Peripheral Vascular Disease – Bypass Surgery

00:01 Here's an image of bypass surgery.

00:04 On this angiogram, the arrow demonstrates a mid-superficial femoral artery occlusion.

00:10 How do we fix this problem? That's right.

00:14 With a vascular bypass.

00:16 Here is a schematic of what happens in vascular surgery bypasses.

00:20 I enjoy vascular surgery because, conceptually, it's very straightforward.

00:25 We need to have excellent inflow.

00:28 We need to have excellent outflow.

00:30 And between the two, a bridging of conduit.

00:34 Any breakdown in any of those three elements can lead the patient to peripheral arterial occlusive disease.

00:40 As you can see in this schematic, the inflow on the left of the screen and the outflow appear normal in size.

00:47 However, this segment in the middle is stenotic.

00:51 There's going to be a significant flow and pressure differential as the vessel diameter goes from normal to stenotic or occlusive.

01:00 Vascular surgeons will then bypass this region as demonstrated by the arc.

01:05 In general, the bypass has the longest patency if we’re able to use a autogenous vein as opposed to synthetic graft.

01:15 Sometimes, it's not an option and grafts are used.

01:20 Let me pose another question to you.

01:23 Thus far, we've discussed atherosclerotic arterial occlusive disease.

01:27 What if the patient has a history of atrial fibrillation and now presents with an acute leg pain? What are your thoughts? What's going on in your mind? I'll give you a second to think about this.

01:41 Let's say, now you go to the bedside and examine the patient, but you feel no pulse in the dorsalis pedis or posterior tibial vessels.

01:49 And the contralateral extremity has strongly palpable posterior, tibial and dorsalis pedis pulses.

01:56 What's going on here? I’ll give you a second to think about this.

02:03 That's right.

02:04 The atrial fibrillation may have caused the clot, and that clot – called an embolus – likely dislodged from the heart and is now occluding a distal vessel.

02:13 This is considered an emergency.

02:16 Very important, if a clinical scenario is presented to you, this is considered an acute threatened extremity and intervention needs to occur right away.

02:26 If the question suggests, what is the next step of management, do you know what to do? First, we will usually use an unfractionated heparin drip.

02:38 The PTT goal is titrated and is variable.

02:42 This is to reduce further propagation of clot.

02:45 Next, most patients with threatened extremities require what's called a surgical embolectomy.

02:51 I’ll get to that in a second.

02:53 And lastly, when the embolectomy is completed, we want to make sure that flow has been restored.

02:58 This is done by an on-table angiography.

03:02 Here's an example of an embolectomy.

03:05 A Fogarty catheter is inserted into the vessel of interest, past the area where we think that there may be a clot, the balloon is inflated and the entire catheter is withdrawn.

03:17 The idea is, as a balloon is withdrawn, clots are brought out through the arteriotomy.

03:22 Here, you can see three large clots.

03:24 These clots, remember, in our patient, came from atrial thrombus.

03:29 After the clot is dislodged, we do an on-table completion angiography.

03:34 The angiogram then should show a normal flow to the distal vessels.

03:40 If the angiography shows persistent occlusion, you should try the Fogarty catheter again.

03:46 And as I mentioned, don't forget to do a completion angiography before closing the incision.

03:52 I’d like to pose another question to you.

03:54 What if this patient that had the atrial fibrillation and suspected of an embolic phenomenon and an acute threatened extremity has been experiencing a cold and pulseless extremity for now eight hours? What’s going on in your mind? What’s the next step of management? That's right.

04:13 You’re thinking compartment syndrome.

04:17 Here's a picture of a four-compartment fasciotomy.

04:20 Remember, any ischemic time greater than six hours puts the patient at a high risk of compartment syndrome.

04:28 Compartment syndrome occurs when edema in the region surpasses the ability of inflow and venous obstruction.

04:37 In these situations, it's usually related to a re-perfusion injury.

04:41 Remember, pulselessness, coldness of the foot are also late signs of arterial occlusive disease or embolic phenomenon.

04:51 Have a low threshold to perform a four-compartment fasciotomy.

04:54 Remember, you can do all the vascular bypass you want, patient is still going to lose their leg or foot if you don't complete your four compartment fasciotomy.

05:05 Now, let's move on to a different topic called Subclavian Steal Syndrome.

05:09 It's rarely seen, but a high-yield topic.

05:13 Subclavian Steal Syndrome occurs with retrograde vertebral artery flow due to a subclavian artery stenosis or occlusion.

05:23 As a result, you may find a reduced ipsilateral upper extremity, pulse or a blood pressure, typically described as a differential pressure between the affected arm and the normal arm.

05:34 As a result of the retrograde vertebral artery flow, the patient can experience syncope, vertigo and confusion.

05:41 This is due to the stealing of the blood from the vertebral artery.

05:45 As a reminder, the vertebral artery supplies the posterior circulation.

05:49 You’ll remember, of course, that the cerebellum contributes to one's positional sense and stability.

05:56 In severe cases of subclavian steal and subclavian artery stenosis, limb ischemia may occur.

06:04 And the treatment is a very advanced carotid to subclavian revascularization.

06:10 Here is a schematic depicting normal arch anatomy.

06:15 Notice the common carotid takeoff on the left side and the subsequent vertebral artery takeoff.

06:21 Now, let's review some high-yield information from peripheral vascular disease.

06:26 Remember, for patients with claudication, surgery is not the first line therapy.

06:31 You can add cilostazol, exercise, smoking cessation.

06:36 Remember, surgery is not the first line therapy.

06:41 Next, patients who present with a cold lake or pulseless should be considered a surgical emergency.

06:47 No further workup should be done.

06:49 The patient should be taken to the operating room and you can do your diagnoses and therapeutics on the table.

06:55 Therapeutically and diagnostically, angiographies are very important and can be performed intraoperatively.

07:04 And remember, any patient with a period of extremity ischemia are at high risk for compartment syndrome.

07:10 Before leaving the operating room, consider performing a four-compartment fasciotomy.

07:16 Thank you very much for joining me on this discussion of peripheral vascular disease.