eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Coronary Artery Anomalies

Author: Andrew N Pelech, MD, Professor, Department of Pediatrics, Medical College of Wisconsin; Director of Cardiac Catheterization Laboratory, Cardiology Research Focus and Cardiology Database, Director of Herma Heart Center Clinical Research, Children's Hospital of Wisconsin; Chairman of Wisconsin Pediatric Cardiac Registry
Contributor Information and Disclosures

Updated: Jun 1, 2009

Introduction

Background

Knowledge of physiology, normal and variant anatomy, and anomalies of coronary circulation is an increasingly vital component in managing congenital and acquired pediatric heart disease. Congenital, inflammatory, metabolic, or degenerative disease may involve coronary circulation, and increasingly complex cardiac surgical repairs demand enhanced understanding to improve operative outcomes.

Variations in coronary anatomy are often recognized in association with structural forms of congenital heart disease. Importantly, coronary artery anomalies are a cause of sudden death in young athletes in the absence of additional heart abnormalities. Understanding the pathophysiology is important in guiding management because variations in coronary anatomy are common. Because of considerable heterogeneity of coronary vasculature, what is considered atypical, abnormal, aberrant, anomalous, accessory, ectopic, incidental, variant, or significant is often unclear. The terms anomalous or abnormal are used to define any variant form observed in less than 1% of the general population.

Normal Coronary Anatomy

The Latin term corona, or crown, aptly describes coronary arteries that supply cardiac parenchyma with nutrient blood flow. Coronary arteries (most often 2) are normally the only vessels arising immediately above the free margin of aortic valve from the ascending aorta. The name and nature of a coronary artery or branch is defined by that vessel's distal vascularization pattern or territory, rather than by its origin. The right coronary artery (RCA) most commonly arises separately from an ostium just below the sinotubular junction of the right (right anterior) sinus of Valsalva (see Media file 2).

The RCA courses in the right atrioventricular groove and provides nutrient branches to the right ventricular free wall, extending to the acute margin of the heart. The distal extent of the RCA varies and may extend posteriorly as far as the obtuse margin of the heart. In 90% of patients, the RCA supplies the posterior descending coronary artery branch at the crux of the heart, which supplies the atrioventricular (AV) node and the posterior aspect of the interventricular septum.

The first branch arising from the RCA is the conal or infundibular branch, which courses anteriorly to supply the muscular right ventricular outflow tract or infundibulum. The RCA supplies blood to the atria with a highly variable pattern of small branches. The sinus node artery arises from the proximal RCA in approximately 50% of patients. The left coronary artery (LCA) arises from the mid position of the left (left anterior) sinus of Valsalva (sinuses on either side of the point of aortic and pulmonary commissural contact) just above the level of the free margin of the aortic valve leaflet and generally below the sinotubular junction.

The left coronary ostium is usually single, giving rise to a short, common LCA trunk that branches into the left anterior descending (LAD) and circumflex (Cx) coronary arteries. The LAD courses in the anterior interventricular groove, giving rise to the anterior septal perforating branches as it extends toward the cardiac apex. Small branches may arise from the LAD and supply the anterior wall of the right ventricle. Diagonal branches arise from the LAD and course at downward angles to supply the anterolateral free wall of the left ventricle.

The Cx coronary artery courses along the left AV groove, around the obtuse margin, and posteriorly toward the crux of the heart. Should the Cx coronary reach the crux of the heart and supply the posterior descending coronary artery, the left coronary system would be termed dominant. This occurs in approximately 10% of patients. Atrial branches may arise from the Cx coronary artery and supply the sinus node in 40% of patients. Obtuse marginal branches arise from the Cx system to supply the posterolateral aspect of the left ventricle. In an estimated 70% of patients, a coronary branch (termed ramus medianus, intermedius, or intermediate branch) arises early off the left coronary system to supply an area between diagonal branches from the LAD and obtuse branches from the Cx systems.

Variability in coronary circulation

Despite the position of the heart within the chest and the position of the great arteries as they arise from the heart, aortic and pulmonary valves normally have a single point of contact, with commissural apposition at this point. Coronary arteries almost always arise normally from the "facing" sinuses of Valsalva on either side of this point of commissural contact. Coronary arteries do not normally arise from "nonfacing" or most distant sinus; however, variations in coronary anatomy are common. Variations that occur in less than 1% of the general population may be considered abnormal or anomalies.^1,2

Number and size of coronary ostia

Normally, an individual has two or, sometimes, three coronary ostia. Often, the conal branch of the RCA may arise separately from the right sinus. The Cx or LAD may, on occasion, arise directly from the aortic root. Coronary ostia are typically equal to, or larger than, the vessel they supply.

