Keywords
aortic valve and root - endocarditis - cardiovascular surgery
Introduction
A fistulous tract formation from the aortic sinus to the right atrium due to an infective
endocarditis (IE) is unusual and affords uncommon treatment. Here, we describe the
case of a 45-year-old woman suffering from such a constellation.
Case Presentation
A 45-year-old woman with a history of anemia and bronchiectasis in her left upper
lobe was referred to the clinic of cardiology due to palpitations and malaise. Since
4 weeks she had suffered from fatigue, weight loss, and elevated temperatures.
Physical examination revealed irregular tachycardia (heart rate, 118/min), hypotension
(95/55 mm Hg), a body temperature of 38.6°C, and a new diastolic murmur (3/6). Electrocardiogram
revealed a narrow complex tachycardia with changing QRS amplitude and irregular P-wave.
Except for an elevated CRP level, all other laboratory values were without pathological
findings.
Because of the new diastolic murmur, a transthoracic echocardiography and a transesophageal
echocardiography were conducted and confirmed the clinical suspicion of IE with visualization
of a perforated right coronary cusp of the aortic valve and an affected tricuspid
annulus with vegetations. The tricuspid aortic valve showed moderate to severe eccentric
insufficiency. In addition to this, an aorto-cavitary fistula (ACF) from the aortic
sinus to the right atrium with a holodiastolic left–right shunt had been detected
by Doppler echocardiography ([Fig. 1]). The cusp was supposed to block the fistula ostium during systole. The right ventricle
showed a moderate tricuspid insufficiency with no evidence of hypertrophy but a slightly
reduced ejection fraction (biplane = 52%). The left ventricle was normal in size and
systolic function. Coronary artery disease was ruled out in coronary angiography.
Fig. 1 Preoperative transesophageal echocardiography. (A) X-plan long axis (left) and short
axis (right) with color Doppler signal. (B) Echocardiographic view of the fistula
with and without color Doppler signal. In both images, the fistula is marked with
a red arrow.
Blood cultures of 2 × 2 were obtained in the beginning and all of them were tested
positive for Streptococci viridans susceptible for penicillin and gentamicin. For exclusion of cerebral septic emboli,
a brain computed tomography was performed without any pathological findings. In the
thoracic computed tomography performed during the same investigation, the fistula
could be confirmed ([Fig. 2]).
Treatment
An empiric antibiotic therapy with penicillin, gentamicin, and vancomycin in accordance
with the national guidelines for the treatment of IE had been undertaken initially.
The patient was scheduled for urgent surgery. Installation of cardiopulmonary bypass
was performed in the standard fashion with cannulation of the ascending aorta and
both caval veins. Bretschneider cardioplegia was administered antegrade into the coronary
ostia. Inspection of the operative situs showed a perforation with a diameter of around
1 cm and vegetation on the margin of the right coronary cusp. Below the right coronary
ostium, a fistula could be identified connecting the aorta directly with the right
atrium. By accessing the right atrium, the end of the fistula was located close to
the septal area of the tricuspid annulus ([Fig. 3]). After the excision of the aortic root, radical debridement of the fistula was
possible. This was followed by a reconstruction of the right atrium and aortic root
with pericardium patches to finally enable the implantation of a 23-mm biological
composite graft (Freestyle Aortic, Freestyle, Medtronic Inc., Minneapolis, United
States). The moderate tricuspid valve insufficiency was accepted to avoid further
implantation of foreign material in the setting of an acute endocarditis.
Fig. 2 Preoperative computed tomography. (A) Aortic annulus; (B) subaortic abscess and fistula;
(C) tricuspid valve.
Fig. 3 Intraoperative situs. (A) Right atrial view; (B) aortic view. 1: right atrium; 2:
orifice of the fistula in the right atrium; 3: annulus of the tricuspid valve; 4:
orifice in the right coronary cusp of the aortic valve.
Material for further microbiological analysis was collected. After the reperfusion
of the heart, sinus rhythm was present with intermittent conduction block. Thus, implantation
of an epicardial pacemaker probe was performed for a potential subsequent need of
a pacemaker.
On postoperative day (POD) 1, X-ray image illustrated a right-sided hemothorax which
required a rethoracotomy and evacuation of a hematoma.
PCR investigation after surgery proved Streptococcus mitis vegetation. Vancomycin was stopped and penicillin and gentamicin were continued for
6 weeks and 14 days, respectively. The patient was discharged at POD 15.
During the rehabilitation, the patient complained about dyspnea, vertigo, thoracic
pressure sensation, and intermittent palpitations. Echocardiography revealed a shunt
from the left outflow tract to the right atrium due to a ventricular septal defect
(VSD) located in the pars membranacea. The biological composite graft was evaluated to be in correct position with normal
valvular function without any evidence of insufficiency. The finding of new VSD indicated
a surgical correction, which was performed 2 months (POD 54) after the first cardiac
intervention. Intraoperatively, the initially implanted patch was detached. The closure
was performed by suturing a new pericardium patch on either side. The following postoperative
course was uneventful and the echocardiographic examination showed a successful closure
of the shunt.
Due to persisting postoperative third-degree atrio-ventricular block, the implantation
of a dual chamber pacemaker was necessary 7 days later.
Four months later, the patient was readmitted for removal of her sternal wires. At
that time, she presented asymptomatic and was discharged home without any signs for
recurrent endocarditis on a transitional anticoagulation with phenprocoumon, which
was switched to aspirin in the further course.
Discussion
Here, we present the case of an aorto–right-atrial fistula in a case of native valve
endocarditis (NVE).
Aorto-atrial fistulae are a rare manifestation of IE. Anguera et al reported a rate
of 1.8% of fistulous formation in patients with NVE and of 3.5% in prosthetic valve
endocarditis.[1] The most frequent infected site in NVE is the aortic valve (38–55%) and the mitral
valve (39–41%) followed by the other valves (6–13%).[2] For the aortic valve, all three sinuses and the four cardiac chambers have been
described as to be equally involved in fistulous tract formation.[1] In our case, the fistula was found to be connected from the right coronary cusp
to the right atrium close to the annulus of the tricuspid valve. This location has
not yet been described to our knowledge. Another unique finding in this case was that
there was only diastolic left–right shunt, due to the suspected occlusion of the fistula
entrance during systole by the aortic valve cusp. Three case descriptions of aorto–right-atrial
fistulation are available[3]
[4]
[5] in the literature. In two of them, the aortic valve was bicuspid and the tricuspid
valve was involved only in one case. Detailed treatment is not described in any of
the cases.
Viridans streptococci were the underlying pathogen in our case. “Viridans streptococci
vary in their invasiveness and abscess potential.”[6] Streptococcus mitis is a member of the S. viridans group and is found more often in tricuspid valve endocarditis of patients with intravenous
drug abuse.[7] Medical history and clinical presentation were negative concerning intravenous drug
abuse in our case.
Early and properly timed operative intervention in combination with optimal antibiotic
therapy and elaborate pre- and postoperative care is the best approach to achieve
an acceptable outcome in case of active IE.[8] In a case of double-sided IE with a fistulous connection and associated extensive
perivalvular damage, therapy is even more complicated.
In conclusion, with this case presentation, we tried to show that for patients with
ACF in aortic NVE, timely diagnosis, accurate antibiotic therapy, and early, aggressive
cardiac surgery are necessary to provide the best possible outcome. A proper postoperative
monitoring with electrocardiography, echocardiography, and other diagnostic instruments
assure timely detection of potential complications of ACF in IE.
