- Email: [email protected]
Open and Endovascular Management of Subclavian and Innominate Arterial Pathology
Open and Endovascular Management of Subclavian and Innominate Arterial Pathology Francesco Aiello, MD, and Nicholas J. Morrissey, MD Innominate and subclavian artery lesions run a wide spectrum of disease manifestation and treatment options. Since the first surgical treatment, multiple variances have been attempted with the desire to maintain high long-term patency rates while reducing perioperative morbidity and mortality. The advent of endovascular procedures in the 1970s provided the opportunity to seek alternative treatment options, but the fear of serious neurologic sequela stalled the adoption of these new techniques. The advancement in endovascular techniques and technology, along with proven clinical success and decreased morbidity and mortality, has led to their adoption as the first-line treatment. Semin Vasc Surg 24:31-35 © 2011 Elsevier Inc. All rights reserved.
Innominate Artery Stenosis and Occlusion
T
HE OVERALL INCIDENCE of innominate artery (IA) stenosis or occlusion is very difficult to determine, with hemodynamically significant disease accounting for ⬍2% of all vascular lesions.1 IA lesions causing hemodynamic disturbances can result in cerebral, ocular, and upper limb ischemia. Until the advancement of endovascular techniques provided an alternative means to patient treatment, open surgical treatment was the only option for this relatively rare disease. Since Debakey and associates performed the first aorto-innominate bypass in 1957, several large series have been published. The 5- and 10-year patency rates are excellent (⬎80%), proving it to be a durable procedure, but there is a high mortality of 3% to 11% and stroke rate of 2.9% to 8%.2-7 The advent of endovascular surgery in the 1970s opened the door to new and less invasive treatment options. Although percutaneous transluminal angioplasty was being performed in peripheral vessels, supraaortic vessels were not treated until the late 1980s because of the fear of cerebral embolization. Clinical symptoms are associated with subclavian steal in 18% to 47% of cases,1,8 but because of the more proximal nature of IA lesions, they can also have an effect on carotid circulation. Degree of stenosis or occlusion has been shown to Columbia University College of Physicians and Surgeons, The New York Presbyterian Hospital, New York, NY. Address reprint requests to Nicholas J. Morrissey, Columbia University College of Physicians and Surgeons, The New York Presbyterian Hospital, 161 Fort Washington Avenue, Suite 538, New York, NY 10032. E-mail: [email protected]
0895-7967/$-see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1053/j.semvascsurg.2011.04.001
cause complete flow reversal in all segments of the right carotid system, but occurs most commonly in the common carotid artery and internal carotid artery, usually sparing the external carotid artery.9 Based on its anatomical location, the most common presenting symptoms are vertebrobasilar insufficiency, upper limb claudication, and transient ischemic attacks.8-12 Unlike the higher male predominance in most supraaortic stenosis, significant IA has an equal gender distribution, with most patients presenting in the 5th and 6th decade.1,8,13 Because of the large caliber of the IA and the progression of this disease, a rich collateral network usually develops, but unlike subclavian artery lesions where most are not symptomatic, it appears that IA lesions have a higher rate of clinical symptomatology.9 Although it has been advocated that only symptomatic lesions should be treated, there is an exception to this rule. Patients with a history of coronary artery bypass procedures make up a special subset of this rare disease and require a lower threshold for intervention because of the risk of coronary steal and resultant myocardial ischemia.14 There is a paucity of studies looking at isolated IA lesions because most studies combine supraaortic lesions.1,8,13 The technical success rate from these studies was 83% to 96%, with occlusions having a lower percutaneous treatment success rate. The primary patency rate is excellent for treated lesions initially, in excess of 95% at up to 2 years with a secondary patency ⬎98%. Long-term data, however, are more variable, with primary patency around 70% and secondary patency approximately 80%.8 The clinical success mirrors technical success with ⬎93% reporting clinical resolution or improvement. Despite the location of this disease, percutaneous intervention carries a much smaller complication rate than open procedure. The rate of minor complica31
32 tions is around 6%, and major complications are even lower at 1% to 2% with a 2% to 4% risk of any neurologic complication.1,8,13
Subclavian Artery Stenosis Subclavian artery (SCA) stenosis is more common that IA disease but remains much less common than lower-extremity disease. The overall occurrence of significant subclavian and IA stenosis is around 0.5% to 2%, but can be as high as 6.4% in patients being evaluated.15,16 Atherosclerosis is the most common cause for hemodynamically significant lesions, up to 98%, with arteritis and aneurysmal disease being far less common.11,17-21 More than 90% are symptomatic at presentation leading up to the diagnosis.18 Since the discovery of flow reversal by Contorni in 1960,22 and subsequent subclavian steal syndrome, multiple surgical interventions have been performed. Lyons and Gailbraiter reported a series of subclavian to carotid bypass grafts in 1957, followed by Parrott’s report of SCA transposition in 1964,23,24 but the first SCA angioplasty would not occur until 1980.16,25 The left SCA is predominately affected with a three- to fourfold higher incidence than the right side.11,19-21,26 SCA is divided into three parts, proximal, from