0:00

The next set of cases that we're going to look at are peripheral arterial disease.

0:05

Atherosclerosis is the most common cause of acute peripheral

0:09

occlusion cases. There's an increasing incidence with age,

0:13

and

0:14

for every symptomatic patient, there is basically at least three

0:18

to four asymptomatic patients, and ultimately, they have the same

0:22

comorbidity as patients with coronary artery disease.

0:25

An ankle-brachial index is 95% sensitive in detecting

0:29

clinically significant stenosis of the lower extremity arteries.

0:33

And on clinical assessment, basically, the vascular

0:36

surgeons or the emergency room physicians are basically looking, is that limb

0:40

viable? Which means there's no sensory or muscular finding.

0:43

Is it threatened? Which means is there a minimal or marginal

0:48

sensory loss?

0:49

Is it salvageable with prompt management or with immediate

0:53

revascularization? Or really the last would be, is it

0:57

irreversible? Is there major tissue loss, major nerve damage, and

1:01

paralysis, which is typically managed by amputation.

1:04

And ultimately, in the setting of peripheral arterial disease,

1:07

the goal of the CT angiogram is to provide the vascular surgeon

1:11

or interventional radiologist an adequate description of the vascular

1:15

lesions and sites and targets for revascularization to

1:19

prevent limb amputation, especially if they're in that threatened

1:22

category,

1:24

until obviously no adequate revascularization options

1:28

are available or remain.

1:30

There are many causes of peripheral arterial disease.

1:33

Obviously, the most common cause is thrombosis, which occurs in 85% of the

1:37

cases, or it can be embolic in 15% of the cases.

1:41

Regarding thrombosis, it typically happens because of progression of preexisting

1:45

atherosclerotic stenosis, where stenosis is defined as

1:49

narrowing of that contrast material opacified lumen

1:53

relative to a normal caliber artery.

1:56

And there's different degrees of stenosis that we report, going from

1:59

mild to severe. So mild is from 1% to 49%,

2:04

moderate is from 50% through 74%, severe is

2:08

anywhere between 75% to 99%, and occlusion represents

2:12

complete non-opacification of a vascular segment.

2:15

Now, not all thromboses lead to acute limb-threatening

2:19

ischemia, and some might be chronic, and collaterals are a

2:22

good indicator to know about the chronicity of a

2:26

vascular stenosis or an occlusion, as collaterals, they

2:30

develop over time as stenoses progress.

2:33

Now, when confronted with peripheral arterial thromboses, you want to

2:37

assess for unifocality or multifocality, how

2:41

good the distal outflow is and how patent it is, presence of

2:45

calcifications, presence of collaterals, because

2:49

you want to be able to guide management.

2:51

For example, a stent or an endovascular therapy might be more

2:55

suited if it's just a unifocal disease.

2:57

But if it's a long length of stenosis, multifocal stenosis,

3:01

lots of calcifications, a bypass graft or a surgery might be the only option.