THÔNG TIN TÀI LIỆU
Introduction The most common congenital malformations afflicting the tricuspid valve are Ebstein malformation and tricuspid valvar dysplasia These lesions are considered in this chapter, together with a brief look at acquired malformations Tricuspid valvar abnormalities, or abnormalities of the morphologically right atrioventricular valve, are also often associated with atrioventricular septal defects with common atrioventricular junction (see Chapter 31), ventricular septal defect with straddling valve (see Chapter 32), atrioventricular discordance (see Chapter 38), or pulmonary atresia with intact septum (see Chapter 43) These lesions are described in detail in other chapters of this book However, Uhl anomaly and fatty replacement of the wall of the right ventricle, the latter now described as arrhythmogenic right ventricular cardiomyopathy, are so frequently discussed in the setting of Ebstein malformation that brief consideration is given to these two entities even though they are not malformations of the tricuspid valve Ebstein Malformation Ebstein malformation has a variable natural history depending on the degree of abnormality of the tricuspid valvar apparatus and right ventricle, both of which may range from mild to severe If the deformity of the tricuspid valve is severe and the ventricle significantly dysfunctional, profound congestive heart failure may occur in the neonatal period or even result in intrauterine death At the other end of the spectrum, patients with a mild degree of displacement of the septal hinge away from the atrioventricular junction may never develop symptoms or may remain asymptomatic until late adult life Ebstein's own description of the malformation, with illustrations by Dr Weiss (Fig 33.1) was based on the anatomic findings relating to the heart of Joseph Prescher, a 19-year-old laborer with cyanosis Prescher had been troubled with dyspnea and palpitations since childhood The first case described in the English literature was published in 1900,1 but it was not until 1951 that the diagnosis was made during life, using angiocardiography.2 By the 1950s, successful surgical palliation had been achieved, and the association with Wolff-Parkinson-White syndrome had been recognized The 1960s heralded the first attempts at corrective surgery, including valvar replacement3 and repair.4 Throughout the 1960s and 1970s, the disease was thought to be extremely rare, accounting for no more than 0.3% of congenital heart disease,5,6 giving an estimated incidence at that time of approximately 24 per 1 million live births FIG 33.1 Illustration of the heart of Joseph Prescher as seen from the anterior aspect, and of the functional right ventricle, as illustrated for Wilhelm Ebstein by Dr Weiss Note how the leaflets of the deformed valve close in bifoliate fashion, forming a keyhole orifice that opens toward the outlet component of the right ventricle Echocardiography provides a convenient and readily available method for diagnosis, even in fetal life.7 The malformation is currently known to be more common and to have a broader spectrum than previously appreciated In fact, a series of more than 200 cases collected from hospitals in southeast England revealed a nearly fivefold increase in the number of diagnosed cases per decade, with more than half of the patients younger than 1 year at diagnosis.8 By the 1990s it was estimated that the incidence of Ebstein malformation, including asymptomatic cases, was approximately 1 in 200,000 live births.9 Anatomy The essence of Ebstein malformation is adherence of variable segments of
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