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Anomalous left main coronary artery causing a myocardial infarction in a 14-year-old boy.

CASE

A 14-year-old boy presented with angina while running at his school. He was running his last lap when he began to experience severe, mid-sternal, non-radiating chest pain associated with severe dyspnea, weakness, dizziness, blurred vision, and a tingling sensation in his legs causing him to sit down. He continued to have chest discomfort, inability to catch his breath, and weakness. His chest pain started to resolve without intervention on his arrival at a local hospital. His past medical history revealed sickle cell trait, but he denied any prior chest pain. He had no family history of coronary artery disease.

His vital signs on arrival were within normal range. Physical exam revealed normal first and second heart sounds without murmurs, gallops, rubs, or clicks in the standing or supine position, and the remainder of the exam was also unremarkable. His serum creatine kinase (CK) was increased from 1,256 to 2,262; his CK-MB, from 7 to 199.7; and his troponin I, from 0.05 to 30.86. His initial and subsequent electrocardiogram showed ST-segment elevation with Twave inversion in the anterolateral leads. (Figures 1,2) Chest computed tomography (CT) with a pulmonary embolism (PE) protocol did not show any evidence of PE. Coronary anatomy was not visualized during this CT scan.

The patient was transferred to Ochsner Medical Center Pediatric Intensive Care Unit (PICU). Transthoracic echocardiogram (TTE) showed dyskinesis of anterior left ventricular wall and mild mitral and tricuspid regurgitation. No coronary anomalies were visualized on the TTE.

The patient was placed on aspirin and loaded with clopidogrel 300 mg before right and left heart catheterization and coronary angiography were performed. He was found to have an anomalous (anterior/superior) origin of the left main coronary artery with an intramural course within the wall of the aorta, and moderate left main stenosis.(Figure 3) Incidentally, he was found to have a patent foramen ovale, and pressures and blood oxygen saturations were normal in all cardicac chambers.

Subsequently, a CT angiogram with cardiac gating was performed using 75 ml of Omnipaque 350 and a General Electric 64 detector row CT scanner. The patient had no detectable coronary calcium for an Agatston score of zero. The right coronary artery (RCA) arose normally from the right coronary sinus and had a normal posterior descending artery (PDA) and several long posterolateral segmental arteries. The left coronary artery arose from the right coronary sinus of Valsalva and coursed between the aorta and pulmonary trunk in the wall of the aorta. The left main artery was only 1 millimeter in diameter during its interarterial course. Beyond that, the vessel returned to a normal size and divided into the left anterior descending and left circumflex arteries, which had normal calibers, distributions, and branches.

The patient subsequently underwent unroofing of the intramural left coronary artery and suture closure of the patent foramen ovale (PFO) using intraoperative cardiopulmonary bypass and cooling to 30 degrees with retrograde cardioplegia every 20-30 minutes while the aorta was cross-clamped. Intraoperatively, a slit-like orifice of the left main coronary artery was found in close proximity to the RCA ostium within the right coronary sinus of Valsalva. The left main then coursed intramurally above the commissure between the right and left coronary cusps and transversed the aortic wall before exiting posteriorly. The intramural segment of the left coronary artery was unroofed using tenotomy scissors and dilated. After the surgical correction of the intraarterial segment of the left main and suture closure of the PFO, crossclamping was removed and rewarming began, when the patient was normothermic, cardiopulmonary bypass was weaned using ionotropic support and a short run of ultrafilteration. The patient recovered uneventfully. On his post-discharge clinic visits, he has been asymptomatic.

DISCUSSION

Hobbs et al. studied 1,686 patients who were found to have anomalous arteries and distinguished lesions as being high or low risk. Of the studied anomalies, 87% were variations of the origin or distribution of the coronary arteries. Benign anomalies are listed in Table 1.2

The potentially harmful coronary anomalies warrant a discussion in more detail and include ectopic origin of the left coronary artery from pulmonary artery (PA) or the Bland-White-Garland syndrome, where a dilated RCA collateralizes blood to the left system (most commonly the LAD), which in turn fills the PA in a retrograde fashion. Even though it is extremely rare, the right coronary can arise from the pulmonary artery. There is a 95% infant mortality with anomalous origin of the left coronary artery from the pulmonary artery, with survival being dependent on intercoronary collaterals. These patients may have continuous murmurs, angina (often presenting as feeding problems in affected infants), mitral regurgitation, congestive heart failure, arrhythmias, syncope, and sudden cardiac death (SCD). Surgical repair, even in asymptomatic patients, is recommended due to the serious morbidity and mortality among these patients. (2)