origin to the vertebral artery, middle, the segment including the vertebral and internal mammary artery (IMA), and distal, from past the IMA to the lateral border of pectoralis minor.27 Proximal lesions are not only more prevalent, 70% to 90% of all cases, but also more prone to being symptomatic because of their anatomic relationship.16,18,27 There is a slight male to female predominance, with the greatest incidence in the 6th decade of life. More than 90% of patients undergoing treatment for SCA are symptomatic.18 The most common presenting symptoms are vertebrobasilar insufficiency (18% to 62%) and upper extremity ischemia (13% to 69%), or both (15% to 56%), followed by transient ischemic attacks (14% to 16%) and asymptomatic lesions (0% to 10%).11,16,20-21,26-29 Subclavian steal is also present in up to 49% to 55% of patients, the hallmark being reversal of flow in the ipsilateral vertebral artery.21,29 Less common causes include protection of arterial-venous fistula and lower-extremity claudication from a previous axillo-femoral bypass.29 Coronary steal syndrome is present in 1% to 2% of patients, but was as high as 25% in one study and has been an increasing cause for intervention during the years, with some recommending preemptive SCA treatment before coronary artery bypass grafting.20,21,27,29 It is recommended that all symptomatic patients undergo treatment. Indications for intervention in asymptomatic patients remain less defined. Potential indications include stenosis in patients with previous LIMA and in those with severe brachiocephalic lesions, particularly involving the carotid arteries.20 Cardiac disease affects ⬎50% of patients presenting with symptomatic SCA stenosis11 and up to 23% to 34% have had some sort of coronary intervention.18,29 One study found that 18% of patients undergoing SCA treatment were in preparation for a coronary procedure and were otherwise asymp-
F. Aiello and N.J. Morrissey tomatic.21 Incidence of proximal subclavian stenosis in patients undergoing coronary artery bypass grafting ranges from 0.5% to 15%.27 Also, the emergence of endovascular repair of the thoracic aorta has led to controversy over the treatment of SCA.30 Hemodynamic relevant stenosis or occlusions of the SCA have the potential to lead to higher rates of neurologic complications after left subclavian artery (LSA) overstenting in endovascular aortic repairs.28 Optimal treatment has been controversial since the introduction of endovascular options, but currently the majority of initial interventions are endovascular. Since one of the first studies to compare endovascular versus open repair, we continue to see a discrepancy in long-term patency, with surgery being more durable.31 Several studies have retrospectively compared their endovascular to open bypass for SCA stenosis and found both a better overall patency, 96% at 5 years in bypass versus 70% for percutaneous transluminal angioplasty (pta) and stent, and lower symptom recurrence in the bypass group.26,27,32 These same studies have also revealed comparable complication rates between endovascular and open bypass procedures. However, the overall complication rate when looking at individual studies appears to remains higher in open bypass than endovascular for both complications (6% to 28.9% v 2% to 11.4%) and mortality (0 to 2.2% v 0% to 1%), therefore making endovascular a more attractive first option despite the lower long-term patency rate.11,16,18,20,26,27,29,33 Endovascular treatment has also become more prevalent in the treatment of aneurysmal disease of the supraaortic vessels of which the SCA is the most commonly affected vessel, but remains far less common than stenotic lesions.34 Since the first endovascular repair on 1980, the prevalence of endovascular intervention for SCA disease has increased and is now the preferred initial treatment.35 Multiple studies have looked at the success and patency rate for endovascular treatment with favorable results. The technical success is excellent at 91% to 100% for all lesions, although occlusive lesions have proven to be more difficult to treat, with technical success ranging from 50% to 100%.11,12,16,18,20,21,26,27,29,33 In a recent review of the literature by Aziz et al looking at ⬎1,300 patients, the technical success for treating brachiocephalic stenosis was 94%, while that for occlusion was only 64%.17 The overall technical success for complete occlusion of the SCA or IA remains far lower than that for stenosis, but has shown improvement since the first case was reported.36 Several case series of SCA occlusion have shown a success rate of 83% to 100%, proving that with time and experience, our ability to treat more complicated lesions will improve.10,33 Despite the increased difficulty in treating complete occlusions, once they are traversed and treated, it appears that their patency remains excellent.21 The primary patency rate is between 78% and 93% at 1 year and 72% and 89% at 3 to 8 years, while secondary patency is ⬎90% at 1 to 5 years.16,18,20,21,26,27,29,33 The resolution of symptoms occurs very soon after the procedure and ⬎70% report complete resolution and almost all report some improvement.21 Although the complication rate is lower than open repair, it is not negligible, with neurologic complications alone reported
Management of subclavian and innominate arterial pathology as high as 9% of cases in earlier studies.12 Minor complications occur in 2% to 11% of cases, with access-site hematoma being the most common. Major complications occur in 0 to 5.8%, with stroke or death occurring in up to 3.6%. The rate of restenosis has also remained fairly constant at 10% to 16%, with symptomatically re-occurring lesions occurring even less frequently. This has all contributed to endovascular intervention being the preferred initial management in most patients.
