Abstract
This chapter focuses on the medical and surgical management of coronary artery anomalies in the pediatric patient without other congenital heart defects. The vast majority of aberrant coronary arteries are without functional consequence and are not clinically significant. However, there are a few anomalies of which the practitioner should be aware because they may lead to ventricular arrhythmia, myocardial ischemia, left ventricular dysfunction, and, in some, sudden cardiac death. This chapter focuses on the following coronary anomalies: anomalous origin of a coronary artery from the pulmonary artery, anomalous origin of a coronary artery from the wrong sinus of Valsalva, and coronary artery fistulae.
Key Words
coronary artery anomaly, congenital heart disease, congenital heart surgery, pediatrics, cardiovascular
This chapter focuses on the medical and surgical management of coronary artery anomalies in the pediatric patient without other congenital heart defects. The vast majority of aberrant coronary arteries are without functional consequence and are not clinically significant. However, there are a few anomalies of which the practitioner should be aware because they may lead to ventricular arrhythmia, myocardial ischemia, left ventricular (LV) dysfunction, and, in some, sudden cardiac death (SCD). This chapter will focus on the following coronary anomalies: anomalous origin of a coronary artery from the pulmonary artery, anomalous origin of a coronary artery from the wrong sinus of Valsalva, and coronary artery fistulae.
Normal Coronary Anatomy
In the structurally normal heart the two coronary arteries arise from the center of the right and left aortic sinuses of Valsalva. The right aortic sinus of Valsalva gives rise to the right coronary artery (RCA), which directly enters the right atrioventricular groove and frequently terminates as the posterior descending artery. The left aortic sinus of Valsalva gives rise to the left main coronary artery (LMCA), which usually bifurcates into the left anterior descending (LAD) and circumflex coronary arteries a short distance from the origin. The LAD subsequently courses in the anterior interventricular groove, whereas the left circumflex coronary artery runs in the left atrioventricular groove ( Fig. 56.1 ). When coronary arteries arise normally, the coronary ostia are round, and the proximal portion of the coronary artery exits the aortic wall perpendicularly. More rarely, the ostium may be located in the correct sinus but somewhat eccentrically, closer to one of the valve commissures. As well, on occasion one or both coronary ostia may originate above the aortic sinuses (i.e., above the sinotubular junction). Although this particular abnormality of coronary origin is usually a benign condition, a high takeoff of a coronary artery may be relevant in the context of planned surgery to address other cardiac abnormalities.
Anomalous Origin of a Coronary Artery From the Pulmonary Artery
Anomalous origin of a coronary artery from the pulmonary artery is a rare congenital anomaly that is associated with a high risk of death in the first year of life if not diagnosed and treated appropriately. This anomaly was first described by Krause in 1865 followed by Brooks in 1885. However, it became known as the Bland-White-Garland syndrome in 1933 after Bland and colleagues reported clinical and autopsy findings of an infant who died from anomalous origin of the LMCA from the pulmonary artery.
The most prevalent form of anomalous origin of a coronary artery from the pulmonary artery is anomalous left coronary artery from the pulmonary artery (ALCAPA). Most commonly the LMCA arises from the pulmonary artery ( Fig. 56.2 ). The RCA may also arise from the pulmonary artery (ARCAPA), but this is approximately 10 times less common than ALCAPA. Very rarely, other coronaries may arise from the pulmonary artery, such as the LAD, circumflex, or both RCA and LMCA; the latter being quite rare and almost always fatal. ALCAPA is the most common cause of myocardial infarction in the pediatric population, and this diagnosis should be high on the differential if a child of any age, but notably an infant, presents with evidence of myocardial infarction or otherwise unexplained severe LV dysfunction. The incidence of ALCAPA ranges from 1 in 30,000 to 1 in 300,000 people, making up 0.25% to 0.5% of congenital heart disease diagnoses. ALCAPA is not considered an inheritable disease, and there is no racial or ethnic predilection; however, there is a 3 : 1 male to female ratio of occurrence. By 1 year of age, approximately 85% of patients will have presented with clinical symptoms of congestive heart failure, although there are rare cases of patients presenting later in childhood and even into adulthood. There is a 90% mortality rate in infancy if not quickly diagnosed and appropriately managed. Although ALCAPA usually occurs in isolation, other known associated cardiac defects include patent ductus arteriosus (PDA), ventricular septal defect (VSD), coarctation of the aorta, and tetralogy of Fallot.