Positioning within sinuses

Coronary arteries arise more or less perpendicular to the aortic wall. Ostia are located in the middle of the sinus, just above the free leaflet margin of the aortic leaflet and below the sinotubular junction. Coronary arteries that arise ectopically usually course tangentially to the aortic wall or arise in close relationship to the commissure of the aortic valve.

Course of coronary arteries

The course of named coronary arteries is mostly epicardial, although the proximal LAD may have an intramural or subepicardial course in 5-25% of the general population. Branches of epicardial vessels generally proceed in a perpendicular course to supply myocardial arterioles and capillaries. This uniquely designed pattern of epicardial (reservoir) and intramyocardial (nutrient) supply optimizes blood flow to the heart.

Pathophysiology

The heart has a very limited capacity for anaerobic metabolism. The primary source of energy is oxidative metabolism of free fatty acids; therefore, the heart has a negligible ability to tolerate periods of ischemia, yet its capacity to extract oxygen is great (although relatively fixed), and limited degrees of hypoxemia are generally well tolerated. At rest, the oxygen requirement of the heart (8-10 mL/min/100 g) is much greater than of the skeletal muscle (0.115 mL/min/100 g). Exercise requires a 50% increase in oxygen demand primarily met by an increase in myocardial flow 3-4.5 times greater than baseline.

The pattern of coronary blood flow is unique. Epicardial coronary vessels serve as capacitance vessels, primarily filling during the period of diastole (as much as 85% of total flow), and intramural pressure and resistance to myocardial perfusion progressively increase from the outer to inner layers of the heart. Myocardial arterioles have tremendous vasodilatory reserve capacity and enable high flow and low resistance in response to exercise. Recent investigations suggest that the coronary vascular tree has a dual mechanism of vasodilatation: larger proximal vessels by endothelium-derived nitric oxide and direct stimulation of smooth muscle cell alpha2-receptors by adenosine and other metabolites.

A coronary artery with an oblique origin, intramural (within the wall of the aorta) course, or positioning between the great arteries puts the coronary arteries at risk for compression and may significantly limit the reservoir capacity of the epicardial coronary system. Comparable pressure in larger vessels creates greater wall tension and is felt to cause compression of smaller vessels that are in continuity by the Laplace law (tension = pressure X radius).

Proximal areas of significant stenosis hamper the heart's capacity to respond to increased myocardial oxygen demands. The major regulators of coronary blood flow are as follows:

• Intramural pressure
• Aortic diastolic perfusion pressure
• Myocardial metabolic rate (in turn related to heart rate, inotropic state, and systolic arterial pressure)
• Autonomic nervous system control
• Endothelial function
• Blood viscosity in response to decreased myocardial oxygen supply

Myocardial ischemia is the primary manifestation of congenital or acquired coronary artery disease (CAD).

In Coronary Artery Anomalies, Angelini comprehensively classifies coronary anomalies in (normal) human hearts as follows:³