Open Surgical Treatment Since the first aorto-IA bypass was performed by Dr. Debakey in 1957 there have been multiple studies reporting excellent patency rates. Despite the proven long-term success of this procedure, the transthoracic approach as first described for repair of aortic arch branches confers with it a significant morbidity and mortality rate.3-7,37 The transthoracic approach for proximal IA repair usually requires a median sternotomy, but this approach may also be used for SCA bypass or endarterectomy.38 Early failure after transthoracic endarterectomy can be seen in up to 9% of patients, but its overall patency rate remains high. Subclavian artery endarterectomy can also be approached via a transcervical approach, depending on location and extent of treated lesion, which can reduce the morbidity and patient discomfort.38 Extraanatomic bypass were performed to reduce surgical morbidity and mortality and is often better suited for highrisk surgical patients or for single vessel subclavian disease with no obvious compromise in patency.17,32 There are numerous options for bypass procedures, including carotidsubclavian bypass, carotid-subclavian transposition, carotidcarotid bypass, subclavian-subclavian bypass, and, in some cases, more than one bypass might be warranted to treat multivessel disease. Carotid-subclavian bypass and carotid subclavian transposition are the most commonly performed extraanatomical bypass procedures. These procedures can be performed through transverse supraclavicular incision, with the carotid-subclavian transposition requiring a more indepth dissection to gain proximal control of the SCA and its associated branches. In a recent review by Aziz et al, the overall mortality and stroke rate for carotid-subclavian transposition was 0.4% and 1%, while carotid-subclavian bypass had a mortality and stroke rate of 1.5% and 1.3%, respectively, and a 10-year patency rate ⬎90%.17 Conduit selection in extraanatomic bypasses has also been explored and retrospectively compared. The overall patency rate of prosthetic grafts at 1, 5, and 10 years remains very high with significant improvement or trends reflecting improved patency over autogenous vein graft.38-40 Use of prosthetic also avoids the more indepth level of dissection required for transposition, with comparable patency and survival rates.
Endovascular Techniques All procedures were performed in the operating room under conscious sedation. Access is initially gained through a femoral approach unless a contraindication exist, ie, occluded
33 femoral artery or extensive known iliac disease. All patients are given a bolus of heparin before aortic arch manipulation, with a goal activated clotting time ⱖ250 seconds. A preintervention angiogram is performed to confirm location, degree, and length of lesion. A cerebral angiogram is also performed pre- and postintervention. Initially a 5Fr sheath is introduced for initial evaluation. A hydrophilic 0.035-in wire is used to cross the lesion with the aid of a long catheter, straight or curved, depending on ease of lesion engagement. If this attempt is unsuccessful, a long sheath is inserted and parked just proximal to the innominate os, providing additional coaxial support. Balloon dilation is performed before stent deployment with size equal to the diameter of the artery just distal to the lesion. In the case that the preselected balloon would not tract through the lesion, predilation with a smaller 3- to 4-mm balloon is performed. Because of the location of the lesion, occlusions were more difficult to cross and, as reported in the previous studies, commonly required retrograde access through either the brachial or axillary artery. Technical success was defined as ⱕ30% residual stenosis, blood pressure difference ⱕ10 mm Hg, and pressure gradient across the lesion ⬍5 mm Hg. Clinical failure is defined as failure to ameliorate presenting symptoms or recurrence. We advocate stenting in all of our patients, especially those with heavily calcified lesions, occlusions, residual stenosis ⬎30% after pta and for flow limiting dissection or thrombus. Schillinger et al41 described lower long-term patency rates in stented patients but newer studies have shown stenting to be an independent predictor of long-term patency.42 Independent risk factors for in stent restenosis are implantation of more than one stent, low stent diameter, and systolic blood pressure difference after the procedure, but this has not been consistently proven by other studies looking at factors affecting restenosis.16 We generally oversize the stents by 1 mm but recommend using balloons of equal diameter to the vessel. The use of balloon-expandable, enabling more precise deployment, or self-expandable, providing increased radial force, is operator-dependent and subject to the location and pathology of the lesion. Vertebral artery protection also remains controversial. If the lesion is near the ostia of the vertebral artery or if it is stenotic, kissing stents can be deployed as described in other studies.20 Ringelstein and Zeumer have shown that flow reversal after percutaneous treatment of subclavian steal can take anywhere from 20 seconds to several minutes, thereby, serving a preventative role for neurologic sequelae after intervention43 (and therefore we do not typically take additional steps to protect the vertebral arteries) Neuroprotection devices were infrequently (ⱕ7%) used when the lesion was located near the vertebral or common carotid artery16 and this is not routinely performed. Femoral access is the preferred approach in all our patients unless contraindicated. Brachial artery access, in particular when punctured with large sheaths required to deliver the stents, have been shown to have a high complication rate. The rate of brachial artery thrombosis can be as high as 6% and have an overall fivefold higher rate of complications than femoral artery approaches.1,44,45 The advent of newer low-
34 profile stents can aid in reducing the rate of brachial artery complications, but we avoid using this access site unless femoral access is not feasible or we are unable to cross the lesion from an antegrade approach. Newer technologies are being employed to aid in both crossing difficult lesions and in evaluating technical success. Intravascular ultrasound has also been used in difficult or occlusive lesions as well as for poststent evaluation. In one study, intravascular ultrasound was employed in 17% of patients and 33% required a stent reexpansion based on these findings,29 suggesting that observational change in luminal diameter may not always be adequate for assessing technical success. Overall, in the 3 decades since the first endovascular treatment of brachiocephalic lesions, our technology, technique, and technical success rate have improved. The long-term patency has failed to match open surgical bypass but the markedly lower complication rate, high secondary patency rate and patient comfort, and decreased hospital stay have made endovascular repair the primary choice and standard of care, with open bypass surgery reserved for lesions not able to be treated by endovascular means or for younger healthier patients who might benefit in the long-term from bypass surgery.
