Cardiac > Congenital > Coronary anomalies

Coronary artery anomalies:

Coronary artery anomalies can be found incidentally in 0.3-1% 0f healthy individuals [6]. These abnormalities can be hemodynamically insignificant or significant (i.e.: associated with a myocardial perfusion abnormality leading to an increased risk for ischemia or sudden death) [6]. A coronary artery that arises from the opposite sinus of Valsalva has 4 potential paths to take: A prepulmonic route (anterior to the RV outflow tract) or a retroaortic (posterior to the aortic root) path are considered benign with little risk for sudden death [10]. The other two paths are interarterial (between the aorta and pulmonary artery) and septal (through the proximal interventricular septum) [10]. Hemodynamically significant abnormalities include either the LCA or RCA arising from the pulmonary artery, an anomolous course between the pulmonary artery and the aorta (interarterial- these patients are at significantly increased risk for sudden cardiac death), myocardial bridging (on occasion), and congenital coronary artery fistula [6].

Anomalies of Origin:

1- High Takeoff:

High takeoff refers to an origin of the LCA or RCA above the level of the junctional zone between the coronary sinus and tubular part of the ascending aorta (more than one cm above the sinotubular junction [13]) [6]. A high origin of the RCA is more common than LMCA and high origin of the RCA is reorted with increased frequency in patients with bicuspid aortic valve [13]. This anomaly is not usually associated with clinical problems, but it can pose difficultly when trying to cannulate the vessels during angiography [6]. Additionally, preoperative identification of a high-origin is important in patients undergoing aortotomy as part of aortic valve surgery or ascending aortic replacement [13]. Cross clamping of the aorta below a high-origin artery may result in unsuccessful induction of cardioplegia [13].

2- Shepherd's crook RCA:

A shepherd's crook RCA occurs when the vessel takes a tortuous and high course immediately after it originates from the aorta [13]. It can be seen in about 5% of patients and it can make percutaneous interventions in the RCA difficult [13].

3- Multiple ostia/Absent left main:

Multiple ostia refer to the origin of more than one vessel from the coronary sinus.

For the left sinus, in absent left main coronary artery the LAD and LCx may arise from the sinus with no LCA, or the LCA and LCx may have separate orifices (seen in 0.4% of the population) [6,12]. This is typically a benign entity, but can be associated with a higher incidence of lft coronary dominance and myocardial bridging [12].

For the right sinus, both the RCA and conus branch may arise from the sinus- this can pose a risk to injury to the conus vessel during ventriculostomy or other maneuvers performed during cardiac surgery [6].

4- Single coronary artery

A single coronary artery is an extremely rare anomaly (0.0024-0.066% of the population) in which there is a single coronary artery arising from a single ostium on the aortic trunk [6,14]. It is most commonly found as an isolated fiding (60%), but it has also been associated with other congenital heart disorders (40%) with a higher mortality [14]. The condition may be compatible with normal life expectancy and patients may be entirely asymptomatic, however, patients are at an increased risk for sudden death if a major coronary branch crosses between the pulmonary artery and aorta [6,14]. Adverse cardiac events occur in 15% of patients before the age of 40 years [14].

The condition is classified into three groups: Group I- the solitary vessel follows the course of either a normal right (eventually traveling in the left AV groove, giving rise to the obtuse marginal branches ,and ending in the LAD) or left coronary artery (the vessel continues into the right AV groove and gives rise to the acute marginal ventricular branches) [14]. Group II- the single coronary artery either arises from the right or left coronary sinus and gives off a large transverse trunk that crosses at the base of the heart to reach the contralateral side [14]. The group is subdivided based on the route of the transverse trunk- anterior or prepulmonary (A), interarterial (B- between the aorta and pulmonary artery), and posterior or retroaortic (P) [14]. Group III- in this case, the sigle coronary artery originates from the right sinus of valsalva, with the LCx and LAD arising separately from the common trunk [14]. The LCx branch usually has a retroaortic course, whereas the LAD has an interarterial course [14].

