Revisiting the Angiographic “Dot” Sign: A Useful Clue to Diagnose Anomalous Origin of Coronary Arteries

Introduction

Coronary artery anomalies are discovered in approximately 1% of patients undergoing coronary angiography, while the incidence in autopsy series is 0.3%.^1,2 The most common anomaly is anomalously arising left circumflex artery originating from the right aortic sinus and following a retroaortic course before reaching the left atrio-ventricular groove. The exact anatomical course is typically identified on performing selective coronary angiography in the left anterior oblique (LAO) and right anterior oblique projections. However visualization of the “dot” sign on the left ventricular (LV) angiogram in the RAO view (just posterior and to the left of the posterior aortic margin) is an easy clue to the identification of an anomalously arising circumflex artery with a retroaortic course.³ We describe such a case with the classical “dot” sign on the LV angiogram; the anomalous origin of circumflex artery and its course were subsequently confirmed on selective coronary angiography. 

Case

The patient was SD, a 52-year-old female who presented with atypical chest pain and occasional palpitations on exertion.  She was hypertensive and had no other associated risk factors.  Baseline 12-lead ECG and echocardiography were normal. The patient was taken up for a diagnostic coronary angiogram via the transradial route. A LV angiogram performed in the RAO view revealed the presence of the classic angiographic “dot” sign, just posterior and to the left of the aorta, suggesting an anomalously arising circumflex artery with a retroaortic course (Figure 1). The “dot” represented the radiopaque dot formed by the contrast column in the anomalous coronary artery that appears “end on” just behind the aorta.

Selective coronary angiography revealed a normally arising left anterior descending artery (LAD) from the left aortic sinus that was free of disease; however, no vessel was visible in the left atrio-ventricular (AV) groove, leading to the suspicion that either the left circumflex artery was blocked at its ostium or most probably, arising anomalously (Figure 2a-b: LAO and RAO views). Since there was no antegrade or retrograde delayed filling of the circumflex, it was further confirmatory of the fact that most probably the vessel had an anomalous origin. This was confirmed during the right coronary artery (RCA) injection. The RCA was a dominant vessel without any disease, while the left circumflex artery arose anomalously from the right sinus, following a typical retroaortic course before reaching the left AV groove. It is interesting to note that during the initial RCA injection with the catheter slightly deeper inside the RCA ostium, the anomalously arising circumflex artery was not well visualized (Figure 3a).

However, since we were quite sure about the anomalous origin (as suspected by the “dot sign”), slight proximal withdrawal of the catheter enabled the anomalous artery to be visualized quite well (Figure 3b-c: LAO and RAO views). The anomalous circumflex artery had mild proximal disease without any critical stenosis.

Discussion

Anomalous origin of coronary arteries is often seen during coronary angiography, and anomalous origin of the left circumflex artery from the right sinus of Valsalva is one of the most frequently encountered anomalies.^4,5  Usually, the anomalous circumflex artery follows a retroaortic course, making a caudal and posterior loop in the respective RAO and LAO views. Absence of a visible vessel (i.e., the left circumflex) in the left AV groove, during left coronary injections, should alert the angiographer that either the vessel is occluded at its ostium, is congenitally atretic (a very rare phenomenon) or is arising anomalously. If, in such cases, no vessel is filling retrogradely (thus making the possibility of a blocked circumflex artery unlikely), one should actively search for anomalously arising circumflex from the right sinus of Valsalva to avoid missing the diagnosis.⁶ In our case, too, the initial RCA injection with the catheter slightly deep inside the proximal RCA did not allow the anomalous circumflex to be well visualized. Since we were aware of the “dot” sign, we were expecting the circumflex to arise anomalously and actively searched for it in the right sinus of Valsalva. Manipulation of the catheter with slight proximal withdrawal allowed the anomalous circumflex with its typical retroaortic course to be easily visualized.

During LV angiography in the RAO view, the left circumflex artery in its retroaortic course appears “end on,” leading to the appearance of the “dot” sign just behind and to the left of the posterior aortic margin. Appearance of the “dot” just anterior and to the right of the aortic root, on the other hand, is suggestive of an anomalously arising left main coronary artery from the right aortic sinus, with an inter-arterial course that is often associated with a risk of sudden cardiac death.⁷

Conclusion

Cardiologists performing diagnostic and interventional coronary procedures should be aware of and revisit the “dot” sign on the LV angiogram so as not to inadvertently miss anomalously arising coronary vessels. Cardiologists should be aware of simple clues in order to easily identify coronary anomalies.

Dr. Aditya Kapoor can be contacted at akapoor65@gmail.com.

References

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