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1 Anatomy

The aortic arch, also referred to as the supra-aortic trunk includes the innominate artery, the subclavian arteries, as well as the common carotid arteries up until their bifurcations. As the aortic arch progresses from an anterior to a posterior position, so do the origins of the great vessels. 20–30 % of patients show anatomic variations with the most common being the bovine arch, in which the innominate artery and the left carotid arise from a common ostium or a common trunk. Other variations seen are:

  1. (a)

    Separate origin of the vertebral artery, most commonly of the left vertebral, which arises between the left common carotid and the left subclavian artery.

  2. (b)

    Truncus bicarotidus: The two carotid arteries take origin together and the two subclavian arteries take origin together.

  3. (c)

    Right sided aortic arch—usually have an associated congenital cardiac defect.

2 Disease Definition

Occlusive lesions of the arch are typically due to:

  1. (a)

    Atherosclerosis (80 %)

  2. (b)

    Inflammatory diseases—Takayasu’s disease or due to therapeutic irradiation.

3 Disease Distribution

Involvement of the arch occurs at an earlier stage than occlusive lesions elsewhere and single vessel involvement presents even earlier. There is an equal distribution amongst the sexes in contrast to occlusive lesions found elsewhere where there is male predominance.

4 Diagnosis: Clinical and Laboratory

Atherosclerotic arch occlusive disease presents with symptoms related to the vessels involved. Unifocal disease is present in about 60 % of cases and multifocal disease in the others.

Multifocal involvement often presents with vertebrobasilar insufficiency related to flow limitation, while unifocal involvement manifests symptoms related to the vessel affected—either as ischemic or embolic events.

Takayasu’s arteritis typically involves all three trunks proximally. This is in distinction from Giant Cell Arteritis which affects the more distal vessels as well as a slightly older population compared to Takayasu’s which typically affects women in their second and third decades. Takayasu’s typically presents with symptoms related to poor flow.

On palpation of the outflow vessel, one finds the presence of diminished or absent flow. Auscultation often demonstrates a bruit over the affected vessel.

The only significant laboratory abnormality noted is in the inflammatory arteritis which will show an elevated ESR.

5 Diagnostic Imaging: USG/CT/MRI/Diagnostic Angiography: Ultrasound

Diagnostic imaging—USG/CT/MRI/Diagnostic angiography: Ultrasound is often used for screening; however, it has the drawback that bony structures impede adequate visualization.

CT scan is quickly replacing invasive angiography for diagnostic purposes in most institutions. It has the advantage of allowing visualization of the pathology from several different angles with new reconstructive software. In addition it has the benefit of providing details of the extent of calcification of the vessels, especially important in open reconstructions vis-à-vis clamp site. CT imaging of the brain should also be done in patients with occlusive disease who have cerebrovascular symptoms.

MR angiography with gadolinium is another modality which allows noninvasive imaging of the arch. It also provides additional benefit of visualizing the stage at which inflammatory occlusive disease is, acute inflammatory phase or the burned-out sclerotic phase, the former being a stage at which intervention should be avoided.

Diagnostic angiography helps in confirmation of the diagnosis, however much of cross-sectional imaging has made this redundant from a diagnostic viewpoint. The steps involved are:

  1. 1.

    Femoral artery access

  2. 2.

    Introduction of starter wire into the ascending aorta just distal to the aortic valve

  3. 3.

    Pigtail flush catheter over the wire in the distal ascending aorta

  4. 4.

    Flush arch aortogram with prolonged run time as the branches fill through collaterals.

  5. 5.

    The aortogram settings are in Table 14.1.

    Table 14.1 Arch aortography
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6 Management

Indications for treatment:

  1. 1.

    Symptomatic disease

    1. (a)

      Cerebrovascular—ocular, hemispheric, or vertebrobasilar symptoms

    2. (b)

      Upper extremity ischemia

  2. 2.

