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Extraanatomic Bypass Technique for the Treatment of Midaortic Syndrome in Children
Roland Hetzer, MD, PhD, Daniel Absi, MD, Oliver Miera, MD, Natalia Solowjowa, MD, Antonia Schulz, Mariano Francisco del Maria Javier, MFDM, and Eva Maria Delmo Walter, MD, MSc, PhD Department of Cardiothoracic and Vascular Surgery and Department of Pediatric Cardiology and Congenital Heart Diseases, Deutsches Herzzentrum Berlin, Charite Universit€atsmedizin Berlin, Berlin, Germany, and Harvard University, Cambridge, Massachusetts
Background. This report aims to introduce the extraanatomic bypass technique to treat the midaortic syndrome and to document its long-term effectiveness and durability. Methods. Fourteen patients (mean age, 6.7 ± 3.76 years; range 8 months to 11 years) received diagnoses of midaortic syndrome, characterized by severe narrowing of the abdominal aorta with involvement of the renal and visceral branches. Angiography showed variable lengths of high-grade midaortic stenosis, with 7 children having visceral artery involvement and 9 having renal artery involvement. All children were hypertensive (mean blood pressure, 165 ± 15.7 mm Hg). Three had had previous nephrectomies. Six patients had had previous percutaneous transluminal renal artery angioplasties. The midaortic obstruction was relieved by descending abdominal aorta bypass (left thoracoabdominal approach) and by an ascending abdominal aorta bypass (median sternotomy and transabdominal approach) in 12 patients. No visceral artery revascularization was done.
Results. There was a considerable blood pressure reduction in all patients and relief of intermittent claudication in 6 affected patients. One patient had a bilateral renal artery bypass 2 weeks postoperatively because of recurrence of renal hypertension. At a mean follow-up time of 5.8 ± 1.36 years (range, 9 months to 15 years), there was no further reoperation nor mortality. Twelve patients had complete relief of hypertension, and 2 had mild hypertension. All patients have normal renal function and no signs or symptoms of visceral malperfusion. Growth and development have proceeded normally. Follow-up magnetic resonance tomography showed patent grafts without any strictures. Conclusions. Extraanatomic bypass provides very effective and long-term relief of hypertension and any malperfusion in midaortic syndrome.
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technique to treat the midaortic syndrome and to document its long-term effectiveness and durability.
idaortic syndrome (MAS), usually seen in children and adolescents, is a rare clinical condition generated by segmental narrowing of the abdominal or distal descending thoracic aorta [1–5]. The segmental aortic stenosis may be located at the suprarenal, interrenal, or infrarenal aorta, with a high propensity for concomitant stenoses in both the renal (63%) and the visceral (33%) arteries [4–8]. Hypertension proximal to the aortic stenosis, and relative hypotension distal to it, are characteristic findings in MAS [9–12]. The symptoms depend largely on the degree and location of vessel narrowing. Few publications have reported the long-term outcome of various surgical interventions to correct MAS. This report aims to introduce the extraanatomic bypass
Accepted for publication March 18, 2013. Presented at the Forty-ninth Annual Meeting of The Society of Thoracic Surgeons, Los Angeles, CA, Jan 26–30, 2013. Address correspondence to Dr Delmo Walter, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; e-mail: [email protected].
Ó 2013 by The Society of Thoracic Surgeons Published by Elsevier Inc
(Ann Thorac Surg 2013;96:183–9) Ó 2013 by The Society of Thoracic Surgeons
Patients and Methods The Institutional Review Board approved this retrospective/prospective study and waived the need for patient consent.
Patients Fourteen patients (mean age, 6.7 3.76 years; median, 7.1 years; range, 8 months to 11 years) received diagnoses of MAS, characterized by severe narrowing of the abdominal aorta with involvement of the renal (n ¼ 9) and visceral (n ¼ 7) branches (Table 1). The signs and symptoms included various manifestations of intractable hypertension (systolic blood pressure >180 mm Hg and diastolic blood pressure >120 mm Hg, despite aggressive antihypertensive treatment) in all, with a mean blood pressure of 165 15.7 mm Hg (median, 150 mm Hg; range, 147–200 mm Hg). All had previously been treated with one or two antihypertensive agents. Six patients had intermittent claudication in addition 0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2013.03.025
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Table 1. Demographic Profile of 14 Patients With Midaortic Syndrome n ¼ 14
Characteristic CONGENITAL HEART
Mean age (median, range), years Sex (M/F) Symptoms Hypertension Intermittent claudication Preoperative mean blood pressure (median, range), mm Hg Renal artery involvement Visceral artery involvement Celiac artery aneurysm Origin of stenosis Suprarenal Spindle-shaped stenosis from bifurcation of celiac trunk to superior mesenteric artery Filiform stenosis proximal to and at the level of superior mesenteric artery Interrenal Infrarenal Subatretic abdominal aorta distal to renal artery Pathology Short segment stenosis Long segment stenosis Multiple stenosis Previous surgical procedures Nephrectomy Percutaneous transluminal renal artery angioplasty
to hypertension. Intestinal angina was not noted despite celiac involvement, superior mesenteric arterial involvement, or both. Three had had previous nephrectomies, and 6 had had previous percutaneous transluminal renal artery angioplasties, with 4 having undergone repeated balloon dilatation of the stented renal artery. No patient had myocardial insufficiency or oliguric renal failure. Aortography (Fig 1) and magnetic resonance tomography (MRT) (Fig 2) showed variable lengths of high-grade midaortic stenosis (short segment, 45 and 58 mm in 2 patients; long segment, 60 to 133 mm in 7 patients; and multiple segment stenosis in 4 patients). The origins of the stenoses were as follows: suprarenal (n ¼ 9) described as spindle-shaped stenosis from celiac trunk to superior mesenteric artery in 6 patients and filiform-shaped stenosis proximal to and at the level of the superior mesenteric artery in 3 patients; at the level of the renal artery in 2 patients; infrarenal, described as subatretic abdominal aorta distal to the renal artery in 3 patients. One patient had an associated celiac artery aneurysm.