Anatomy and Embryology
There are different theories regarding the embryologic development of ALCAPA. In one very early theory, Abrikossoff proposed that ALCAPA occurs when there is abnormal aorticopulmonary septation of the conotruncus. Alternately, according to Hackensellner, a persistence of the pulmonary buds, along with involution of the aortic buds that form the coronary arteries, together could lead to ALCAPA formation in utero. Most recently, Sharma et al. studied normal cardiac embryogenesis in the mouse embryo and observed that VEGF-C stimulates vascular growth near the outflow tract while a vessel-free zone directly surrounds the aorta and pulmonary artery. Coronary vessels develop around the outflow tracts but do not invade the vessel-free zone. Wild-type islet 1 gene expression levels in the embryo allow cardiomyocytes to differentiate specifically in the aortic wall, where they support vessel growth and facilitate connections between coronary vessels and luminal endothelium. The result is correctly positioned coronary artery stems on the aorta. They also demonstrated in murine models that VEGF-C –deficient hearts exhibited severely hypoplastic peritruncal vessels, resulting in delayed and abnormally positioned coronary stems. Mice heterozygous for islet 1 (Isl1) exhibited decreased aortic cardiomyocytes and abnormally low coronary artery stems. In hearts with outflow tract rotation defects, misplaced stems were associated with shifted aortic cardiomyocytes and myocardium-induced ectopic connections, including abnormal connections of a coronary artery with the pulmonary artery. These data support a model in which coronary artery stem development first requires VEGF-C to stimulate vessel growth around the outflow tract. Then, aortic cardiomyocytes facilitate interactions between peritruncal vessels and the aorta. Derangement of either step can lead to mispatterned coronary artery stems.
In ALCAPA the LMCA arises from the main pulmonary artery (MPA) but on occasion may arise from one of the branch pulmonary arteries. Although the ALCAPA usually originates from the rightward aspect of the posterior (facing) sinus of the MPA, it may also arise from the leftward portion of the posterior (facing) sinus. In ARCAPA the anomalous RCA most often arises from the anterior portion of the pulmonary artery. In ALCAPA the anomalous LMCA takes its usual course but is often much smaller in caliber, resembling a vein more than an artery. The RCA arises normally, but, notably in those who have survived infancy and are diagnosed later in childhood or adulthood, the RCA is quite dilated, and there are significant collateral branches from the RCA to the LMCA.
Pathophysiology
During fetal life there are similar systemic and pulmonary circulation pressures secondary to an unrestrictive PDA; as well, there are similar oxygen concentrations in the MPA and aorta, resulting in adequate myocardial perfusion despite the anomaly of coronary origin. At this stage there is no need for RCA collateralization to occur. After birth, in the neonatal period, the pulmonary artery resistance and pressure remains elevated, thereby maintaining perfusion of the LV myocardium through the anomalous coronary artery. Soon after birth, with the transition to postnatal circulation (systemic and pulmonary circulations in series, rather than parallel), there is a decrease in MPA pressure, pulmonary vascular resistance (PVR), and oxygen content in the pulmonary artery. With the LV being perfused with desaturated blood at a low pressure and in the face of inadequate collateral circulation from right coronary artery to left, myocardial ischemia and ventricular dysfunction result from insufficient myocardial perfusion.
At first, myocardial ischemia occurs only during periods of increased myocardial demands, for instance, when the infant is feeding or crying. Further increases in myocardial oxygen consumption with inadequate collateral circulation lead to infarction of the anterolateral LV free wall, which results in mitral valve papillary muscle dysfunction, significant mitral valve regurgitation, and LV volume overload. Flow reversal occurs from the LMCA into the pulmonary trunk during diastole due to the low PVR. If some intercoronary collaterals are present, this may set up left-to-right shunting and coronary steal. Because of this, the LV myocardium continues to be underperfused. Congestive heart failure, with elevated LV end-diastolic and left atrial pressure, is the outcome from a combination of LV systolic dysfunction, left-to-right shunt, and significant mitral valve insufficiency.