1. Anomalies of origination and course
   1. Absent left main trunk (split origination of LCA)
   2. Anomalous location of coronary ostium within aortic root or near proper aortic sinus of Valsalva (for each artery):
      1. High
      2. Low
      3. Commissural
   3. Anomalous location of coronary ostium outside normal "coronary" aortic sinuses
      1. Right posterior aortic sinus
      2. Ascending aorta
      3. Left ventricle
      4. Right ventricle
      5. Pulmonary artery Variants:
         1. LCA arising from posterior facing sinus
         2. Cx arising from posterior facing sinus
         3. LAD arising from posterior facing sinus
         4. RCA arising from anterior right facing sinus
         5. Ectopic location (outside facing sinuses) of any coronary artery from pulmonary artery
            • From anterior left sinus
            • From pulmonary trunk
            • From pulmonary branch
      6. Aortic arch
      7. Innominate artery
      8. Right carotid artery
      9. Internal mammary artery
      10. Bronchial artery
      11. Subclavian artery
      12. Descending thoracic aorta
   4. Anomalous origination of the coronary ostium from opposite, facing "coronary" sinus (which may involve joint origination or adjacent double ostia). Variants:
      1. RCA arising from left anterior sinus, with anomalous course:
         1. Posterior atrioventricular groove* or retrocardiac
         2. Retroaortic†
         3. Between aorta and pulmonary artery†
         4. Intraseptal†
         5. Anterior to pulmonary outflow† or precardiac
         6. Posteroanterior interventricular groove†
      2. LAD arising from right anterior sinus, with anomalous course:
         1. Between aorta and pulmonary artery
         2. Intraseptal
         3. Anterior to pulmonary outflow or precardiac
         4. Posteroanterior interventricular groove
      3. Cx arising from right anterior sinus, with anomalous course:
         1. Posterior atrioventricular groove
         2. Retroaortic
      4. LCA arising from right anterior sinus, with anomalous course:
         1. Posterior atrioventricular groove† or retrocardiac
         2. Retroaortic†
         3. Between aorta and pulmonary artery†
         4. Intraseptal†
         5. Anterior to pulmonary outflow† or precardiac
         6. Posteroanterior interventricular groove†
   5. Single coronary artery
2. Anomalies of intrinsic coronary arterial anatomy
   1. Congenital ostial stenosis or atresia (LCA, LAD, RCA, Cx)
      1. Coronary ostial dimple
      2. Coronary ectasia or aneurysm
   2. Absent coronary artery
   3. Coronary hypoplasia
   4. Intramural coronary artery (muscular bridge)
   5. Subendocardial coronary course
   6. Coronary crossing
   7. Anomalous origination of posterior descending artery from anterior descending branch or septal penetrating branch
   8. Absent PD (split RCA)
      Variants:
      1. (Proximal + distal) PDs, both arising from RCA
   9. Absent LAD (split LAD). Variants:
      1. LAD + first large septal branch
      2. LAD, double
   10. Ectopic origination of first septal branch
3. Anomalies of coronary termination
   1. Inadequate arteriolar/capillary ramifications?
   2. Fistulas from RCA, LCA, or infundibular artery to:
      1. Right ventricle
      2. Right atrium
      3. Coronary sinus
      4. Superior vena cava
      5. Pulmonary artery
      6. Pulmonary vein
      7. Left atrium
      8. Left ventricle
      9. Multiple, right + left ventricles
4. Anomalous collateral vessels

† If a single, common ostium is present, the pattern is considered to represent "single" coronary artery.

Frequency

United States

A higher incidence of coronary anomalies is observed in young victims of sudden death than in adults (4-15% vs 1%, respectively). Several large studies address the frequency of minor and major coronary anomalies in different subsets of patients by varying techniques and recording methods. Angelini's comprehensive review identified an incidence of coronary anomalies in 5.6% of consecutive patients undergoing angiographic study (see Media file 1).³

Mortality/Morbidity

Many coronary anomalies are clinically silent and are recognized only at the time of autopsy. The incidence of incidental coronary anomalies at autopsy includes a single coronary artery in 0.024% and coronary arterial fistulae in 0.2%. After hypertrophic cardiomyopathy, coronary artery abnormalities are the second most common cause of sudden death in young athletes.

Race

No racial predisposition is known.

Sex

No sexual predisposition is known.

Age

Anomalous origin of the LCA from the pulmonary artery presents in early infancy. Significant coronary anomalies usually result in symptoms or sudden death in older children or young adults. Numerous incidental coronary anomalies may be detected at the time of coronary angiography in later adult life.

Clinical

History

• Manifestations of coronary artery disease (CAD) reflect myocardial ischemia and are recognized clinically as the following:
  • Myocardial dysfunction
  • Angina
  • Syncope
  • Dysrhythmia
  • Infarction⁴
  • Death
• Pediatric CAD usually presents in infancy as cardiogenic shock or later in childhood or adolescence as an activity-related phenomenon, syncope, or chest pain.
• In infants, angina may be recognized by the following symptoms:
  • Irritability
  • Diaphoresis
  • Gray or poor color in association with symptoms
  • Poor output or congestive heart failure (CHF)
• Most infants present at age 2-3 months with the following symptoms:
  • Poor feeding
  • Dyspnea
  • Wheezing
  • Periods of pallor
  • Failure to thrive
• In the older child or adolescent, anginal chest pain or syncope associated with activity is suggestive of CAD.
• Unfortunately, in a significant number of patients, symptoms may not be evident before a sudden catastrophic, presumably dysrhythmic, event.
  • Sudden death is most often associated with activity.
  • Sudden death is frequently observed in association with anomalous origin of the left coronary artery (LCA) from the right sinus of Valsalva and coursing between the 2 great arteries. In this circumstance, the coronary artery often has an oblique origin, slitlike ostia, and intramural and interarterial course.
  • Coronary ischemia is felt to arise from disturbed kinetics from oblique origin, ostial stenosis, compression of intramural course, loss of reservoir capacity, and increased myocardial oxygen demands associated with exercise.
  • Sudden death is less commonly seen in association with anomalous origin of the right coronary artery (RCA) from the left sinus of Valsalva.
  • Sudden death has also been reported in association with ostial stenosis, atresia, or hypoplasia.
  • Ventricular dysrhythmias are usually the terminal event in these circumstances.