6.7 3.76 (7.1, 8 months–11 years) 8/6 14 6 165 15.7 (150, 147–200) 9 7 1
6 3 2 3 2 8 4 3 6
(1 mg/kg), the aortic obstruction was relieved by a descending aorta to an infrarenal (n ¼ 1) or suprarenal (n ¼ 1) abdominal aorta bypass by use of a Gore-Tex prosthesis (descending aorta to suprarenal abdominal aorta, diameter 10 mm, length 20 cm; descending aorta to infrarenal abdominal aorta, diameter 12 mm, length
Surgical Technique Owing to progressive, uncontrollable hypertension despite maximal medical therapy, we performed singlestage revascularization using an extraanatomic bypass technique on these children. In our first two cases in the early 1990s, we performed a single-stage extraanatomic bypass through a left thoracoabdominal approach. After systemic heparinization
Fig 1. Preoperative aortogram showing a short-segment high-grade midaortic stenosis (suprarenal).
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Fig 2. Preoperative magnetic resonance imaging scans. (A) Long-segment high-grade midaortic stenosis (suprarenal– infrarenal). (B) Long-segment high-grade midaortic stenosis (suprarenal).
25 cm) (Fig 3A) in an end-to-side fashion by use of 4-0 polypropylene continuous suture. Later, we performed the extraanatomic bypass technique through a median sternotomy and an upper midline laparotomy approach in 12 patients without using extracorporeal circulation. The ascending aorta and the abdominal aorta below the level of the inferior mesenteric artery was exposed. The left lobe of the liver was dissected from the diaphragm, and a route was designed for the prosthetic graft. After a small incision was made in the midportion of the diaphragm, the lesser omentum was cut, and a hole was made in the transverse mesocolon and the radix mesenteri. After systemic heparinization, a woven Dacron graft (mean diameter 14 mm, mean length 30 cm) (n ¼ 11) or a Gore-tex (diameter 12 mm, length 30 cm) (n ¼ 1) was anastomosed to the infrarenal abdominal aorta distal to the stenosis in an end-to-side fashion with a 4-0 polypropylene continuous suture. Then the graft was passed through the route facilitated previously and anastomosed proximally to the ascending aorta (Fig 3B) in the same fashion. To allow for linear growth of patients, without graft kinking, the graft was oversized in length and
diameter, depending on the patient’s size, and placed more dorsally with a loose arch behind the left kidney to protect it. Nine patients had associated mild visceral artery narrowing (20% to 30%), but excellent collaterals were present so that no visceral artery revascularization was required. Inasmuch as the renal artery stenosis had previously been stented in 6 patients, no renal artery procedures were performed in this group. In a patient with a previous right nephrectomy and a left renal artery stenosis, a renal artery bypass by use of a 5-mm Gore-Tex prosthesis was performed simultaneous with the descending aorta to infrarenal abdominal aorta bypass. In 1 patient with a celiac artery aneurysm, the aneurysm was wrapped with a Dacron patch to prevent further dilation or rupture. These patients were given aspirin 50 mg once daily starting on the first postoperative day and continuing for 6 months.
Follow-Up Complete follow-up data were provided by the Department of Pediatric Cardiology/Congenital Heart Fig 3. Extraanatomic bypass techniques. (A) Descending aorta–suprarenal abdominal aorta bypass with use of a Gore-Tex graft, anastomosed distally to the narrowing of the abdominal aorta infrarenally and proximally to the descending aorta. (B) Ascending aorta– infrarenal abdominal aorta bypass with use of a Dacron graft anastomosed distally to the narrowing of the abdominal aorta infrarenally and proximally to the ascending aorta through a diaphragmatic tunnel.
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Disease and Department of Clinical Studies, Deutsches Herzzentrum Berlin, and written correspondence from the referring physicians. CONGENITAL HEART
Statistical Analysis All data were analyzed with SPSS 16.0 (SPSS Inc, Chicago, IL) software program. Data are expressed as absolute and percentage frequency values and continuous data as mean standard deviation, as appropriate. Freedom from reoperation was analyzed according to Kaplan-Meier estimates with 95% confidence interval. Because there was no mortality, no Kaplan-Meier survival curve was plotted.
Results The perioperative course was unremarkable. There was an immediate considerable reduction in blood pressure in all patients and relief of intermittent claudication in 6 affected patients. One 11-year-old patient who had a preoperative low-grade bilateral renal artery stenosis as seen on computed tomographic angiogram underwent a bilateral renal artery bypass with use of a 7-mm GoreTex prosthesis 2 weeks postoperatively because of recurrence of renal hypertension (Fig 4). A tissue sample from the renal artery showed dysplastic features in the media, intima, and internal lamina. At a mean follow-up time of 5.8 1.36 years (range, 9 months to 15 years), no further operation was done for MAS and no mortality occurred (Fig 4). Twelve patients had complete relief of hypertension, and 2 had mild hypertension but are normotensive while receiving a single antihypertensive medicine. All had normal renal function, and there were no signs or symptoms of visceral malperfusion. No patient had thromboembolism. Their latest follow-up evaluations showed normal growth and development. Follow-up MRT showed patent grafts without any strictures or length restrictions (Fig 5).
Fig 4. Freedom from reoperation after extraanatomic bypass.
Fig 5. Follow-up magnetic resonance tomographic image showing a patent graft without any strictures.
