J Cardiol 2007 Jul; 50（1）: 65 – 70

Accessory Mitral Valve AssociatedWith Aortic and Mitral Regurgitation and Left Ventricular Outflow
Tract Obstruction in an Elderly
Patient : A Case Report
Hidekazu
HiroyaTANAKA, MD
KAWAI, MD, FJCC

Kazuhiro

TATSUMI, MD

Toshiya

KATAOKA, MD

Tetsuari ONISHI, MD
Mitsuhiro
YutakaYOKOYAMA, MD, FJCCOKITA, MD＊

Abstract ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
A 65-year-old man was admitted to our hospital because of exertional dyspnea. Transthoracic and transesophageal echocardiography showed a parachute-like structure measuring 20 × 16 mm, which projected
into the left ventricular outflow tract（LVOT）and passed through the aortic valve in systole, and prolapsed
back into the left ventricular cavity in diastole. Moderate aortic and mitral regurgitation were also
observed, as well as LVOT obstruction with a peak gradient of 30 mmHg. There were no other congenital
cardiac abnormalities. In addition, real-time three-dimensional transthoracic echocardiography showed thatthe parachute-like structure in the LVOT was attached to the anterior mitral leaflet and left ventricular lateral wall by a chorda tendineae-like structure. The diagnosis of accessory mitral valve was based on theechocardiographic characteristics. Surgical treatment was performed because of the presence of accessory
mitral valve, moderate aortic and mitral regurgitation, and LVOT obstruction. The postoperative course
was uneventful, and the patient has been asymptomatic during a follow-up period of 24 months.
Echocardiographic examination proved to be useful for the detection of accessory mitral valve.
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────J Cardiol 2007 Jul; 50（1）: 65−70

Key Words■ Aortic regurgitation■ Congenital heart disease（accessory mitral valve）■ Mitral regurgitation

INTRODUCTION
Accessory mitral valve（AMV）is a congenital
anomaly that can lead to left ventricular outflow
tract（LVOT）obstruction and is extremely rare inadults. More than half of the cases show other congenital cardiac anomalies.1−4）This report concernsa 65-year-old man who had AMV associated withLVOT obstruction, significant aortic regurgitation（AR）and mitral regurgitation（MR）. Surgical treatment was successful and echocardiographic examination proved to be useful for the detection ofAMV.

──────────────────────────────────────────────
神戸大学大学院医学系研究科 循環呼吸器病態学，＊呼吸循環器外科学 : 〒 650−0017 神戸市中央区楠町 7−5−2
Division of Cardiovascular and Respiratory Medicine, Department of Internal Medicine, ＊Department of Cardiovascular, Thoracic, andPediatric Surgery, Kobe University Graduate School of Medicine, Kobe
Address for correspondence : KAWAI H, MD, FJCC, Division of Cardiovascular and Respiratory Medicine, Department of InternalMedicine, Kobe University Graduate School of Medicine, Kusunoki-cho 7−5−2, Chuo-ku, Kobe 650−0017 ; E-mail :hkawai@med.kobe-u.ac.jp
Manuscript received February 28, 2007 ; revised April 7, 2007 ; accepted April 10, 20076566

Tanaka, Kawai, Tatsumi et alⅠ

V1ⅡV2ⅢV3aVL

V4aVR

V5aVF

V6Fig. 1 Electrocardiogram

Fig. 2 Transthoracic echocardiograms
String-like abnormal structure was visible in the left ventricular outflow tract（arrow）, with moderate mitralregurgitation（B）and aortic regurgitation（C）. Mild left ventricular outflow tract obstruction was present
with a peak gradient of 30 mmHg.
LV ＝ left ventricle ; LA ＝ left atrium ; Ao ＝ aorta.

CASE REPORT
A 65-year-old man was admitted to our hospital
because of exertional dyspnea. Electrocardiography
had shown an abnormality 7 years previously,
which had not been identified. Physical examination found his blood pressure was 148/72 mmHg
and pulse regular at 72 beats/min. A Levine Ⅲ toand-fro type heart murmur was detected at the left

sternal border in the third intercostal space.
Laboratory test results were normal except for brain
natriuretic peptide level（120 pg/ml）. Chest radiography indicated a cardiothoracic ratio of 62% andenlargement of the left ventricle, and electrocardiography（Fig. 1）
showed complete left bundle-branchblock. Transthoracic echocardiography（ Fig. 2）
showed a string-like abnormal structure in theLVOT, moderate AR and MR, and mild LVOT
J Cardiol 2007 Jul; 50（1）: 65 – 70

Accessory Mitral Valve67

Fig. 3 Transesophageal echocardiograms
A parachute-like structure measuring 20 × 16 mm projected into the left ventricular outflow tract andthrough the aortic valve in systole（A）and prolapsed back into the left ventricular cavity in diastole（B）.
Moderate aortic regurgitation（C）and mitral regurgitation（D）.
Abbreviations as in Fig. 2.

