal wave forms.

02:32 This slide shows you abnormal wave forms that are associated with decreased blood flow velocity beyond an area of obstruction. And you can also see that there is no flow detected below the point of obstruction. This is used for the diagnosis of venous thrombosis – or a blood clot – in the legs, a very common condition which will also be discussed in a subsequent lecture.

03:01 Here we actually see the blood clot visualised in a vein. And the Doppler shows the flow and this image just shows you that there’s a clot in the vein.

03:13 We can also use the venous and arterial ultrasound imaging techniques to show us areas of the artery or vein that are abnormal, markedly dilated or increased in size.

03:29 Here we see an aneurysm – that is an outpouching, a weakening of the wall in the abdominal aorta.

03:36 And you can see how large and round this is. These entities can actually rupture and be fatal. And so we follow them very closely with periodic ultrasound studies. And you can see that there’s only flow in part of this aneurysm in the lower left-hand figure because the rest has clots in it, which is another complication of the aneurysm.

04:01 I mentioned before that atrial fibrillation puts patients at risk for developing blood clots in the heart that can break off and cause a stroke or kidney damage. And what you see here is using a two-dimensional echocardiogram put into the esophagus. We can actually see, where the arrow is, that there’s a blood clot sitting in the left atrium ready to break off and cause a stroke. This is of course an indication for anticoagulation – that is blood thinners – to prevent this clot from getting bigger and, eventually, letting the body dissolve it.