Coronary artery anomalies: classification and ECG-gated multi-detector row CT findings with angiographic correlation

Does the myocardial bridge protect the coronary from atherosclerosis? A comparison between the branches of the dual-left anterior descending coronary artery type 3: an autopsy study

OBJECTIVE

The best way to prove the protective role of myocardial bridges in the development of atherosclerotic changes in portions of the coronary beneath the bridge is to compare the morphological changes of the walls of the coronaries with and without a myocardial bridge, in those who have a so called 'dual left anterior descending coronary artery (dual LAD) type 3'.

METHODS

A prospective autopsy study was performed over a 12-year period and approximately 3000-3500 hearts were examined, in order to establish the presence of a dual LAD type 3.

RESULTS

A total of 10 such cases were observed and further analysed. The group entirely consisted of men, who were of an average age of 62.1 ± 20.4, and whose age ranged from 24 to 86. It could be assumed that both the short and long LAD artery were exposed quite equally to all major non-modifiable and major potentially controllable factors for atherosclerosis. Consequently, the degree of severity of atherosclerosis in the short and long dual LAD artery, as well as the difference between degrees, depends only on the presence of a myocardial bridge. This difference increased with the age of the deceased (Spearman's correlation coefficient ρ = 0.695, P = 0.026).

CONCLUSION

If the observed subject was older, the atherosclerotic changes were more prominent and severe in the short rather than in the long dual LAD. The protective role of the myocardial bridge has been established more accurately than has been found in other studies; however, this didn't mean that atherosclerosis was absent in intramyocardial course of coronary artery, but it was less prominent.

Malignant anomalous left coronary artery associated with acute coronary syndrome and subsequent post-operative secondary stenosis of the reimplanted anomalous left coronary artery

We present a case of a 14-year-old boy who presented with symptoms resulting from an anomalous left coronary artery. He underwent corrective surgery to reimplant the left coronary artery into the left coronary sinus. After 3 months, he developed new symptoms. On further investigation, a tight ostial stenosis of the left coronary artery was observed and the patient underwent left internal mammary artery to left anterior descending coronary artery bypass graft. This case showcases the importance of multi-modality imaging in the diagnosis of coronary artery anomalies and potential post-surgical complications.

An anomalous configuration of coronary artery: a cadaveric study

Anatomical variations in relation to coronary artery and its branches will help cardiac surgeons for refining imaging techniques and coronary artery bypass grafting. A heart was detected with multiple anomalies of coronary arteries in a cadaver. The anomalies of coronary arteries in terms of origin, number of ostia, courses, and presence of myocardial bridges were described, and related clinical implications were highlighted in the present study. The knowledge of variant anatomy may be of paramount importance to anatomists for variant anatomy and to cardiac surgeon for proper diagnosis and treatment of cardiac ailments including radiologists to refine image interpretation.

Myocardial bridging: what have we learned in the past and will new diagnostic modalities provide new insights?

The clinical significance of myocardial bridging has been a subject of discussion and controversy since the introduction of coronary arteriography (CAG) in the early 1960s. More recently computed tomography coronary angiography (CTCA) has made it possible to visualise the overlying muscular bands and appears to have a higher sensitivity for detecting myocardial bridging than CAG. Combining CTCA with invasive techniques such as CAG should make it possible to improve our understanding of the pathophysiology of myocardial bridging and to provide answers to hitherto unresolved questions. This paper critically reviews the outcomes of previous studies and defines remaining questions that should be answered to optimise the management of the presumably fast growing number of patients in whom a diagnosis of myocardial bridging has been made.

Role of computed tomography coronary angiography in the management of coronary anomalies

Congenital abnormalities of coronary arteries are an uncommon cause of sudden cardiac death and are difficult to detect at coronary angiography. We describe two patients with acute coronary syndrome and non-occlusive coronary artery disease in which a 64-multidetector computed tomography (MDCT) coronary angiography showed the presence of a malignant coronary anomaly. Sixty-four-MDCT with the possibility of 3D reconstructions allows for easier diagnosis of coronary anomalies and provides essential details necessary for operative intervention.

Malignant anomalous right coronary artery detected by multidetector row computed tomography coronary angiography

We report a case of an anomalous origin of a right coronary artery from the left coronary sinus with an inter-arterial course, between the aorta and the main pulmonary artery. This variant has been called malignant because of its association with sudden death, especially in young asymptomatic athletes. Although these variants are rare, knowledge of cross sectional anatomy of the coronary arteries and their variants is critical, especially because some variants are associated with sudden death.

Prevalence of Congenital Coronary Artery Anomalies and Variants in 2697 Consecutive Patients Using 64-Detector Row Coronary CTAngiography

BACKGROUND

Coronary artery anomalies are not common, but could be very serious.

