Compression of an Anomalous Circumflex Artery due to Aortic Valve Prosthesis

This article received a double-blind peer review from members of the Cath Lab Digest editorial board.

Disclosures: The authors report no conflicts of interest regarding the content herein.

The authors can be contacted via Dr. Vishal Mundra at mundravishal@hotmail.com.

Introduction

Anomalous origin of circumflex artery is one of the most common incidental findings during cardiac catheterization. The incidence has been described to vary from 0.67 to 1.5% amongst various reports.^1-2 Although it has a benign clinical course, it is prudent to identify this abnormal vessel during valve surgeries, as its retro aortic course may warrant special technical considerations during surgery.³ Herein, we describe a case of a patient who had a myocardial infarction due to compression of a retro aortic anomalous circumflex artery from a prosthetic aortic valve. 

Case 

A 69-year-old male patient had severe aortic stenosis with a bicuspid aortic valve, for which he underwent bio-prosthetic aortic valve replacement (23 mm Magna Ease bovine, Edwards Lifesciences). A pre-operative cardiac catheterization showed no evidence of coronary artery disease. He had a left dominant circulation, and the left circumflex arose anomalously from the right sinus of Valsalva and had a retro aortic course (Figure 1). At the time of valve replacement, a coronary artery bypass with a saphenous vein graft to 1st obtuse marginal (SVG to OM1) was also performed. The circumflex artery was bypassed due to concerns of compression from the prosthetic valve. The patient’s post op course was uneventful and he was discharged home. 

Three months later, he presented to the emergency department (ED) for severe, left-sided chest pain. Cardiac enzymes showed very mild elevation of troponin to 0.31 ng/mL. An electrocardiogram (EKG) showed sinus bradycardia and ST depressions in the lateral and inferior leads. A repeat EKG, done a few hours later, showed persistent ST depressions. He had transient relief with nitroglycerin in the ED. 

Due to persistent chest pain, the patient was taken for emergent cardiac catheterization (Figures 2-3). His coronary angiogram showed a 30% mid stenosis in the left anterior descending coronary artery (LAD). The right coronary artery (RCA) was a small and non-dominant vessel, with mild irregularities. A dominant left circumflex had an anomalous origin from the right coronary cusp and had a 100% mid vessel occlusion with TIMI-1 flow. This lesion was the culprit for patient’s myocardial infarction. The SVG to OM1 had a severe, diffuse 99% stenosis in the mid segment, with TIMI-1 flow.

Successful percutaneous coronary intervention of the left circumflex with thrombectomy was performed and two overlapping Xience drug-eluting stents (Abbott Vascular) were placed (Figure 4). The compression could be seen clearly in the angiograms after the first stent was deployed. Therefore, a second stent to cover the segment that was being compressed was placed. Excellent angiographic results and zero residual stenosis with TIMI-3 flow were obtained (Figure 5). Post intervention, the patient was symptom free and discharged home successfully. 

Discussion

In this case, an anomalous circumflex was bypassed due to concerns for compression of the artery due to the prosthetic valve. The patient’s bypass graft probably did not mature due to brisk, competitive flow from the native circumflex, which was angiographically normal. The native circumflex did have acute thrombosis, most likely from compression due to the prosthetic aortic valve. 

An anomalous circumflex artery may have a separate origin from the sinus, may share an origin with the right coronary artery, or may arise as a branch from the right coronary artery. This may pose some angiographic difficulties due to selective visualization. Multiple detector computed tomography (MDCT) has been described as one of the most accurate diagnostic modalities in such cases.⁴ Patients undergoing aortic valve repair can undergo injury to the circumflex artery due to ligation of coronary structure with sutures, laceration, or dissection or compression due to the valve prosthesis. Sudden cardiac death has also been reported due to compression by the valve ring. We believe that compression due to the valve prosthesis, readily visualized on catheterization, was the mechanism of injury in our patient. Some have proposed an undersized prosthesis, complete mobilization of the artery, and coronary artery bypass graft to the circumflex in order to circumvent this problem.⁵ 

In this case, successful bypass of an anomalous circumflex artery at the time of valve replacement due to concerns of compression did not prevent thrombosis of this anomalous vessel. However, it was managed successfully with percutaneous coronary intervention. The patient does remain at risk for another adverse outcome due to his anatomy, but has remained symptom free since hospital discharge. He continues in follow-up and a surveillance catheterization has been planned. It remains to be seen if the stents will be able to prevent any future compression of the anomalous artery. 

References

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2. Wilkins CE, Betancourt B, Mathur VS, Massumi A, De Castro CM, Garcia E, Hall RJ. Coronary artery anomalies: A review of more than 10,000 patients from the Clayton Cardiovascular Laboratories. Tex Heart Inst J. 1988;15: 166-173.
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