References 1. Paukovits TM, Lukacs L, Berczi V, Hirschberg K, Nemes B, Huttl K: Percutaneous endovascular treatment of innominate artery lesions: a single-centre experience on 77 lesions. Eur J Vasc Endovasc Surg 40: 35-43, 2010 2. Reul GJ, Jacobs MJ, Gregoric ID, et al: Innominate artery occlusive disease: surgical approach and long-term results. J Vasc Surg 14:405412, 1991 3. Berguer R, Morasch MD, Kline RA: Transthoracic repair of innominate and common carotid artery disease: immediate and long-term outcome for 100 consecutive surgical reconstructions. J Vasc Surg 27:34-41, 1998 4. Rhodes JM, Cherry KJ Jr, Clark RC, et al: Aortic-origin reconstruction of the great vessels: risk factors of early and late complications. J Vasc Surg 31:260-269, 2000 5. Kieffer E, Sabatier J, Koskas F, Bahnini A: Atherosclerotic innominate artery occlusive disease: early and long-term results of surgical reconstruction. J Vasc Surg 21:326-337, 1995 6. Crawford ES, Stowe CL, Powers RW Jr: Occlusion of the innominate, common carotid, and subclavian arteries: long-term results of surgical treatment. Surgery 94:781-791, 1983 7. Crawford ES, DeBakey ME, Morris GC Jr, Howell JF: Surgical treatment of occlusion of the innominate, common carotid, and subclavian arteries: a 10-year experience. Surgery 65:17-31, 1969 8. Huttl K, Nemes B, Simonffy A, Entz L, Berczi V: Angioplasty of the innominate artery in 89 patients: experience over 19 years. Cardiovasc Intervent Radiol 25:109-114, 2002 9. Grant EG, El-Saden SM, Madrazo BL, Baker JD, Kliewer MA: Innominate artery occlusive disease: sonographic findings. AJR Am J Roentol 186:394-400, 2006 10. Woo EY, Fairman RM, Velazquez OC, Golden MA, Karmacharya J, Carpenter JP: Endovascular therapy of symptomatic innominate-subclavian arterial occlusive lesions. Vasc Endovasc Surg 40:27-33, 2006 11. Brountzos EN, Petersen B, Binkert C, Panagiotou I, Kaufman JA: Primary stenting of subclavian and innominate artery occlusive disease: a single center’s experience. Cardiovasc Intervent Radiol 27:616-623, 2004
F. Aiello and N.J. Morrissey 12. Korner M, Baumgartner I, Do DD, Mahler F, Schroth G: PTA of the subclavian and innominate arteries: long-term results. Vasa 2:117-122, 1999 13. van Hattum ES, de Vries J-P, Lalezari F, van den Berg J, Moll F: Angioplasty with or without stent placement in the brachiocephalic artery: feasible and durable? A retrospective cohort study 18:1088-1093, 2007 14. Bicknell CD, Subramanian A, Wolfe JH: Coronary subclavian steal syndrome. Eur J Vasc Endovasc Surg 27:220-221, 2004 15. Harjola PT, Valle M: The importance of aortic arch or subclavian angiography before coronary reconstruction. Chest 66:436-439, 1974 16. Przewlocki T, Kablak-Ziembicka A, Pieniazek P, et al: Determinants of immediate and long-term results of subclavian and innominate artery angioplasty. Cathet Cardiovasc Intervent 67:519-526, 2006 17. Aziz F, Gravett MH, Comerota AJ: Endovascular and open surgical treatment of brachiocephalic arteries. Ann Vasc Surg 2011 2011 Jan 31. [Epub ahead of print] 18. Sixt, S, Rastan A, Schwarzwalder U, et al: Results after balloon angioplasty or stenting of atherosclerotic subclavian artery obstruction. Cathet Cardiovasc Interv 73:395-403, 2009 19. Faries P, Morrissey NJ, Teodorescu V, et al: Recent advances in peripheral angioplasty and stenting. Angiology 53:617-626, 200 20. Henry M, Amor M, Henry I, Ethevenot G, Tzvetanov K, Chati Z: Percutaneoous transluminal angioplasty of the subclavian arteries. J Endovasc Surg 6:33-41, 1991 21. De Vries JP, Jager LC, van den Berg JC, et al: Durability of percutaneous transluminal