Comment Midaortic syndrome presents clinically with severe hypertension in young individuals in association with either weak or absence of femoral pulses, resulting from localized or diffuse narrowing of the aorta in its midthoracoabdominal course, with frequent involvement of renal and superior mesenteric arteries. The syndrome is rare and is usually discovered during evaluation of hypertension in a child. Although it was described almost seven decades ago [1], classically as coarctation of the abdominal aorta [1–8, 12, 13], its exact cause remains obscure and its pathogenesis speculative, most authors attempting to develop a single hypothesis to explain all reported cases. It was postulated to be related to developmental error in the fusion and maturation of the paired embryonic dorsal aortas during the fourth week of gestation or aortic growth arrest [1, 13]. In addition, support for the congenital hypothesis comes from the known association of MAS with various congenital syndromes [14–17], including neurofibromatosis, infantile hypercalcemia, fibromuscular dysplasia, retroperitoneal fibrosis, mucopolysaccharidosis, and Williams syndrome. The syndrome may be acquired, caused by Takayasu’s arteritis, rubella, and tuberous sclerosis [5, 11]. Support for the acquired hypothesis [18, 19] comes largely from reports from Asia [6, 18, 19], whose authors contend
that MAS is secondary to a localized aortitis resulting in segmental aortic stenosis often complicated by atherosclerosis [20]. Sen and colleagues [21] reported a clinicopathologic study of 16 patients with MAS, the majority of whom had tuberculosis; each had evidence of aortitis. Lande [20] reported that reevaluation of the pathology of the original case reported by Maycock [1] shows undoubted evidence of aortitis. Whatever the cause, the characteristic findings in MAS are hypertension proximal to the aortic stenosis and relative hypotension distal to it. It is manifested by headache, early fatigue on exertion, and bilateral lowerlimb claudication. The severity of hypertension is the primary indication for intervention and the sole factor determining timing of the intervention. If MAS is left untreated, the majority of patients will die of complications of severe hypertension and ischemia by 40 years of age [12, 22]. The causal treatment of MAS is either endovascular therapy [23, 24], operation [25–28], or a combination [29]. Balloon angioplasty has been used for approximately 3 decades in the treatment of MAS [30–32]. In the developing aorta of children, it enables effective dilatation of the luminal impairment without interfering with vessel growth. Further dilatation is also feasible, with repeated angioplasty at a later date. However, at least some recoil is inevitable after balloon angioplasty, and a weakened arterial wall may result in later aneurysm formation, reported to occur in 5% to 20% of cases [33, 34]. Hence, the immediate clinical improvement is short-lived in many patients. Stent technology has generated increasing interest in the management of MAS; nonetheless, limited data are available on the efficacy and durability of stenting for this lesion. Until fenestrated stent grafts [35] and branched aortic endografts [32] prove their feasibility and efficacy in complex MAS, only selected cases with discrete lesions not involving the renal and mesenteric arteries can be considered for endovascular therapy. Moreover, on the premise that arteries can grow longer in response to longitudinal stretch [36, 37], Kim and colleagues [29] reported performing a left nephrectomy on a 3-year-old girl with neonatal hypertension and MAS. They inserted a tissue expander directly posterior to the aortic bifurcation to induce longitudinal growth of the normal distal abdominal aorta and iliac arteries, which permitted resection of the 4-cm segment of the diseased aorta with a primary end-to-end anastomosis 9 months after tissue expansion. This is promising; however, no further reports or follow-up on such an intervention have been made. Our experience shows that initial conservative blood pressure management and endovascular therapy is feasible, but outcome is unsatisfactory, and patients are continuously exposed to sequelae of hypertension and risks of repeated interventions. In our case series, 9 of these 14 patients had been previously treated for severe renovascular hypertension. These treatments were unable to improve the blood pressure even with antihypertensive agents. Four patients had even required three further angioplasty procedures
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and still needed two antihypertensive agents. Apparently, lasting results were not achieved. Success in medical or endovascular control of their hypertension was shortlived. No patients showed long-term success, presumably because of the progressive nature of the disease. Hence, we are strongly convinced that all symptomatic patients with MAS, regardless of the severity of hypertension, should undergo immediate operative correction. This is then the absolute indication for an operation. The timing of operation depends on the severity of hypertension, not the age of the patient. Although it may be preferable to delay the operation until the patient has reached his or her full growth potential, we believe that the presence of severe intractable hypertension necessitates an immediate operation, independently of the age of the patient, to avoid the complications of stroke and heart failure and their sequelae. We assume that these patients may eventually require a change of the graft as they grow; therefore, careful timing and planning of the most appropriate technique must be chosen to delay, or even avoid, this course. The clinical benefits of early surgical intervention to reverse refractory hypertension must be weighed against the impact of the operation on the developing aorta, inasmuch as a great proportion of patients with MAS are children or teenagers. In the selection of an appropriate technique, future body growth and long-term graft durability are of utmost importance. Surgical procedures for MAS require a unique approach in each individual patient. Careful preoperative angiography is essential for a successful operative strategy. This includes multiple oblique views of the renal arteries and a lateral aortogram to determine the status of the remainder of the visceral arteries. It is vital to visualize the entire course of these vessels before embarking upon any surgical technique to be used. The renal artery stenoses are often short ostial lesions that are signaled by the presence of a dilated distal artery. The incidence of visceral artery involvement in our patients (57%) is much higher than that in most other reports. We believe that this is not due to patient selection but rather to the routine use of lateral aortography. Various surgical techniques have been reported, including bypass grafting, graft replacement, and patch angioplasty [25–28]. Relief of the aortic constriction by either patch aortoplasty or bypass are complementary options. Patch aortoplasty is a technique applicable to the very young patient who requires revascularization for severe hypertension, which leaves open the possibility of thoracoabdominal bypass at an older age when the patient is physically mature. This report confirms the view of others that a singlestage operation results in long-term relief of hypertension and its attendant complications [6, 24, 38]. Although the natural history of the disease is practically unknown, the course of symptomatic patients has been followed up by several authors. In a series of 32 patients reported by Senning and Johansson [22], death resulting from cerebral hemorrhage occurred in 10 of them before the age of 34, whereas Onat and Zerren [39] reported that death occurred at a mean age of 34 years in