obstruction with a peak gradient of 30 mmHg. The
end-diastolic and end-systolic diameters of the left
ventricle were 59 mm and 40 mm, respectively, andthe left ventricular ejection fraction was 54%.
Transesophageal echocardiography（Fig. 3）indicated that a parachute-like structure measuring
20 × 16 mm projected into the LVOT and passed
through the aortic valve in systole, and prolapsed
back into the left ventricular cavity in diastole.
Moderate AR and MR were also observed, but noother congenital cardiac abnormalities. Real-time
three-dimensional transthoracic echocardiography
clarified that the parachute-like structure in theLVOT was attached to the anterior mitral leaflet andleft ventricular lateral wall by a chorda tendineaelike structure（Fig. 4）
. The diagnosis of AMV wasbased on the echocardiographic findings.
Coronary angiography showed no significantstenosis. The patient s AR was Sellers grade Ⅲ,
J Cardiol 2007 Jul; 50（1）: 65 – 70

and pulmonary capillary wedge pressure, pulmonary blood pressure, and cardiac index were
9 mmHg, 29/6 mmHg, and 3.78 l/min/m2, respectively. Left ventriculography was not performed
because of the presence of the abnormal tissue inthe LVOT. Surgical treatment was recommended
because of the presence of AMV, and significant
AR, MR, and LVOT obstruction.
At surgery, the mass was confirmed to be a parachute-like structure attached to the lateral site of theanterior mitral leaflet and left ventricular lateralwall by a chordae tendineae-like structure and tethered to the anterior mitral leaflet. The mass wasremoved without complications by aortotomy, andgross examination（Fig. 5−A）indicated a smoothand valvular leaflet-like structure. Because of thethickened aortic valves and enlarged fenestrationsof the left coronary cusp, the aortic valve wasreplaced with a 23 mm Carpentier-Edwards valve.

68

Tanaka, Kawai, Tatsumi et alFig. 4 Real-time three-dimensional echocardiograms
A : The parachute-like structure was attached to the anterior mitral leaflet（arrow）.
B : The parachute-like structure was attached to the left ventricular lateral wall by a chorda tendineae-likestructure（arrow）.
AMV ＝ accessory mitral valve. Other abbreviations as in Fig. 2.

Fig. 5 Photograph and photomicrograph of the accessory mitral valve
Gross examination（A）showed a smooth and valvular leaflet-like structure. Histological examination（B ;hematoxylin-eosin staining × 100）showed normal mitral valve tissue. No fibrous tissue or myxoid dysplasia was found.

The mitral valve was repaired with a 30 mm
Physio-ring. Histological examination（Fig. 5−B）
showed normal mitral valve tissue, leading to adiagnosis of AMV.
After surgery, transthoracic echocardiographydemonstrated resolution of the LVOT obstruction
and absence of residual AMV, AR and MR. The
postoperative course was uneventful, and thepatient has been asymptomatic during a follow-up
period of 24 months.

DISCUSSION
The present elderly patient with AR, MR, andLVOT obstruction caused by AMV could be successfully treated with surgery. Transthoracic, transesophageal, and real-time three-dimensionaltransthoracic echocardiography proved to be usefulfor the detection of AMV.
AMV is an extremely rare congenital cardiac
anomaly, which can cause a variety of clinical feaJ Cardiol 2007 Jul; 50（1）: 65 – 70

Accessory Mitral Valvetures.1−4）Currently, fewer than 100 cases of AMV
have been reported, with adults accounting forfewer than 30, since the first description in 1963.5）
AMV has been diagnosed immediately after birth,and in a 77-year-old patient. The mean age at diagnosis is around 6.5 years.6）Little is known about
the etiology and course of AMV. AMV is probably
the result of incomplete separation of the mitralvalve from the endocardial cushion tissue to theventricular septum during embryological development.7）Histological descriptions of tissue specimens in some cases of AMV indicate that about
half show normal mitral valve tissue（including ourpatient）, and the remainder have fibrous tissue or
myxoid dysplasia.1, 8−10）AMV is usually（more than70%）associated with other congenital cardiac
anomalies and often produces significant cardiac
symptoms in the neonatal period or early child要

69

hood. Ventricular septal anomalies, mainly ventricular septal defect and septal aneurysm, are the mostfrequently encountered anomalies.11）Most cases
were associated with LVOT obstruction, and about
80% presented severe LVOT obstruction with apeak gradient of more than 50 mmHg.12）The symptoms in patients with AMV depend on the degree ofLVOT obstruction.12,13）However, our patient had
been asymptomatic until 65 years old. The cause of
his exertional dyspnea might be significant AR orMR.
The main indication for surgery for AMV issevere LVOT obstruction, other congenital malformations, or exploration of an intracardiac mass.12,13）
Early surgical removal is recommended for AMV
causing LVOT obstruction because the pressure
gradient may increase with age.13）約大動脈弁，僧帽弁閉鎖不全症と左室流出路狭窄を伴った高齢者の僧帽弁副組織の 1 例
田中秀和

川合宏哉

辰巳和宏

片岡大西哲存横山光宏

大 北裕俊哉症例は 65 歳，男性．労作時の呼吸困難のため当院に入院となった．経胸壁および経食道心エコー図断層図では左室流出路に 20 × 16 mm のパラシュート状の構造物を認め，収縮期には大動脈弁側へ，拡張期には左室側へ移動していた．カラードップラー法により大動脈弁および僧帽弁逆流はともに中等度であり，連続波ドップラー法により推定圧較差が 30 mmHg の左室流出路狭窄を伴っていた．他の先天性心疾患の合併は認められなかった．さらに，経胸壁リアルタイム三次元心エコー図ではパラシュート様の膜様構造物が僧帽弁前尖と左室側壁に腱索様の組織で付着していることが観察された．以上の心エコー図所見より，異常構造物は僧帽弁副組織と診断した．左室流出路に異常構造物が存在すること，有意な大動脈弁および僧帽弁逆流と左室流出路狭窄が認められることより，外科的手術を行った．術後の経過は良好で，現在，無症状で術後 24 ヵ月経過している．
今回我々が経験した僧帽弁副組織の観察には，経胸壁リアルタイム三次元心エコー図検査を含めた心エコー図検査が有用であった．

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