    Asymptomatic disease— >75 % stenosis

7 List of the Open Operative Choices

Transthoracic reconstruction

  1. 1.

    Innominate artery disease

  2. 2.

    Multivessel disease

Remote cervical reconstruction

  1. 1.

    With single vessel occlusive disease

  2. 2.

    Patients with prohibitive operative risk factors

8 Intervention: Techniques and Pitfalls

Prior to scheduling these patients, it is worthwhile to start them on ASA and Plavix (75 mg once a day) for 5 days. During the procedure they should receive intravenous heparin so as to maintain an activated clotting time between 250 and 300. The size of the stent is determined by the size of the blood vessel (Table 14.2).

Table 14.2 Vessel Size
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8.1 Orificial Lesions

A.Subclavian Artery Lesions

  1. 1.

    Occlusion: These are typically lesions which are difficult to recanalize. They usually extend from the origin of the subclavian artery to just proximal to the origin of the vertebral and the internal mammary arteries. Retrograde recanalization allows for more pushability to recanalize the occlusion

    1. (a)

      Access the brachial artery, preferably using a 4-Fr. micropuncture system under ultrasound visualization.

    2. (b)

      Femoral artery access is often useful using a 5-Fr. sheath and a pigtail catheter. Perform a flush aortogram to determine the location of the ostium of the artery as a target for the recanalization.

    3. (c)

      Exchange the brachial artery sheath to a to a 6-Fr. shuttle sheath (35–55 mm) over a 0.035″ non-hydrophilic wire.

    4. (d)

      Using a Kumpe catheter and a hydrophilic glide wire, attempt to recanalize the occluded lesion.

    5. (e)

      Change the wire to a stiff 0.014″ wire if the glide wire is unable to recanalize the lesion. This often requires the placement of a 0.014″ microcatheter (Quick Cross catheter, Spectranetics) for support.

    6. (f)

      Once the lesion has been recanalized, exchange the catheter for the dilator of the sheath and push the sheath forward across the lesion.

    7. (g)

      Introduce a balloon expandable stent (6–8 mm) once the sheath has traversed the lesion and the dilator removed. A balloon expandable stent is more appropriate for ostial lesions as they are more precise and also because they provide more radial force against these tough calcified lesions.

    8. (h)

      Position the stent at its appropriate location and pull back the sheath.

    9. (i)

      Deploy the stent and confirm position and patency

  2. 2.

    Stenosis: These can typically be treated through a common femoral approach, but difficult arches (Type III) are sometimes easier to treat through the brachial approach.

    1. (a)

      Common femoral artery access is obtained.

    2. (b)

      A starter wire is placed over which the access needle is exchanged to a 6-Fr. sheath (35 cm).

    3. (c)

      Over the wire a pigtail catheter is placed and a flush aortogram is done.

    4. (d)

      Once the anatomy has been delineated, the appropriately shaped selective catheter (Kumpe/Simmons 1/Vitek) is preloaded through a guiding catheter (6 Fr.). These are loaded on the wire in exchange for the flush catheter, making sure that the wire has been exchanged to a stiffer variety for support.

    5. (e)

      The lesion is accessed.

    6. (f)

      If the lesion is very tight, the catheter needs to be exchanged to a balloon (4–6 mm) to predilate the lesion.

    7. (g)

      The guiding catheter is then pushed across the lesion as the balloon is being deflated so as to minimize the risk of plaque embolization.

    8. (h)

      Once the guiding catheter is across the lesion, the stent system is delivered over the wire and after appropriate positioning the guide catheter is then withdrawn to the orifice of the lesion.

    9. (i)

      The balloon expandable stent is deployed and position confirmed.

B.Common carotid artery lesions

  • These may be approached through a retrograde or antegrade manner.

    1. 1.

      Retrograde approach: Initial attempts at pursuing this technique had a high incidence of neurovascular complications and is not a technique we perform except in cases of tandem lesions of the internal carotid artery and common carotid artery.

