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Mitral Valve Dysplasia Syndrome Mitral valve (MV) dysplasia syndrome is a rare and distinctive fetal cardiac malformation combination. The main characteristics of MV dysplasia syndrome include MV dysplasia, severe mitral regurgitation (MR), aortic outflow obstruction, a restrictive foramen ovale or an intact atrial septum, and marked left ventricular (LV) and left atrial (LA) dilatation. Patients with this malformation usually have high neonatal mortality with or without intervention.1–2 A case of a fetus with gradual development of MV dysplasia syndrome is reported. The pathologic anatomy confirmed the abnormalities in the mitral apparatus, aortic valve, and intact atrial septum. The sonographic changes at different gestational ages suggest that MV dysplasia syndrome may be a continuously developing disease. A fetus with MV dysplasia syndrome was reported at 30 weeks’ gestation. The maternal and pregnancy medical histories were normal. The first conventional obstetric sonographic examination performed at 23 weeks’ gestation showed no obvious abnormality. Four weeks later, during the second pregnancy check, a large LA, severe mitral regurgitation, and a small aortic artery were observed. To find the primary heart deformity, the patient was sent to our center for a detailed fetal heart echocardiographic examination. The most notable anatomic and physiologic features included an MV apparatus abnormality, in which the tips of leaflets and the chordae tendineae were thickened, with echo enhancement and motion amplitude reduction (Figure 1A). Color Doppler flow imaging showed severe mitral regurgitation in systole (Figure 1B). The aortic valve and aortic artery were dysplastic: the valve appeared thickened, fused, and immobile; the root and ascending aorta were small. No forward flow was detected across the aortic valve, and retrograde flow was visible in the ascending aorta. The atrial septum was intact in different views (Figure 1A). The LV, LA, and LA appendage were all dilated (Figure 1A). Left ventricular wall motion was decreased. Pulsed Doppler imaging showed that the pulmonary venous spectrum was abnormal, and double-reversal wave was detected in both systole and late diastole (atrial systole). After being informed of the results, the woman opted to terminate the pregnancy. The cardiac autopsy and pathologic findings verified our fetal echocardiographic discoveries: The heart weighed 26.7 g, which was about twice the weight expected for its age. The LV, LA, and LA appendage were dilated, and the atrial septum was intact. The myocardium was abnormally thickened, with endocardial fibroelastosis. The MV apparatus was abnormal, with dysplastic and nodular leaflets, a hypoplastic orifice, 358

and thickened, short chordae (Figure 1, C and D). The aortic annulus and ascending aorta were severely hypoplastic. The aortic valve showed commissural fusion, with a stenotic valve orifice. Mitral valve dysplasia syndrome is a congenital fetal heart anomaly. It is characterized by MV dysplasia, severe aortic valve stenosis, substantial mitral regurgitation, left heart dilatation, an intact atrial septum, and a restrictive foramen ovale. The primary anatomic anomaly in MV dysplasia syndrome is thought to be the dysplastic MV, resulting in severe mitral regurgitation and mild mitral stenosis. These lesions in turn result in an increased LA volume and LA hypertension. Given that fetuses with MV dysplasia syndrome often have a restrictive or absent foramen ovale, the mitral regurgitation may alter septal morphologic characteristics by promoting premature adherence between the septum primum and septum secundum.2 The accompanying aortic valve stenosis may be due to decreased flow through the LV as the LA abnormalities worsen and foraminal flow decreases, or it may simply accompany the mitral abnormalities. The aortic valve stenosis is thought to lead to increased wall stress, initial LV dilatation, and endocardial fibroelastosis. Aortic outflow obstruction compounds severe mitral regurgitation by disallowing adequate forward blood through the LV, contributing to LV dilatation. The resultant left heart dilatation likely leads to compression of the right side of the heart, which may impede both Figure 1. Mitral valve dysplasia syndrome. A, Two-dimensional fetal echocardiogram in the 4-chamber view showing severe LA, LV, and LA appendage enlargement, with an intact atrial septum bulging left to right. The leaflets of the MV (arrow) are bright and immobile. RPV indicates right pulmonary vein. B, Color Doppler flow image showing severe mitral regurgitation in systole. C, Autopsy specimen from the fetus showing LV and LA dilatation, with an enlarged and lobulated LA appendage (LAA). D, Severely abnormal nodular MV with a leaflet-tension apparatus (arrows) along with fused and shortened chordae.

