Bilateral Subclavian Artery Aneurysm Associated with Idiopathic Cystic Medial Necrosis Henry J. Fee, M.D., Harold S . Gewirb, M.D., Theodore X. O’Connell, M.D., and Jules H. Grollman, M.D. ABSTRACT Although cystic medial necrosis, either idiopathic or associated with Marfan’s syndrome, usually becomes manifest as an ascending aortic aneurysm, aortic insufficiency, aortic dissection, or a combination of these disorders, a rare case of bilateral subclavian artery aneurysm secondary to idiopathic cystic medial necrosis has occurred. Subclavian artery aneurysms most commonly represent poststenotic dilatation from anterior scalene or cervical rib compression, occasionally are associated with generalized arteriosclerotic peripheral vascular disease, and rarely are secondary to syphilitic or mycotic infections. Subclavian artery aneurysms have a major risk of rupture, embolus, or thrombosis, and therefore should be repaired. A reverse saphenous vein or prosthetic bypass graft from the carotid to the axillary artery provides adequate flow to the upper extremity. The aneurysm should be completely excised if possible, since reexpansion through small collaterals or through insufficient closure by ligation can occur and compress the brachial plexus after successful bypass. The clinical presentation, angiographic findings, and operative repair of a subclavian artery aneurysm secondary to cystic medial necrosis are described. #
Cystic medial necrosis secondary to Marfan’s syndrome or of an idiopathic nature has been described in association with aneurysms or dissection of the ascending aorta. Occasionally this disease process may involve other segments of the aorta, its branches, or the pulmonary artery [5]. We recently treated a patient with bilateral subclavian and carotid artery aneurysms secondary to idiopathic cystic medial necrosis. A discussion of the symptomatology, radioFrom the Departments of Surgery and Radiology, UCLA School of Medicine, Los Angeles, CA. Accepted for publication Jan 20, 1978. Address reprint requests to Dr. O’Connell, Division of Oncology, Department of Surgery, UCLA School of Medicine, Los Angeles, CA 90024.
387 0003-4975/78/0026-0413$01.00 @ 1978 by Henry J. Fee
graphic characteristics, pathophysiology, and surgical approach to this interesting disease forms the basis of this report. A 42-year-old man was admitted one year after suffering an anterior myocardial infarction because of pain and paresthesias of the left arm that had lasted one day. He gave no personal or family history of diabetes, hypertension, aneurysms, or Marfan’s syndrome. His medications had included theophylline and ibuprofen (Motrin). Lipoprotein electrophoresis was normal, and an electrocardiogram demonstrated an old anterior myocardial infarction. The only abnormality on physical examination was absence of the left brachial and radial pulses. A left brachial artery thrombectomy restored circulation to the upper extremity. Subsequent arteriograms revealed bilateral subclavian artery aneurysms located between the internal mammary and axillary arteries (Figs 1, 2). Residual thrombus was identified in the distal portion of the aneurysm. There was mild fusiform dilatation of both distal common carotid and proximal internal carotid arteries (Fig 3). The proximal ascending aorta was visualized during cineangiocardiography, performed to rule out intracardiac mural thrombi, and was normal in size. A reverse saphenous vein bypass from the left common carotid to the left brachial artery with ligation of the aneurysm was performed without difficulty, and four months later a similar procedure was performed on the right. The patient did well for five months and then noted gradual onset of paresthesias in the left shoulder and arm. On physical examination there was a pulsatile 5 cm mass in the left supraclavicular fossa and good brachial and radial pulses. Arteriography disclosed enlargement of the left subclavian artery aneurysm, which filled anterograde through a small collateral channel to the ligated segment and retrograde from the patent graft. During the interim the
388
The Annals of Thoracic Surgery Vol 26 No 4 October 1978
Fig 1 . Selective left subclavian arteriogram showing a lobulated fusiform aneurysm of the subclavian, axillary, and proximal brachial arteries. There is a small amount of residual clot in the distal portion of the aneurysm just after the origin of the circumflex humeral artery. Fig 3. Right posterior oblique arteriogram of the aortic arch showing gradual mild dilatation of the distal onethirds of both common carotid arteries extending through the internal carotid sinuses and into the proximal internal carotid arteries. The distal ascending aorta is not dilated.