    2. 2.

      Antegrade approach: This is commonly used approach and is similar to that used for treatment of stenotic lesions of the subclavian with the exception of the use of embolic protection devices.

      1. (a)

        Common femoral artery access is obtained.

      2. (b)

        A starter wire is placed over which the access needle is exchanged to a 6-Fr. sheath (35 cm).

      3. (c)

        Over the wire a pigtail catheter is placed and a flush aortogram is done.

      4. (d)

        Once the anatomy has been delineated, the appropriately shaped catheter (Kumpe/Simmons 1/Vitek) is preloaded through a guiding catheter (6 Fr.). These are loaded on the wire in exchange for the flush catheter.

      5. (e)

        Using a 0.014″ wire the lesion is traversed. If needed one can switch to a 0.035″ hydrophilic wire—with either a straight or a floppy tip.

      6. (f)

        The guiding sheath is then appropriately positioned just proximal to the lesion. The protection device is deployed in the prepetrous portion of the internal carotid artery similar to its position for internal carotid interventions. This is still important at this stage as the highest risk of embolizing is at the time of balloon inflation or stent deployment.

      7. (g)

        Over the same wire the stent is introduced and deployed.

      8. (h)

        The protection device is collapsed and withdrawn after the position of the stent is confirmed angiographically.

C.Innominate Artery Lesions

  • These lesions require caution as they are at risk of embolization to the anterior cerebral circulation. Another important consideration is that of cerebral protection and the use of an embolic protection device.

    1. (a)

      For this the right brachial artery access is obtained using a micropuncture system and ultrasound.

    2. (b)

      This is exchanged over to a 6-Fr., 35-cm sheath.

    3. (c)

      A 6-Fr. IMA guide is passed through this sheath over a hydrophilic 0.035″ wire and positioned at the origin of the CCA. The 0.035″ wire is exchanged for the filter wire which is then positioned in the usual prepetrous portion of the ICA.

    4. (d)

      Common femoral artery access is obtained with a short 8-Fr. sheath.

    5. (e)

      A flush aortogram of the arch is performed and the pigtail is exchanged over a stiff wire to a combination of a guiding catheter mounted on a selective catheter.

    6. (f)

      The guide catheter should be positioned outside the ostium of the vessel.

    7. (g)

      Recanalization (if an occlusion is being treated) is then attempted using a 0.014″ or a 0.035″ wire system.

    8. (h)

      Once the wire traverses the lesion it should be directed into the external carotid artery. The catheter is then progressed across the lesion and the wire changed to a stiff non-hydrophilic one so as to track the guiding catheter on the selective catheter across the lesion as well. This allows one to introduce the stent in a protected manner to the lesion.

    9. (i)

      Remove the selective catheter and place stent delivery system.

    10. (j)

      Once positioned, the guiding catheter is pulled back and the stent position confirmed angiographically and then deployed.

    11. (k)

      A completion angiogram is done.

    12. (l)

      The protection device is then collapsed and withdrawn from the brachial approach and the wire is removed from the external carotid artery followed by removal of the entire system from the groin.

Distal lesions: These are accessed in the same way as the proximal orificial lesions. However, they differ in the nature of the stent to be deployed. Self-expanding stents are more commonly used in these locations. This is because these parts of the artery take a tortuous route, often in close proximity to overlying bone which puts at increased risk the deformation of the balloon expandable stents. In addition the same degree of accuracy is not needed for these lesions.

9 Complications and Management

When working on this part of the aorta with the cerebrovascular system a part of the circuit of treatment, any complication has the potential to be debilitating. With the ongoing increase in diabetes all over the world, not to mention the high rate of smoking in the majority of the world, this shall only increase the number of procedures that shall be done and thus the number at risk of complications. Nonetheless this should not dissuade us from providing the appropriate care.