Interestingly, in the presence of another cardiac defect, such as a PDA or VSD, the pulmonary artery pressure will remain elevated, and there may be adequate LV perfusion pressure to prevent ischemia. A thorough investigation of the coronary arteries should be done before attempting surgical or catheter closure of these cardiac defects because the diagnosis will become apparent shortly after closure due to the abrupt drop in pulmonary arterial pressure, usually with a fatal outcome. Alternatively, a small number of patients develop significant collateralization. If this occurs, then perfusion of the left coronary system is maintained. However, as the PVR starts to drop, a left-to-right (coronary-pulmonary) shunt develops from the RCA to the MPA, with the LMCA acting as a conduit from the RCA to the MPA, leading to a pulmonary-coronary steal. This leads to progressive dilation of the RCA and left coronary artery systems. Patients who have LMCA ostial stenosis are somewhat protected because it reduces the coronary steal phenomenon. Although the left-right shunt is relatively small compared with overall cardiac output, it is significant because it pertains to coronary blood flow. Although children with extensive collaterals may survive past infancy, there is commonly progressive LV dysfunction. In a small number of patients the collateralization is enough to ensure adequate myocardial perfusion at rest and potentially even with exercise, and these patients may not be diagnosed until adulthood. When this occurs, the most common presentations are angina, dyspnea, palpitations, or fatigue.
Clinical Presentation
Children with ALCAPA are born healthy and often do not come to medical attention until approximately 6 to 8 weeks of age, when the physiologic consequences of the decrease in PVR become apparent. However, many infants may not be diagnosed until closer to 3 months of age, when symptoms have invariably increased in frequency and severity. Approximately 85% of infants will present with signs and symptoms of myocardial ischemia and congestive heart failure, including sweating and pain (crying or restlessness) with feeding, nursing, or stooling; tachypnea; poor weight gain; and pallor. In fact, the chest pain from myocardial ischemia may initially be mistaken for infantile colic, which may delay parents seeking medical attention.
The remainder of the patients may present in either childhood or adulthood. In childhood they come to attention due to the loud murmur of mitral regurgitation or exercise-induced symptoms. A small percentage may remain asymptomatic until adulthood, when they may present with exertional chest pain, presyncope, or syncope. These patients remain at risk of SCD. Their late presentation is believed to be due to early formation of adequate collateralization to the LV myocardium. The symptoms associated with ARCAPA are less severe, and patients generally present later in childhood or into adulthood; however, myocardial ischemia and SCD can still occur.
Physical examination of the infant with ALCAPA will likely show signs of congestive heart failure, including tachypnea, tachycardia, and hepatomegaly. The left heart is usually enlarged, often with associated mitral regurgitation. The LV precordial impulse may appear prominent and displaced inferiorly and laterally. The first heart sound is either normal or diminished (from the mitral regurgitation), and the second heart sound is normal or closely split with a loud P 2 , if pulmonary hypertension is present. An S 3 gallop rhythm is commonly present. In infants with significant mitral regurgitation a pansystolic murmur at the apex may be audible. In older children, adolescents, and adults a continuous murmur may be audible at the left upper sternal border due to continuous retrograde blood flow from the left coronary artery to the pulmonary artery, resulting from the intercoronary collateral communication. Although this may be hard to differentiate from a PDA, this murmur does not peak around the second heart sound and has a louder diastolic component when compared to a PDA murmur.
Diagnostic Imaging
Infants with ALCAPA generally have cardiomegaly on chest radiograph, especially from the enlarged left atrium and LV, with or without pulmonary venous congestion. However, this is not sensitive or specific for ALCAPA. However, the electrocardiogram (ECG) can be useful when an infant presents with congestive heart failure. There may be classic findings of an anterolateral infarct pattern with deep and narrow (>3 mm) Q waves in leads I, aVL, V 5 , and V 6 , poor R wave progression across the precordial leads, and ST-segment depression or inversion in the inferior and lateral leads ( Fig. 56.3 ). Although this pattern can be found in other causes of myocardial infarction or cardiomyopathy, if these ECG abnormalities are seen in an infant or child in congestive heart failure, the diagnosis of ALCAPA needs to be strongly considered. Certainly, any infant with dilated cardiomyopathy should be evaluated for ALCAPA, and the diagnosis should also be in the differential in older patients presenting with dilated cardiomyopathy.
Echocardiography usually demonstrates a dilated LV with global or regional hypokinesis, decreased LV function, and severe mitral regurgitation with left atrial dilation. These findings may also be seen in young patients with dilated cardiomyopathy as well as those with myocarditis. Careful attention should be paid to the origins of both coronary arteries, including the possibility of abnormal origin of the LMCA from the pulmonary artery. The short-axis view should demonstrate the coronary origins. In ALCAPA the LMCA will not be seen arising from the aorta but rather from the pulmonary artery. Color flow Doppler should reveal retrograde flow from the coronary artery to the pulmonary artery and is pathognomonic for ALCAPA. As well, in the absence of retrograde flow from the coronary artery into the pulmonary artery, ALCAPA can be distinguished from ostial atresia of the left coronary artery, because retrograde flow in both branches of the LMCA (i.e., LAD and circumflex coronaries) will be seen with ALCAPA, whereas retrograde flow in the LAD coronary along with antegrade flow in the circumflex coronary suggests LMCA atresia. Additionally, an enlarged RCA is almost always present and should raise suspicion of this diagnosis. Another echocardiographic finding is increased echogenicity (or echo brightness) of the LV papillary muscles due to infarction. Although echocardiographic imaging of coronary artery origins has improved significantly over the past several years, identifying coronary origin and course can be challenging in some cases. Therefore, if any question remains about visualization of both coronary ostia, then further evaluation is mandatory to rule out ALCAPA.
