Unusual Case of Giant Nonthrombosed Right Coronary Artery Pseudoaneurysm With Coronary Artery Fistula

Coronary artery aneurysm and pseudoaneurysm are rare and mainly result from atherosclerosis. We present a successfully treated case of a giant right coronary artery aneurysm and pseudoaneurysm with a coronary artery fistula, which might have developed after cardiac surgery for a right ventricular tumor 35 years earlier. (Level of Difficulty: Advanced.)

her blood pressure was 118/57 mm Hg, and her oxygen saturation was 98% on room air. There was no difference in blood pressure between the limbs, and no abnormal heart murmurs were detected. Electrocardiography showed an ST-segment elevation in the inferior leads, with an elevated troponin I value of 420 pg/ml and normal levels of creatine phosphokinase. She did not develop heart failure symptoms such as shortness of breath and leg edema.

PAST MEDICAL HISTORY
The patient had undergone right ventricular tumor resection via median sternotomy 35 years earlier, with no major complications thereafter. The histological examination had revealed a hemangioendothelioma. She had no other risk factors of atherosclerosis except for hypertension.

DIFFERENTIAL DIAGNOSIS
Based on the patient's clinical symptoms and the findings of electrocardiography, the differential diagnosis included angina, acute myocardial infarction, acute aortic dissection, and pulmonary thromboembolism.

INVESTIGATIONS
Chest radiography showed an abnormal shadow on the right side of the heart ( Figure  1).

LEARNING OBJECTIVES
To understand the anatomical relationships between RCA aneurysm, pseudoaneurysm, and RCA fistula in CT.
To consider a previous cardiac surgery as a potential cause of coronary artery aneurysm and fistula.  imaging was performed before coronary angiography.
Enhanced CT imaging showed a right coronary artery (RCA) aneurysm with a diameter of 28 mm, anterior to, and on the left of, the ascending aorta (Figures 2A   and 2B). In addition, a giant saccular RCA aneurysm (maximum size 63 mm) with a different CT value was located between the sternum and ascending aorta on the right and lay on the right atrioventricular groove ( Figures 2B and 2C). Furthermore, abnormally dilated fistulas were seen horizontally located anterior to the giant aneurysm and RV ( Figure 2C).
On three-dimensional CT imaging, the left coro-  Because the aneurysm extended from the right coronary sinus to just proximal to the CAF, and the RCA immediately distal to the CAF was healthy, we speculated that the aneurysm developed secondary to CAF, presumably owing to the high blood flow from the RCA to the RV through the CAF. In addition, the patient's coronary system was normal, and no fistulas Abnormal shadow on the right side of the heart (red arrowheads).  Table 1). To the best of our knowledge, this report is the first on coronary aneurysm, pseudoaneurysm, and CAF that developed in association with a previous right ventricular tumor surgery.

A B B R E V I A T I O N S
Previous studies have reported that coronary aneurysms are mostly associated with thrombus formation (2,4) (Supplemental Table 1). It was therefore reasonable to hypothesize that the myocardial infarction was caused by a thrombus from the RCA aneurysm. However, no thrombus was seen in the coronary aneurysm and/or pseudoaneurysm on pre-operative CT scanning or intraoperatively. This could be because the high blood flow in the aneurysm secondary to the high-pressure gradient between the RCA and RV prevented thrombus formation. Instead, this suggested that the myocardial infarction was not due to thromboembolism but due to the rupture of the proximal RCA aneurysm, which might have resulted in the sudden loss of a large amount of blood, thereby leading to persistent coronary ischemia. This theory can be supported by the

CONCLUSIONS
We presented a rare case of giant coronary artery aneurysm, pseudoaneurysm, and CAF, which might

FUNDING SUPPORT AND AUTHOR DISCLOSURES
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.