Asian Cardiovasc Thorac Ann 2007;15:360-361
© 2007 Asia Publishing EXchange Ltd
IMAGES IN CARDIOTHORACIC MEDICINE AND SURGERY |
Obstructive Mechanical Mitral Valve Dysfunction Detected by MRI
Atsushi Fukumoto, MD,
Hirotoshi Ito, PhD1,
Masaaki Yamagishi, PhD,
Kiyoshi Doi, PhD,
Tsunehiko Nishimura, PhD1,
Hitoshi Yaku, PhD
Department of Cardiovascular and Thoracic Surgery
1 Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
For reprint information contact: Atsushi Fukumoto, MD Tel: 81 75 251 5752 Fax: 81 75 257 5910 Email: fukumoto{at}koto.kpu-m.ac.jp, D465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
A 54-year-old man who had undergone mitral valve replacement (MVR; CarboMedicsTM 29M, Austin, TX, USA) 1 year before presented with palpitations and dyspnea for duration of 3 days. On admission symptoms was intensified, and the electrocardiogram showed paroxysmal atrial fibrillation at 100–120 beats·min–1 with monofocal premature ventricular contractions (Lown grade III). The oxygen saturation by pulse oximeter was 89% in room air. Auscultation revealed a decreased intensity of metallic clicks without an abnormal murmur. Two-dimensional transthoracic echocardiography (TTE) showed paradoxical movement of the intraventricular septum. The mechanical valve and thrombus could not be clearly visualized because of intense echo reverberations from the prosthetic valve (Figure 1
). Subsequently, EKG-gated, cardiac magnetic resonance imaging (Intera 1.5 TTM, Philips, Eindhoven, Netherlands) was performed. When viewed as a movie, irregular transvalvular regurgitation and asymmetrical inflow to the left ventricle were observed. Measurement of blood flow at the ascending aorta disclosed low cardiac output (2.1 L·min–1). Cineradiography revealed decreased movement of one of the disks of the mechanical bileaflet valve in the mitral position; another disk was almost fixed in a semi-closed position. Finally, acute heart failure due to obstructive mechanical valve thrombosis was diagnosed. We performed urgent re-Mitral valve replacement. At the operation, we found that a large thrombus had overgrown on the atrial side of the mechanical valve. The thrombus interfered with movement of one of the leaflets and fixed another in closed position. We carefully removed the thrombus and the mechanical valve, and re-implanted a bioprosthesis (MosaicTM 29M, Medtronic, Minneapolis, MN, USA) (Figure 4).
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Figure 1. A long axis view of color doppler transthoracic echocardiogram. There seemed to be no major thrombus or transvalvlar regurgitation in mitral position (a, diastolic phase); (b, systolic phase).
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Figure 4. At the operation, we found that a large thrombus had overgrown on the atrial side of the mechanical valve, interfered with movement of one of the leaflets (a), and fixed another (b) (Surgeon’s view) (Ao, ascending aorta; SVC, superior vena cava; RA, right atrium; RV, right ventricle; a, thrombus; b, a leaflet of mechanical mitral valve; c, Swan-Ganz catheter).
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Figure 2. An EKG-gated, cine cardiac magnetic resonance image, showing asymmetrical in-flow to the left ventricle (a, diastolic phase) and irregular transvalvular regurgitation (b, systolic phase).
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Figure 3. Cineradiography revealed decreased movement of one of the disks of the mechanical bileaflet valve in the mitral position; another disk was almost fixed in a semi-closed position. (a) diastolic phase; (b) systolic phase.
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