Magnetic resonance imaging (MRI) is a useful noninvasive diagnostic tool for delineating congenital coronary anomalies. Although there are case reports of using MRI in diagnosing ALCAPA, there are no case series with this anomaly. Computed tomography angiography (CTA) has been used extensively for coronary artery delineation in adults. Advantages of this technique include rapid acquisition time and high resolution, but the disadvantages include radiation exposure and the need for a slower heart rate with ECG gating, largely precluding its use in infants.
For diagnosis of ALCAPA the gold standard remains cardiac catheterization with angiography and should be performed before surgery. Cardiac catheterization in these patients will demonstrate elevated filling and pulmonary artery pressures along with a low cardiac output. In those patients diagnosed at an older age, it may show only mildly elevated pulmonary artery pressures but with normal filling pressures and cardiac output. An aortogram should be performed to delineate the coronary artery origins. The aortogram will demonstrate a dilated RCA arising normally from the aorta but no LMCA arising from the aorta. If collaterals are present, it should show blood flow from the RCA through the collaterals providing late, retrograde filling of the left coronary artery and a blush of contrast into the MPA. A step-up in oxygen saturation may be noted in the MPA in the presence of a significant left-to-right shunt from the collaterals. If any doubt remains, a main pulmonary arteriogram with distal balloon occlusion should clearly demonstrate the anomalous left coronary artery.
Treatment and Management
Medical Management.
Initial medical management of ALCAPA is stabilization, mechanical ventilation, and treatment of congestive heart failure before surgical repair. This includes diuretics, afterload reduction medications, and inotropic agents. Mechanical ventilator support may be required. Delivery of oxygen at high fraction of inspired oxygen (FiO 2 ) should be done judiciously because this may further decrease the PVR, increasing the coronary steal from the RCA to the MPA. As well, caution should be taken with aggressive afterload reduction because that may decrease RCA perfusion, which subsequently leads to decreased left coronary artery blood flow and increased ischemia. Inotropic medication should also be used judiciously because it may increase myocardial oxygen consumption, thereby worsening the ongoing ischemia due to decreased myocardial blood flow. Occasionally, mechanical circulatory support (extracorporeal membrane oxygenation [ECMO]) may be required, but this is usually in the setting of delayed diagnosis with the misconception of idiopathic dilated cardiomyopathy.
Surgical Management.
All patients diagnosed with ALCAPA should undergo surgical repair. In infants presenting with congestive heart failure, surgery should occur as soon as possible after stabilization due to ongoing risk of myocardial ischemia and death. In patients who are older and are asymptomatic, surgery can be performed electively. Because infants requiring surgery are usually critically ill, centers that perform ALCAPA surgery should have the ability to use LV assist devices and ECMO; if not, the child should be transferred to a hospital with these abilities.
The goal of surgical repair is the creation of a two-coronary system. Simple ligation of the anomalous coronary is now of historical interest only; it should not be performed. Indeed, even patients who present with severe LV dysfunction and mitral insufficiency should undergo repair that establishes two-coronary antegrade circulation because significant recovery of function may be expected and improvement in mitral regurgitation often occurs. Because the degree of mitral valve regurgitation nearly always improves after surgery, LV aneurysmectomy and mitral valve repair or replacement are rarely indicated at the time of initial procedure.
Surgical Techniques
Historically the first successful operation for ALCAPA was simple ligation of the anomalous LMCA at the pulmonary artery ( Fig. 56.4 ). The ligation prevents the left-to-right shunt, which allows perfusion of the LV through collateral vessels from the RCA. However, this procedure is no longer recommended because myocardial perfusion remains solely from the RCA and its collateralization, leading to increased risk of early mortality and late SCD events. Instead, a variety of techniques were developed to create a dual coronary artery system.