angioplasty for obstructive lesions of proximal subclavian artery: long term results. J Vasc Surg 41:19-23, 2005 22. Contorni L: The vertebra-vertebral collateral circulation in obliteration of the subclavian artery at its origin. Minerva Chir 15:268-271, 1960 23. Lyons C, Gailbraiter G: Surgical treatment of atherosclerotic occlusions of the internal carotid artery. Ann Surg 146:487-494, 1957 24. Parrott JC: The subclavian steal syndrome. Arch Surg 88:661-665, 1964 25. Bates MC, Broce M, Lavigne PS, Stone P: Subclavian artery stenting: factors influencing long-term outcome. Catheter Cardiovasc Interv 61: 5-11, 2004 26. AbuRahma AF, Bates MC, Stone PA, et al: Angioplasty and stenting versus carotid-subclavian bypass for the treatment of isolated subclavian artery disease. J Endovasc Ther 14:698-704, 2007 27. Palchik E, Bakken AM, Wolford HY, Saad WE, Davies MG: Subclavian artery revascularization: an outcome analysis based on mode of therapy and presenting symptoms. Ann Vasc Surg 22:70-78, 2008 28. Weigang E, Luehr M, Harloff A, et al: Incidence of neurological complications following overstenting of the left subclavian artery. Eur J Cardiothorac Surg 31:628-636, 2007 29. Rodriguez-Lopez JA, Werner A, Martinez R, Torruella LJ, Ray LI, Diethrich EB: Stenting for atherosclerotic occlusive disease of the subclavian artery. Ann Vasc Surg 13:254-260, 1999 30. Matsumura JS, Rizvi AZ: Left subclavian artery revascularization: Society for Vascular Surgery practice guidelines. J Vasc Surg 52:65S-70S, 2010 (suppl) 31. Farina C, Mingoli A, Schultz RD, et al: Percutaneous transluminal angioplasty versus surgery for subclavian artery occlusive disease. Am J Surg 158:511-514, 1989 32. Modarai B, Ali T, Dourado R, Reidy JF, Taylor PR, Burnand KG: Comparison of extra-anatomic bypass grafting with angioplasty for atherosclerotic disease of the supra-aortic trunks. Br J Surg 91:1453-1457, 2004 33. Gonzalez A, Gil-Peralta A, Gonzalez-Marcos JR, Mayol A: Angioplasty and stenting for total symptomatic atherosclerotic occlusion of the subclavian or innominate arteries. Cerebrovasc Dis 13:107-113, 2002 34. Cury M, Greenberg RK, Morales JP, Mohabbat W, Hernandez AV. Supra-aortic vessels aneurysm: diagnosis and prompt intervention. J Vasc Surg 49:4-10, 2009 35. Bachman DM, Kim RM: Transluminal dilation for subclavian steal syndrome. AJR Am J Roentgenol 135:995-996, 1980 36. Mathias KD, Luth I, Haarman P: Percutaneous transluminal angioplasty of proximal subclavian artery occlusions. Cardiovasc Intervent Radiol 16:214-218, 1993
Management of subclavian and innominate arterial pathology 37. Crawford ES, DeBakey ME, Morris GC Jr, Cooley DA: Thrombo-obliterative disease of the great vessels arising from the aortic arch. Thorac Cardiovasc Surg 43:38-53, 1962 38. Ziomek S, Quiñones-Baldrich WJ, Busuttil RW, Baker JD, Machleder HI, Moore WS: The superiority of synthetic arterial grafts over autologous veins in carotid-subclavian bypass. J Vasc Surg 3:140-145, 1986 39. AbuRahma AF, Robinson PA, Jennings TG: Carotid-subclavian bypass grafting with polytetrafluoroethylene grafts for symptomatic subclavian artery stenosis or occlusion: a 20-year experience. J vasc Surg 32:411-418, 2000 40. Law MM, Colburn MD, Moore WS, Quinones-Baldrich WJ, Machleder JI, Gelabert HA: Carotid-subclavian bypass for brachiocephalic occlusive disease. Choice of conduit and long-term follow-up. Stroke 26:1565-1571, 1995 41. Schillinger M, Haumer M, Schillinger S, Ahmadi R, Minar E: Risk stratification for subclavian artery angioplasty: is there an increased
35
42.
43.
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45.
