Multidetector-row Computed Tomography in

Diagnosis of a Large Right Coronary Artery

Aneurysm Resulting from Arteriovenous Fistula

Kun-Eng Lim,1 Kuei-Ton Tsai2 and Yu-Lin Ko3

Coronary artery aneurysm with arteriovenous fistula is an uncommon condition. We report a 52-year-old male with

a large right coronary artery aneurysm resulting from a coronary artery-to-right ventricle fistula. The aneurysm and

the fistula were demonstrated by an electrocardiography-gated multidetector-row computed tomography coronary

angiography. Three months after surgery, the computed tomography coronary angiography showed no fistula, and

the distal right coronary artery was bypassed with a saphenous graft. Thus, we concluded that in some instance

multidetector-row computed tomography coronary angiography may be helpful for diagnosis and demarcation of

coronary artery aneurysm with arteriovenous fistula.

Key Words: Coronary arteriovenous fistula � Computed tomography

INTRODUCTION

Coronary artery aneurysm is an uncommon disease.

Coronary artery aneurysm is defined as coronary dilata-

tion that exceeds the diameter of normal adjacent seg-

ment or the diameter of the patient’s largest coronary

vessel by 1.5-2 times.1 The incidence of this anomaly is

between 1.4% and 5%.2,3 Coronary artery aneurysm

caused by coronary arteriovenous fistula is an even more

uncommon condition.4-7 Currently, multidetector-row

computed tomography (MDCT) coronary angiography

has become a valuable method for evaluation of coro-

nary artery disease and the heart.7-9 Herein, we report

MDCT coronary angiography is helpful for demonstrat-

ing a large right coronary aneurysm resulting from a cor-

onary artery- to- right ventricle (RV) fistula.

CASE REPORT

A 52-year-old male suffered from effort-related

chest tightness and palpitation for about 2 weeks. He had

cardiac murmur and had been told he had heart disease

by her family physician a long time before. He family

history was unremarkable. He had a history of hyper-

lipidemia (at admission, triglyceride measured 211 mg/

dl) and peptic ulcer for many years. On physical exami-

nation, the patient appeared essentially well. However, a

harsh grade 2-3/6 continuous murmur was audible over

the left lower parasternal border. Chest radiography

showed widening of the right mediastinum. Electrocardi-

ography (ECG) showed left atrial enlargement and right

bundle branch block. Transthoracic 2-dimensional and

color-Doppler echocardiography showed mildly dilated

left ventricle and aortic root, thick interventricular sep-

tum, mild mitral and tricuspid regurgitations, and moder-

ate aortic regurgitation. Furthermore, there was a large

right coronary artery (RCA) orifice due to a suspected

coronary arterio-venous fistula. Transesophageal echo-

47 Acta Cardiol Sin 2008;24:47�50

CT Showed a Right Coronary Aneurysm with Arteriovenous FistulaCase Reports Acta Cardiol Sin 2008;24:47�50

Received: July 21, 2007 Accepted: September 17, 20071Departments of Radiology, 2Cardiovascular Surgery, 3Cardiology,

Buddist Tzu Chi General Hospital, Xindian City, Taipei County,

Taiwan.

Address correspondence and reprint requests to: Dr. Kun-Eng Lim,

Department of Radiology, Buddist Tzu Chi General Hospital, 289,

Jiauguo Road, Xindian City, Taipei County, Taiwan, R.O.C. Tel: 886-

2-6628-9779 ext. 1100; Fax: 886-2-2546-1665; E-mail: kevinblueski

@yahoo.com.tw

cardiography showed a dilated aortic root and a large

RCA from the right coronary sinus along the RV free

wall. In addition, the large RCA also compressed the RV

inflow tract and drained into the RV near the tricuspid

valve level. Yet, the left ventricular systolic function was

preserved. Invasive coronary angiography demonstrated

a large RCA aneurysm about 3.3 cm in diameter origi-

nating from the ostium of the RCA, with the draining

site of arteriovenous fistula not being able to be identi-

fied. The left main coronary trunk and its tributaries

were patent, and left ventricular ejection was about 66%.

For further evaluation of any additional findings as pre-

operative work-up, an ECG-gated enhanced MDCT was

acquired with a 64-slice scanner (Light Speed VCT,

General Electric, Milwaukee, Wisconsin). Contrast agent

transit time was determined using a 20-ml bolus injec-

tion of contrast agent (Ultravist 370 mg/dl, Schering,

Berlin, Germany), followed by a 40-ml saline chaser.

For acquisition of the volume data set, the patient re-

ceived a total of 65 ml contrast agent via antecubital vein

at a rate of 5 ml/s, followed by a 40-ml saline chaser.

The scan parameters were: 64 � 0.625-mm collimation,

caudocranial scan direction, 350-ms rotation time,

120-kV tube voltage, and 600-mA tube current. Images

were reconstructed with ECG gating to obtain optimal

motion-free image quality. All reconstructed images

were transferred to dedicated workstation for postpro-

cessing and evaluation (Advantage 4.2, General Electric,

Milwaukee, Wisconsin). Volume-rendered images of

MDCT coronary angiography showed a large RCA aneu-

rysm, without any luminal stenosis (Figures 1A and 1B).

There was no evidence of wall calcification of the RCA

aneurysm. The distal portion of RCA aneurysm draining

directly into the posterior wall of the RV was demon-

strated on thick-slab maximum intensity projection

image (Figure 2).