In 1968 Meyer and colleagues reported the first successful left subclavian artery–to–left coronary artery bypass. This technique is rarely used today in patients with ALCAPA ( Fig. 56.5 ). The Takeuchi operation, or intrapulmonary artery tunnel, is an alternative surgical strategy for two-vessel coronary repair of ALCAPA. Originally Takeuchi and colleagues described the creation of an aortopulmonary window and used a portion of anterior pulmonary artery wall to form the roof of a tunnel directing blood from the aorta to the abnormally placed ostium of the anomalous coronary artery within the pulmonary artery. The MPA must then be augmented with a patch of pericardium or prosthetic material. This technique, which does not involve excision and reimplantation of the origin of the left coronary artery, has been modified by constructing a baffle using a polytetrafluoroethylene (PTFE) patch rather than the flap of MPA anterior wall. The main complications of the modified Takeuchi operation include baffle leak, baffle occlusion, and supravalvar pulmonary artery stenosis. Finally, the procedure of choice for most surgeons is direct reimplantation of the anomalous coronary onto the aorta, especially as experience with coronary mobilization and transfer has increased over the years based on the arterial switch operation for transposition of the great vessels.
Coronary Artery Bypass Grafting.
Coronary artery bypass grafting is rarely used in patients with ALCAPA. In the current era, bypass grafting is usually used to create a dual coronary artery system after previous ligation or if previous repair has resulted in coronary artery stenosis or occlusion. If this technique is used, the internal mammary artery is the conduit of choice, even in neonates and infants. The saphenous vein or the left subclavian artery should not be used because of the risk of anatomic stenosis or occlusion and poor long-term results.
Direct Reimplantation.
In most patients with ALCAPA, direct reimplantation of the anomalous coronary artery onto the aorta can be performed ( Fig. 56.6 ). When the anomalous coronary ostium is in the posterior-facing sinus, the procedure is fairly straightforward. Direct implantation is possible even if the ostium is located in the nonfacing sinus by excising a large button or flap of pulmonary artery wall in continuity with the coronary artery. Such a flap of autologous tissue may be converted to a cylinder to extend the coronary artery, thus minimizing tension on the anastomosis to the aorta.
After induction of anesthesia and placement of monitoring lines, a median sternotomy is performed. Because of the risk of ventricular fibrillation from myocardial ischemia and LV dysfunction, the heart should be manipulated or disturbed as little as possible before the patient is placed on cardiopulmonary bypass. This operation may be performed using either continuous low-flow bypass with moderate hypothermia (25°C to 28°C) or deep hypothermic circulatory arrest (18°C) in very small infants. The pulmonary artery and course of the left coronary artery are visualized on the epicardial surface. If the anomalous left coronary artery originates far leftward in the posterior-facing sinus or on the anterior nonfacing sinus, direct reimplantation may be more challenging, requiring special techniques to establish connection to the aorta. An alternative technique that may be necessary if the coronary arises anteriorly from the pulmonary artery or from a branch pulmonary artery is extending the coronary artery with a tube constructed from pulmonary artery wall to allow reimplantation. The pulmonary artery can be repaired primarily with a continuous suture of 7-0 polypropylene (Prolene), or, more commonly, the pulmonary artery is repaired with a patch of autologous pericardium.
Modified Takeuchi Operation.
The Takeuchi operation, or intrapulmonary artery tunnel, is an alternative surgical strategy for repair of ALCAPA. Takeuchi and colleagues originally described creating an aortopulmonary window with a portion of the anterior pulmonary artery wall that would baffle blood from the aorta to the anomalous coronary artery ostium. Alternatively, the baffle is constructed using an expanded PTFE (Gore-Tex) patch in the modified Takeuchi operation.
Postoperative Management
The management issues expected after surgical repair are usually related to the child’s preoperative medical status, including low cardiac output, LV dysfunction, and hypotension. Care should be taken to optimize the patient’s hemoglobin level and normalize the electrolyte levels, acid-base and fluid status and provide adequate inotropic support. In those with severe cardiac dysfunction preoperatively, placement on ECMO support or use of an LV assist device may be temporarily needed. Bleeding is commonly encountered, more often in small infants and those who require mechanical support. Whenever necessary, platelets and fresh frozen plasma should be used to replace ongoing loss. Delayed sternal closure may be necessary in those patients with continued low cardiac output or bleeding issues. Cardiac dysrhythmia due to preoperative LV myocardial ischemia or infarction remains a concern, and patient should be monitored expectantly.
Outcomes.