rate of restenosis after stent implantation. J Endovasc Ther 8:550-557, 2001 Sixt S, Rastan A, Schwarzwalder U, et al: Long term outcome after balloon angioplasty and stenting of subclavian artery obstruction: a single centre experience. Vasa 37:174-182, 2008 Ringelstein EB, Zeumer H: Delayed reversal of vertebral artery blood flow following percutaneous transluminal angioplasty for subclavian steal syndrome. Neuroradiology 26:189-198, 1984 Rodriguez-Lopez JA, Werner A, Martinez R, Torruella LJ, Ray LI, Diethrich EB: Stenting for artherosclerotic occlusive disease of the subclavian artery. Ann Vasc Surg 13:254-260, 1999 Sullivan TM, Gray BH, Bacharach JM, et al: Angioplasty and primary stenting of the subclavian, innominate and common carotid arteries in 83 patients. J Vasc Surg 25:1059-1065, 1998
Innominate Artery Stenosis and Occlusion
T
HE OVERALL INCIDENCE of innominate artery (IA) stenosis or occlusion is very difficult to determine, with hemodynamically significant disease accounting for ⬍2% of all vascular lesions.1 IA lesions causing hemodynamic disturbances can result in cerebral, ocular, and upper limb ischemia. Until the advancement of endovascular techniques provided an alternative means to patient treatment, open surgical treatment was the only option for this relatively rare disease. Since Debakey and associates performed the first aorto-innominate bypass in 1957, several large series have been published. The 5- and 10-year patency rates are excellent (⬎80%), proving it to be a durable procedure, but there is a high mortality of 3% to 11% and stroke rate of 2.9% to 8%.2-7 The advent of endovascular surgery in the 1970s opened the door to new and less invasive treatment options. Although percutaneous transluminal angioplasty was being performed in peripheral vessels, supraaortic vessels were not treated until the late 1980s because of the fear of cerebral embolization. Clinical symptoms are associated with subclavian steal in 18% to 47% of cases,1,8 but because of the more proximal nature of IA lesions, they can also have an effect on carotid circulation. Degree of stenosis or occlusion has been shown to Columbia University College of Physicians and Surgeons, The New York Presbyterian Hospital, New York, NY. Address reprint requests to Nicholas J. Morrissey, Columbia University College of Physicians and Surgeons, The New York Presbyterian Hospital, 161 Fort Washington Avenue, Suite 538, New York, NY 10032. E-mail: [email protected]
0895-7967/$-see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1053/j.semvascsurg.2011.04.001
cause complete flow reversal in all segments of the right carotid system, but occurs most commonly in the common carotid artery and internal carotid artery, usually sparing the external carotid artery.9 Based on its anatomical location, the most common presenting symptoms are vertebrobasilar insufficiency, upper limb claudication, and transient ischemic attacks.8-12 Unlike the higher male predominance in most supraaortic stenosis, significant IA has an equal gender distribution, with most patients presenting in the 5th and 6th decade.1,8,13 Because of the large caliber of the IA and the progression of this disease, a rich collateral network usually develops, but unlike subclavian artery lesions where most are not symptomatic, it appears that IA lesions have a higher rate of clinical symptomatology.9 Although it has been advocated that only symptomatic lesions should be treated, there is an exception to this rule. Patients with a history of coronary artery bypass procedures make up a special subset of this rare disease and require a lower threshold for intervention because of the risk of coronary steal and resultant myocardial ischemia.14 There is a paucity of studies looking at isolated IA lesions because most studies combine supraaortic lesions.1,8,13 The technical success rate from these studies was 83% to 96%, with occlusions having a lower percutaneous treatment success rate. The primary patency rate is excellent for treated lesions initially, in excess of 95% at up to 2 years with a secondary patency ⬎98%. Long-term data, however, are more variable, with primary patency around 70% and secondary patency approximately 80%.8 The clinical success mirrors technical success with ⬎93% reporting clinical resolution or improvement. Despite the location of this disease, percutaneous intervention carries a much smaller complication rate than open procedure. The rate of minor complica31
32 tions is around 6%, and major complications are even lower at 1% to 2% with a 2% to 4% risk of any neurologic complication.1,8,13
Subclavian Artery Stenosis Subclavian artery (SCA) stenosis is more common that IA disease but remains much less common than lower-extremity disease. The overall occurrence of significant subclavian and IA stenosis is around 0.5% to 2%, but can be as high as 6.4% in patients being evaluated.15,16 Atherosclerosis is the most common cause for hemodynamically significant lesions, up to 98%, with arteritis and aneurysmal disease being far less common.11,17-21 More than 90% are symptomatic at presentation leading up to the diagnosis.18 Since the discovery of flow reversal by Contorni in 1960,22 and subsequent subclavian steal syndrome, multiple surgical interventions have been performed. Lyons and Gailbraiter reported a series of subclavian to carotid bypass grafts in 1957, followed by Parrott’s report of SCA transposition in 1964,23,24 but the first SCA angioplasty would not occur until 1980.16,25 The left SCA is predominately affected with a three- to fourfold higher incidence than the right side.11,19-21,26 SCA is divided into three parts, proximal, from origin to the vertebral artery, middle, the segment including the vertebral and internal