Anomalous Left Coronary Arteries: A Rare Case of a Single Ostium and Deadly Pathway
- Volume 17 - Issue 4 - April 2009
- Posted on: 4/3/09
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Congenital anomalies of the coronary arteries occur with a reported incidence of 0.3% to 1.3% of the population undergoing a coronary angiography procedure. The most frequently found anomalies include a circumflex artery (CX) originating with a separate ostium from the left sinus of Valsalva, or left coronary cusp; an origin of the CX taking off from the right coronary artery; or the CX arising separately from the right sinus of Valsalva, or right coronary cusp.
Representing one of the rarest forms of coronary anomalies is an origin of the entire left coronary artery (LCA) from the right sinus of Valsalva. Although these anomalies are present at birth, they are often not diagnosed until late adolescence or adulthood, due to the lack of symptoms or because the symptoms may not be recognized.
When the LCA originates from the right sinus of Valsalva, the anomalous artery pathway can present in four variants. The deadliest of pathways, with the worst prognosis, is the inter-arterial course. This is when the LCA makes its course between the aortic root and right ventricular outflow tract (RVOT). Myocardial ischemia, ventricular fibrillation, syncope, congestive heart failure and sudden cardiac death are associated with this anomaly. Most literature would agree that coronary angiography is the primary modality for discovering these anomalies. There are other modalities, including multi-slice computed tomographic angiography (CTA), magnetic resonance angiography (MRA), and transesophageal echocardiogram (TEE) that have also been used to diagnose anomalous pathways.
Presented is a case of a single ostium originating from the right sinus of Valsalva, giving rise to an anomalous left anterior descending artery (LAD) and CX, confirmed by coronary angiography and CTA.
A 44-year-old male was admitted to the Oklahoma Heart Hospital after an episode of severe chest pain and shortness of breath. He stated that the pain was progressive in nature for one week and that symptoms occurred with any exertion. He had previously been diagnosed with hypertension, treated with anti-hypertensive medication, and he was a non-smoker. The day following hospital admission, coronary angiography was performed to investigate the patient’s symptoms. Coronary angiography revealed the anomalous origin of the LAD and CX from the right sinus of Valsalva. The right coronary artery (RCA) appeared to have a normal course (Figure 1). It was evident that he had no significant coronary artery disease. The patient also underwent myocardial perfusion imaging. He exercised for 10.15 minutes on a regular Bruce protocol treadmill test, achieving 94% of maximal target heart rate (166 bpm). The patient experienced chest discomfort and mild dyspnea; however, his baseline and exercised EKG showed no ST-segment changes, blood pressure response was normal and no defects were detected on imaging.
A 64-slice CTA was performed to determine the course of the anomalous coronary arteries. The results of the CTA revealed the LAD to have an interarterial course between the aortic root and RVOT (Figure 2). The CX courses lateral and wraps posteriorly around the aorta (Figure 3 A and B). The CTA also revealed that not only had the LAD and CX originated from the right sinus of Valsalva, but that the LAD, CX and RCA had all originated from a single ostium (Figure 3 B and C). The RCA was confirmed as to having a normal course.
Congenital coronary artery anomalies are rare occurrences, with a reported incidence of 0.3% to 1.3%.1-2 However, anomalous origin of the LCA from the right sinus of Valsalva is reported in 0.09% to 0.15% of cases.3–5 The anomalous LCA can take various courses. These various proposed courses are classified according to the pathway to left (contralateral) aspect of the heart:
• Type A – Anterior: LCA turns anteriorly in front of RVOT;
• Type B – Inter-arterial: LCA lies between the aorta and RVOT;
• Type C – Septal: LCA courses through the crista supraventricularis portion of the septum;
• Type D – Posterior: LCA turns posteriorly behind aorta.6-7
The inter-arterial course has been known to have the worst prognosis and be associated with sudden cardiac death (>50%), particularly during or shortly after exercise.8 Many have hypothesized as to why this phenomenon occurs. Myocardial ischemia and cardiac death can occur due to impaired coronary flow either by coronary structure (acute angulation at the origin) or expansion of the aortic root and RVOT.9 The expansion of the roots compresses or “squeezes” the coronary artery lumen during the systolic phase, which in return, impedes flow to the heart muscle. As previously stated, during or shortly after vigorous exercise is when this compression of the artery takes place. These types of coronary anomalies are responsible for approximately 13% of sudden cardiac death in young athletes.10-11
The gold standard for discovering such anomalies is coronary angiography. However, coronary angiography provides only two-dimensional views of a vessel’s complex three-dimensional path, so the anatomic course of the anomalous vessel with respect to the aorta and RVOT may be difficult to differentiate. Furthermore, during the coronary angiography procedure, the anomalous vessel may be erroneously overlooked, or assumed to be occluded since it is not in the correct anatomical position.12 Therefore, alternative imaging methods have been suggested, such as CTA or MRA.13 The use of CTA establishes a capacity to view the heart in the necessary three-dimensional view to precisely identify coronary pathways and other potential anomalous structures. In the case presented, after having been diagnosed by coronary angiography, a 64-slice CTA was performed with 3-dimensional volume rendering to confirm the interarterial course of the LAD, posterior course of the CX and normal course of the RCA.
Once the testing is complete and the diagnosis has been made, the next step is medical management. Many patients were asymptomatic before their fatal event, with no previous diagnosis of coronary abnormalities. Therefore, when patients are identified as having this anomaly, aggressive surgical management is often recommended.14 There are currently two surgical procedures for the correction of this anomaly: re-implantation and coronary artery bypass grafting (CABG). CABG involves using the internal mammary artery, or harvested vein, as conduit and attached to the anomalous artery.15 The native artery is then ligated proximal to the grafting site, to inhibit competitive flow from the native vessel. Re-implantation involves direct placement of the coronary artery in the proper sinus of Valsalva with the native vessel or grafting material. With an inter-arterial course, the LCA has a close proximity to the aorta and RVOT. It has been argued that re-implantation is risky when dissecting and relocating this pathway with these structures nearby, and therefore, CABG is the favorable procedure.
Our 44-year-old patient has a unique case of a single ostium from the right sinus of Valsalva. What makes this case exceptional is that there are separate anomalous courses for the LAD and CX. Few clinical details concerning patients with both of these anomalous pathways are available in literature, which makes this case extremely rare. Due to the severity of this patient’s anomaly, the best surgical decision, with the best prognosis, is CABG. This patient underwent a successful, single-vessel coronary bypass of the left internal mammary artery (LIMA)-to-LAD at the Oklahoma Heart Hospital a few days after discovery. He is currently doing well.
We report this case because of the uniqueness and rarity of this patient’s congenital anomaly. This case demonstrates the need for angiography and CTA in establishing a diagnosis and treatment course. Special care should be taken when evaluating young individuals and athletes with chest pain resembling angina, since sudden death can occur with an anomalous origin of LCA. Finally, the importance of recognizing symptoms and understanding various coronary anomalies by heath care professionals will help anticipate the needs of future patients.
All coronary angiography images and volume-rendered CTA images were produced at the Oklahoma Heart Hospital in Oklahoma City.
Travis Cooper can be contacted at firstname.lastname@example.org
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