As discussed previously, simple ligation for ALCAPA has unacceptable early and late mortality rates. In general, survival after establishment of a dual coronary system is excellent. Vouhe and colleagues from France reported on 31 consecutive patients who underwent reimplantation of the anomalous coronary. In the short term, there were 3 hospital deaths and 2 additional deaths within the first 3 months. There were no late deaths. Of the 23 who were studied at more than 1 year after repair, all had normal LV function; in the 5 who had severe mitral regurgitation preoperatively, the severity had decreased to mild or no regurgitation. The reimplanted anomalous coronary artery was patent in all patients. In another study of 23 infants who underwent ALCAPA repair, 16 underwent aortic reimplantation, and 7 underwent trapdoor flap or tubular extension technique repair. Four patients died early in the postoperative period, but LV function was improved in all of the remaining patients. However, only 1 of 5 infants with preoperative severe mitral valve regurgitation had significant improvement, and 2 patients ultimately underwent mitral valve replacement. This differs from a report by Lange and colleagues, who evaluated the long-term results of 56 patients with ALCAPA who underwent either subclavian artery anastomosis or coronary artery transfer. There was no early mortality in those who underwent repair in the current decade. Late mortality was similar in each group, with 1 patient each. At final follow-up, 95% of patients had normal LV function, and 84% had less than grade 2 severity mitral regurgitation.
Anomalous Aortic Origin of a Coronary Artery With Course Between the Aorta and the Pulmonary Artery
Anomalous aortic origin of a coronary artery (AAOCA) consists of either an anomalous aortic origin of the LMCA (AAOLCA) or the RCA (AAORCA). The anomaly of origin most often consists of an origin that is not within the expected or “appropriate” sinus of Valsalva. The proximal course of the anomalous coronary artery is important and should be determined because this largely serves to determine the clinical significance and potential risk of SCD to the patient. When the anomalous coronary courses anterior to the pulmonary artery (prepulmonic) or posterior to the aorta (posterior/retroaortic), these have generally been considered benign, although there are a couple of case reports of SCD with retroaortic AAOLCA. Additionally, the anomalous LMCA or LAD can course through the conal septum, termed intraseptal or intraconal or intramyocardial, and this is also generally believed to not be clinically significant; however, the importance of the anomalous intraseptal coronary is differentiating it from the interarterial AAOLCA. Interarterial AAORCA or AAOLCA occurs when both coronary arteries arise from, or above, the same aortic sinus with either a single ostium or two separate ostia and the anomalous coronary courses between the aorta and pulmonary artery. Several population and autopsy series have identified both interarterial AAORCA and AAOLCA as the subtypes that lead to increased risk of SCD, notably in young otherwise healthy athletic individuals, with the risk much greater with AAOLCA than AAORCA.
The prevalence of congenital coronary anomalies in the general population is difficult to ascertain. A number of studies have attempted to quantify this value, with estimates ranging between 0.1% and 1% in both the adult and pediatric populations. The differing rates are likely a combination of differing definitions of coronary anomalies, imaging modality, and patient population studied.
When looking specifically at the prevalence of interarterial AAOCA, which is the subtype of greatest clinical concern, a recent MRI study evaluating several thousand middle school children found this anomaly in 0.7% of this population, of which 0.5% were AAORCA and 0.2% AAOLCA. This prevalence of interarterial AAOCA is larger than the previously cited of 0.1% to 0.3%. In most studies, interarterial intramural AAORCA occurs three to six times more often than AAOLCA. AAOCA appears to be more prevalent in males than females at approximately a 3 : 1 ratio. Although no specific genetic abnormality has been found, there have been several reports of familial occurrences.
Anatomy
When there are two separate coronary ostia, either the RCA or the LMCA may arise from, or above, the “wrong” sinus of Valsalva with a subsequent course of the aberrant coronary artery between the aorta and pulmonary artery ( Fig. 56.7 ). The interarterial anomalous coronary artery also frequently has an intramural (i.e., shared wall with the aorta) proximal segment of varying lengths before exiting from the aorta onto the epicardium. When the two ostia arise from the same sinus, the ostium of the anomalous coronary artery is commonly elliptical and slit-like with an acute-angle takeoff. Much more rare is when there is a single coronary artery origin within or above the right aortic sinus and the single coronary artery gives rise to an LMCA or LAD that runs between the aorta and pulmonary artery, or the single coronary artery origin within or above the left aortic sinus gives rise to an RCA that courses between the great vessels. In the cases with the single coronary artery, the anomalous coronary almost always has a round orifice and does not have an intramural component when it arises from the proximal portion of the single coronary.