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symptomatic patients. They reported that hypertensive encephalopathy was seen in 42 patients, with the majority dying of either stroke or heart failure. Because we performed the surgical intervention early enough, we did not encounter such complications in our longterm follow-up. An important consideration in the performance of an aortic bypass is the site of the proximal anastomosis. In our last 10 patients, we performed the proximal anastomosis on the ascending aorta, simply for its technical ease and excellent anatomic exposure. If ever bleeding or anastomotic complications arise, they are technically easy to manage. The options for renal artery reconstruction are multiple, including autogenous arterial/venous/prosthetic grafts, patch angioplasty, and autotransplantation [4]. As much as possible, and when it is avoidable, we refrain from performing any renal artery procedures, especially on infants and small children. Our approach is to reserve arterial grafts in the renal position for the very young patient with very small vessels. Prosthetic graft is recommended in the older patient who has reached physical maturity, inasmuch as larger vessels with poststenotic dilatation are easily revascularized with an antegrade graft. We are convinced that the extraanatomic bypass from the ascending aorta to the infrarenal abdominal aorta not only provides better flow to the lower extremities but also provides significant antegrade flow to permit optimal renal perfusion. This is reflected in the relief of hypertension and improvement of renal function of the 6 patients who had previously undergone endovascular renal angioplasties but no aortorenal bypass performed and to the 2 patients with aorto-renal bypass with immediate normalization of blood pressure and renal function. The indications for visceral artery revascularization are less well defined. Although chronic abdominal pain thought to be secondary to chronic visceral ischemia was apparently common when the syndrome was first described [21], it was not seen in our series. Messina and colleagues [4] described their patients who had MAS and proposed prophylactic revascularization in asymptomatic patients with demonstrated stenosis of the celiac and/or superior mesenteric arteries. We have taken a different approach from theirs. Although 7 patients had visceral artery (celiac trunk and superior mesenteric artery) involvement, none of them underwent visceral artery revascularization because they had such extensive collateralization from the inferior mesenteric artery to the superior mesenteric artery and celiac arterial circulation. None of these patients have had symptoms of intestinal ischemia; hence, we preferred not to take the risk of prophylactic revascularization. One had celiac artery aneurysm, which was wrapped with Dacron graft to prevent further dilatation. It is of interest that with follow-up periods over 15 years, we have not had any reason to change this policy. Further longer-term follow-up will determine whether the policy has been appropriate, but late repair can always be performed when necessary.
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On the basis of our experience with these 14 patients with MAS, we recommend single-stage revascularization using extraanatomic surgical bypass grafting as the optimal technique for MAS. The basic surgical principle is restoration of renal blood flow to relieve the hypertension, andrestoration of blood flow to the viscera and relief of claudication, if there is any. We chose ascending aorta—infrarenal abdominal aorta bypass, because with this technique, long-term patency is expected, its effectiveness on relief of hypertension is unquestionable, and the afterload of the left ventricle is more effectively reduced. The surgical approach depends largely on the presence of direct renal or visceral artery involvement. Thus, patients who have renovascular hypertension, lower limb claudication with midaortic stenosis without branch involvement, or both can have effective relief by simple thoracic to abdominal aortic bypass. The long-term follow-up of these patients indicates that the results were durable. The lone problem encountered in the postoperative course was the recurrence of renal hypertension in the 11-year-old patient with mild renal artery stenosis. His renal function and blood pressure have normalized after the operation. This illustrates two important points in the treatment of such patients. First, careful lateral aortography should be performed to precisely determine the severity of renal artery stenosis. Second, revascularization of patients with MAS results in very effective relief of hypertension and, as such, a second operation may be avoided if careful assessment of renal artery stenosis is performed before the operation. We may say that whatever the cause of MAS, the prognosis after uncompromised surgical revascularization is rewarding in the mid-term and long-term followup of these patients. The durability of these prosthetic aortic bypass grafts is the ultimate determinant of patients’ quality and length of life. The high flow in the vascular beds reconstructed in these patients favors prolonged patency, allowing these patients the opportunity to grow and live a full, healthy life.
Conclusions Single-stage revascularization using an extraanatomic bypass technique by an ascending aorta to infrarenal abdominal aorta graft provides very effective and durable long-term relief of hypertension and any malperfusion in MAS. The authors thank Anne Gale, medical editor, for assistance with this article. We appreciate the assistance of Astrid Benhennour for literature search, Daniela Moeske-Scholz and Heike Schultz for data collection, Julia Stein for statistical analysis, and Carla Weber for graphics.