Anomalous origin of the right coronary artery

Clinical:

Congenital coronary artery anomalies occur in approximately 0.5% to 1.5% of the general population [3]. The anomalies can occur in conjunction with complex congenital heart disease or as an isolated anomaly [3]. Approximately 20% of coronary artery anomalies produce life-threatening symptoms including arrhythias, MI, and sudden death (in up to 30% of patients, usually at a young age [9]) [4]. A coronary artery arising from the opposite aortic sinus can take each of five courses, depending on the anatomic relationship of the anomalous coronary artery to the aorta and the pulmonary trunk: (1) retrocardiac, (2) retroaortic, (3) interarterial, (4) intraseptal, or (5) prepulmonic [9]. Retrocardiac, retroaortic, intraseptal, and prepulmonic courses seem to be benign, but interarterial carries a high risk for sudden cardiac death [9]. It is speculated that arterial flow is compromised in this location due to compression of the coronary artery by the aorta and pulmonary trunk, restriction at the site of its orifice (slit-like ostium), and kinking of the vessel itself [9]. The term "intramural segment" refers to a proximal portion of an anomalous coronary artery that is contained within the wall of the aorta [15]. An intramural segment confers a higher risk for sudden cardiac death and is typically seen in association with an inter-arterial course, not ll inter-arterial vessels have an intramural segment [15].

The right coronary artery normally arises from the right coronary sinus of Valsalva [2]. It runs anteriorly between the pulmonary trunk and the auricle of the right atrium and then continues within the right atrioventricular groove [2]. There are several anomalies of the right coronary artery which can be associated with cardiac complications.

1- Anomalous origin of the right coronary artery from the main pulmonary artery: This is a rare congenital malformation. Most affected patients are asymptomatic. Symptomatic patients can present with congestive heart failure, angina, infarction, or cardiac arrest. Associated cardiac defects are reported in 40% of patients- most commonly an aortopulmonary window. Corrective surgery is recommended even if the patient is asymptomatic.

2- Anomolous origin of the right coronary artery from the left sinus of Valsalva occurs in 0.03%-0.17% of patients who undergo angiography [6]. In the most common variant, the RCA arises from the left sinus of Valsalva and then courses between the pulmonary truck and aorta (interarterial) before entering the right atrioventircular groove [2,6]. Anomalous RCA from the left sinus is three times more common than anomalous LCA from the right coronary sinus, but has a weaker association with sudden cardiac death [15]. This condition is associated with sudden death in 25-40% of patients (particularly with exercise) [2,6]. The likelihood for major adverse cardiac event (MACE) is associated with the path taken by the anomalous vessel [11]. For patients in which the RCA courses lower (between the RV outflow tract and the aorta) there is a lower likelihood for MACE and angina symptoms (this is because the RVOT contracts during systole and the vessel is less compressed) [11]. With a higher course, above the pulmonary valve, there is a greater likelihood for vascular compression between the aorta and pulmonary artery which both distend during systole [11]. Other causes for restricted coronary blood flow include an acute take-off angle of the vessel and a slit-like ostium [11]. Surgical repair is indicated when the vessel courses between the aorta and pulmonary artery with evidence of ischemia [15].

3- Anomolous origin of the RCA from the non-coronary sinus: A rare anomaly that is usually of no clinical relavance [6].

