Anatomic Definition and Imaging of Ebstein’s Malformation

Ebstein’s malformation is a rare disease, with a prevalence of 114 per million live birth [1]. The index case was described by Willem Ebstein, who was born in Jauer, Austria, in 1836. He was educated in Berlin and Breslau, and became a professor of medicine at the University of Gottingen in 1874, dying there in 1912 [2]. He was the author of over 300 papers before the era of publish or perish. Among his most noted works was a section on renal disease in the book Senile Diseases, a standard medical text, published with Gustav Albert Schwalbe. Other eponymous diseases or syndromes attributed to him include the Pell–Ebstein phenomenon, an afternoon pyrexia associated with lymphomas, described in 1887, and Ebstein nephropathy, a hyaline degeneration and necrosis of the epithelial cells of the renal tubules, sometimes seen in diabetes mellitus. In 1892, he published the article ‘Diagnosis of incipient pericardial effusions’. During the course of Ebstein’s tenure in Gottingen, an 18-year-old laborer, Joseph Prescher, presenting with fatigue, cyanosis, and arrhythmia, died during the course of his admission to hospital [3], Ebstein, himself a pathologist, studying under Virchow, performed the autopsy. He commissioned an etcher to make copies of the specimen, and described and illustrated the tricuspid valvar disorder disease that now bears his name. The plates are exquisite in their detail and accuracy. The first accounts of Ebstein’s malformation based on echocardiographic examination describe the large saillike antero-superior leaflet, and late systolic prolapse of the valve. Using cross-sectional echocardiography from the apical four-chamber plane view, valvar displacement is clearly displayed [4, 5] (Fig. 34.1). The echocardiographic literature has largely focused on displacement of the septal leaflet of the tricuspid valve as an index of morphological severity, stating that the essence of the disease lies in apical displacement of the septal leaflet at its junction with the inferior or mural leaflet exceeding 20 or 8 mm/m in adults [6–10]. The prerequisites for understanding Ebstein’s malformation by echocardiography are appreciation of embryological and fetal development and pathology. Elsewhere in this book, there is consideration given to the fetal presentation of patients with Ebstein’s malformation, but several points are immediately necessary for understanding the morphological features. First, malformation of the tricuspid valve is related to the delamination of the valve from the underlying myocardium. If this delamination is incomplete, the malformation is expressed to a variable degree along the tricuspid annulus, varying from complete delamination in the normal heart, to a spectrum of lack of delamination in Ebstein’s malformation (Fig. 34.2). It is important to note that the same process occurs throughout the fetal myocardium. Another expression of this phenomenonmaywell be persistence of the fetal spongy myocardium represented by noncompaction, now called hypertrabeculation syndrome. In Ebstein’s malformation, this disorder occurs in up to one-fifth of patients (Fig. 34.3). The other important aspect to understanding the development of Ebstein’s malformation is the peculiar nature of the fetal physiology [11, 12]. The particular pathophysiology is created by ineffective forward flow across the pulmonary valve caused by the combination of tricuspid regurgitation in the presence of systemic pressure, and systemic arterial pressure applied to the pulmonary valve through the arterial duct. Because form, or morphology, follows function, or flow and pressure in the developing heart, in Ebstein’s malformation pathological specimens exhibit these progressive changes in the developing heart [11, 12] (Fig. 34.4). As a consequence of tricuspid N.H. Silverman (*) Professor of Pediatrics, Division of Pediatric Cardiology, The Roma and Marvin Auerback Scholar in Pediatric Cardiology, Director, Pediatric and Echocardiography Laboratory, Lucile Packard Children’s Hospital, Stanford University Medical Center, 750 Welch Road – Suite 305, Palo Alto, California 94304 e-mail: norm.silverman@stanford.edu