The patient underwent surgical intervention with

closure of the fistula using a hemashield patch; the RCA

aneurysm was excluded from the right coronary circula-

tion to avoid late rupture and thromboembolism compli-

cation by closure of both the proximal and distal ends of

this lesion. Direct aneurysmorrhaphy was done, and the

distal RCA was bypassed with a saphenous vein graft.

Post operation recovery was uneventful, and the patient

was discharged from hospital 18 days after operation.

Post-operative echocardiography revealed thickened

posterior left ventricular wall, abnormal septal wall mo-

tion, adequate left ventricle and RV systolic function,

and dilated aortic root with mild to moderate aortic re-

gurgitation. Three months after surgery, the computed

tomography coronary angiography showed no fistula,

and the distal right coronary was bypassed with a patent

saphenous graft (Figure 3).

Acta Cardiol Sin 2008;24:47�50 48

Kun-Eng Lim et al.

(A)

(B)

Figure 1. Three-dimensional volume-rendered images of computed

tomography coronary angiography showed a large right coronary

artery aneurysm and its distal portion directed to the right ventricle. Ao,

RA, RCA, LV, RV, LAD, and LCX indicate aorta, right atrium, right

coronary artery, left ventricle, right ventricle, left anterior descending

coronary artery, and left circumflex artery, respectively.

DISCUSSION

Coronary artery aneurysm is a rare coronary artery

disease in adult patients.1-3 It may be a congenital

anomaly, or secondary to other diseases, such as athe-

rosclerosis, post coronary intervention, infection, Ka-

wasaki’s disease, trauma, systemic degenerative dis-

ease, or other inflammatory diseases.1,2,10,11 In our pa-

tient, no aforementioned causes were found, so we

thought this patient might suffer from a congenital fis-

tula. The majority of fistulae terminate in the right

side of the heart. The most frequent sites of termina-

tion, in descending order, are the RV, right atrium, cor-

onary sinus, pulmonary trunk, left ventricle, and supe-

rior vena cava.

Coronary angiography, currently the reference stan-

dard for imaging of coronary artery disease and anat-

omy, is an invasive procedure that requires highly trained

personnel, with significant cost and low, but not negligi-

ble, procedure-related morbidity and mortality.12 In addi-

tion, there is a radiation dose to the operator. Owing to

the complex three-dimensional nature of coronary artery

fistula combined with a large coronary artery aneurysm,

invasive angiography usually cannot fully delineate the

complete outline of the large coronary artery aneurysm,

side branches, and the fistula, as in our case.

Magnetic resonance (MR) imaging is a suitable

non-invasive imaging tool for evaluation of coronary ar-

tery anomalies and their courses, yet it requires longer

time, is more expensive, and is limited with regard to de-

termination of the distal coronary arterial course.13 Also,

the spatial resolution achieved with this imaging is mar-

ginal for coronary artery imaging. MR imaging is used

for evaluation of coronary artery anomalies only when

the patient has contraindication for CT because of a se-

vere allergic reaction to iodinated contrast agent or due

to impaired renal function (creatinine level of > 1.5

mg/dl).

MDCT coronary angiography is a faster, safer, more

convenient, and non-invasive diagnostic modality to de-

tect the presence of coronary artery anomalies.9,14 In this

case, the entire examination was completed within 5

minutes and was performed as an outpatient procedure.

MDCT combines the advantages of coronary angio-

graphy and intravascular ultrasound in one noninvasive

modality, which allows full demonstration of the course

of the coronary artery aneurysm, side branches, and

other important information like diameter, lumen, and

wall of the coronary artery, any presence or absence of

calcification, and the myocardium.6,9 In addition, MDCT

also can identify other significant non-cardiac findings

during the same examination. All these data are crucial

49 Acta Cardiol Sin 2008;24:47�50

CT Showed a Right Coronary Aneurysm with Arteriovenous Fistula

Figure 2. Axial thin-slab maximal intensity projection reconstructed

image showed a large right coronary aneurysm (long arrow) with its

distal portions draining into the RV. A, F, and RV indicate aneurysm,

fistula, and right ventricle, respectively.

Figure 3. Three months after surgery, follow-up computed tomography

coronary angiography with volume-rendered technique showed no more

fistula, and the distal right coronary was bypassed with a patent

saphenous vein graft.

in planning possible surgical or therapeutic interven-

tions. In this case, the morphological findings of fistula

and the RCA aneurysm were adequately provided by

MDCT. Although MDCT has many aforementioned ad-

vantages when assessing coronary artery anomalies, ra-

diation exposures are relatively high in using this tech-

nique, ranging from 5-18 mSV, as compare with those

for invasive coronary angiography (5-7 mSv).15,16 There-

fore, appropriate use of this technique is needed, espe-

cially for pediatric patients.

In contrast transesophageal echocardiography is a

practical and diagnostic test for assessing the coronary

artery anomalies, yet it is not totally non-invasive, is

operator-dependent, and may fail to completely delin-

eate the complex anatomy of the coronary anomalies.

Furthermore, this test requires full cooperation of the

patient. As MDCT is a fast, accurate, and non-invasive

technique that can delineate the complex coronary ano-

malies and extracardiac findings, we advocate that

MDCT may be very helpful in some instance for inves-

tigating the adult patients suspected of having coronary

anomalies.

In summary, we have reported a large coronary ar-

tery aneurysm resulting from coronary artery fistula to

the RV, which was demonstrated by MDCT coronary

angiography. When patient refuses coronary angio-

graphy or for whatever reasons coronary angiography

cannot be performed, MDCT angiography may serve as

an alternative diagnostic tool for assessing coronary ar-

tery anomalies.

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