Subclavian Steal Syndrome in the Pediatric Age Group

Transcription

1 Subclavian Steal Syndrome in the Pediatric Age Group Frank M. Midgley, M.D., and James E. McClenathan, M.D. ABSTRACT Four pediatric patients with subclavian steal syndrome (SSS) are described. One patient with congenital SSS had persistence of the lesion following surgical repair of coarctation of the aorta due to a gradient across a hypoplastic aortic arch. In 3 patients SSS developed on an acquired basis as a sequel to corrective operation, for coarctation in 1 patient, and interrupted aortic arch in 2 patients. Contributory factors included hypoplasia of the aortic arch, anatomical variation of the origin of the vertebral artery, and discrete recoarctation involving the ostium of the subclavian artery. Treatment was by vertebral artery ligation in 3 patients and by prosthetic patch arterioplasty in the patient with recoarctation. The 4 patients remain asymptomatic on follow-up of 16 to 25 months. Retrograde blood flow in the vertebral artery is the pathophysiological hallmark of the subclavian steal syndrome (SSS). The underlying abnormality is a focal occlusive lesion of the prevertebral artery segment of the ipsilateral subclavian artery or aortic arch causing relative hypotension of the more distal subclavian artery, which eventuates in retrograde vertebral artery flow. First described by Contorni [ll and further elucidated by Reivich and associates [51, the SSS is a distinctive clinical entity that has major central nervous or upper extremity symptomatology. Atherosclerotic occlusion of the proximal subclavian artery is the underlying cause in thle majority of instances, while in From the Department of Cardiovascular Surgery, Children s Hospital National Medical Center, and the Department of Child Health,and Development, George Washington University Medical School, Washington, DC. We wish to thank David L. Breckbill for the performance of the cerebral arteriographic studies. Presented at the Twenty-third Annual Meeting of the Southern Thoracic Surgical Association, Nov 4-6,1976, Acapulco, Mexico. Address reprint requests to Dr Midgley, Department of Cardiovascular Surgery, Children s Hospital National Medical Center, Washington, DC others it may be congenital or acquired secondary to operation, gross trauma, or embolism. In an 18-month period we treated 4 patients aged 4 to 13 who evidenced SSS, 1 on a congenital basis and 3 acquired. This report details the clinical courses of these patients, who underwent surgical repair of congenital occlusive lesions of the aortic arch or isthmus and sub- -equently developed (or had persistent) SSS. Case Reports Patient 1 A 13-year-old boy was evaluated after femoral pulses were noted to be absent on a school physical examination. Symptoms included headaches and paresthesias of the legs. Excellent physical development was apparent, but there was some underdevelopment of the left arm and forearm. The left brachial blood pressure was 30 mm Hg less than the right brachial pressure. Catheterization data confirmed the clinically suspected coarctation of the thoracic aorta, which also involved the ostium of the left subclavian artery. Systolic pressure was 140 mm Hg in the ascending aorta, 110 mm Hg in the left subclavian artery, and 95 mm Hg in the descending aorta. Angiograms revealed abundant collateralization with retrograde flow in both the left vertebral artery and the proximal left subclavian artery with subsequent filling of the descending aorta. Additionally, hypoplasia of the aortic arch from the innominate artery to the left subclavian artery was noted. Prosthetic patch arterioplasty of the aorta and proximal left subclavian artery was performed. Intraoperative measurements revealed no abnormal pressure gradients between the distal aortic arch, left subclavian artery, or descending aorta. However, at discharge there was a brachial artery pressure gradient of 20 mm Hg, with equal pressures in the left arm and lower extremi ties. Three months postoperatively, while raking leaves, the patient evidenced a sudden left 252