mammary artery (IMA), and distal, from past the IMA to the lateral border of pectoralis minor.27 Proximal lesions are not only more prevalent, 70% to 90% of all cases, but also more prone to being symptomatic because of their anatomic relationship.16,18,27 There is a slight male to female predominance, with the greatest incidence in the 6th decade of life. More than 90% of patients undergoing treatment for SCA are symptomatic.18 The most common presenting symptoms are vertebrobasilar insufficiency (18% to 62%) and upper extremity ischemia (13% to 69%), or both (15% to 56%), followed by transient ischemic attacks (14% to 16%) and asymptomatic lesions (0% to 10%).11,16,20-21,26-29 Subclavian steal is also present in up to 49% to 55% of patients, the hallmark being reversal of flow in the ipsilateral vertebral artery.21,29 Less common causes include protection of arterial-venous fistula and lower-extremity claudication from a previous axillo-femoral bypass.29 Coronary steal syndrome is present in 1% to 2% of patients, but was as high as 25% in one study and has been an increasing cause for intervention during the years, with some recommending preemptive SCA treatment before coronary artery bypass grafting.20,21,27,29 It is recommended that all symptomatic patients undergo treatment. Indications for intervention in asymptomatic patients remain less defined. Potential indications include stenosis in patients with previous LIMA and in those with severe brachiocephalic lesions, particularly involving the carotid arteries.20 Cardiac disease affects ⬎50% of patients presenting with symptomatic SCA stenosis11 and up to 23% to 34% have had some sort of coronary intervention.18,29 One study found that 18% of patients undergoing SCA treatment were in preparation for a coronary procedure and were otherwise asymp-
F. Aiello and N.J. Morrissey tomatic.21 Incidence of proximal subclavian stenosis in patients undergoing coronary artery bypass grafting ranges from 0.5% to 15%.27 Also, the emergence of endovascular repair of the thoracic aorta has led to controversy over the treatment of SCA.30 Hemodynamic relevant stenosis or occlusions of the SCA have the potential to lead to higher rates of neurologic complications after left subclavian artery (LSA) overstenting in endovascular aortic repairs.28 Optimal treatment has been controversial since the introduction of endovascular options, but currently the majority of initial interventions are endovascular. Since one of the first studies to compare endovascular versus open repair, we continue to see a discrepancy in long-term patency, with surgery being more durable.31 Several studies have retrospectively compared their endovascular to open bypass for SCA stenosis and found both a better overall patency, 96% at 5 years in bypass versus 70% for percutaneous transluminal angioplasty (pta) and stent, and lower symptom recurrence in the bypass group.26,27,32 These same studies have also revealed comparable complication rates between endovascular and open bypass procedures. However, the overall complication rate when looking at individual studies appears to remains higher in open bypass than endovascular for both complications (6% to 28.9% v 2% to 11.4%) and mortality (0 to 2.2% v 0% to 1%), therefore making endovascular a more attractive first option despite the lower long-term patency rate.11,16,18,20,26,27,29,33 Endovascular treatment has also become more prevalent in the treatment of aneurysmal disease of the supraaortic vessels of which the SCA is the most commonly affected vessel, but remains far less common than stenotic lesions.34 Since the first endovascular repair on 1980, the prevalence of endovascular intervention for SCA disease has increased and is now the preferred initial treatment.35 Multiple studies have looked at the success and patency rate for endovascular treatment with favorable results. The technical success is excellent at 91% to 100% for all lesions, although occlusive lesions have proven to be more difficult to treat, with technical success ranging from 50% to 100%.11,12,16,18,20,21,26,27,29,33 In a recent review of the literature by Aziz et al looking at ⬎1,300 patients, the technical success for treating brachiocephalic stenosis was 94%, while that for occlusion was only 64%.17 The overall technical success for complete occlusion of the SCA or IA remains far lower than that for stenosis, but has shown improvement since the first case was reported.36 Several case series of SCA occlusion have shown a success rate of 83% to 100%, proving that with time and experience, our ability to treat more complicated lesions will improve.10,33 Despite the increased difficulty in treating complete occlusions, once they are traversed and treated, it appears that their patency remains excellent.21 The primary patency rate is between 78% and 93% at 1 year and 72% and 89% at 3 to 8 years, while secondary patency is ⬎90% at 1 to 5 years.16,18,20,21,26,27,29,33 The resolution of symptoms occurs very soon after the procedure and ⬎70% report complete resolution and almost all report some improvement.21 Although the complication rate is lower than open repair, it is not negligible, with neurologic complications alone reported
Management of subclavian and innominate arterial pathology as high as 9% of cases in earlier studies.12 Minor complications occur in 2% to 11% of cases, with access-site hematoma being the most common. Major complications occur in 0 to 5.8%, with stroke or death occurring in up to 3.6%. The rate of restenosis has also remained fairly constant at 10% to 16%, with symptomatically re-occurring lesions occurring even less frequently. This has all contributed to endovascular intervention being the preferred initial management in most patients.
