A hidden echocardiographic pitfall: the Gerbode defect
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The Gerbode defect is characterized by a perimembranous ventricular septal defect (VSD) between the left ventricle and the right atrium. It is a rare defect representing less than 1 % of congenital cardiac defects . Acquired cases have been described, most often due to endocarditis, but also secondary to valvular surgery, thoracic trauma and ischemic heart disease. Frank Gerbode was the first surgeon to report a successful series of patients who underwent surgery for left ventricular to right atrium shunt in 1958 .
Type A: In this form, the concurrent presence of a perimembranous VSD plus the tricuspid valve defect are visible. The shunt starts from the left ventricle to the right ventricle and through the tricuspid valve into the right atrium. This is referred to as an indirect left ventricle–right atrium shunt.
Type B: This form is characterized by a left ventricle to the right atrium shunt.
This rare form of interventricular septal defect should be suspected during the performance of an echocardiogram, when there is an unusually dilatated right atrium, and when, in the presence of an interventricular septal defect, high velocity flows or aliasing are absent in the right ventricle (mainly in inflow tract) . A particular feature of the Gerbode defect is the high Doppler gradient of the shunt, due to the higher pressure gap between the left ventricle and the right atrium rather than left ventricle–right ventricle (especially in the presence of pulmonary hypertension).
In conclusion, a superficial glance in the technical execution of echocardiography instead of a careful and critical examination could produce a misinterpretation that might have a direct impact on clinical decision making.
Conflicts of interest
We have no conflicts to disclose.
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- 2.Kelle AM, Young L, Kaushal S, Duffy CE, Anderson RH, Backer CL.(2013) The Gerbode defect: a ventriculo-atrial defect. http://www.ctsnet.org/sections/clinicalresources/congenital/article-24.html Accessed 3 Aug 2013