Another potentially dangerous anomaly discussed by Hobbs et al. is ectopic origin of left coronary artery from the right sinus of valsalva, which could be shared with the RCA ostium. There are five anatomic variations depending on the anatomic course of the artery between the aorta and the pulmonary artery - anterior, between, septal, posterior, or combined. The septal subtype has been found to be the most common type and the most benign. In the most dangerous variant, and also the rarest subtype, the left main coronary artery courses between the aorta and PA. This anomaly could lead to angina, syncope, myocardial infarction, ventricular tachycardia, cardiac arrest, and SCD. Symptomatic patients have been found to have good results with coronary artery bypass grafts. (2)

Ectopic origin of the RCA from left sinus of Valsalva occurred in less than 0.1% of the patients with coronary anomalies in the large series by Hobbs et al. In these cases, the RCA originated anterior to left main and coursed between the aorta of the PA. Due to this path, aortic expansion during exercise can lead to occlusion and myocardial ischemia. Other symptoms can include angina, syncope, myocardial infarction, syncope, ventricular tachycardia, and sudden cardiac death. (2)

Another rare anomaly is the single coronary artery, which is usually categorized using the Lipton classification as "R" or "L" depending on the origin of the artery being the left or right sinus of Valsalva. Depending on its course, it is classified into groups I (course of RCA or left sided system), II (origin of anomalous vessel from proximal part of right or left coronary artery before crossing the base of the heart and assuming its normal position), or III (LAD and LCX arise from proximal part of RCA). Letters "A" (anterior), "B" (between), or "P" (posterior) describe the position of the anomalous vessel relative to the PA and aorta. (2,4,5)

Coronary artery fistulae causing large intracardiac shunts are mostly discovered during childhood, leading to repair. Symptoms include continuous murmur, dyspnea on exertion, exercise intolerance, right ventricular volume overload if the fistula drains to the RV, or congestive heart failure. Symptomatic patients with large fistula should undergo surgical repair or may be candidates for catheter-based intervention. (2)

Methods of detection

These anomalies may be discovered during non-invasive imaging (such as computed tomographic angiography, magnetic resonance angiography, and in some instances, transthoracic echocardiography or transesophageal echocardiography), coronary angiography, cardiac operation, and autopsy. (2,6,8) Angiography of anomalous coronary arteries can be challenging depending on the variation involved. It might be difficult to know if there is a separate origin of LAD and LCX or a very short or absent left main trunk (LMT) at times. The left anterior oblique caudal projection is the recommended view for the left coronary sinus of Valsalva. If the catheter is not positioned correctly, it can be mistakenly thought that one of the vessels is absent or occluded. (2)

Management

Previous studies have shown that intracoronary hemodynamic alterations during exercise cause ischemia in patients with coronary anomalies. For example, if a coronary artery courses between the aorta and the PA, exerciseinduced aortic and pulmonary arterial dilation could lead to ischemia due to coronary artery compression. Therefore, there is a role for stress testing to assess whether coronary anomalies cause ischemia. (9,10) If there is inducible ischemia, revascularization has been found to have a mortality benefit. (11) There is a role for coronary angioplasty that has been described in select clinical scenarios if there is coronary atherosclerotic disease in patients with anomalous coronary arteries. (12) Surgery is most frequently performed, however, when symptoms occur in the absence of atherosclerotic disease. (2,13) As in our patient, when a coronary artery arises from the opposite sinus of Valsalva, the coronary ostium is often slit-like. Although a positive stress test is useful, a negative test does not rule out a risk for sudden death.

CONCLUSION

Coronary anomalies are found in 1.3% of patients undergoing coronary arteriography can be a cause of serious morbidity and mortality, especially in younger patients. While these anomalies might be discovered incidentally, knowledge of possible variations of coronary anatomy is essential for assessing and treating patients who may or may not present with typical anginal symptoms. Some anomalies can be difficult to detect on coronary angiography or transesophageal echocardiography, and non-invasive methods of detection such as coronary computed tomographic angiography or cardiac magnetic resonance angiography often provides necessary information. It is essential to know whether the coronary anomalies are benign or high risk before making decisions about treating the patient medically, percutaneously or surgically. Both the anatomy and hemodynamic assessment of ischemia are useful in these decisions.

REFERENCES

(1.) Yamanaka O, Hobbs RE. Coronary artery anomalies in 126,595 patients undergoing coronary arteriography. Cathet Cardiovasc Diagn 1990;21:28-40.

(2.) Taylor A, Rogan K, Virmani R. Sudden cardiac death associated with isolated congenital coronary artery anomalies. Journal of the American College of Cardiology 1992;20:640-7.