Open Surgical Treatment Since the first aorto-IA bypass was performed by Dr. Debakey in 1957 there have been multiple studies reporting excellent patency rates. Despite the proven long-term success of this procedure, the transthoracic approach as first described for repair of aortic arch branches confers with it a significant morbidity and mortality rate.3-7,37 The transthoracic approach for proximal IA repair usually requires a median sternotomy, but this approach may also be used for SCA bypass or endarterectomy.38 Early failure after transthoracic endarterectomy can be seen in up to 9% of patients, but its overall patency rate remains high. Subclavian artery endarterectomy can also be approached via a transcervical approach, depending on location and extent of treated lesion, which can reduce the morbidity and patient discomfort.38 Extraanatomic bypass were performed to reduce surgical morbidity and mortality and is often better suited for highrisk surgical patients or for single vessel subclavian disease with no obvious compromise in patency.17,32 There are numerous options for bypass procedures, including carotidsubclavian bypass, carotid-subclavian transposition, carotidcarotid bypass, subclavian-subclavian bypass, and, in some cases, more than one bypass might be warranted to treat multivessel disease. Carotid-subclavian bypass and carotid subclavian transposition are the most commonly performed extraanatomical bypass procedures. These procedures can be performed through transverse supraclavicular incision, with the carotid-subclavian transposition requiring a more indepth dissection to gain proximal control of the SCA and its associated branches. In a recent review by Aziz et al, the overall mortality and stroke rate for carotid-subclavian transposition was 0.4% and 1%, while carotid-subclavian bypass had a mortality and stroke rate of 1.5% and 1.3%, respectively, and a 10-year patency rate ⬎90%.17 Conduit selection in extraanatomic bypasses has also been explored and retrospectively compared. The overall patency rate of prosthetic grafts at 1, 5, and 10 years remains very high with significant improvement or trends reflecting improved patency over autogenous vein graft.38-40 Use of prosthetic also avoids the more indepth level of dissection required for transposition, with comparable patency and survival rates.
Endovascular Techniques All procedures were performed in the operating room under conscious sedation. Access is initially gained through a femoral approach unless a contraindication exist, ie, occluded
33 femoral artery or extensive known iliac disease. All patients are given a bolus of heparin before aortic arch manipulation, with a goal activated clotting time ⱖ250 seconds. A preintervention angiogram is performed to confirm location, degree, and length of lesion. A cerebral angiogram is also performed pre- and postintervention. Initially a 5Fr sheath is introduced for initial evaluation. A hydrophilic 0.035-in wire is used to cross the lesion with the aid of a long catheter, straight or curved, depending on ease of lesion engagement. If this attempt is unsuccessful, a long sheath is inserted and parked just proximal to the innominate os, providing additional coaxial support. Balloon dilation is performed before stent deployment with size equal to the diameter of the artery just distal to the lesion. In the case that the preselected balloon would not tract through the lesion, predilation with a smaller 3- to 4-mm balloon is performed. Because of the location of the lesion, occlusions were more difficult to cross and, as reported in the previous studies, commonly required retrograde access through either the brachial or axillary artery. Technical success was defined as ⱕ30% residual stenosis, blood pressure difference ⱕ10 mm Hg, and pressure gradient across the lesion ⬍5 mm Hg. Clinical failure is defined as failure to ameliorate presenting symptoms or recurrence. We advocate stenting in all of our patients, especially those with heavily calcified lesions, occlusions, residual stenosis ⬎30% after pta and for flow limiting dissection or thrombus. Schillinger et al41 described lower long-term patency rates in stented patients but newer studies have shown stenting to be an independent predictor of long-term patency.42 Independent risk factors for in stent restenosis are implantation of more than one stent, low stent diameter, and systolic blood pressure difference after the procedure, but this has not been consistently proven by other studies looking at factors affecting restenosis.16 We generally oversize the stents by 1 mm but recommend using balloons of equal diameter to the vessel. The use of balloon-expandable, enabling more precise deployment, or self-expandable, providing increased radial force, is operator-dependent and subject to the location and pathology of the lesion. Vertebral artery protection also remains controversial. If the lesion is near the ostia of the vertebral artery or if it is stenotic, kissing stents can be deployed as described in other studies.20 Ringelstein and Zeumer have shown that flow reversal after percutaneous treatment of subclavian steal can take anywhere from 20 seconds to several minutes, thereby, serving a preventative role for neurologic sequelae after intervention43 (and therefore we do not typically take additional steps to protect the vertebral arteries) Neuroprotection devices were infrequently (ⱕ7%) used when the lesion was located near the vertebral or common carotid artery16 and this is not routinely performed. Femoral access is the preferred approach in all our patients unless contraindicated. Brachial artery access, in particular when punctured with large sheaths required to deliver the stents, have been shown to have a high complication rate. The rate of brachial artery thrombosis can be as high as 6% and have an overall fivefold higher rate of complications than femoral artery approaches.1,44,45 The advent of newer low-
34 profile stents can aid in reducing the rate of brachial artery complications, but we avoid using this access site unless femoral access is not feasible or we are unable to cross the lesion from an antegrade approach. Newer technologies are being employed to aid in both crossing difficult lesions and in evaluating technical success. Intravascular ultrasound has also been used in difficult or occlusive lesions as well as for poststent evaluation. In one study, intravascular ultrasound was employed in 17% of patients and 33% required a stent reexpansion based on these findings,29 suggesting that observational change in luminal diameter may not always be adequate for assessing technical success. Overall, in the 3 decades since the first endovascular treatment of brachiocephalic lesions, our technology, technique, and technical success rate have improved. The long-term patency has failed to match open surgical bypass but the markedly lower complication rate, high secondary patency rate and patient comfort, and decreased hospital stay have made endovascular repair the primary choice and standard of care, with open bypass surgery reserved for lesions not able to be treated by endovascular means or for younger healthier patients who might benefit in the long-term from bypass surgery.
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