The first reported case of a CAF was in the year 1865 by Krause [2]. The coronary artery fistula is a rare coronary artery anomaly. The overall population prevalence of the coronary artery fistula is unclear, and it occurs as an incidental finding in 0.13–0.18% of the coronary artery angiography [3, 4]. The bilateral CPFs were previously described [5]; nevertheless, multiple CPFs arising from all 3 major coronary arteries draining into the pulmonary artery were extremely rare. In our study, we reported about a female with bilateral CPFs and what strategy we had undertook.
As for the experienced sonologist, a transthoracic echocardiography may find continuous turbulent flow in the pulmonary artery during the diastolic phase in the short axis view. Small or moderate CPFs are often missed by most sonologists. Furthermore, it is difficult to find the origin of the turbulent color flow. Generally, the CPFs are detected by the multidetector computed tomography (MDCT) and coronary angiography. MDCT is a noninvasive imaging technique that has been successfully utilized for visualization of the unilateral and multilateral fistulas and for the diagnosis of coronary artery anomalies [6, 7]. Coronary angiography remains the gold standard method for CPFs, and it can be used to evaluate the size, number of fistulas, and anatomical features of the fistulous tract [8].
The results of the CPFs’ origin were inconsistent. The right coronary artery, or its branches, was the site of the fistula in 50–55% of cases. Additionally, the left coronary artery was involved in about 35–40%, and both the coronaries were involved in 5–10% [9]. However, some studies reported that most of them originated from the proximal LAD [10, 11]. The CPFs seldom cause symptoms in the first 2 decades of life, but after that, the symptoms and complications may likely increase, including dyspnea, angina, endocarditis, arrhythmias, high output cardiac failure, myocardial ischemia, thrombosis or myocardial infarction.
In our case, palpitations and chest tightness were the chief complaints of the patient. We speculated that these symptoms may be associated with increased pulmonary blood flow and dysplasia of distal LAD. The steal phenomenon arousing from the CPFs was controversial. The coronary steal theory is that runoff from a comparatively large proximal arterial segment occurs preferentially through a lower resistance vascular bed (like a fistula), which reduces the flow to the higher resistance nutrient coronary branches. The hemodynamic balance between the fistulous runoff and the nutrient branches improves when the cardiac load is increased (which causes coronary arteriolar vasodilation), to the extent that effort related angina or ischemia is usually absent. In addition, if functional ischemia or infarction does occur in a patient with a coronary fistula, this is generally the result either of coronary occlusive disease in the nutrient branches or of fistulous tract degeneration [12]. However, the previous view was challenged. Some studies supported that the CPFs cause cause myocardial ischemia [13] an ipsilateral myocardial infarction in the absence of an obstructive CAD due to the coronary steal phenomenon [14] or association with a thrombotic CAD [15]. Despite a debate about the occurrence of the continuous steal phenomenon in the CPFs, FFR remains a promising diagnostic technique that has recently been reported to successfully depict the coronary steal phenomenon. In the CPFs, despite the presence of normal pulmonary artery pressure and small magnitude left-to-right shunt, a myocardial infarction can still develop without the stenotic CAD [14]. Accurate functional evaluation of the CPFs using the FFR measurement under maximal hyperemia of the distal segment of the nutrient coronary artery during temporary balloon occlusion of the fistulous vessel demonstrated the steal phenomenon.
In the past, the treatment of CPF patients depends on the size and anatomic features of the fistula, presence of symptoms, patient’s age, and presence of other cardiovascular diseases. Symptomatic fistula should be occluded by percutaneous intervention or by surgical ligation. Further, occlusion is reasonable for the management of patients with moderate or large coronary artery fistulae without clinical symptoms [16]. Nevertheless, the best approach to the asymptomatic CPFs remains controversial. Nonetheless, at present, we possess a new tool to assess the hemodynamic significance of coronary artery fistulas.
