Case report: a common trunk of the coronary arteries

Among the variations of the coronary arteries, the presence of a common trunk of the coronary arteries is well known [1, 11, 27]. The hitherto largest study on this topic found 1.3 % of congenital coronary artery anomalies in 126,595 patients undergoing coronary arteriography [1, 30]. Nevertheless, angiological studies reported more coronary anomalies than anatomical studies, as angiographies are performed only on patients with clinical signs [11]. Therefore, such studies are biased by selection.

Variations and anomalies of the coronary arteries are of clinical interest as unrecognized coronary variations and anomalies may lead to errors in diagnoses, and surgical problems may follow if a variant or anomalous coronary artery is excluded from perfusion during open heart surgery, or if it is unwittingly incised by the surgeon [27].

After excision from the corpse, the isolated heart was dissected in detail to isolate the coronary vessels completely. This dissection allowed for a continuous documentation.

Prior to dissection, the two coronary arteries were injected from their common origin with a mixture of a red, hardening latex and a barium sulfate solution as contrast agent. To prevent the solution from leaking out, gaps in the vessels’ walls were closed with wax. The injection solution facilitates the appropriate dissection and CT imaging of vessels.

The documentation was carried out with photographs, film sequences, and CT scans (Discovery CT750 HD, GE Medical Systems). Measurements were taken from multi-planar reconstructions of these scans. Furthermore, three-dimensional reconstructions of the vessels were calculated (Slicer Dicer©, Ver 5.2, Pixotec, LLC, Renton, WA, USA).

This case of a common trunk of the coronary arteries was found during the regular topographical dissection course for second-year students in the winter term 2014/15 in a 79-year-old woman [ID 2/056], who died in 2012 from ovarian and lung cancer. No cardiac complaints were known.

The body was donated to the Division of Clinical and Functional Anatomy of the Medical University of Innsbruck [14, 23].

The cadaver was preserved using an arterial injection of a formaldehyde-phenol solution and consecutive immersion in phenolic acid in water for about 3 months [20]. A recent analysis showed that bodies donated to our division are a representative sample of the general Austrian population at the age of death [10].

The right sinus of Valsalva gives rise to an extremely short [outer surface: 8 mm; luminal: 4 mm] common (or mixed) trunk [single coronary type II from sinus #1; 17], which immediately divides into a regular right coronary artery (RCA) and a variant left coronary artery (LCA) (Figs. 1, 2). The ostium is slightly oval (6 × 7 mm). The RCA shows a straight course for about 20 mm with a diameter of about 4 mm and then turns into the right coronary sulcus at an angle of about 55°; the sinoatrial branch leaves at a distance of about 6 mm. The LCA turns after about 10 mm (diameter 5 mm) approximately 70° upwards along the ascending aorta forming a cranial-anterior loop with a 110° bend, then runs gently curved anteriorly around the pulmonary trunk and reaches the intersection of the anterior interventricular sulcus and the left coronary sulcus, where it divides into the regular branches, the anterior interventricular branch (left anterior descending, LAD) and the circumflex branch (left circumflex, LCx). All further branching resembles a normal distribution with the posterior interventricular branch coming for the RCA. According to the Leiden convention, this anomaly could be described as 1R LCx;2- [7].

Detailed analysis of the serial CT scans revealed no further—intracardiac—anomaly of this heart.

According to Muresian [16], “the transition from ‘variation’ toward ‘anomaly’ is gradual and precise limits are impossible to be set. Anomalies should, however, be seen in the context of the heart and of the cardiovascular system: probably pure or singular anomalies do not exist (when single, the term ‘variation’ probably would be more suited).” As this case resembled a real singular situation, we would like to term this a ‘variant LCA’, whereas in the literature the terms “anomaly” and “variation” are mainly mixed with “anomaly” in favor.

The first part of the left coronary artery of this case, between its origin and its bifurcation into the LAD and LCx, resembles an intercoronary anastomosis of both the right and left conus branches. This would be the anterior part of a so-called arterial “Circle of Vieussens” [12, 13, 22] or periinfundibular route [17]. Such anastomoses are congenitally determined channels, which are prominent during fetal life and persist until about the eighth postnatal month, when they usually diminish in size [27]. A single coronary artery and an origin of both coronary arteries from the same aortic sinus have been traditionally regarded as having little clinical significance and as compatible with a long and active life [27]; especially, a preinfundibular course as described here is benign in terms of the influence on arterial flow [19]. Variant or anomalous origins and/or courses of the coronary arteries are very often found in major cardiac syndromes such as the transposition of the great arteries or a complete tetralogy of Fallot. Therefore, the formation of a common (mixed) trunk of all elementary coronary trunks can be a challenging finding in pediatric cardiac surgery. Nevertheless, our case presented a variant, preinfundibular course of two of the three elementary coronary trunks (LAD, LCx), without associated alterations of the major cardiac outflows or intrinsic modifications.

However, recognition and angiographic demonstration of such a variation assume the highest priority in a patient undergoing evaluation for direct coronary artery surgery or prosthetic valve replacement [27]. As the course of the LCA in this case shows several quite sharp angulations, these might prevent or at least impede appropriate catheterization either for angiography or (percutaneous) coronary intervention. Zaacks et al. [31] defined a segment angulation of 45° to 89° as moderate and if >90° as extremely angulated. Overall, although benign, such a case with a preinfundibular course of the LCA should be recognized before or during surgery [17].