OBJECTIVES

This study determines the frequency of coronary anomalies and normal variants by multi-detector-row computed tomography (MDCT).

PATIENTS AND METHODS

The results of cardiac MDCT study in 2697 consecutive patients were analyzed retrospectively. Acquisition was performed by a 64-detector row CT machine. Imaging results were assessed by experienced radiologists.

RESULTS

Myocardial bridging was by far the most frequent coronary variant (n = 576, 21.3%). Eighty-three subjects (3.1%) showed other coronary anomalies and variants. Anomalies of origination and course of the left main coronary artery (LMCA) were detected in 1.09% of the subjects. The frequency of these anomalies in the right coronary artery (RCA), left circumflex artery (LCx), left anterior descending artery (LAD), posterior descending artery (PDA) and obtuse marginal (OM) artery were 1.24%, 0.33%, 0.1%, 0.07% and 0.03%, respectively. The single coronary pattern was seen in 0.18% and coronary fistulas in 0.07%.

CONCLUSION

Based on the fact that coronary CT-angiography using MDCT can display different coronary anomalies, this study shows similar results to other reports on the subject. Future advances in the performance of CT machines will further improve the quality of CT-based cardiac imaging.

Identifying, characterizing, and classifying congenital anomalies of the coronary arteries

The clinical manifestations of coronary artery anomalies vary in severity, with some anomalies causing severe symptoms and cardiovascular sequelae and others being benign. Cardiovascular computed tomography (CT) has emerged as the standard of reference for identification and characterization of coronary artery anomalies. Therefore, it is important for the reader of cardiovascular CT images to be thoroughly familiar with the spectrum of coronary artery anomalies. Hemodynamically significant anomalies include atresia, origin from the pulmonary artery, interarterial course, and congenital fistula. Non-hemodynamically significant anomalies include duplication; high origin; a prepulmonic, transseptal, or retroaortic course; shepherd's crook right coronary artery; and systemic termination. In general, coronary arteries with an interarterial course are associated with an increased risk of sudden cardiac death. Coronary artery anomalies that result in shunting, including congenital fistula and origin from the pulmonary artery, are also commonly symptomatic and may cause steal of blood from the myocardium. Radiologists should be familiar with each specific variant and its specific constellation of potential implications.

Absent left main with anomalous origin of all three coronary arteries from left aortic sinus: a previously undescribed combination of coronary anomalies

Coronary artery anomalies resulting in all three coronary arteries arising separately from single sinus of Valsalva is very rare. We report a patient with two coincidental coronary anomalies: absent left main with left anterior descending, and left circumflex arteries arising separately from left sinus of Valsalva along with anomalous origin of right coronary artery from left sinus of Valsalva. Computed tomography angiogram and conventional coronary angiogram showed anomalous right coronary artery from left sinus with an interarterial course, but with no significant lesions. However, there was significant stenosis of left anterior descending and circumflex arteries that was treated with angioplasty and stenting. To the best of our knowledge, absent left main with all three major coronary arteries arising separately from left aortic sinus has never been reported previously.

[Role of multidetector CT scan in the diagnosis of congenital coronary artery anomalies with inter-aortopulmonary course: about two cases and literature review]

Coronary anomalies are a rare entity. The gold standard remains the coronary angiogram. However, the identification of the origin and the course of aberrant coronary arteries using angiography may be difficult. We report two cases regarding two patients who underwent coronary angiography in order to evaluate coronary heart disease. In the first case, angiography has shown a left anterior descending artery (LAD) originating from the right anterior sinus. A multidetector CT scan (MDCT) showed an inter-aortopulmonary course of the LAD. In the second case, selective catheterization of the right coronary artery could not be done. A MDCT scan was performed. An abnormal origin of the right coronary artery was detected. It originates from the left sinus with a separate ostium of the left main coronary artery. This artery had an inter-aortopulmonary course. The 64 MDCT scan can be useful as a complementary tool for the diagnosis of coronary artery anomalies. Detection of the inter-aortopulmonary course is essential, since this situation will require surgical treatment to avoid sudden cardiac death.

Imaging of congenital coronary artery anomalies

Imaging of the coronary arteries is an important part of the evaluation of children with congenital heart disease and isolated congenital coronary artery anomalies. Echocardiography remains the main imaging modality and is complemented by MRI and CT angiography in the older or difficult-to-image child. We review echocardiography, MRI, and CT angiography for coronary artery imaging, with emphasis on techniques. The clinical implications of isolated congenital coronary artery anomalies are also addressed, along with a discussion about the current consensus on optimal management of these anomalies.

