A Giant Left Main Trunk and Left Circumflex Artery-to-Right Ventricle Fistula.

Coronary artery fistula including the left trunk and left circumflex is uncommon. We present a 24-year-old male patient with a giant left main trunk and left circumflex artery to right ventricle fistula, which is diagnosed by transthoracic echocardiography and coronary computed tomography angiography. In this paper, the case report is to provide a better understanding of clinical characteristics for this disease.

INTRODUCTION

Coronary artery fistula (CAF) is an unusual coronary artery abnormality, where connection exists between coronary artery and cardiac chamber or another blood vessel. It occurs in 0.3-0.8% of patients undergoing selective coronary angiography.[1] It predominantly originates from the right coronary artery. The left circumflex coronary artery is seldom involved.[2] CAF originating from the left main trunk and left circumflex artery is very unusual and rarely reported in the literature. We describe a case of giant left main trunk and left circumflex artery fistula to the right ventricle.

CASE REPORT

A 24-year-old male patient presented with complaints of dyspnea and palpitation during exercise. On physical examination, his blood pressure was 120/80 mmHg and pulse rate was 75 bpm. The heart was rhythmic and chest auscultation revealed a continuous murmur of grade 3/6 at the upper left sternal border. Electrocardiography demonstrated no apparent ST segment and T-wave abnormalities.

Transthoracic echocardiography (TTE) showed enlargement of the left main trunk and left circumflex coronary artery, with a 25-mm inner diameter, diffusely tortuous dilated and drained into the posterior wall of the right ventricle [Figure 1]. Left anterior descending artery, right coronary artery, and major side branches were normal. The left ventricular systolic function was normal with an ejection fraction of 65% and there were no abnormalities in the regional wall motion and cardiac valves. Mild right ventricular hypertrophy and enlargement were detected. Pulmonary artery systolic pressure measured using tricuspid regurgitant jet velocity was 40 mmHg. Laboratory investigations were normal. In order to further evaluate the fistula in more detail, a 320-slice dynamic volume CT (Aquilion ONE, software release v. 4.3, Toshiba Medical Systems, Japan) angiogram was performed, using 3-dimensional volume-rendered (VR) and curved-plain reconstruction (CPR). It demonstrated a large fistula arising from the left main trunk and left circumflex artery emptying to the right ventricle [Figure 2]. We confirmed the location and course of the fistula. Surgical ligation and transcatheter occlusion operation was recommended. The patient, however, refused any treatment.

Figure 1

Color-Doppler echocardiography revealed enlarged and tortuous of LM and LCX (white arrows) origin from AO, abnormal flow from AO passing LM and LCX to RV through a fistula (red arrow). (AO: Aorta, LM: Left main trunk, LCX: Left circumflex artery, LV: Left ventricle, RV: Right ventricle, RA: Righe atrium, LA: Left atrium)

Figure 2

Contrast-enhanced CT coronary angiogram. 3-dimensional volume-rendered (VR) and curved-plain reconstruction (CPR) shows origin and course of the fistula. The vessel runs from the left main trunk and left circumflex coronary artery and drained into the posterior wall of the right ventricle through a fistula (red arrow). (AO: Aorta, LM: Left main trunk, LCX: Left circumflex artery, LV: Left ventricle, RV: Right ventricle)

DISCUSSION

CAF can be congenital or acquired anomaly of vascular communications.

Congenital CAF is caused by a cardiovascular abnormality in embryo period, which accounts for 0.27-0.40% of all congenital cardiac defects.[3] Acquired CAF has been described after surgical procedures, endomyocardial biopsy, trauma, inflammation, atherosclerosis, and collagen vascular disease.[4] The prevalence of right CAF is higher than that of left coronary artery. Low pressure structures are the most common sites of CAF drainage. CAF usually drains into the right chamber, pulmonary artery, pulmonary veins, superior vena cava, inferior vena cava, and coronary sinus.[5]

Most CAF patients are usually asymptomatic and are found incidentally during angiographic evaluation for other cardiac diseases. Clinical symptoms of patients with CAF are dependent on the size of fistula and the pressure of its terminal chamber. In our patient, the giant CAF increases the volume load of the right heart chambers and the pulmonary artery. If the shunt of CAF is significant, steal blood phenomenon may occur and cause myocardial ischemia or infarction, which increases risk of infective endocarditis, accelerates atherosclerosis, and even heart failure.[6]

Generally, TTE is an important primary non-invasive tool for diagnosis of coronary artery abnormality and confirmed by coronary angiography. With the cardiac CT technological improvement in recent years, particularly in temporal/spatial resolution and reduced radiation dose, coronary computed tomography angiography (CCTA) has been a relatively new imaging modality and non-invasive method for assessment of coronary artery disease.[7] CCTA not only precisely demonstrate the origin, course, and drainage site of the fistula, but also provides surgical plan for treatment. However, coronary angiography still remains the gold standard for diagnosing coronary anomalies. Current treatment options include surgical ligation and percutaneous embolization. It is suggested that CAF should be treated as soon as possible to avoid the potential risk of complications, no matter whether clinical symptom exists or not. In our case, the patient refused treatment, because of a terrible fear of operation. He experienced no serious cardiac events over half a year of follow-up.

In conclusion, the giant left main trunk and left circumflex artery fistula to the right ventricle are rarely seen. CCTA is a very useful tool in the diagnosis of CAF. The optimal treatment for CAF is surgical ligation and percutaneous embolization.