Physical

• In infancy with coronary ischemia, patients present with signs of CHF and low output. The apex beat is diffuse with a palpable or audible third heart sound (S₃) gallop. Heart sounds are often reduced in intensity with a holosystolic murmur of mitral valve insufficiency audible at the apex. In the older child, physical examination findings vary from entirely normal (most often) to findings of cardiogenic shock caused by myocardial infarction (rare).
• Older patients with a coronary arterial fistula may present with signs of CHF, a continuous murmur, and, rarely, endocarditis.

Causes

Associated syndromes

Coronary anomalies may be commonly associated with other congenital cardiac malformations, most notably, transposition of the great arteries, tetralogy of Fallot malformation, and different forms of pulmonary atresia. Each of these topics is addressed specifically in other chapters.

• Williams syndrome Patients with Williams syndrome: (elfin facies, infantile hypercalcemia, hypoplastic teeth) may have coronary ostial narrowing as a component of supravalvar aortic stenosis characteristic of this disease. Patients with aortic valve disease commonly have variants in ostial origin. Those with varied forms of left ventricular outflow tract obstruction are at greater risk for increasing myocardial oxygen demand with limited ability to augment oxygen supply, placing them at increased risk for myocardial underperfusion.
• D-transposition of the great arteries
  • Coronary arteries in transposition of the great arteries normally arise from facing sinuses of Valsalva.
  • Variation in coronary arterial patterning is frequent, and distribution of coronary pattern, as described by Sim et al, is presented in Media file 3.⁵
    
    

    

    Thirteen patterns of origin and proximal epicardial course of coronary arteries in 255 hearts with complete transposition of the great arteries. LAD = left anterior descending coronary artery; LCA = left coronary artery; LCx = left circumflex coronary artery; RCA = right coronary artery. (Image courtesy of Excerpta Medica, Inc).

    [ CLOSE WINDOW ]

    

    Thirteen patterns of origin and proximal epicardial course of coronary arteries in 255 hearts with complete transposition of the great arteries. LAD = left anterior descending coronary artery; LCA = left coronary artery; LCx = left circumflex coronary artery; RCA = right coronary artery. (Image courtesy of Excerpta Medica, Inc).

  • Correct identification of origin and course of coronary vasculature is important for patients undergoing Jatene arterial switch procedure.
  • The presence of an intramural coronary artery course in this condition may prohibit arterial repair.
  • According to Pasquini, this anomaly may be suggested on echocardiographic study by the eccentric origin of the coronary ostia arising away from the middle third of the aortic sinus and coursing within the aortic wall (see Transposition of the Great Arteries).⁶
• Tetralogy of Fallot
  • Operative repair of pulmonary outflow obstruction often involves patching of the right ventricular outflow tract and resection of the obstructing right ventricular muscle.⁷
  • An estimated 2-9% of patients with tetralogy of Fallot have coronary arterial anomalies, possibly affecting timing or approach to operative repair. The most common anomaly is origin of the left anterior descending (LAD) coronary artery from the RCA, which then courses across the pulmonary outflow tract. This is estimated to occur in approximately 4% of patients (see Media file 3).
  • Frequently, the conus branch of the RCA is large and supplies a significant portion of right ventricular infundibular muscle. Surgical techniques to avoid transection include limited incisions, varied tunneling techniques, and perhaps conduit placement. Cardiologists must predefine these abnormalities by noninvasive or invasive study (see Tetralogy of Fallot with Absent Pulmonary Valve, Tetralogy of Fallot with Pulmonary Atresia).
• Pulmonary atresia with intact ventricular septum
  • In this condition, absence of effective egress of blood from the cavity of the right ventricle may preserve primitive embryonic sinusoidal connections to coronary vasculature, resulting in the filling of the connections from the right heart in systole and filling from the aorta in diastole.
  • These abnormal right ventricular coronary sinusoidal connections can be recognized echocardiographically and angiographically.⁸ The coronary vessel most often affected is the RCA, but the LAD system or, less frequently, the distal extent of the circumflex (Cx) coronary artery may also be affected. In addition, 70% of these coronary arteries may demonstrate severe intimal thickening, occlusion, or interruption.
  • In most cases, endocardial fibroelastosis, myocardial fibrosis, and acute myocardial infarction are observed. Optimal coronary arteriography often is required to delineate the extent of these abnormalities. Medical and surgical management strategies are varied and often ineffective (see Pulmonary Atresia with Intact Ventricular Septum).

• Search for CME/CE on This Topic »

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