Fig 2 . Selective right subclavian arteriogram also showing a lobulated fusiform aneu y s m of the same arteries. There is no clot.
dilatation of the carotid arteries had increased slightly. The aneurysm was excised without difficulty, and the patient was asymptomatic six months postoperatively. Microscopic examination of the aneurysm specimen demonstrated cystic medial necrosis (Fig 4).
Comment Subclavian artery aneurysms are unusual and comprise only a small percentage of peripheral aneurysms 1101. Until recently, the most common etiology was syphilis, but now the principal causes are arteriosclerotic peripheral vascular disease, trauma, and postobstructive dilatation secondary to a cervical rib or proximal scalene muscle [21. A case of subclavian artery aneurysm secondary to cystic medial necrosis was reported by Persaud in 1968 [121 when he described successful right subclavian aneurysmectomy and bypass with a prosthetic graft. Only lately has the significance of idiopathic cystic medial necrosis as a cause of descending aortic aneurysms been fully recognized [5], and it is possible that many “arteriosclerotic” peripheral aneurysms are actually due to this entity. The etiology of cystic medial necrosis is unknown. Multiple instances of familial occurrence in the absence of Marfan’s syndrome have
389
Case Report: Fee et al: Bilateral Subclavian Artery Aneurysm
Fig 4 . Microscopic examination of the aneurysm specimen demonstrating cystic medial necrosis. ( H 6 E ; original magnification ~ 9 7 . )
been noted, suggesting an inherited factor, but most such cases are sporadic. Several toxins have been proposed as pathogenetic. Aortic degeneration has been produced with diphtheria toxin [41 and sweet peas [ll (in which the toxic agent is p-aminopropiononitrile). Anoxia secondary to occlusion of the vasa vasorum has likewise been implicated. In view of its connection with Marfan’s syndrome, cystic medical necrosis has also been considered a degenerative connective tissue disease. It has been associated with EhlersDanlos syndrome [7], osteogenesis imperfecta [3], and Hurler’s syndrome [13] in addition to Marfan’s syndrome. The metabolic defect in Marfan’s syndrome appears to be in the production of ground substance; thus far, a biochemical defect has not been identified in idiopathic cystic medial necrosis. The action of P-aminopropiononitrile is to block collagen cross-linking. This may be one of several causes of the idiopathic necrosis, but there is no evidence that it is the basic defect in the clinical disease.
The relationship between idiopathic cystic medial necrosis and Marfan’s syndrome is unclear. Most pathologists consider the vascular lesions of the two disorders to be identical both microscopically and grossly [14], although others have found that idiopathic medial necrosis does not exhibit dilatation of the vasa vasorum and whorling of smooth muscle. Assuming that the lesions are histologically identical, the question remains whether idiopathic cystic medial necrosis represents a forme fruste of Marfan’s syndrome. Patients with the disorder have been shown in kindreds with and without Marfan’s syndrome [9, 111. Unfortunately, no biochemical marker for Marfan’s has been found; this would help clarify the relation between the two diseases. The convention we accept is to consider patients with cystic medial necrosis and no family history of Marfan’s syndrome to have an idiopathic disease and those with a family history of Marfan‘s syndrome to represent a forme fruste of that syndrome. The angiographic findings of cystic medial necrosis are characteristic and easily differentiated from those of arteriosclerotic vascular disease, syphilis, trauma, and postobstructive dilatation. There is uniform dilatation of the proximal ascending aorta extending down to include the aortic sinuses, which are effaced [5, 61. The aortic wall is smooth, and the process can extend up to involve the aortic arch and descending thoracic aorta as well. Although the dilatation is usually symmetrical (as it was in the carotid arteries in our patient), it is occasionally asymmetrical (as in our patient’s subclavian arteries). A large proportion of patients develop associated dissection of the aortic wall. Aortography will show multiple intimal flaps manifested by radiolucent curvilinear lines [B]. Aortic valve incompetence due to dilatation of the valve ring is likewise common. As with all aneurysms, those of the subclavian artery are best treated with surgical excision whenever possible. The majority of subclavian artery aneurysms can be safely approached through a supraclavicular incision and, after total excision, bypassed with either a reverse saphenous vein or a prosthetic graft. Ligation is not recommended because the aneurysm often recurs, as it did in our patient.
