Keywords
congenital defect - myocardial infarction - pulmonary arteries
Introduction
Coronary artery fistulae are usually abnormal connections between a coronary artery
and a cardiac chamber or major intrathoracic vessels with substantially lower pressure.
Most coronary fistulae are congenital, but they can also be acquired. In the largest
series of cases undergoing coronary angiography, relevant coronary fistulae were found
in 62 out of 126,595 cases (0.05%).[1] More recent studies by computed tomography (CT) coronary angiography, screening
15,548, 8,864, and 2,573 patients found higher incidences of 0.19, 0.15, and 0.15%,
respectively.[2]
[3]
[4] Most patients are asymptomatic. The most common findings in symptomatic patients
are heart failure resulting from left to right shunting, ischemia due to coronary
steal, arrhythmia, rupture, thrombosis, and infective endocarditis.[5]
Case Description
A 60-year-old man suffered a non-ST-segment elevation myocardial infarction at the
age of 49 years (year 2009) and underwent interventional treatment of the left anterior
descending artery (LAD, bare metal stent implantation) and mechanical recanalization
(balloon only) of the ramus intermedius. At this time, intervention via the femoral
route was challenging because of difficulty to selectively intubate the ostium of
the left coronary artery and challenging wire passage into the LAD. A large coronary
fistula ([Fig. 1], panel A) arising from the circumflex artery (CX) had already been described, but
at that time, no further action had been taken. Now, more than 10 years later, the
patient returned with exertional dyspnea and again underwent coronary angiography.
LAD and ramus intermedius showed intermediate lesions without any further progress
of his coronary artery disease. Since he was symptomatic, but his lesions did not
appear flow limiting, interventional closure of the fistula was considered, but a
CT angiography of the chest was performed to further evaluate the fistula and its
target vessel or chamber. His chest CT showed a smaller left and larger right hemithorax
together with fibrotic and emphysematous changes of the left lung ([Fig. 1], panel B). The underlying cause was an agenesis of the left pulmonary artery ([Fig. 1], panel B). Collaterals from the heart (fistula coming from the CX), the left and
right subclavian arteries, as well as the superior phrenic artery ([Fig. 1], panels C and D) ensured left lung tissue supply. In addition, it revealed a right
descending thoracic aorta. Detailed history revealed dyspnea since childhood which
led to discharge from military service later in life due to hemoptysis induced by
maximum strength exercise. The decision for conservative treatment was made.
Fig. 1 Coronary angiography in right anterior oblique 30-degree projection showing intermediate
lesions of the proximal left anterior descending artery and the ramus intermedius
as well as a large “fistula” (arrow heads) taking off from the circumflex artery (panel
A); CT of the chest indicating a smaller left hemithorax and the absence of the left
pulmonary artery (panel B); CT angiography showing the right descending aorta and
multiple collaterals (arrow heads) close to the ascending aorta (panel C); and three-dimensional
reconstruction of the intrathoracic structures with large collateral vessels arising
from both subclavian arteries (arrows, panel D). CT, computed tomography.
Discussion
Unilateral absence of a pulmonary artery (UAPA) is an extremely rare condition affecting
∼1 in 250,000 persons in the general population and is mostly associated with other
congenital defects and is mainly diagnosed in childhood.[6]
[7]
[8]
[9] In the studies searching for coronary anomalies in ∼175,000 patients, not a single
case of UAPA had been described, underlining the uniqueness of this case.[1]
[2]
[3]
[4]
Here, a large fistula arising from the CX triggered CT coronary angiography and thereby
the diagnosis. It showed that the “fistula” had no clear target vessel or target cardiac
chamber but corresponded to collaterals ensuring tissue integrity of the left lung.
Since these collaterals supplied the tissue of the left lung, an interventional closure
was not indicated. In addition, his coronary lesions were not flow limiting. Thus,
the patient's dyspnea was most likely caused by the congenital defect (UAPA) and associated
consequences rather than by a steal phenomenon at the level of the heart. Fistulae
arising from the coronary tree which do not have a clear target vessel or target cardiac
chamber should therefore be evaluated by CT coronary angiography before considering
interventional or surgical closure.