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3. Scott HW, Dean RH, Boerth R, Sawyers JL, Meacham P, Fisher RD. Coarctation of the abdominal aorta: pathophysiologic and therapeutic considerations. Ann Surg 1979;189:746–57. 4. Messina LM, Reilly LM, Goldstone J, Ehrenfeld WK, Ferrell LD, Stoney RJ. Middle aortic syndrome: effectiveness and durability of complex arterial revascularization techniques. Ann Surg 1986;204:331–9. 5. Connolly JE, Wilson SE, Lawrence PL, Fujitani RM. Middle aortic syndrome: distal thoracic and abdominal coarctation, a disorder with multiple etiologies. J Am Coll Cardiol 2002;194:774–81. 6. De Bakey ME, Garett HE, Howell JF, Morris GC Jr. Coarctation of the abdominal aorta with renal artery stenosis: surgical considerations. Ann Surg 1967;165:830–43. 7. Vaccaro PS, Myers JC, Smead WL. Surgical correction of abdominal aortic coarctation and hypertension. J Vasc Surg 1986;3:643–8. 8. Mickley V, Fleiter T. Coarctations of descending and abdominal aorta: long-term results of surgical therapy. J Vasc Surg 1998;28:206–14. 9. Das BB, Recto M, Shoemaker L, Mitchell M, Austin EH. Midaortic syndrome presenting as neonatal hypertension. Pediatr Cardiol 2008;29:1000–1. 10. Gospin TA, Knudson JD, Petit CJ. Neonatal midaortic syndrome and renal artery atresia presenting as malignant hypertension. Pediatr Cardiol 2012;33:869–71. 11. Panayiotopolous YP, Tyrell MR, Koffmann G, Reidy JF, Haycock GB, Taylor PR. Midaortic syndrome presenting in childhood. Br J Surg 1996;83:235–40. 12. Cohen JR, Birnbaum E. Coarctation of the abdominal aorta. J Vasc Surg 1988;8:160–4. 13. Graham LM, Zelenock GB, Erlandson EE, Coran AG, Lindenauer SM, Stanley JC. Abdominal aortic coarctation and segmental hypoplasia. Surgery 1979;86:519–29. 14. Halpern M, Currarino G. Vascular lesions causing hypertension in neurofibromatosis. N Engl J Med 1965;273: 248–52. 15. Siassi B, Klyman G, Emmanouilides GC. Hypoplasia of the abdominal aorta associated with the rubella syndrome. J Dis Child 1970;120:476–9. 16. Flynn PM, Robinson MB, Stapelton FB, Roy S 3rd, Koh G, Tonkin IL. Coarctation of the aorta and renal artery stenosis in tuberous sclerosis. Pediatr Radiol 1984;14:337–9. 17. Riemenschreider TA, Emmanouilides GC, Hirose F, Luide LM. Coarctation of the abdominal aorta in children: report of the cases and review of the literature. Pediatrics 1969;44:716–26. 18. Daimon S, Kitamura K. Coarctation of the abdominal aorta. Jpn Heart J 1964;5:562–73. 19. Inada K, Shimizu J, Kobayashi T, Ishishi S, Kawamoto S. Pulseless disease and typical coarctation of the aorta. Arch Surg 1962;84:306–11. 20. Lande A. Takayasu’s arteritis and congenital coarctation of the descending thoracic and abdominal aorta: a critical review. Am J Roentgenol 1976;127:227–33. 21. Sen PK, Kinare SG, Engineer SD, Parulkas DB. The middle aortic syndrome. Br Heart J 1963;25:610–8.
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Background. This report aims to introduce the extraanatomic bypass technique to treat the midaortic syndrome and to document its long-term effectiveness and durability. Methods. Fourteen patients (mean age, 6.7 ± 3.76 years; range 8 months to 11 years) received diagnoses of midaortic syndrome, characterized by severe narrowing of the abdominal aorta with involvement of the renal and visceral branches. Angiography showed variable lengths of high-grade midaortic stenosis, with 7 children having visceral artery involvement and 9 having renal artery involvement. All children were hypertensive (mean blood pressure, 165 ± 15.7 mm Hg). Three had had previous nephrectomies. Six patients had had previous percutaneous transluminal renal artery angioplasties. The midaortic obstruction was relieved by descending abdominal aorta bypass (left thoracoabdominal approach) and by an ascending abdominal aorta bypass (median sternotomy and transabdominal approach) in 12 patients. No visceral artery revascularization was done.
Results. There was a considerable blood pressure reduction in all patients and relief of intermittent claudication in 6 affected patients. One patient had a bilateral renal artery bypass 2 weeks postoperatively because of recurrence of renal hypertension. At a mean follow-up time of 5.8 ± 1.36 years (range, 9 months to 15 years), there was no further reoperation nor mortality. Twelve patients had complete relief of hypertension, and 2 had mild hypertension. All patients have normal renal function and no signs or symptoms of visceral malperfusion. Growth and development have proceeded normally. Follow-up magnetic resonance tomography showed patent grafts without any strictures. Conclusions. Extraanatomic bypass provides very effective and long-term relief of hypertension and any malperfusion in midaortic syndrome.
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technique to treat the midaortic syndrome and to document its long-term effectiveness and durability.
idaortic syndrome (MAS), usually seen in children and adolescents, is a rare clinical condition generated by segmental narrowing of the abdominal or distal descending thoracic aorta [1–5]. The segmental aortic stenosis may be located at the suprarenal, interrenal, or infrarenal aorta, with a high propensity for concomitant stenoses in both the renal (63%) and the visceral (33%) arteries [4–8]. Hypertension proximal to the aortic stenosis, and relative hypotension distal to it, are characteristic findings in MAS [9–12]. The symptoms depend largely on the degree and location of vessel narrowing. Few publications have reported the long-term outcome of various surgical interventions to correct MAS. This report aims to introduce the extraanatomic bypass
Accepted for publication March 18, 2013. Presented at the Forty-ninth Annual Meeting of The Society of Thoracic Surgeons, Los Angeles, CA, Jan 26–30, 2013. Address correspondence to Dr Delmo Walter, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; e-mail: [email protected].
Ó 2013 by The Society of Thoracic Surgeons Published by Elsevier Inc
(Ann Thorac Surg 2013;96:183–9) Ó 2013 by The Society of Thoracic Surgeons
Patients and Methods The Institutional Review Board approved this retrospective/prospective study and waived the need for patient consent.
