Multiple complications of a well-known disease: a case report of acquired Gerbode defect after bicuspid aortic valve endocarditis

Abstract Background Infective endocarditis is a rare but serious disease with high morbidity and mortality due to its potential life-threatening complications. Gerbode defect is an anomalous connection between the left ventricle and the right atrium that can be either congenital or acquired, with previous rare reports following abscess formation in infective endocarditis. Case summary A 27-year-old woman presented in hospital with Janeway lesions, stroke, splenic and hepatic abscesses, and transient complete auriculoventricular block. Bicuspid aortic valve infective endocarditis to methicillin-sensitive Staphylococcus aureus and acquired Gerbode defect were diagnosed. After intravenous antibiotics and aortic valve replacement, the patient was discharged without sequelae. Discussion Bicuspid aortic valve patients have a higher risk of infective endocarditis than the general population. Infective endocarditis may present with multiple complications, including systemic embolization and local perivalvular lesions. Acquired Gerbode defect is a rare complication of infective endocarditis where transoesophageal echocardiography plays an important role for small shunt detection before surgical intervention.


Background
Infective endocarditis is a rare but serious disease with high morbidity and mortality due to its potential life-threatening complications. Gerbode defect is an anomalous connection between the left ventricle and the right atrium that can be either congenital or acquired, with previous rare reports following abscess formation in infective endocarditis.
Case summary A 27-year-old woman presented in hospital with Janeway lesions, stroke, splenic and hepatic abscesses, and transient complete auriculoventricular block. Bicuspid aortic valve infective endocarditis to methicillin-sensitive Staphylococcus aureus and acquired Gerbode defect were diagnosed. After intravenous antibiotics and aortic valve replacement, the patient was discharged without sequelae.

Discussion
Bicuspid aortic valve patients have a higher risk of infective endocarditis than the general population. Infective endocarditis may present with multiple complications, including systemic embolization and local perivalvular lesions. Acquired Gerbode defect is a rare complication of infective endocarditis where transoesophageal echocardiography plays an important role for small shunt detection before surgical intervention.

Learning Points
• Be aware of the multiple complications of infective endocarditis, currently less frequently encountered in clinical practice due to better prevention and timely diagnosis and treatment.
• Recognize acquired Gerbode defect as a possible complication of infective endocarditis and the importance of transoesophageal echocardiography for its diagnosis.

Introduction
Infective endocarditis (IE) is a potentially life-threatening endocardial infection, affecting 10 per 100 000 persons annually. 1,2 Bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality, with a prevalence of 0.5-2%. 3 According to the public health preventive guidelines, these patients have an intermediate risk of IE, and therefore, antibiotic prophylaxis is not recommended. 4 Gerbode defect is a rare abnormal communication between the left ventricle (LV) and right atrium (RA) that can cause a LV-to-RA shunt. 5 This abnormality can be either congenital or acquired after a cardiac insult as myocardial infarction, IE, blunt chest trauma, or previous cardiac surgery. 6,7 An increasing number of case reports regarding acquired Gerbode due to IE had been published, including in BAV. [8][9][10]

