Ann Thorac Surg 2005;80:2364-2365
© 2005 The Society of Thoracic Surgeons
Case report
Saccular Aneurysm of the Aortic Cusp Associated With Discrete Subaortic Stenosis
Seiji Matsukuma, MD
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,
Kiyoyuki Eishi, MD,
Shiro Yamachika, MD,
Tomayoshi Hayashi, MD, PhD,
Shiro Hazama, MD,
Hiroichiro Yamaguchi, MD,
Tsuneo Ariyoshi, MD,
Hideaki Takai, MD,
Tomohiro Odate, MD,
Daisuke Onohara, MD,
Makoto Yanatori, MD
Department of Cardiovascular Surgery, Nagasaki University School of Medicine, Nagasaki, Japan
Accepted for publication July 14, 2004.
* Address correspondence to Dr Matsukuma, Nagasaki University School of Medicine, Department of Cardiovascular Surgery, 1-7-1 Sakamoto, Nagasaki City, Nagasaki 852-8501, Japan; (Email: seiji731{at}net.nagasaki-u.ac.jp).
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Abstract
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A 54-year-old male who experienced a syncopal episode underwent aortic valve replacement for aortic stenosis and regurgitation. The aortic valve was incompetent as a result of thickening of the left coronary cusp and noncoronary cusp. In addition a saccular aneurysm was indicated on the left coronary cusp. A shelf of tissue protruding at right angles from the ventricular septum was particularly prominent below the right coronary cusp, resulting in subvalvular stenosis. The cause of the saccular aneurysm was most likely caused by the long-term effects of the jet stream instigated by discrete subaortic stenosis.
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Introduction
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Saccular aneurysm of the aortic cusp is extremely rare and most valvular saccular aneurysms result from infective endocarditis. This report describes a saccular aneurysm of the left coronary cusp associated with discrete subaortic stenosis (DSS). Saccular aneurysms associated with DSS are not currently available, although DSS is itself associated with several congenital anomalies including aortic valve abnormalities.
A 54-year-old male who had experienced a syncopal episode and chest pain was referred for surgical treatment of aortic stenosis (AS) and aortic regurgitation (AR). The patient exhibited a history of heart murmur since childhood. In addition occasional dyspnea and palpitation developed. When the patient was 31 years of age, it was indicated that he possessed a double chamber right ventricle (DCRV) and underwent resection of the anomalous muscle bundle in the right ventricle. At that time enlargement of the ascending aorta and grade I AR were detected by aortography, but no remarkable pressure gradient was evident across the aortic valve. On admission a two-dimensional echocardiography revealed a 15-mm length of fixed subaortic obstruction on the thickened interventricular septum (Fig 1). Doppler echocardiography revealed grade III AR and a pressure gradient of 54 mm Hg across the subaortic obstruction. The coronary arteries and neck vessels were intact and there was no history of infection or endocarditis.
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Fig 1. Transthoracic echocardiography revealed a 15-mm length of fixed subaortic obstruction (arrow) on the thickened interventricular septum at the left ventricular (LV) outflow tract. (Ao = aorta.)
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The operation performed was a median sternotomy using a standard cardiopulmonary bypass with cold crystalloid cardioplegia. The ascending aorta was opened through a horizontal incision. When the aortic cusps were retracted the subvalvular shelf and the saccular aneurysm of the left coronary cusp were exposed (Fig 2A). The shelf was located approximately 1 cm proximal to the base of the aortic cusps and was particularly prominent below the right coronary cusp. The aortic valve was tricuspid but was incompetent because of thickening of the left coronary cusp, whereas the right coronary cusp seemed to be relatively less degenerated than the other cusps. The aneurysm exhibited an orifice surrounded by a thickened portion on the aortic side of the cusp (Fig 2B). After the aortic valve and subvalvular shelf were resected, aortic valve replacement was performed using a mechanical valve (24 mm ATS AP).
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Fig 2. (A) Aortic valve viewed through an aortotomy during surgery. A saccular aneurysm (short arrow) of the left coronary cusp and a subvalvular shelf (long arrow) were exposed when the aortic cusps were retracted. (B) The aortic cusps removed during surgery. The right coronary cusp seemed to be less degenerated than the other cusps. The aneurysm exhibited an orifice that was surrounded by a thickened portion on the aortic side of the left coronary cusp (L = left coronary cusp; R = right coronary cusp; N = noncoronary cusp).