Patients Fourteen patients (mean age, 6.7 3.76 years; median, 7.1 years; range, 8 months to 11 years) received diagnoses of MAS, characterized by severe narrowing of the abdominal aorta with involvement of the renal (n ¼ 9) and visceral (n ¼ 7) branches (Table 1). The signs and symptoms included various manifestations of intractable hypertension (systolic blood pressure >180 mm Hg and diastolic blood pressure >120 mm Hg, despite aggressive antihypertensive treatment) in all, with a mean blood pressure of 165 15.7 mm Hg (median, 150 mm Hg; range, 147–200 mm Hg). All had previously been treated with one or two antihypertensive agents. Six patients had intermittent claudication in addition 0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2013.03.025
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Table 1. Demographic Profile of 14 Patients With Midaortic Syndrome n ¼ 14
Characteristic CONGENITAL HEART
Mean age (median, range), years Sex (M/F) Symptoms Hypertension Intermittent claudication Preoperative mean blood pressure (median, range), mm Hg Renal artery involvement Visceral artery involvement Celiac artery aneurysm Origin of stenosis Suprarenal Spindle-shaped stenosis from bifurcation of celiac trunk to superior mesenteric artery Filiform stenosis proximal to and at the level of superior mesenteric artery Interrenal Infrarenal Subatretic abdominal aorta distal to renal artery Pathology Short segment stenosis Long segment stenosis Multiple stenosis Previous surgical procedures Nephrectomy Percutaneous transluminal renal artery angioplasty
to hypertension. Intestinal angina was not noted despite celiac involvement, superior mesenteric arterial involvement, or both. Three had had previous nephrectomies, and 6 had had previous percutaneous transluminal renal artery angioplasties, with 4 having undergone repeated balloon dilatation of the stented renal artery. No patient had myocardial insufficiency or oliguric renal failure. Aortography (Fig 1) and magnetic resonance tomography (MRT) (Fig 2) showed variable lengths of high-grade midaortic stenosis (short segment, 45 and 58 mm in 2 patients; long segment, 60 to 133 mm in 7 patients; and multiple segment stenosis in 4 patients). The origins of the stenoses were as follows: suprarenal (n ¼ 9) described as spindle-shaped stenosis from celiac trunk to superior mesenteric artery in 6 patients and filiform-shaped stenosis proximal to and at the level of the superior mesenteric artery in 3 patients; at the level of the renal artery in 2 patients; infrarenal, described as subatretic abdominal aorta distal to the renal artery in 3 patients. One patient had an associated celiac artery aneurysm.
6.7 3.76 (7.1, 8 months–11 years) 8/6 14 6 165 15.7 (150, 147–200) 9 7 1
6 3 2 3 2 8 4 3 6
(1 mg/kg), the aortic obstruction was relieved by a descending aorta to an infrarenal (n ¼ 1) or suprarenal (n ¼ 1) abdominal aorta bypass by use of a Gore-Tex prosthesis (descending aorta to suprarenal abdominal aorta, diameter 10 mm, length 20 cm; descending aorta to infrarenal abdominal aorta, diameter 12 mm, length
Surgical Technique Owing to progressive, uncontrollable hypertension despite maximal medical therapy, we performed singlestage revascularization using an extraanatomic bypass technique on these children. In our first two cases in the early 1990s, we performed a single-stage extraanatomic bypass through a left thoracoabdominal approach. After systemic heparinization
Fig 1. Preoperative aortogram showing a short-segment high-grade midaortic stenosis (suprarenal).
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Fig 2. Preoperative magnetic resonance imaging scans. (A) Long-segment high-grade midaortic stenosis (suprarenal– infrarenal). (B) Long-segment high-grade midaortic stenosis (suprarenal).
25 cm) (Fig 3A) in an end-to-side fashion by use of 4-0 polypropylene continuous suture. Later, we performed the extraanatomic bypass technique through a median sternotomy and an upper midline laparotomy approach in 12 patients without using extracorporeal circulation. The ascending aorta and the abdominal aorta below the level of the inferior mesenteric artery was exposed. The left lobe of the liver was dissected from the diaphragm, and a route was designed for the prosthetic graft. After a small incision was made in the midportion of the diaphragm, the lesser omentum was cut, and a hole was made in the transverse mesocolon and the radix mesenteri. After systemic heparinization, a woven Dacron graft (mean diameter 14 mm, mean length 30 cm) (n ¼ 11) or a Gore-tex (diameter 12 mm, length 30 cm) (n ¼ 1) was anastomosed to the infrarenal abdominal aorta distal to the stenosis in an end-to-side fashion with a 4-0 polypropylene continuous suture. Then the graft was passed through the route facilitated previously and anastomosed proximally to the ascending aorta (Fig 3B) in the same fashion. To allow for linear growth of patients, without graft kinking, the graft was oversized in length and
diameter, depending on the patient’s size, and placed more dorsally with a loose arch behind the left kidney to protect it. Nine patients had associated mild visceral artery narrowing (20% to 30%), but excellent collaterals were present so that no visceral artery revascularization was required. Inasmuch as the renal artery stenosis had previously been stented in 6 patients, no renal artery procedures were performed in this group. In a patient with a previous right nephrectomy and a left renal artery stenosis, a renal artery bypass by use of a 5-mm Gore-Tex prosthesis was performed simultaneous with the descending aorta to infrarenal abdominal aorta bypass. In 1 patient with a celiac artery aneurysm, the aneurysm was wrapped with a Dacron patch to prevent further dilation or rupture. These patients were given aspirin 50 mg once daily starting on the first postoperative day and continuing for 6 months.
Follow-Up Complete follow-up data were provided by the Department of Pediatric Cardiology/Congenital Heart Fig 3. Extraanatomic bypass techniques. (A) Descending aorta–suprarenal abdominal aorta bypass with use of a Gore-Tex graft, anastomosed distally to the narrowing of the abdominal aorta infrarenally and proximally to the descending aorta. (B) Ascending aorta– infrarenal abdominal aorta bypass with use of a Dacron graft anastomosed distally to the narrowing of the abdominal aorta infrarenally and proximally to the ascending aorta through a diaphragmatic tunnel.
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Disease and Department of Clinical Studies, Deutsches Herzzentrum Berlin, and written correspondence from the referring physicians. CONGENITAL HEART
Statistical Analysis All data were analyzed with SPSS 16.0 (SPSS Inc, Chicago, IL) software program. Data are expressed as absolute and percentage frequency values and continuous data as mean standard deviation, as appropriate. Freedom from reoperation was analyzed according to Kaplan-Meier estimates with 95% confidence interval. Because there was no mortality, no Kaplan-Meier survival curve was plotted.