Non-coronary cardiac findings and pitfalls in coronary computed tomography angiography

Non-coronary incidental findings are not rare. Kirsch et al found 67% non-coronary abnormalities with coronary computed tomography angiography (CCTA). Radiologists are expected to identify the extracoronary, intra- and para-cardiac anatomical structures and distinguish them from pathologic processes in CCTA. We have reviewed 2000 CCTA studies done at our institution with 64-MDCT. This pictorial essay presents case studies of non-atherosclerotic cardiovascular findings to recognize cardiac anatomic structures and how to distinguish them from pathologic processes. Correct interpretation of benign, clinically insignificant findings is crucial to avoid unnecessary additional imaging tests.

Anomalous origination of a coronary artery from the opposite sinus

Anomalous origination of a coronary artery from the opposite sinus (ACAOS) is estimated to be present in 0.2-2.0% of the population. In the majority of individuals, ACAOS has no hemodynamic or prognostic implications, but in a minority of cases, typically where the anomalous coronary artery takes an interarterial course to reach its correct myocardial territory, it can precipitate ischemia and sudden cardiac death (SCD). With the growing use of CT coronary angiography (CTCA) in the investigation of ischemic heart disease, we can expect increasing rates of incidental detection of this anomaly. Although CTCA and magnetic resonance coronary angiography can effectively characterize these lesions anatomically, they fail to describe and quantitatively assess the basic defect that leads to coronary insufficiency, such as mural intussusception. The key challenge lies in the identification of which patients are at risk of SCD and, therefore, who should be offered corrective surgical or (potentially) percutaneous intervention. Conventional, noninvasive stress testing has limited sensitivity, but emerging, invasive stress tests, which utilize intravascular ultrasonography and measurements of fractional flow reserve, show the potential to provide more-accurate hemodynamic and prognostic assessment.

Congenital anomalies of coronary arteries: Diagnosis with 64 slice multidetector CT

OBJECTIVE

Congenital coronary artery anomalies are generally incidental, uncommon and asymptomatic. Some can cause severe potentially life threatening symptoms. The common mode of studying the coronary arteries is Conventional Coronary Angiogram. ECG-gated-multidetector CT is a non invasive modality. The objective of our study was to identify rare congenital coronary artery anomalies and discuss their clinical significance.

MATERIAL AND METHODS

A total number of 900 MDCT coronary angiograms were carried out at our institution between the period of April 2006 and October 2010. Patients with coronary artery anomaly constituted the subject of study.

RESULTS

The incidence of anomalous anatomical origin and course of the coronary arteries in our study was 1.55%. Hemodynamical significance was seen in five patients. 3 cases of single coronary artery originating from right coronary sinus were seen. 1 case of anomalous left coronary artery arising from main pulmonary artery was seen. 4 cases of anomalous RCA arising from left aortic cusp, 6 cases of absent LMCA with separate origin of LAD and LCX were seen.

CONCLUSION

Multidetector row CT is a noninvasive modality in cardiac imaging. It provides superior resolution of coronary tree and its variant. No projectional vascular overlap is seen. Various postprocessing techniques outclass catheter angiography imaging. Definition of ostia and proximal course of the coronary arteries by Multidetector CT is better than catheter angiography.

[Diagnosis of atresia of the main left coronary artery using 320-detector volumetric cardiac computed tomography [corrected]]

The congenital absence of the left coronary trunk is one of the rarest anomalies of the coronary artery. We present a case in which this anomaly was suspected at cardiac catheterization and confirmed at volumetric cardiac computed tomography (CT) with a single heart beat.

Imaging the heart-lung relationships during a chest computed tomography examination: is electrocardiographic gating the only option?

Before the advent of fast-scanning multidetector-row computed tomography (CT) technology, thoracic CT studies were exclusively used for the morphologic assessment of thoracic organs, as the concurrent examination of the heart was hampered by image degradation from cardiac motion artifacts. The introduction of fast rotation speed and dedicated cardiac reconstruction algorithms has opened new possibilities for chest imaging, starting with the possibility to integrate cardiac morphologic and functional information into a diagnostic CT scan of the chest. Initiated with 16-slice multidetector-row CT, this concept of integrating morphology and function has been further simplified with 64-slice CT scanners, thus allowing radiologists to provide vital information in the management of patients with a wide variety of acute or chronic respiratory disorders. Because this CT technology offers the possibility of generating high-resolution and motion-free images of the coronary arteries, evaluation of the coronary arteries during CT examinations of the chest should further widen the clinical applications of CT for respiratory patients, keeping in mind that cigarette smoking is a shared risk factor for both impaired lung function and cardiovascular events. The recent advent of high temporal resolution and high pitch modes with dual-source CT simplifies the concept of integrated cardiothoracic imaging, introducing non-electrocardiographic-gated coronary artery imaging. The purpose of this article is to review the successive approaches of these redefined borders of thoracic imaging.

Prevalence of anomalous origin of coronary artery detected by multi-detector computed tomography at one center

BACKGROUND

Anomalous origin of coronary artery (AOCA) has been described by coronary angiography or autopsy. However the actual prevalence of such abnormalities is unknown. Multi-detector computed tomography (MDCT) offers the possibility to visualize AOCA non-invasively. The purpose of this study was to report the prevalence AOCA by MDCT.

