AJR 2002; 179:1535-1537
© American Roentgen Ray Society
Single Coronary Artery as Cause of Acute Myocardial Infarction in a 12-Year-Old Girl: A Comprehensive Approach with MR Imaging
Benedetta Giorgi1,
Steven Dymarkowski1,
Frank E. Rademakers2,
Fréderic Lebrun3 and
Jan Bogaert1
1 Department of Radiology, Gasthuisberg University Hospital, Herestraat 49,
B-3000 Leuven, Belgium.
2 Department of Cardiology, Gasthuisberg University Hospital, B-3000 Leuven,
Belgium.
3 Department of Cardiology, Centre Hospitalier de Luxembourg, rue barblé,
4, L-1210 Luxembourg.
Received April 1, 2002;
accepted after revision June 6, 2002.
B. Giorgi is supported by a Marie-Curie fellowship of the European
Commission.
Address correspondence to J. Bogaert.
Introduction
Anomalies of the coronary arteries are rare conditions that are often
asymptomatic. However, if perfusion by the coronary artery is impaired, this
anomaly can lead to a life-threatening situation, such as myocardial ischemia
or infarction, and sudden cardiac death. In symptomatic patients, diagnosis is
made by depicting the congenital coronary artery anomaly and by assessing the
impact of ischemia on myocardial integrity and function. Of all cardiac
imaging techniques, MR imaging is the sole technique to provide adequate
information for this assessment.
Case Report
A 12-year-old girl presented with a history of three syncopal episodes that
occurred during physical exercise. During the third attack, she experienced
chest pain, for which she was admitted to a nearby hospital. Routine ECG
showed ST-segment abnormalities suggestive of myocardial ischemia and positive
cardiac enzymes (i.e., values for total creatine kinase, 1800 IU; creatine
kinase myocardial fraction, 240 IU; and troponin T, 2.5 µg/L) that
confirmed myocardial necrosis. Transthoracic echocardiography showed a
hypo-kinetic motion pattern of the left anterior wall. No congenital
abnormalities were shown. All other biochemical and serologic tests revealed
no abnormalities. Follow-up echocardiography 1 week later showed a recovery of
contractility. The presumptive diagnosis was viral myocarditis with myocardial
necrosis. To exclude structural cardiac abnormalities and to evaluate the
extent of myocardial damage and the repercussion on ventricular function, we
referred the patient to our hospital for MR imaging.
MR imaging was performed on a 1.5-T Gyroscan Intera CV system (Philips,
Best, The Netherlands) equipped with a five-element cardiac synergy coil and
Vectorcardiogram triggering. Morphologic MR imaging of the heart using a
breath-hold fast-spin-echo technique did not reveal any abnormalities. MR
coronary angiography, using a commercially available, three-dimensional turbo
field-echo technique with real-time navigator correction, was performed along
the course of the right coronary artery and the left main and left anterior
descending coronary arteries (Figs.
1A and
1B)
[1]. These curved
maximum-intensity-projection images, using a Soapbubble analysis tool (Philips
Medical Systems), showed a normal origin and course of the right, left
circumflex, and left anterior descending coronary arteries. However, the left
main coronary artery did not originate from the left sinus of Valsalva.
Instead, the proximal portion of the left coronary artery tree could be
followed between the aortic root and the main pulmonary artery to the right
atrio-ventricular groove, where it originated from the right coronary
artery.
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Fig. 1A. —12-year-old girl with single coronary artery and myocardial
infarction. Curved 8-mm-thick maximum-intensity-projection image, using
Soapbubble analysis tool (Philips Medical Systems, Best, The Netherlands),
from three-dimensional MR coronary angiogram with real-time navigator
correction in transverse plane at level of aortic root shows normal origin and
proximal part of right coronary artery (white arrow) and proximal and
mid parts of left anterior descending coronary artery (arrowheads).
Proximal part of left coronary artery (black arrow) does not
originate from left coronary sinus but can be followed between aorta and
pulmonary trunk to right atrioventricular groove, where it originates from
right coronary artery.