390 The Annals of Thoracic Surgery Vol 26 No 4 October 1978
Microscopic examination of the wall of the involved vessel usually demonstrates fragmentation of elastic fibers of the lining of the media, mucoid degeneration, a n d separation of the elastic lamina by cystic spaces [5, 121. In cystic medial necrosis of the ascending aorta this process is usually confined proximal to the first aortic branch. In o u r patient, however, the bilaterality of the subclavian artery process a n d evidence of carotid aneurysms would indicate that the process can be diffuse. In view of the paucity of information in the literature, no prognosis can be made. The aneurysmal enlargement of the carotid arteries is worrisome a n d necessitates close observation a n d eventual surgical intervention if the dilatation progresses. References Bachhuber TE, Lalich JJ: Production of dissecting aneurysms in rats fed Lathyrus odoratus. Science 120:712, 1954 Beal J: Subclavian aneurysm (surgical grand rounds). I11 Med J 147:354, 1975 Criscitiello MG, Ronan JA Jr, Besterman EMM, et al: Cardiovascular abnormalities in osteogenesis imperfecta. Circulation 31:255, 1965 Duff GL: Medial degeneration in the aorta of the
rabbit produced by diphtheria toxin. Arch Pathol 12543, 1932 5. Eisen S, Elliott LP: The roentgenology of cystic medial necrosis of the ascending aorta. Radiol Clin North Am 6:437, 1968 6. Figley MM: Angiocardiography in valvular heart disease. Morphologic and volumetric considerations. Radiol Clin North Am 2:409, 1964 7. Freiden J, Hurwitt ES, Leader E: Ruptured aortic cusp associated with heritable disorders of connective tissue. Am J Med 33:615, 1962 8. Grollman JH, Lecky JW, Rosch J: Miscellaneous disease of arteries; or, all arterial lesions aren’t fatty. Semin Roentgen01 5:306, 1970 9. Hanley WB, Jones NB: Familial dissecting aortic aneurysms. A report of three cases within two generations. Br Heart J 29352, 1967 10. Howell JF, Crawford ES, Morris GC, et al: Surgical treatment of peripheral arteriosclerotic aneurysm. Surg Clin North Am 46:979, 1966 11. McKusick VA: Heritable Disorders of Connective Tissue. St. Louis, Mosby, 1972, p 189 12. Persaud V: Subclavian artery aneurysm and idiopathic cystic medionecrosis. Br Heart J 30:436, 1968 13. Strauss L: Pathology of gargoylism. Report of case and review of literature. Am J Pathol24:855, 1948 14. Wagenvoort CA, Neufeld HN, Edwards JE: Cardiovascular system in Marfan’s syndrome and in idiopathic dilatation of the AA. Am J Cardiol 9:496, 1962
Cystic medial necrosis secondary to Marfan’s syndrome or of an idiopathic nature has been described in association with aneurysms or dissection of the ascending aorta. Occasionally this disease process may involve other segments of the aorta, its branches, or the pulmonary artery [5]. We recently treated a patient with bilateral subclavian and carotid artery aneurysms secondary to idiopathic cystic medial necrosis. A discussion of the symptomatology, radioFrom the Departments of Surgery and Radiology, UCLA School of Medicine, Los Angeles, CA. Accepted for publication Jan 20, 1978. Address reprint requests to Dr. O’Connell, Division of Oncology, Department of Surgery, UCLA School of Medicine, Los Angeles, CA 90024.