2 253 Midgley and McClenathan: Subclavian Steal Syndrome Fig 1. Right vertebral arteriogram (subtraction technique) in Patient 1, showing large intervertebral collateral anastomoses, diffuse dilatation of both vertebral arteries, and retrograde filling of left vertebral artery with subsequent opacification of the distal left subclavian artery. hemianopsia lasting several minutes, followed by persistent frontal headache. Subsequent catheterization studies revealed a 30 mm Hg pressure gradient across the hypoplastic aortic arch. Angiography (Fig 1) demonstrated antegrade flow in the proximal left subclavian artery with retrograde flow in the left vertebral artery. Surgical ligation of the left vertebral artery was then accomplished, and the patient has remained asymptomatic for 23 months. Pa tien t 2 A 6-year-old asymptomatic boy with absent femoral pulses underwent physical examination which revealed brachial artery hypertension, with 172/88 in both upper extremities. A bruit was audible in both supraclavicular areas. Catheterization studies showed interruption of the aortic arch distal to the left subclavian artery, with an 85 mm Hg pressure gradient between the aortic arch and the femoral artery. Aortic arch hypoplasia was also noted. Surgical repair was by anastomosis between the divided end of the left subclavian artery and Fig 2. Right vertebral arteriogram (sub traction technique) in Patient 2, showing retrogradefilling of an enlarged left vertebral artery with subsequent antegrade filling of the left subclavian and left internal mammary artery. the descending aorta (Blalock-Park operation) to bridge a 28 mm interruption. Additionally, the first branch of the subclavian artery, believed to be the left vertebral artery, was ligated. Nine months postoperatively the patient underwent restudy for symptomatology of intermittent headaches and persistent hypertension. Catheterization data indicated pressure gradients of 25 mm Hg across the aortic arch and 20 mm Hg at the anastomosis. Right vertebral arteriography (Fig 2) demonstrated retrograde flow in the left vertebral artery with subsequent filling of the left subclavian artery. Filling of the left internal mammary artery was also noted. The patient subsequently underwent ligation of the left vertebral artery without incident and has remained asymptomatic for 25 months. Patient 3 A 41/z-year-old boy who had undergone coarctation repair (resection-reanastomosis) at age 2% underwent repeat catheterization for symptoms of headaches and signs of decreased left brachial and lower extremity pulses. Catheterization data indicated a pressure gradient of 30 mm Hg, and aortography revealed a discrete recoarctation of the anastomosis site, which involved the

3 254 The Annals of Thoracic Surgery Vol 24 No 3 September 1977 was accomplished by prosthetic tube graft interposition. Nine months postoperatively the patient had a seizure episode with loss of consciousness. Subsequent catheterization data indicated a 20 mm Hg gradient between the aortic arch and left subclavian artery, but no clear site of obstruction was evident by aortography. Cerebral arteriograms were normal except for the demonstration of retrograde flow in the left vertebral artery following right vertebral artery injection (Fig 4). Transcervical ligation of the left vertebral artery was accomplished without incident, and she has remained asymptomatic for 16 months. Fig3. Right subclavian arteriogram (subtraction technique) in Patient3, showingretrogradefilling of the left vertebral and left subclavian artery. Note the anastomosis between the right and left inferior thyroid arteries. Profuse colla teral circulation is evident by the size of the vertebral arteries, the right internal mammary artery, and other vessels. Ostium Of the left artery. Right subarteriography (Fig 3, demonstrated abundant collateralization involving the right and the branches Of the thyrocervical and costocervical trunks. Additionally, retrograde filling of the left vertebral artery, with subsequent opacification of the distal subclavian artery, was readily apparent. The recoarctation was surgically repaired transthora.cica1ly by prosthetic patch arterioplasty across the aortic and subclavian stenosis. The child has remained asymptomatic on follow-up of 22 months, with equal pressures in both arm:; and legs. Patient 4 A 12-year-old girl with Turner s syndrome and hypothyroidism was evaluated for absent femoral pulses. She was symptomatic with headaches, nose bleeds, and lower extremity discomfort accentuated by exercise. Catheterization studies revealed an interrupted aorta beyond the left subclavian artery. Surgical repair Operative Technique Transcervical ligation of the left vertebral artery is carried out under general anesthesia. A small incision is made over the lateral border of the sternocleidomastoid muscle 2 cm cephalad and parallel to the clavicle, basically the approach to the scalene fat pad (Fig 5). The plane of the anterior scalene muscle is reached, the phrenic nerve is identified, and the dissection is continued medially (remaining cephalad to the thoracic duct), with the dissection passing behind the internal jugular vein and the carotid sheath. The vertebral artery and vein are located at, and running parallel to, the medial edge of the anterior scalene muscle. Double ligation of the vertebral artery in continuity is then accomplished with 2-0 ties; standard wound closure completes the procedure. The patients were routinely discharged one day postoperat~ve~y~ Comment Obstructive lesions of the aortic arch and great vessels predispose to a variety of alterations of normal hemodynamic patterns. The combination of proximal subclavian artery obstruction with retrograde flow in the ipsilateral vertebral artery define the SSS. Attendant ischemic neurological or upper extremity symptomatology completes the full clinical picture. The symptom patterns are frequently episodic, being related to activity of the upper extremity. These symptoms may include headaches, seizure, dizziness, vertigo syncope, speech difficulties, and hemianopia. Physical signs of decreased pulsa-

