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showed no evidence of vegetation or abscess. Given the patient's
history of Marfan syndrome and prior type A aortic dissection
with Bentall repair, we suspect the ﬁstula developed as a complication of surgery. Additionally, we suspect that our patient was
without heart failure symptoms or a change in oxygen saturation
during catheterization because of the small size of the ﬁstula.
This case highlights the role that cardiac catheterization with
aortogram can play in the detection of aorto-atrial ﬁstulas.
1.
2.

Figure 2. Intraoperative transesophageal echocardiogram showing the aortoright atrial shunt (arrow).

sinus of Valsalva aneurysm, infective endocarditis, paravalvular
abscess, chest trauma, congenital etiologies, and postsurgical
complications (1-10). Classically, two distinct clinical settings
of aorto-atrial ﬁstula have been described. The ﬁrst is an acute
presentation where chest pain is the predominant feature. The
second is a progressive presentation with developing symptoms of
congestive heart failure (11). The size of the shunt determines the
clinical presentation and can vary from a nonclinically signiﬁcant
murmur to chest pain with refractory heart failure (12).
Clues to diagnosis include the presence of a continuous thrill
murmur and electrocardiographic ﬁndings of a conduction abnormality (13). Transthoracic echocardiograms have been reported
to detect ﬁstulous tracts in ∼50% of cases, but the detection rate
is increased to ∼97% with the addition of transesophageal echocardiograms with Doppler (14). Additionally, due to its ability to
delineate cardiac structures in unconventional views, three-dimensional echocardiography is becoming an increasingly useful tool
in ﬁstula detection (12). Although cardiac computed tomography
can complement echocardiography by providing a noninvasive
evaluation of the coronary artery anatomy, cardiac catheterization
and aortography better depict ﬂow through the aorto-atrial ﬁstula
(10). This was demonstrated in our patient, where the aortogram
provided the only evidence of a ﬁstula. Right heart catheterization often reveals high right atrial pressure and, in some cases,
an increase in oxygen saturation at the level of the right atrium.
Since the ﬁrst successful repair in 1966, treatment has revolved around surgical correction (15). Although surgery is
currently the standard treatment, percutaneous closure using an
Amplatzer device has been described in cases when the location
and size of the ﬁstula are appropriate (16). Prompt intervention
is critical given repair dramatically relieves symptoms, decreases
mortality, and is a reversible cause of heart failure (17).
Infectious etiologies for aorto-atrial ﬁstulas were high on
the diﬀerential diagnosis for our patient. Invasive Mycobacterium chimera infections related to heater-cooler units have been
shown to develop years after cardiac bypass surgery (18). Additionally, the presentation was classic for infectious endocarditis
from an infected knee. However, the patient remained without
a recorded fever, all cultures returned negative, and imaging
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11.
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13.

14.
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Baylor University Medical Center Proceedings

Volume 30, Number 3

Table of Contents for the Digital Edition of Baylor University Medical Center Proceedings July 2017