387 0003-4975/78/0026-0413$01.00 @ 1978 by Henry J. Fee
graphic characteristics, pathophysiology, and surgical approach to this interesting disease forms the basis of this report. A 42-year-old man was admitted one year after suffering an anterior myocardial infarction because of pain and paresthesias of the left arm that had lasted one day. He gave no personal or family history of diabetes, hypertension, aneurysms, or Marfan’s syndrome. His medications had included theophylline and ibuprofen (Motrin). Lipoprotein electrophoresis was normal, and an electrocardiogram demonstrated an old anterior myocardial infarction. The only abnormality on physical examination was absence of the left brachial and radial pulses. A left brachial artery thrombectomy restored circulation to the upper extremity. Subsequent arteriograms revealed bilateral subclavian artery aneurysms located between the internal mammary and axillary arteries (Figs 1, 2). Residual thrombus was identified in the distal portion of the aneurysm. There was mild fusiform dilatation of both distal common carotid and proximal internal carotid arteries (Fig 3). The proximal ascending aorta was visualized during cineangiocardiography, performed to rule out intracardiac mural thrombi, and was normal in size. A reverse saphenous vein bypass from the left common carotid to the left brachial artery with ligation of the aneurysm was performed without difficulty, and four months later a similar procedure was performed on the right. The patient did well for five months and then noted gradual onset of paresthesias in the left shoulder and arm. On physical examination there was a pulsatile 5 cm mass in the left supraclavicular fossa and good brachial and radial pulses. Arteriography disclosed enlargement of the left subclavian artery aneurysm, which filled anterograde through a small collateral channel to the ligated segment and retrograde from the patent graft. During the interim the
388
The Annals of Thoracic Surgery Vol 26 No 4 October 1978
Fig 1 . Selective left subclavian arteriogram showing a lobulated fusiform aneurysm of the subclavian, axillary, and proximal brachial arteries. There is a small amount of residual clot in the distal portion of the aneurysm just after the origin of the circumflex humeral artery. Fig 3. Right posterior oblique arteriogram of the aortic arch showing gradual mild dilatation of the distal onethirds of both common carotid arteries extending through the internal carotid sinuses and into the proximal internal carotid arteries. The distal ascending aorta is not dilated.
Fig 2 . Selective right subclavian arteriogram also showing a lobulated fusiform aneu y s m of the same arteries. There is no clot.
dilatation of the carotid arteries had increased slightly. The aneurysm was excised without difficulty, and the patient was asymptomatic six months postoperatively. Microscopic examination of the aneurysm specimen demonstrated cystic medial necrosis (Fig 4).
Comment Subclavian artery aneurysms are unusual and comprise only a small percentage of peripheral aneurysms 1101. Until recently, the most common etiology was syphilis, but now the principal causes are arteriosclerotic peripheral vascular disease, trauma, and postobstructive dilatation secondary to a cervical rib or proximal scalene muscle [21. A case of subclavian artery aneurysm secondary to cystic medial necrosis was reported by Persaud in 1968 [121 when he described successful right subclavian aneurysmectomy and bypass with a prosthetic graft. Only lately has the significance of idiopathic cystic medial necrosis as a cause of descending aortic aneurysms been fully recognized [5], and it is possible that many “arteriosclerotic” peripheral aneurysms are actually due to this entity. The etiology of cystic medial necrosis is unknown. Multiple instances of familial occurrence in the absence of Marfan’s syndrome have
389
Case Report: Fee et al: Bilateral Subclavian Artery Aneurysm
Fig 4 . Microscopic examination of the aneurysm specimen demonstrating cystic medial necrosis. ( H 6 E ; original magnification ~ 9 7 . )
been noted, suggesting an inherited factor, but most such cases are sporadic. Several toxins have been proposed as pathogenetic. Aortic degeneration has been produced with diphtheria toxin [41 and sweet peas [ll (in which the toxic agent is p-aminopropiononitrile). Anoxia secondary to occlusion of the vasa vasorum has likewise been implicated. In view of its connection with Marfan’s syndrome, cystic medical necrosis has also been considered a degenerative connective tissue disease. It has been associated with EhlersDanlos syndrome [7], osteogenesis imperfecta [3], and Hurler’s syndrome [13] in addition to Marfan’s syndrome. The metabolic defect in Marfan’s syndrome appears to be in the production of ground substance; thus far, a biochemical defect has not been identified in idiopathic cystic medial necrosis. The action of P-aminopropiononitrile is to block collagen cross-linking. This may be one of several causes of the idiopathic necrosis, but there is no evidence that it is the basic defect in the clinical disease.