4 255 Midgley and McClenathan: Subclavian Steal Syndrome A Fig4. Right vertebral arteriogram (subtraction technique) in Patient 4, showing a large right vertebral artery and diminutive left vertebral artery. Retrogradefilling of the left vertebral artery is seen 1 second (A) and 4 seconds (B) follozving injection of contrast medium. \Surgical Plane Vertebral Artery Fig5. Cross-section of the neck at the level of C7. The surgicalplane between the left internaljugular vein and the anterior scalene muscle is indicated. The vertebral artery is seen running vertically between the anterior scalene and longus colli muscles. B tion and pressure of the involved extremity are usually noted. Proximal subclavian artery obstruction does not necessarily cause retrograde flow in the vertebral artery, as adequate distal subclavian artery pressure may be maintained by the abundant collateral channels that are available. Previous studies [2, 5, 71 have shown that brachial artery gradients of 20 mm Hg or more are necessary to cause retrograde vertebral artery flow. The greater the pressure gradient between the circle of Willis and the distal subclavian artery, the more likely retrograde vertebral artery flow will occur. One aspect of the syndrome s pathophysiology is that not only does the brain lose its blood supply from the vertebral artery, it loses in addition a potentially important portion of the carotid and contralateral vertebral artery flow. This occurs by way of a siphonage effect from the circle of Willis to the circulation of the affected upper extremity. Due to the otherwise normal nature of the cerebral circulation in the