Case presentation
A 27-year-old woman with known BAV without valvular dysfunction presented in the emergency room with fever, chills, asthenia, and headache that started 5 days prior. She had no current chronic medication, denied intravenous drug abuse, and recent dental interventions.
During admission, she presented sudden onset of left hemiplegia and dysarthria, with brain computed tomography (CT) showing a deep ischaemic lesion in temporal right hemisphere (right middle cerebral artery).
Transthoracic echocardiogram (TTE) was performed, showing a BAV pattern with mobile filiform mass (22 mm of maximum length) in aortic valve with moderate regurgitation, without obstruction (see Supplementary material online, Video S1), non-dilated LV, and preserved LV ejection fraction (LVEF) of 62% (Simpson biplane).
Transoesophageal echocardiogram (TOE) confirmed BAV type 2 without raphe (Schaefer classification), with two mobile vegetations attached to the mitral-aortic intervalvular fibrosa and perforation of the posterior/left cusp (Video 1,2 and S2) with moderate regurgitation directed to the anterior leaflet of the mitral valve. A small connection between the membranous portion of interventricular septum at outflow LV tract (LVOT) and RA was found, with LVOT-RA shunt (Video 3 and see Supplementary material online, Video S2; Figure 3).
A definite diagnosis of IE was established by the modified Duke criteria. The patient was admitted in the intensive care unit (ICU) for careful monitorization. Empiric intravenous antibiotic therapy was started with ampicillin 12 g/day, ceftriaxone 2 g/day, and flucloxacillin 12 g/ day and thereafter adjusted to flucloxacillin 12 g/day (during 31 days before surgery, continued 4 weeks after surgery), rifampicin 900 mg/day (during 24 days before surgery, continued 2 weeks after surgery), and linezolid 12 g/day (during 28 days before surgery, continued 2 weeks after surgery). Routine laboratorial tests and bedside echocardiogram were performed as needed.
At Day 1 after admission, she presented transient complete AV block ( Figure 2B), with fully recovery after 7 days. An abdominal and pelvic CT scan was performed due to laboratorial abnormalities and abdominal pain, diagnosing systemic embolization to the liver and spleen, with abscess formation and bilateral renal ischaemic lesions ( Figure 4B and C).
Control brain CT showed right petechial non-confluent haemorrhagic transformation ( Figure 4A), without neurological worsening. Cardiac surgery was deferred during 4 weeks. During hospitalization, the patient recovered from dysarthria and showed a significant improvement of the left hemiparesis.
Until the scheduled surgery, the patient remained haemodynamically stable, without HF signs, preserved LVEF, and without aortic regurgitation worsening. Control blood cultures were negative after 3 weeks of antibiotics.
Thirty-one days after the admission, she underwent aortic valve replacement (AVR) with a bioprosthetic aortic valve (27 mm), as the patient Multiple complications of a well-known disease: a case report of acquired Gerbode defect after bicuspid aortic valve endocarditis wished. Acquired Gerbode defect was repaired with direct suture using pledgeted prolene on its ventricular face, without post-intervention residual shunt. Aortic valve and pericardium cultures were negative.
After 45 days of hospitalization, the patient was discharged to outpatient follow-up consultation at 3 months and 1 year after. In both follow-up consultations, the patient remained asymptomatic, without clinical events, and had a preserved bioprothesis function.

Discussion
We described a case of a young woman with BAV without previous documented significant valvular dysfunction that presented with aortic valve IE. This case illustrates the multiple potential life-threatening complications of IE that should be careful managed, including a rare case of acquired Gerbode defect.  Multiple complications of a well-known disease: a case report of acquired Gerbode defect after bicuspid aortic valve endocarditis The incidence of IE in native BAV patients is higher than that in the general population, usually presenting at younger age, with higher rates of perivalvular complications (abscess formation, valve perforation, and destruction), frequently requiring surgical intervention and exposing patients to more adverse outcomes. 11,12 Staphylococcus aureus is usually responsible for destructive IE, playing an important role in fistula formation. 13 According to Prifti et al., in 21 cases of acquired Gerbode due to endocarditis, S. aureus was the agent in 7, mostly involving the aortic valve and the mitral-aortic intervalvular fibrosa into the upper part of the interventricular septum. 14 The patient presented perforation of the posterior cusp of the aortic valve, and the two identified vegetations were in continuity with mitral-aortic intervalvular fibrosa, where acquired Gerbode defect was found. Possibly, the fistula resulted from a ruptured abscess.
There are three types of acquired Gerbode defect: (i) supravalvular defect superior to the septal leaflet of the tricuspid valve and involving the membranous portion of the septum (direct), (ii) infravalvular defect below the septal leaflet of the tricuspid valve possibly with leaflet perforation (indirect), and (iii) intermediate-both supravalvular and infravalvular septal communication. 15 Our patient had a supravalvular defect, without involvement of the tricuspid septal leaflet.
Small acquired Gerbode defects are usually asymptomatic and can be easily missed in TTE. Transoesophageal echocardiogram presents a higher sensitivity and specificity than TTE for diagnosis and detection of IE perivalvular complications, including LV-to-RA small shunts. The communication can be visualized with colour Doppler as a high velocity jet through the shunt. 4 However, larger acquired Gerbode defects may cause more significant LV-to-RA shunt that may provoke severe acute HF, with sudden dyspnoea due to pulmonary congestion, elevated jugular venous pressure, and hypotension mimicking right ventricular (RV) failure or tamponade. Longstanding shunts may cause RV overload, with progressive RV and RA dilatation and HF symptoms. 15 In our case report, the acquired Gerbode defect was small and the patient had no symptoms of acute HF, even considering the presence of moderate aortic regurgitation.
Although all the present complications represent an indication for early surgical intervention, the cardiac surgery was deferred due to stroke haemorrhagic transformation, according to the European Society of Cardiology (ESC) guidelines in treatment of IE. 4 However, evolution was benign at medical therapy despite the worst expected prognosis, allowing the uneventful surgical correction. The patient was discharged without sequelae.

Conclusion
This case report exposes the IE multiple life-threatening complications that may occur, the complexity of its management, and the importance of TOE in detecting perivalvular complications, as acquired Gerbode defect. Its identification is important for surgical planning since an additional correction besides the AVR may be required.

Supplementary material
Supplementary material is available at European Heart Journal -Case Reports.