(3.) Desmet W, Vanhaecke J, VroMx M, et al. Isolated single coronary artery: A review of 50,000 consecutive coronary angiographies. European Heart Journal 1992;13:1637-40.

(4.) Lipton M, Barry W, Obrez I, Silverman J, Wexler L. Isolated single coronary artery: Diagnosis, angiographic classification, and clinical significance. Radiology 1979;130:39-47.

(5.) Ing-Sh Chiu, Robert H. Anderson. Can we better understand the known variations in coronary arterial anatomy? Annals of Thoracic Surgery 2012;94:1751-60.

(6.) Giorgi B, Dymarkowski S, Rademakers F, Lebrun F, Bogaert J. Single coronary artery as cause of acute myocardial infarction in a 12-year-old girl: A comprehensive approach with MR imaging. American Journal of Roentgenology 2002;179:1535-7.

(7.) Fernandes F, Alam M, Smith S, Khaja F. The role of transesophageal echocardiography in identifying anomalous coronary arteries. Circulation 1993;88:183-4.

(8.) De Luca L, Bovenzi F, Rubini D, Niccoli-Asabella A, Rubini G, de Luca I. Stress-rest myocardial perfusion SPECT for functional assessment of coronary arteries with anomalous origin or course. Journal of Nuclear Medicine 2004;45:532-6.

(9.) Schwarza E, Hagera P, Uebisb R, Hanratha P, Kluesa H. Myocardial ischaemia in a case of a solitary coronary ostium in the right aortic sinus with retroaortic course of the left coronary artery: Documentation of the underlying pathophysiological mechanisms of ischaemia by intracoronary Doppler and pressure measurements. Heart 1998;80:307-311.

(10.) Hachamovitch R, Hayes S, Friedman J, Cohen I, Berman D. Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography. Circulation 2003;107:2900-7.

(11.) Yabe Y, Tsukahara R. Percutaneous transluminal coronary angioplasty for culprit lesions in patients with post myocardial infarction angina based on dextrocardia and anomalous coronary arteries: Case reports and methods. Angiology 1995;46:431-40.

(12.) Kafrouni G, Khan H, Wolf sen J. Single right coronary artery: Clinical and angiographic findings with surgical management. Annals of Thoracic Surgery 1981; 32:80-4.

Saima Karim, DO; Thomas Young, MD; John P. Reilly, MD; Patrick Delaney, MD

Dr. Karim is a Cardiology Fellow at Ochsner Heart and Vascular Institute in New Orleans. Drs. Young, Reilly, and Delaney are Staff Cardiologists at Ochsner Heart and Vascular Institute.

Table 1: Benign Coronary Arterial Anomalies

Type of anomaly     Origin                Course

Separate LAD        Separate LAD and      Normal
  and LCX             LCX origin from
  origin              the left sinus
                      of Valsalva

Absent LCX          No LCX origin         None

LCX origin from     LCX originates        Posterior
  right coronary      from R or right       course
  system              sinus of Valsalva

Ectopic origin      R or LM original      Normal
  of R or LM          from posterior
                      sinus of Valsalva

Ectopic coronary    Coronary artery       Normal
  origin from the     origin usually
  ascending aorta     within 2 cm of
                      ascending aorta

Intercoronary       Normal                AV branch of
  communication                             R and LCX or
                                            LAD and distal
                                            PD are contiguous

Small coronary      Normal coronary       Destination of the
  artery fistulae     origin                coronary artery
                                            to a single cardiac
                                            chamber

Type of anomaly     Main Variable           Hemodynamic
                                            significance

Separate LAD        Left main trunk         None
  and LCX             absent
  origin

Absent LCX          R supplies LCx          None
                      territory

LCX origin from     LCX origin from         None
  right coronary      right
  system

Ectopic origin      Coronary origin         None
  of R or LM          from posterior
                      sinus of Valsalva

Ectopic coronary    Origin from ascending   None
  origin from the     aorta
  ascending aorta

Intercoronary       Communication between   None
  communication       right and left
                      coronary system

Small coronary      Communication between   None
  artery fistulae     coronary artery and
                      a cardiac chamber

After Yamanaka and Hobbs. (2) LAD=left arterial descending;
LCK=left circumflex; LM=left main; PD=posterior descending;
R=right.
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Author:Karim, Saima; Young, Thomas; Reilly, John P.; Delaney, Patrick
Publication:The Journal of the Louisiana State Medical Society
Article Type:Case study
Date:Nov 1, 2013
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