Gerbode ventricular septum defect covered by a ballooning membranous ventricular septum

Abstract

A 55-year-old man was admitted due to a new cardiac murmur diagnosed by his general practitioner during check-up. The patient was asymptomatic and denied chest pain or dyspnea. Physical examination revealed a grade 3/6 holosystolic heart murmur at the left sternal border with increased intensity to handgrip maneuvers. In addition, mild edema was present at his ankles up to mid of the lower legs that the patient himself had not recognized before. Electrocardiogram, blood sample, and cardiac markers were unremarkable. Transthoracic echocardiography (TTE) revealed enlargement of heart chambers with normal systolic ventricular function and elevated pulmonary pressure. In addition, a cystic thin walled structure was seen with adhesion at the septal tricuspid valve ring that yo-yoed between the right atrium (RA) and the right ventricle (RV) like a table tennis ball. Colour Doppler echocardiography showed a complete systolic filling of this structure. Diagnostic work-up revealed a congenital defect of subaortic perimembranous ventricle septum (VSD) with conjunction between left ventricle (LV) and RA, a so-called Gerbode-VSD, covered by a prolapsing cystic formation of 38 9 29 9 27 mm (Figs. 1, 2). By MRI and heart catheterization, a relevant left-to-right shunt of 1:2 was measured. Hemodynamic parameters are given in Table 1. MRI confirmed a perforation of the cystic sack causing the shunt with direct flow to RA (Fig. 2b). Surgery under cardiopulmonary bypass was undertaken and revealed a right sided whitish cystic mass typical for a large diverticulum of the membranous ventricular septum with basis above the tricuspid valve and riding above a Gerbode-VSD of 6 mm. Opposite to the VSD, the cystic structure was perforated resulting in a direct communication between LV and RA (Figs. 2b and 3a, b). The diverticulum was removed, VSD was closed with a bovine pericardial patch and the tricuspid valve was successfully reconstructed. Pathohistologic inspection of the cystic structure showed endoand myocardium with fibrotic and sclerotic conversion and only mild chronic inflammatory reaction (Fig. 3c). Patient was discharged in stable conditions 10 days after surgery. The specific feature of our patient is the coverage of the Gerbode-VSD by the expanded membranous ventricular septum protruding into the RA with extension through the tricuspid valve during heart cycle. A small rupture of the cystic formation caused a nearly indirect shunt between LV and RA. Shunts between LV and RA are rare forms of VSD and can be either congenital or acquired. They were first described in 1857 and represent \1 % of all congenital cardiac defects [1]. The surgeon Frank Gerbode at Stanford had published the first successful series of patients operated on a LV–RA shunt in 1958 [2]. Acquired defects can occur secondarily after bacterial endocarditis, trauma, myocardial infarction, repair or replacement of either the mitral or aortic valves or are reported after catheter ablation of the atrioventricular node [1, 3–7] and are diagnosed using varying U. M. Muller (&) U. Pittl G. C. Schuler Department of Internal Medicine/Cardiology, Heart Center, University of Leipzig, Strumpellstrase 39, 04289 Leipzig, Germany e-mail: ulrike.mueller@herzzentrum-leipzig.de