The authors report the occurrence of infective endocarditis in a 32-year-old man with a ventricular septal defect and a left ventricular–to–right-atrial shunt who adhered to the revised 2007 American Heart Association guidelines for infective endocarditis. The patient had received antibiotic prophylaxis prior to multiple previous dental procedures. At a recent dental evaluation for fillings, he was informed that he no longer needed prophylaxis. Fatigue and fevers developed 1 week later, and he was treated with an oral course of ciprofloxacin. The symptoms recurred, and blood cultures grew Streptococcus viridans . A 7-mm vegetative mass was seen on the septal leaflet of the tricuspid valve during transesophageal echocardiography. This report raises the concern that patients with ventricular septal defects and left ventricular–to–right-atrial shunts are at higher risk for endocarditis and may require antibiotic prophylaxis.
Case Presentation
We report an occurrence of infective endocarditis in a patient with a ventricular septal defect (VSD) who adhered to the revised 2007 American Heart Association (AHA) and American College of Cardiology (ACC) guidelines for infective endocarditis.
The patient was a 32-year-old male health care worker with a VSD who carefully complied with the AHA’s endocarditis recommendations. He is followed by a primary care physician and received antibiotics prior to multiple previous dental procedures, including biannual cleaning visits. At the time of a recent, routine dental procedure consisting of 3 fillings and an examination, the dentist informed him that according to the updated 2007 guidelines, he no longer fulfilled the criteria for antibiotic prophylaxis.
One week after the dental procedure, the patient reported fatigue and intermittent fever to his primary care physician and was treated with an oral course of ciprofloxacin. He transiently improved, but fevers and fatigue recurred 3 weeks later. He was referred to our adult congenital heart disease clinic 5 weeks after the dental procedure.
Transthoracic echocardiography documented a small, perimembranous VSD with aneurysm formation and a left ventricular (LV)–to–right atrial (RA) shunt (also known as Gerbode-type VSD; Figure 1 , Video 1 ). Urinalysis confirmed microscopic hematuria, and blood cultures grew Streptococcus viridans within 24 hours. The patient was admitted to our institution for treatment. A 7-mm vegetative mass was seen on the septal leaflet of the tricuspid valve (in the path of the turbulent VSD jet) on transesophageal echocardiography ( Figure 2 , Video 2 ). The patient received a 6-week course of intravenous antibiotics and following recovery underwent uneventful surgical suture closure of the VSD. Typical “windsock” transformation of the septal and anterior tricuspid valve leaflet was present. No other defects or vegetation of the tricuspid valve were identified at the time of surgery.
Discussion
VSD is a common congenital heart defect, accounting for approximately 10% of all congenital heart disease. The incidence of infective endocarditis in patients with VSDs is rare, with an average rate of 16 per 10,000 patient-years (range, 3-38 per 10,000 patient-years). VSDs with LV-RA shunts are reported to be associated with a higher risk for endocarditis (58 per 10,000 patient-years) compared with typical VSDs or mitral regurgitation (5.2 per 10,000 patient-years).
The necessary prerequisites for endocarditis are endocardial injury and microbial adherence. The high-velocity jet, such as is seen in VSDs and mitral regurgitation, traumatizes the endothelium and predisposes to the formation of nonbacterial thrombotic endocarditis. It is known that vegetations tend to form in the area immediately downstream of turbulent flow, a short distance from the anatomic obstruction, where the velocity is the highest. Experiments have shown that the highest concentration of bacterial growth is located in these low-pressure and low-flow areas immediately distal to the narrowing. Thus, vegetations in patients with VSDs are often located on the right ventricular side of the defect or on the tricuspid valve. The predisposing factors for endocarditis in our patient were the narrow orifice of the VSD, aneurysmal transformation of the tricuspid valve leaflets in close proximity to the VSD, and the high-velocity jet from the left ventricle to the right atrium. The reason for the reported increased incidence of infective endocarditis in patients with VSDs and LV-RA shunts (Gerbode defects) is unknown. The pressure drop from the left ventricle to the right atrium is slightly higher than that from the left ventricle to the right ventricle and may only contribute slightly, if at all, to this increased incidence. We speculate that the combination of the aneurysmal tissue in the path of the high-velocity jet with multiple eddy currents and areas of stasis and low flow near the VSD may lead to more “chaotic” flow characteristics and play a contributing role in the development of infective endocarditis. This set of hemodynamic disturbances could predispose to a higher risk for infective endocarditis than simple VSD or mitral valve regurgitation alone.
VSDs are not classified as high-risk lesions in the revised 2007 AHA/ACC endocarditis guidelines, so these patients have not been receiving antibiotic prophylaxis prior to dental work since the publication of these guidelines. Prosthetic cardiac valves are considered high-risk lesions for which antibiotic prophylaxis is recommended in the 2007 AHA/ACC guidelines. It is important to note that the reported incidence of infective endocarditis in patients with VSDs and LV-RA shunts (58 per 10,000 patient-years ) is similar to that reported by Steckelberg and Wilson of 63 per 10,000 person-years for prosthetic cardiac valves.
We wish to bring this case report to the attention of our colleagues. The reported higher risk for infective endocarditis in patients with VSDs and LV-RA shunts as well as the association in our patient of first-time lack of antibiotic prophylaxis and the development of infective endocarditis is concerning. Although a single case report does not warrant a change in guidelines, by reporting this case, we raise the concern that patients with VSDs and LV-RA shunts might be considered at higher risk and should receive antibiotic prophylaxis. We support the establishment of a multicenter registry to document the incidence of infective endocarditis since the publication of the 2007 guidelines.
Acknowledgment
This work was supported in part from the Allan C. Hudson and Helen Lovaas Endowed Chair of Cardiac Imaging (V.L.S.).
Supplement Data
Parasternal short-axis video showing color flow Doppler originating from the perimembranous ventricular septum coursing through the tricuspid valve into the right atrium.
Video 2Video documenting a mobile, echogenic mass attached to the septal leaflet of the tricuspid valve consistent with a vegetation.
This work was supported in part from the Allan C . Hudson and Helen Lovaas Endowed Chair of Cardiac Imaging (V.L.S.).
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