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Microscopic examination revealed that the bundle of elastic fibers of the left coronary cusp was curved toward the ventricular side at the orifice of the saccular aneurysm. At the top of the saccular aneurysm, the wall had become thinned and the bundle of elastic fibers disappeared (Fig 3). Furthermore, there was no evidence of infective endocarditis in the wall of the saccular aneurysm.
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Fig 3. Histology of the left coronary cusp saccular aneurysm protruding into the left ventricle. The bundle of elastic fibers, which is stained black, is curved toward the ventricular side at the orifice. At the top of the saccular aneurysm, the wall becomes thin and the bundle of elastic fibers disappears (arrow). (A = aortic side, V = ventricular side.) (Elastica van Gieson stain.)
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Comment
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Four occurrences of saccular aneurysm of the aortic cusp have been reported [1–4], but literature concerning saccular aneurysm of the aortic cusp accompanied by DSS is not currently available. DSS was described in 1842 by Chevers [5] and was subsequently divided into two distinct types by Kelly [6]. Type I DSS is characterized by a thin discrete membrane located immediately below the aortic valve, whereas type II DSS involves fibromuscular stenosis associated with considerable muscular hypertrophy of the outflow tract. Many patients with DSS also exhibit other congenital anomalies including ventricular septal defects, persistent ductus arteriosus, and congenital aortic valve abnormalities [7]. Our patient's aneurysm was associated with a DCRV and Corone and associates have reported that 22% of DCRVs exhibit associated DSS and that DCRV is observed in 9% of subaortic stenosis occurrences [8]. DSS produces a high velocity jet stream that can traumatize the aortic valve causing a resultant thickening of the cusps, that, in turn, leads to AR. The etiology of saccular aneurysm formation in our patient is probably caused by a thickening of the aortic cusps instigated as a result of long-term trauma from the jet stream. Moreover the center of the thickened portion was beaten into a thinner region and the diastolic aorto-left ventricular pressure gradient might have precipitated dilation of the thin portion of the cusp into the left ventricle. The bundle of elastic fibers was pulled and disrupted by excessive extension during the diastolic phase and thus it is probable that the saccular aneurysm will rupture in the near future.
To prevent an eventual hemodynamic collapse, early surgical resection is recommended for DSS, because it may cause complications such as subaortic stenosis, AR, and saccular aneurysm and such complications can increase with age, as illustrated in the present patient.
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References
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- Morimoto K, Matsuzaki M, Anno Y, et al. Echocardiographic assessment of aneurysm of the aortic valve caused by infective endocarditis—a case report Jpn Circ J 1989;53:819-824.[Medline]
- Nyui S, Inoue S, Sato T, Nakase A. Unruptured aneurysm of the right coronary cusp Jpn Circ J 1991;55:695-698.[Medline]
- Nakayama M, Isobe F, Yutani C. Aneurysmal pouch on left coronary cusp accompanied by bacterial endocarditis Jpn J Thorac Cardiovasc Surg 1998;46:667-670.[Medline]
- Alpaslan M, Evcik D, Onrat E. Aortic valve aneurysma novel cardiac manifestation of rheumatoid arthritis?. J Am Soc Echocardiogr 2001;14:1137-1138.[Medline]
- Chevers N. Observations on the diseases of the orifice and valves of the aorta Guy Hosp Rep 1842;7:387-442.
- Kelly DT, Wulfsberg E, Rowe RD. Discrete subaortic stenosis Circulation 1972;46:309-322.[Abstract/Free Full Text]
- Somerville J, Stone S, Ross D. Fate of patients with fixed subaortic stenosis after surgical removal Br Heart J 1980;43:629-647.[Abstract/Free Full Text]
- Corone S, Corone P, Dor X, Leriche H, Binet JP, Planche C. Double-chamber right ventricle, aortic subvalvular stenosis and interventricular septal defect. Apropos of 12 cases Arch Mal Coeur Vaiss 1993;86:609-616.[Medline]
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Abstract
Introduction