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Fig. 1B. —12-year-old girl with single coronary artery and myocardial
infarction. Curved 8-mm-thick maximum-intensity-projection image, using
Soapbubble analysis tool, from three-dimensional MR coronary angiogram with
real-time navigator correction in oblique plane through right atrioventricular
groove shows origin of right coronary artery from right sinus of Valsalva and
normal course in right atrioventicular groove (white arrows). Normal
course of proximal part of left circumflex coronary artery
(arrowheads) is in left atrioventricular groove. Proximal part of
left coronary artery does not originate from left coronary sinus but can be
followed between aorta and pulmonary trunk (black arrow) to right
atrioventricular groove, where it originates from right coronary artery.
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Assessment of ventricular function, using breath-hold balanced
fast-field-echo cine MR imaging in the cardiac short axis and vertical and
horizontal long axes, showed a preserved end-diastolic wall thickness, a
normal regional myocardial contractility pattern, and a normal global left
ventricular function. MR perfusion imaging (0.05 mmol/kg of body weight of
gadopentetate dimeglumine) did not reveal any myocardial perfusion deficits.
MR imaging after the administration of gadopentetate dimeglumine (total dose,
0.2 mmol/kg of body weight) using a T1-weighted turbo-field-echo technique
with an inversion pulse set at 250 msec to optimally suppress the signal of
normal myocardium, acquired 10 min after contrast administration, showed a
subendocardial enhancement in the left ventricular anteroseptal wall (Figs.
1C and
1D).
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Fig. 1C. —12-year-old girl with single coronary artery and myocardial
infarction. Late-enhancement MR image using turbo-field-echo sequence with
inversion pulse of 250 msec at 10 min after injection of 0.2 mmol/kg of
gadopentetate dimeglumine in cardiac short-axis direction shows subendocardial
enhancement in anteroseptal left ventricular wall (arrow).
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Fig. 1D. —12-year-old girl with single coronary artery and myocardial
infarction. Late-enhancement MR image using turbo-field-echo sequence with
inversion pulse of 250 msec at 10 min after injection of 0.2 mmol/kg of
gadopentetate dimeglumine in cardiac horizontal long-axis direction shows
subendocardial enhancement in anteroseptal left ventricular wall
(arrow).
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Thus, using a comprehensive MR imaging approach, we confirmed that the
subendocardial myocardial infarction was not caused by myocarditis but by the
presence of a single coronary artery. A squeezing of the interarterial part of
the proximal left coronary artery probably caused the myocardial infarction in
the left coronary artery territory. Because of limited transmural extension of
the infarction, the impact of the subendocardial necrosis on regional and
global left ventricular function was negligible. The MR imaging diagnosis was
confirmed at thoracotomy. Surgical reimplantation of the left coronary artery
to the left coronary sinus was performed, and the follow-up was
uneventful.
Discussion
Several groups of researchers have highlighted the potential value of MR
imaging for revealing the coronary arteries noninvasively
[1,
2]. Although detection of
coronary artery stenoses with MR coronary angiography in a clinical setting is
still premature [3], assessment
of anomalous coronary arteries is considered a solid indication for MR
coronary angiography [4,
5]. To our knowledge, ours is
the first report of a single-session MR imaging examination to assess cardiac
morphology, coronary artery anatomy (i.e., origin and course), myocardial
perfusion, cardiac function, and late-enhancement imaging in a patient with an
anomalous left coronary artery. Our approach allowed not only the depiction of
the anomalous origin and course of the coronary artery but also the direct
visualization of the structural and functional myocardial damage caused by the
interarterial coronary artery constriction.
A single coronary artery is a rare congenital anomaly and, as an isolated
finding, occurs in approximately 0.03-0.4% of the population. According to the
site of origin and the anatomic distribution of the branches, isolated
coronary arteries can be angiographically classified into different groups
[6]. In our patient, the single
coronary artery arises from the right coronary sinus, and from this a large
trunk crosses the base of the heart to arrive in the vicinity of the normal
contralateral coronary artery. This long transverse trunk courses the aorta
and the main pulmonary artery. In this type of single coronary artery,
symptoms occur by compression of the intramural segment of the left coronary
artery by the great vessels, usually during exercise or other stress, which
leads to exertional chest pain, syncope, myocardial ischemia and infarction,
and the potential for sudden death
[7]. Other hypothetic
mechanisms causing symptoms can be related to a decrease in coronary artery
blood flow because of a kinking of the left coronary artery at its origin from
the right coronary artery. Kinking may be caused by an increased angulation
resulting from distention of the aorta during increased cardiac activity.
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Introduction
Case Report