Results The perioperative course was unremarkable. There was an immediate considerable reduction in blood pressure in all patients and relief of intermittent claudication in 6 affected patients. One 11-year-old patient who had a preoperative low-grade bilateral renal artery stenosis as seen on computed tomographic angiogram underwent a bilateral renal artery bypass with use of a 7-mm GoreTex prosthesis 2 weeks postoperatively because of recurrence of renal hypertension (Fig 4). A tissue sample from the renal artery showed dysplastic features in the media, intima, and internal lamina. At a mean follow-up time of 5.8 1.36 years (range, 9 months to 15 years), no further operation was done for MAS and no mortality occurred (Fig 4). Twelve patients had complete relief of hypertension, and 2 had mild hypertension but are normotensive while receiving a single antihypertensive medicine. All had normal renal function, and there were no signs or symptoms of visceral malperfusion. No patient had thromboembolism. Their latest follow-up evaluations showed normal growth and development. Follow-up MRT showed patent grafts without any strictures or length restrictions (Fig 5).
Fig 4. Freedom from reoperation after extraanatomic bypass.
Fig 5. Follow-up magnetic resonance tomographic image showing a patent graft without any strictures.
Comment Midaortic syndrome presents clinically with severe hypertension in young individuals in association with either weak or absence of femoral pulses, resulting from localized or diffuse narrowing of the aorta in its midthoracoabdominal course, with frequent involvement of renal and superior mesenteric arteries. The syndrome is rare and is usually discovered during evaluation of hypertension in a child. Although it was described almost seven decades ago [1], classically as coarctation of the abdominal aorta [1–8, 12, 13], its exact cause remains obscure and its pathogenesis speculative, most authors attempting to develop a single hypothesis to explain all reported cases. It was postulated to be related to developmental error in the fusion and maturation of the paired embryonic dorsal aortas during the fourth week of gestation or aortic growth arrest [1, 13]. In addition, support for the congenital hypothesis comes from the known association of MAS with various congenital syndromes [14–17], including neurofibromatosis, infantile hypercalcemia, fibromuscular dysplasia, retroperitoneal fibrosis, mucopolysaccharidosis, and Williams syndrome. The syndrome may be acquired, caused by Takayasu’s arteritis, rubella, and tuberous sclerosis [5, 11]. Support for the acquired hypothesis [18, 19] comes largely from reports from Asia [6, 18, 19], whose authors contend
that MAS is secondary to a localized aortitis resulting in segmental aortic stenosis often complicated by atherosclerosis [20]. Sen and colleagues [21] reported a clinicopathologic study of 16 patients with MAS, the majority of whom had tuberculosis; each had evidence of aortitis. Lande [20] reported that reevaluation of the pathology of the original case reported by Maycock [1] shows undoubted evidence of aortitis. Whatever the cause, the characteristic findings in MAS are hypertension proximal to the aortic stenosis and relative hypotension distal to it. It is manifested by headache, early fatigue on exertion, and bilateral lowerlimb claudication. The severity of hypertension is the primary indication for intervention and the sole factor determining timing of the intervention. If MAS is left untreated, the majority of patients will die of complications of severe hypertension and ischemia by 40 years of age [12, 22]. The causal treatment of MAS is either endovascular therapy [23, 24], operation [25–28], or a combination [29]. Balloon angioplasty has been used for approximately 3 decades in the treatment of MAS [30–32]. In the developing aorta of children, it enables effective dilatation of the luminal impairment without interfering with vessel growth. Further dilatation is also feasible, with repeated angioplasty at a later date. However, at least some recoil is inevitable after balloon angioplasty, and a weakened arterial wall may result in later aneurysm formation, reported to occur in 5% to 20% of cases [33, 34]. Hence, the immediate clinical improvement is short-lived in many patients. Stent technology has generated increasing interest in the management of MAS; nonetheless, limited data are available on the efficacy and durability of stenting for this lesion. Until fenestrated stent grafts [35] and branched aortic endografts [32] prove their feasibility and efficacy in complex MAS, only selected cases with discrete lesions not involving the renal and mesenteric arteries can be considered for endovascular therapy. Moreover, on the premise that arteries can grow longer in response to longitudinal stretch [36, 37], Kim and colleagues [29] reported performing a left nephrectomy on a 3-year-old girl with neonatal hypertension and MAS. They inserted a tissue expander directly posterior to the aortic bifurcation to induce longitudinal growth of the normal distal abdominal aorta and iliac arteries, which permitted resection of the 4-cm segment of the diseased aorta with a primary end-to-end anastomosis 9 months after tissue expansion. This is promising; however, no further reports or follow-up on such an intervention have been made. Our experience shows that initial conservative blood pressure management and endovascular therapy is feasible, but outcome is unsatisfactory, and patients are continuously exposed to sequelae of hypertension and risks of repeated interventions. In our case series, 9 of these 14 patients had been previously treated for severe renovascular hypertension. These treatments were unable to improve the blood pressure even with antihypertensive agents. Four patients had even required three further angioplasty procedures
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and still needed two antihypertensive agents. Apparently, lasting results were not achieved. Success in medical or endovascular control of their hypertension was shortlived. No patients showed long-term success, presumably because of the progressive nature of the disease. Hence, we are strongly convinced that all symptomatic patients with MAS, regardless of the severity of hypertension, should undergo immediate operative correction. This is then the absolute indication for an operation. The timing of operation depends on the severity of hypertension, not the age of the patient. Although it may be preferable to delay the operation until the patient has reached his or her full growth potential, we believe that the presence of severe intractable hypertension necessitates an immediate operation, independently of the age of the patient, to avoid the complications of stroke and heart failure and their sequelae. We assume that these patients may eventually require a change of the graft as they grow; therefore, careful timing and planning of the most appropriate technique must be chosen to delay, or even avoid, this course. The clinical benefits of early surgical intervention to reverse refractory hypertension must be weighed against the impact of the operation on the developing aorta, inasmuch as a great proportion of patients with MAS are children or teenagers. In the selection of an appropriate technique, future body growth and long-term graft durability are of utmost importance. Surgical procedures for MAS require a unique approach in each individual patient. Careful preoperative angiography is