9.1 Embolization

This is clearly one of the most important risks in treating arch occlusive disease. In stenting lesions of the subclavian artery origin there is a risk of embolizing to the vertebral artery or into the arm. Embolization of the vertebral artery is prevented by placing a protective occluding balloon at the origin of the vertebral artery so as to prevent embolization. In addition a blood pressure cuff being inflated at the time of deployment in the ipsilateral arm reduces antegrade flow volume and provides some protection to the arm as well. Another method of providing protection to the ipsilateral vertebral artery is to you a cerebral protection device.

9.2 Dissection

A problem seen when one treats a highly calcified lesion especially occlusions. However, this can also happen simply from wire access of the subclavian artery such as in coronary angiography when trying to access the internal mammary artery. The concern with dissections is that the side branches will be involved and occlude a disastrous complication for LIMA grafts or vertebral arteries which might be the sole source of flow to the posterior part of the brain. The treatment is to stent the culprit lesion. Tacking of this flap should resolve the distal dissection.

9.3 Restenosis

There are certain lesions which are more prone to restenosis, such as long lesions, lesions which have residual stenosis, and lesions which have been stented. Typically restenosis is seen in the arch vessels which have been treated, with an incidence of upto 19 %. Lesions recurring after balloon angioplasty alone can be stented, typically with a balloon expandable stent, especially if it is a lesion at the orifice. In stent stenosis can be redilated with a slightly larger balloon than used previously.

9.4 Pseudoaneurysm

This is treated with placement of a covered stent or open repair.

9.5 Rupture

This is a consequence of overdilation of the stenotic or occluded lesion. Typically seen with the use of balloon expandable stents or with simple overdilation of a lesion with the balloon. In either case the key is in not losing wire access. If this complication is suspected do not remove the balloon which was used for the dilatation too far from the lesion. Inject contrast through the sheath/guide catheter, reintroduce the balloon and inflate to a lower pressure so as to stop the extravasation and place a covered stent across the rupture site. If this does not work, the patient will need an emergent exploration by a vascular or a cardiac surgeon.

9.6 Stent Migration

This can happen in several circumstances.

  1. (a)

    Migration at the time of delivery/typically happens in the hand mounted balloon expandable stents. The goal in such cases is to either push or pull the undeployed stent using either a snare or a balloon to a position where either the stent can be deployed in the least harmful way or to a position where it is surgically retrievable or better if it can be delivered into the sheath and then the sheath removed with the stent inside.

  2. (b)

    Migration at site of deployment/When a balloon expandable stent is deployed in a very calcified lesion, it often jumps. This can happen with migration of the stent into the aorta or distally further downstream into the branch vessel. It is usually too risky to move the stent once it has migrated.

9.7 Hyperperfusion Syndrome

This is rarely seen in the arch vessels. When seen in the upper extremity it should be treated symptomatically. When seen in the cerebrovascular circulation, it should be treated in the same way that hyperperfusion of the brain is treated with internal carotid artery revascularization/lowering of the blood pressure, with intravenous medications if necessary.

9.8 Misdiagnosis

This is a very important reason for inadequate treatment of patients. More so than in any part of the body, the overlap of the vessels needs to be accounted for and correct orthogonal views to be taken (Table 14.3)

Table 14.3 Imaging system position for optimal visualization
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9.9 Access site Complications

Please see Chapter 36.

10 Outcomes

Endovascular treatment of ostial lesions (within 5 mm of the origin of the vessel) has shown technical success of upto 100 %. It is more likely to succeed in stenotic lesions compared to occluded ones. The periprocedural complications range 0–14 % with low to no operative mortality compared with a mortality rate of 0.5–6 %, with open repair (transthoracic and cervical). The stenting of these lesions showed a patency rate comparable to open bypasses, 80–96 % at 3 years, with a higher reintervention rate of 7 % and an overall symptom recurrence rate about 4 %.

11 Flowchart Summarizing the Role of Endovascular Treatment (See below)

figure 00014a

The flowchart—endovascular treatment of aortic arch occlusive disease