A Systematic Review of Acquired Left Ventricle to Right Atrium Shunts (Gerbode Defects).

T he left ventricle-right atrium (LVRA) shunt, a rare and special type of ventricular septal defect (VSD), was first reported by Gerbode et al1 in 1958, and was thus termed “Gerbode defect”, after the first author. In 1967, Riemenschneider and Moss2 classified Gerbode defects into two types: direct (or true) and indirect (or false). The direct type is a direct shunt between the left ventricle and right atrium across the membranous septum, while the indirect type is a VSD with a left-to-right shunt at the ventricular level associated with tricuspid regurgitation, with the high-velocity shunt being directed into the right atrium. Later, Sakakibara and Konno3 termed the above two types as supravalvular and infravalvular types. In addition, they added a Type III (valvular type), an intermediate type (or a combination) of types I and II, to the categories. In the early years, it was estimated that the incidences of the three types were 32%, 62% and 6%, respectively,4 and that type II accounted for an overwhelming majority.5 More recently, Sinisalo et al6 stated that the incidences of the three types had changed dramatically, accounting for 76%, 16% and 8%, respectively. The LV-RA shunt can be either congenital or acquired in nature. The congenital Gerbode defect is rare, and its clinical features have been well described.4 By contrast, the acquired LVRA shunts have actually outnumbered the congenital, as there have been more predisposing risk factors, including infective endocarditis (IE), trauma, cardiac surgical procedures, and myocardial infarction, responsible for the development of the acquired shunt in the current era.7 The acquired LV-RA shunts have been reported individually case by case in recent years. A review of acquired LV-RA shunts was published recently; however, it included incomplete patient information, most probably based on abstracts without referring to the full texts of the articles, and also improper inclusion of duplicate publications.8 Therefore, the clinical characteristics and mechanisms remain to be sufficiently elaborated.