The relationship between idiopathic cystic medial necrosis and Marfan’s syndrome is unclear. Most pathologists consider the vascular lesions of the two disorders to be identical both microscopically and grossly [14], although others have found that idiopathic medial necrosis does not exhibit dilatation of the vasa vasorum and whorling of smooth muscle. Assuming that the lesions are histologically identical, the question remains whether idiopathic cystic medial necrosis represents a forme fruste of Marfan’s syndrome. Patients with the disorder have been shown in kindreds with and without Marfan’s syndrome [9, 111. Unfortunately, no biochemical marker for Marfan’s has been found; this would help clarify the relation between the two diseases. The convention we accept is to consider patients with cystic medial necrosis and no family history of Marfan’s syndrome to have an idiopathic disease and those with a family history of Marfan‘s syndrome to represent a forme fruste of that syndrome. The angiographic findings of cystic medial necrosis are characteristic and easily differentiated from those of arteriosclerotic vascular disease, syphilis, trauma, and postobstructive dilatation. There is uniform dilatation of the proximal ascending aorta extending down to include the aortic sinuses, which are effaced [5, 61. The aortic wall is smooth, and the process can extend up to involve the aortic arch and descending thoracic aorta as well. Although the dilatation is usually symmetrical (as it was in the carotid arteries in our patient), it is occasionally asymmetrical (as in our patient’s subclavian arteries). A large proportion of patients develop associated dissection of the aortic wall. Aortography will show multiple intimal flaps manifested by radiolucent curvilinear lines [B]. Aortic valve incompetence due to dilatation of the valve ring is likewise common. As with all aneurysms, those of the subclavian artery are best treated with surgical excision whenever possible. The majority of subclavian artery aneurysms can be safely approached through a supraclavicular incision and, after total excision, bypassed with either a reverse saphenous vein or a prosthetic graft. Ligation is not recommended because the aneurysm often recurs, as it did in our patient.
390 The Annals of Thoracic Surgery Vol 26 No 4 October 1978
Microscopic examination of the wall of the involved vessel usually demonstrates fragmentation of elastic fibers of the lining of the media, mucoid degeneration, a n d separation of the elastic lamina by cystic spaces [5, 121. In cystic medial necrosis of the ascending aorta this process is usually confined proximal to the first aortic branch. In o u r patient, however, the bilaterality of the subclavian artery process a n d evidence of carotid aneurysms would indicate that the process can be diffuse. In view of the paucity of information in the literature, no prognosis can be made. The aneurysmal enlargement of the carotid arteries is worrisome a n d necessitates close observation a n d eventual surgical intervention if the dilatation progresses. References Bachhuber TE, Lalich JJ: Production of dissecting aneurysms in rats fed Lathyrus odoratus. Science 120:712, 1954 Beal J: Subclavian aneurysm (surgical grand rounds). I11 Med J 147:354, 1975 Criscitiello MG, Ronan JA Jr, Besterman EMM, et al: Cardiovascular abnormalities in osteogenesis imperfecta. Circulation 31:255, 1965 Duff GL: Medial degeneration in the aorta of the
rabbit produced by diphtheria toxin. Arch Pathol 12543, 1932 5. Eisen S, Elliott LP: The roentgenology of cystic medial necrosis of the ascending aorta. Radiol Clin North Am 6:437, 1968 6. Figley MM: Angiocardiography in valvular heart disease. Morphologic and volumetric considerations. Radiol Clin North Am 2:409, 1964 7. Freiden J, Hurwitt ES, Leader E: Ruptured aortic cusp associated with heritable disorders of connective tissue. Am J Med 33:615, 1962 8. Grollman JH, Lecky JW, Rosch J: Miscellaneous disease of arteries; or, all arterial lesions aren’t fatty. Semin Roentgen01 5:306, 1970 9. Hanley WB, Jones NB: Familial dissecting aortic aneurysms. A report of three cases within two generations. Br Heart J 29352, 1967 10. Howell JF, Crawford ES, Morris GC, et al: Surgical treatment of peripheral arteriosclerotic aneurysm. Surg Clin North Am 46:979, 1966 11. McKusick VA: Heritable Disorders of Connective Tissue. St. Louis, Mosby, 1972, p 189 12. Persaud V: Subclavian artery aneurysm and idiopathic cystic medionecrosis. Br Heart J 30:436, 1968 13. Strauss L: Pathology of gargoylism. Report of case and review of literature. Am J Pathol24:855, 1948 14. Wagenvoort CA, Neufeld HN, Edwards JE: Cardiovascular system in Marfan’s syndrome and in idiopathic dilatation of the AA. Am J Cardiol 9:496, 1962
