Discussion

Although high take-off coronary artery is defined differently in literature, the most accepted definition is the presence of coronary ostium is 1 cm above sinotubular junction in adult patients and that coronary ostium above sinotubular junction which is greater than 20% of sinus depth in children. ^{Reference Loukas, Andall and Khan5} In our patient, the distance between the coronary ostium and the sinotubular junction was almost equal to the depth of the sinus. High take-off coronary artery anomaly is a rare coronary artery anomaly. There is not still consensus about its clinical significance. It is sometimes detected in asymptomatic cases incidentally by imaging methods or intraoperatively; ^{Reference Deng, Huang and Chen6,Reference Yeşilyurt, Aksu and Kalkan7} however, it is sometimes associated with myocardial ischemia and even sudden cardiac death. ^{Reference Salehi, Abdi, Pouraliakba and Vakili-Zarch8-Reference Priemer, Danon and Guzman10}

High take-off coronary artery anomaly is generally seen as an isolated anomaly. The prevalence of high take-off coronary artery anomaly with CHD is 2.7%. ^{Reference Loukas, Andall and Khan5} In the literature, there are very few studies case reports describing the association with tetralogy of Fallot. ^{Reference Li, Soukias, Carvalho and Yen Ho11,Reference Tuzcu, Moodie, Chambers, Keyser and Hobbs12} The prevalence of coronary artery anomalies in patients with tetralogy of Fallot ranges from 5% to 12%. ^{Reference Gupta, Saxena and Kothari1-Reference Kapur, Aeron and Vojta3,Reference Meng, Eckner and Lev13,Reference Dabizzi, Caprioli and Aiazzi14} The most common coronary artery anomalies in patients with tetralogy of Fallot have been described as left anterior descending artery arising from right coronary artery, single coronary root origin, large conal branch arising from right coronary artery, and double left anterior descending artery. ^{Reference Kervancioglu, Tokel, Varan and Yildirim2-Reference Freire and Miller15} In echocardiographic evaluation of our patient, right coronary artery origin could not be shown in standard sections. Only left coronary artery origin from the left coronary sinus could be demonstrated. Fortunately, we had suspected of collateral circulation between the aorta-pulmonary artery and decided for angiography. Otherwise, we would operate the patient for total correction with the diagnosis of single coronary artery. We were able to detect the coronary artery anomaly of the patient by angiography. In the presence of high take-off coronary artery anomalies, since the coronary origin cannot be seen in standard echocardiographic windows is always the risk of underdiagnose. Especially, when accompanying tetralogy of Fallot in our patient, it can easily mislead the physician since single coronary origin is one of the well-known coronary artery anomalies tetralogy of Fallot. Our patient showed us the importance of evaluating coronary arteries with advanced imaging methods. In many centres, CT angiography is performed in patients with tetralogy of Fallot in the pre-operative period for this purpose.

The importance of coronary artery anomaly in tetralogy of Fallot is mostly apparent when it is crossing right ventricular outflow tract. This prevents the reconstruction of right ventricular outflow tract during surgical correction and causes conduit to be used. In our patient, we found that a high take-off right coronary artery is arising from the left lateral surface of the ascending aorta well above the synotubular junction by catheter angiography. Angiography images showed that the right coronary artery crossed the aorta not the right ventricular outflow tract. However, we evaluated the patient with CT angiography, since high take-off coronary arteries may also have an intramural course. ^{Reference Loukas, Andall and Khan5,Reference Deng, Huang and Chen6} It was observed that the right coronary artery did not show an intramural course; however, during its course, it was very close to the lateral aspect of the right ventricular outflow tract. Another important issue in the presence of high take-off coronary artery is aortic cannulation site. The surgeon needs to cannulate the aorta more proximally. Otherwise, coronary circulation cannot be achieved and may cause catastrophic consequences. In our patient, it was planned to perform both right ventricular outflow tract repair more laterally and aortic cannulation more proximally.

High take-off coronary artery anomaly is quite a rare and usually isolated anomaly. However, it must be considered that it can be seen in patients with tetralogy of Fallot. Echocardiography may not be sufficient for diagnosis. In the presence of a high localised coronary artery, it is very important to show the level and course of the coronary artery to determine the type of surgical repair and the location of the cannulation. Cardiac CT or catheterisation should be considered in cases where coronary anatomy is not well defined or uncertain.