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the filling and emptying of the right heart, impair cardiac output, and elevate systemic pressures. In some fetuses, this state can result in hydrops, ascites, and skin edema.3 This unusual constellation of abnormalities is distinct from simple aortic outflow obstruction and hypoplastic left heart syndrome. Aortic outflow obstruction in the presence of an intact ventricular septum can be associated with a diminutive LV, although a small percentage of patients may have a normal LV because of the accompanying interventricular septal defect. Substantial mitral regurgitation in aortic outflow obstruction is rare; therefore, the LA size is typically normal. The MV abnormality of hypoplastic left heart syndrome is severe stenosis or atresia; only minimal to mild mitral regurgitation can be detected in some patients, and the LA is usually small. Prenatal interventions for MV dysplasia syndrome that have been reported include balloon aortic valvuloplasty, to promote forward flow and decompress the LV, and balloon atrial septostomy, to open the atrial septum. Unfortunately, the prognosis is usually poor regardless of whether a prenatal intervention is performed.1 The cardiac mortality of this rare complex of anomalies is higher than that reported for hypoplastic left heart syndrome.1,4–5 In reviews of some fetal echocardiographic characteristics that predict mortality and an unstable transition at birth, such as a left-to-right heart area ratio greater than 1.5, had a higher risk of overall cardiac mortality. A Doppler flow pulmonary venous doublereversal pattern is predictive of the need for an immediate postnatal intervention to alleviate LA hypertension. Mitral valve dysplasia syndrome is a unique critical left-sided heart disease with a poor prognosis. It has not received much attention to date, with only some isolated case reports and research.6–8 It should be borne in mind that MV dysplasia syndrome is a progressive condition and may not manifest itself until the late second trimester. Fetal diagnosis and serial follow-up fetal echocardiography can provide important information about the overall mortality risk and can also identify patients who need immediate postnatal interventions. The echocardiographic findings can also help in parental counseling.

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Rogers LS, Peterson AL, Gaynor JW, Rome JJ, Weinberg PM, Rychik J. Mitral valve dysplasia syndrome: a unique form of left-side heart disease. J Thorac Cardiovasc Surg 2011; 142:1381–1387. Vogel M, McElhinney DB, Wilkins-Haug LE, et al. Aortic stenosis and severe mitral regurgitation in the fetus resulting in giant left atrium and hydrops: pathophysiology, outcomes, and preliminary experience with pre-natal cardiac intervention. J Am Coll Cardiol 2011; 57:348–355. Rudolph AM. Congenital Diseases of the Heart: Clinical-Physiologic Considerations. Armomnk, NY: Futura Publishing; 2001:657–658. Vida VL, Bacha EA, Larrazabal A, et al. Hypoplastic left heart syndrome with intact or highly restrictive atrial septum: surgical experience from a single center. Ann Thorac Surg 2007; 84:581–586. Glatz JA, Tabbutt S, Gaynor JW, et al. Hypoplastic left heart syndrome with atrial level restriction in the era of prenatal diagnosis. Ann Thorac Surg 2007; 84:1633–1638. Bharati S, Patel A, Varga P, Husain AN, Lev M. In utero echocardiographic diagnosis of premature closure of the formen ovale with mitral regurgitation and large left atrium. Am Heart J 1991; 122:597–600. Nowlen TT, Ayres NA, Kearney DL, Nihill MR, Grifka RG. Premature closure of the foramen ovale associated with aortic stenosis, left ventricular dilation with thrombus and early mortality. Am J Cardiol 2000; 85:1159–1161. Williams IA, Kleinman CS. Is hydrops fetalis is a manifestation of fetal pulmonary edema caused by impaired lymphatic drainage? Ultrasound Obstet Gynecol 2008;31:96–99.

Xiaowei Liu, MD, Yihua He, MD, Ye Zhang, MD, Zhian Li, MD Ultrasonography Center, Beijing Anzhen Hospital, Capital Medical University, Beijing, China Funding: National Natural Science Fund (project 81171350), Beijing Natural Science Fund (project 7122059), Beijing Health System high-level talented project, key project of the Beijing Municipal Science and Technology Commission (project Z111100074911001), key project of the Beijing Municipal Education Commission (project KZ201210025029), and project Capital Clinical Characteristics (project Z101107050210019).

doi:10.7863/ultra.33.2.358

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Mitral valve dysplasia syndrome.

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