Anomalous origin of the left coronary artery

Clinical:

1- Bland-White-Garland Syndrome: Anomalous origin of the left coronary artery (LCA) from the pulmonary artery is a rare congenital anomaly accounting for only 0.25-0.5% of all congenital heart defects [5,13]. It is most commonly an isolated defect, but in 5% of cases it may be associated with other cardiac anomalies (such as ASD, VSD, and aortic coarctation) [5]. Prior to one month of age, physiologic pulmonary hypertension tends to preserve antegrade flow in the left coronary artery [5]. However, ischemia can still occur due to the low oxygen saturation within the pulmonary artery and low perfusion pressure [7]. Symptoms generally occur in infants after they are 1-2 months old (other authors indicate symptoms start in the first few weeks of life and become more severe as pulmonary vascular resistance falls [13]) due to reversal/retrograde flow in the LCA (left-to-right shunting) with resultant left ventricular myocardial ischemia, infarction, LV failure, or dysrhythmia [5,7,15]. As the pulmonary resistance falls, blood flows from the aorta to the RCA, through coronary-coronary collaterals to the LMCA, and in a retrograde fashion into the pulmonary artery (stealing blood from the myocardium) [13].

Infants typically present with failure to thrive, profuse sweating, dyspnea, and pallor [8]. The condition is one of the common causes of myocardial infarction and dilated cardiomyopathy in infants [7]. Without treatment, this anomaly most commonly results in death during early infancy (mortality rates of greater than 90% in the first year of life [7,15]), but survival into adulthood can occur if collateral coronary flow via the RCA is sufficient [8]. However, the risk for sudden cardiac death due to ischemic malignant ventricular dysrhythmia exits even in asymptomatic adult patients (sudden cardiac death occurs in 80-90% of cases) [5]. Treatment is surgical repair [5]- in infants this is done preferably using the coronary button transfer that produces the most anatomic correction and has excellent long-term results [8]. In adults, the preferred method is ligation of the LCA at its origin form the PA and placement of a CABG using the internal mammary artery or a saphenous vein graft [8]. In this syndrome, the LCA typically arises from the left inferolateral aspect of the main pulmonary artery just beyond the pulmonary valve [8].

Patients are generally noted to have an anterior wall ischemic perfusion defect and mitral insufficiency. An inferior/posterior perfusion defect may also be seen secondary to a right coronary artery to left coronary artery to pulmonary artery shunt.

2- Anomolous origin of the LCA from the right coronary sinus occurs in 0.09-0.11% of patients who undergo angiography [6]. To return to it's proper position, the vessel may travel anterior to the pulmonary artery (type 1), between the aorta and the pulmonary artery (type 2A- malignant subtype), between the aorta and pulmonary artery but with an intramyocardial course through the septum (type 2B), or posrterior to the great vessels (type 3) [12]. The vessel travels in an interarterial course (or malignant course) in up to 75% of patients and this is associated with a high risk for sudden cardiac death- particularly in young athletes (the risk for sudden cardiac death may be as high as 30%) [6,10,13]. The risk for sudden cardiac death in a middle-aged or elderly individual with an incidentally discovered anomalous vessel with an interarterial course is unclear, but is probably lower than the risk of sudden death in a younger patient [10]. Several reasons have been suggested for why the interarterial course is associated with sudden cardiac death including compression between the aorta and pulmonary artery during physical exertion and a more slit-like orifice due to the acute angle between the vessel and the aorta that results in a stenotic ostium which is more prone to occlusion [13].

Less commonly, the vessel can take a retroaortic, prepulmonic, or septal (subpulmonic) course [6]. Prepulmonic coronary arteries are particularly common in patients with terology of Fallot [13]. With a transeptal course, the anomalous coronary artery has a lower position and is located caudal to the crista supraventrciularis [13]. The vessel is usually surrounded by septal myocardium at some point and it should not have an oblong or slit-like orifice [13]. On 3D imaging, a downward dip of the transseptal artery can be seen- this is known as the "hammock sign" at conventional angiography [13]. With a retroaortic course, the artery courses posteriorly and passes in the space between the posterior aorta (the non-coronary cusp) and the interatrial septum [13]. A retroaortic course can complicate aortic valve surgery because it partially encircles the valve [13].,

3- Anomolous origin of the LCA from the non-coronary sinus: A rare anomaly that is usually of no clinical relavance [6].

 

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