essential for a successful operative strategy. This includes multiple oblique views of the renal arteries and a lateral aortogram to determine the status of the remainder of the visceral arteries. It is vital to visualize the entire course of these vessels before embarking upon any surgical technique to be used. The renal artery stenoses are often short ostial lesions that are signaled by the presence of a dilated distal artery. The incidence of visceral artery involvement in our patients (57%) is much higher than that in most other reports. We believe that this is not due to patient selection but rather to the routine use of lateral aortography. Various surgical techniques have been reported, including bypass grafting, graft replacement, and patch angioplasty [25–28]. Relief of the aortic constriction by either patch aortoplasty or bypass are complementary options. Patch aortoplasty is a technique applicable to the very young patient who requires revascularization for severe hypertension, which leaves open the possibility of thoracoabdominal bypass at an older age when the patient is physically mature. This report confirms the view of others that a singlestage operation results in long-term relief of hypertension and its attendant complications [6, 24, 38]. Although the natural history of the disease is practically unknown, the course of symptomatic patients has been followed up by several authors. In a series of 32 patients reported by Senning and Johansson [22], death resulting from cerebral hemorrhage occurred in 10 of them before the age of 34, whereas Onat and Zerren [39] reported that death occurred at a mean age of 34 years in
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symptomatic patients. They reported that hypertensive encephalopathy was seen in 42 patients, with the majority dying of either stroke or heart failure. Because we performed the surgical intervention early enough, we did not encounter such complications in our longterm follow-up. An important consideration in the performance of an aortic bypass is the site of the proximal anastomosis. In our last 10 patients, we performed the proximal anastomosis on the ascending aorta, simply for its technical ease and excellent anatomic exposure. If ever bleeding or anastomotic complications arise, they are technically easy to manage. The options for renal artery reconstruction are multiple, including autogenous arterial/venous/prosthetic grafts, patch angioplasty, and autotransplantation [4]. As much as possible, and when it is avoidable, we refrain from performing any renal artery procedures, especially on infants and small children. Our approach is to reserve arterial grafts in the renal position for the very young patient with very small vessels. Prosthetic graft is recommended in the older patient who has reached physical maturity, inasmuch as larger vessels with poststenotic dilatation are easily revascularized with an antegrade graft. We are convinced that the extraanatomic bypass from the ascending aorta to the infrarenal abdominal aorta not only provides better flow to the lower extremities but also provides significant antegrade flow to permit optimal renal perfusion. This is reflected in the relief of hypertension and improvement of renal function of the 6 patients who had previously undergone endovascular renal angioplasties but no aortorenal bypass performed and to the 2 patients with aorto-renal bypass with immediate normalization of blood pressure and renal function. The indications for visceral artery revascularization are less well defined. Although chronic abdominal pain thought to be secondary to chronic visceral ischemia was apparently common when the syndrome was first described [21], it was not seen in our series. Messina and colleagues [4] described their patients who had MAS and proposed prophylactic revascularization in asymptomatic patients with demonstrated stenosis of the celiac and/or superior mesenteric arteries. We have taken a different approach from theirs. Although 7 patients had visceral artery (celiac trunk and superior mesenteric artery) involvement, none of them underwent visceral artery revascularization because they had such extensive collateralization from the inferior mesenteric artery to the superior mesenteric artery and celiac arterial circulation. None of these patients have had symptoms of intestinal ischemia; hence, we preferred not to take the risk of prophylactic revascularization. One had celiac artery aneurysm, which was wrapped with Dacron graft to prevent further dilatation. It is of interest that with follow-up periods over 15 years, we have not had any reason to change this policy. Further longer-term follow-up will determine whether the policy has been appropriate, but late repair can always be performed when necessary.
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On the basis of our experience with these 14 patients with MAS, we recommend single-stage revascularization using extraanatomic surgical bypass grafting as the optimal technique for MAS. The basic surgical principle is restoration of renal blood flow to relieve the hypertension, andrestoration of blood flow to the viscera and relief of claudication, if there is any. We chose ascending aorta—infrarenal abdominal aorta bypass, because with this technique, long-term patency is expected, its effectiveness on relief of hypertension is unquestionable, and the afterload of the left ventricle is more effectively reduced. The surgical approach depends largely on the presence of direct renal or visceral artery involvement. Thus, patients who have renovascular hypertension, lower limb claudication with midaortic stenosis without branch involvement, or both can have effective relief by simple thoracic to abdominal aortic bypass. The long-term follow-up of these patients indicates that the results were durable. The lone problem encountered in the postoperative course was the recurrence of renal hypertension in the 11-year-old patient with mild renal artery stenosis. His renal function and blood pressure have normalized after the operation. This illustrates two important points in the treatment of such patients. First, careful lateral aortography should be performed to precisely determine the severity of renal artery stenosis. Second, revascularization of patients with MAS results in very effective relief of hypertension and, as such, a second operation may be avoided if careful assessment of renal artery stenosis is performed before the operation. We may say that whatever the cause of MAS, the prognosis after uncompromised surgical revascularization is rewarding in the mid-term and long-term followup of these patients. The durability of these prosthetic aortic bypass grafts is the ultimate determinant of patients’ quality and length of life. The high flow in the vascular beds reconstructed in these patients favors prolonged patency, allowing these patients the opportunity to grow and live a full, healthy life.
Conclusions Single-stage revascularization using an extraanatomic bypass technique by an ascending aorta to infrarenal abdominal aorta graft provides very effective and durable long-term relief of hypertension and any malperfusion in MAS. The authors thank Anne Gale, medical editor, for assistance with this article. We appreciate the assistance of Astrid Benhennour for literature search, Daniela Moeske-Scholz and Heike Schultz for data collection, Julia Stein for statistical analysis, and Carla Weber for graphics.
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