5 256 The Annals of Thoracic Surgery Vol 24 No 3 September 1977 pediatric age group, symptomatic cerebrovascular disease is uncommon. Additionally, the abundant collateralization helps to prevent or minimize the siphonage aspects of the entity. In a review article by Killen and colleagues [21 in 1966, a collected experience of 110 patients manifesting SSS was detailed. Of these, only 2 were younger than 10 years of age. A review article by E ieroni and co-workers [41 in 1972 described a collected series of 27 patients with congenital SSS. An additional instance of congenital subclavian and pulmonary artery steal syndrome was reported by Shaher and associates in 1972 [91. The preoperative demonstration of subclavian-aortic steal syndrome seen in Patient 1 has been previously described by Love [31. Of particular interest is the hypoplasia of the aortic arch that is frequently seen in congenital obstructive lesions of coarctation and interrupted aortic arch, as in Patients 1 and 2. It seems reasonable to assume that in most instances the arch is anatomically and histologically normal, the hypoplasia being due to lack of normal systemic flow through this area sufficient to cause normal hemodynamic growth and development of the arch. Likewise, it seems reasonable to assume that when normal flow is provided, growth of the arch will eventually ensue. It was on this premise that we based our surgical correction of SSS by ligation of the vertebral artery. We anticipate that the gradient across the arch will diminish with time as the diameter of the arch grows because of the increased flow. However, due to noticeable neurological symptoms, the physiology had to be altered acutely, the simplest approach being ligation of the vertebral artery. Therapeutic ligation of the vertebral artery was first described by Rob in Filling of the left vertebral artery by way of its muscular branches, retrograde from the circle of Willis, and by other well-developed collateral channels so graphically demonstrated in Figure 1 will undoubtedly continue. Siphonage, however, should certainly be prevented and adequate cerebral perfusion maintained. The subclavian-internal mammary artery steal following Blalock-Park reconstruction in Patient 2 represents a logical physiological progression of the basic disease process, being a reflection of pressure gradients between the circle of Willis and the distal subclavian artery and between the distal subclavian artery and the descending aorta. The antegrade internal mammary artery flow is a collateral pathway to the descending aorta around a persistently hypoplastic aortic arch and a small anastomotic gradient. Apparently Patient 2 had an anatomical variant in which the first branch of the subclavian artery, ligated at the time of the original operation, was not the vertebral artery but another vessel, possibly the inferior thyroid or transverse cervical artery. As with Patient 1, ligation of the vertebral artery was accomplished. We hope growth of the aortic arch will follow to minimize the aortic gradient. Potentially the patient may require a thoracic reoperation if a high gradient persists. As is seen in coarctation series from most institutions, recoarctation at the anastomosis can occur in the early or late follow-up period. This may be due to fibrosis, incomplete excision of coarctation tissue, a technically compromised anastomosis, or thrombus formation, or it may be unexplainable. Discrete stenosis at the anastomosis involved the ostium of the left subclavian artery in Patient 3, in whom patch arterioplasty was performed to correct the SSS and the recoarctation. Because intraoperative pressures were equal in the aortic arch, left subclavian artery, and descending aorta, ligation of the vertebral artery was considered unnecessary. As demonstrated by the angiograms of all 4 patients, there is considerable variation in the size of the vertebral arteries among individuals, and even in the same individual (Patient 4). As was pointed out by Shockman [91, directpressure injection of contrast material into a vertebral artery can cause reversal of blood flow in the contralateral vertebral artery due to the sudden pressure rise. However, antegrade flow resumes as soon as the injection pressure is dissipated. Knowing of this normal occurrence of retrograde flow in the vertebral artery and giving due consideration to the small size of the left vertebral artery, we were uncertain whether SSS

6 257 Midgley and McClenathan: Subclavian Steal Syndrome was present in Patient 4. However, retrograde flow persisted through 4 seconds postinjection (see Fig 4B), and because of the serious neurological symptomatology, ligation of the vertebral artery was elected. SSS is not an uncommon occurrence in the pediatric age group. Certainly development of the syndrome should be added to the list of possible sequelae of the surgical treatment of occlusive lesions of the aortic arch and isthmus. Factors influencing its development include hypoplasia of the aortic arch, anatomical variation of the origin of the vertebral artery, recoarctation, and the collateral potential of the vascular bed. SSS can be effectively treated in the pediatric patient by ligation of the vertebral artery or by direct repair of a coarctation or recoarctation involving the ostium of the subclavian artery. To provide ultimately successful treatment a diligent, aggressive, prolonged care program is necessary for all patients undergoing operation for coarctation. References 1. Contomi L: I1 circolo collaterale vertebral-vertebral nella obliterazione dell 'arteria subclavia alle sue origini. Minerva Chir 15:268, Killen DA, Foster JH, Gobbel WG, et al: The subclavian steal syndrome. J Thorac Cardiovasc Surg 51:539, Love JW: Varieties of congenital subclavian steal with and without the syndrome. J Cardiovasc Surg (Torino) 9:358, Pieroni DR, Brodsky ST, Rowe RD: Congenital subclavian steal: report of a case occurring in a neonate and a review of the literature. Am Heart J 84:801, Reivich M, Holling HE, Roberts 8, et al: Reversal of blood flow through the vertebral artery and its effect on cerebral circulation. N Engl J Med , Rob C: Incipient strokes: technique of surgical therapy (third Princeton conference), in Cerebral Vascular Disease. Edited by CH Millikan, RG Siekert, JP Whisant, New York, Grune & Stratton, 1961, p Sammartino WF, Toole JF: Reversed vertebral artery flow. Arch Neurol 10:590, Shaher RM, Patterson P, Stranahan A, et al: Congenital pulmonary and subclavian arteries steal syndrome. Am Heart J 84:103, Shockman AT: Retrograde vertebral artery flow as an artifact of technique. Am J Roentgen01 91:1258, 1964