METHODS AND RESULTS

In 5869 consecutive subjects who underwent coronary MDCT (Aquilion 64, Toshiba Medical Systems Corporation, Otowara, Japan) at one center, the prevalence of AOCA was 89 (1.52%) patients. The most common abnormality (33 cases, 0.56%) was the origin of the coronary artery or branch from the opposite or non-coronary sinus. The right coronary arteries (RCA) arising from the left coronary artery sinus (LCS) was observed in 27 cases (0.46%). Vascular cross-sectional area of such RCA arising from LCS was significantly smaller in 11 patients with angina than in 10 patients without symptoms [3.02 (1.68-7.67) mm² vs 5.93 (2.54-12.04) mm² p < 0.05]. The left coronary artery arising from the non-coronary sinus was observed in 2 cases (0.03%), and the left anterior descending coronary artery (LAD) or left circumflex coronary artery (LCX) arising from the right coronary sinus was observed in 4 cases (0.07%). Single coronary arteries were found in 5 cases (0.09%). Fifteen patients (0.26%) presented multiple coronary ostia, all of 15 (0.26%) had the LAD and LCX separately arising from the left coronary sinus. High take off was found in 36 cases (0.60%).

CONCLUSION

MDCT can accurately detect and characterize the type of AOCA.

Incidence of anomalous origin of coronary artery in 1879 Chinese adults on dual-source CT angiography

Background and Objective. Dual-source CT (DSCT) has been used to detect coronary artery anomalies. The purpose of this study was to assess the incidence of anomalous origin of the coronary artery in Chinese adults. Methods. We summarised all patients who underwent DSCT coronary angiography (CTCA) from December 2006 to February 2008, and data of anomalous origin of the coronary artery in Chinese adults were recorded. Results. 1879 patients underwent CTCA during that period; 24 patients with an anomalous origin of the coronary artery were detected, giving an incidence of 1.3%. Fifteen patients had an anomalous origin of the right coronary artery (12 from left coronary sinus, 3 high takeoff), eight patients had an anomalous origin of the left coronary artery (LCA from posterior sinus of Valsalva in three cases, LCX from the right coronary sinus, LCX from RCA, high takeoff, LCA from right coronary sinus, and single coronary artery in one case, respectively), and one patient had an anomalous origin of both coronary arteries (high takeoff). Conclusion. The incidence of anomalous origin of the coronary artery in Chinese adults in this study is 1.3%. DSCT can clearly visualise the anomalous origin and course of the coronary artery and is a useful screening modality. (Neth Heart J 2010;18:466-70.).

Imaging of coronary artery anomalies

Coronary artery anomalies (CAA) are uncommon congenital variations in coronary anatomy, occurring in 0.2% to 1.2% of the general population, the majority of which are detected incidentally and have little clinical significance. A minority of CAA, primarily due to an interarterial course, is clinically significant, and may present with symptoms of myocardial ischemia, malignant ventricular arrhythmias, and even sudden cardiac death. Until recently, CAA were primarily detected at catheter coronary angiography. With recent advances in multidetector computed tomography (CT) technology and the use of electrocardiographic gating, coronary CT angiography provides an exquisite omnidimensional display of the anomalous coronary arteries and their relation to the adjacent structures noninvasively, and is the diagnostic test of choice. Understanding CAA morphology and clinical significance of CAA is important for establishing a diagnosis, and is essential for appropriate patient management and treatment planning.

Clinical applications of cardiac CT angiography

ECG-gated multislice CT provides a cost-effective, non-invasive technology for evaluation of the coronary arteries, as well as for additional clinical applications, which require morphological assessment of the heart and adjacent structures with simultaneous evaluation of the coronary circulation.The excellent negative predictive value of a normal coronary CTA (cCTA) examination excludes the presence of significant coronary disease in the symptomatic patient. Triple rule-out studies provide evaluation of the aorta and pulmonary arteries without loss of image quality in the coronary circulation. The ability to visualize surrounding vascular structures along with the coronary arteries is essential in the evaluation of coronary anomalies.Cardiac CTA is useful in non-coronary applications, including evaluation of the thoracic aorta, cardiac valves and other aspects of cardiac morphology that may require surgical or percutaneous repair. Although radiation exposure is a limitation of cCTA relative to echocardiography and MRI, recent technological advances allow coronary imaging with effective doses as low as 1 mSv.Recent advances in evaluation of coronary plaque morphology as well as myocardial perfusion will allow a more complete noninvasive cardiac assessment in the future and may provide a highly effective method of cardiac risk stratification to facilitate preventive cardiac care.

Coronary artery aneurysms and ectasia: role of coronary CT angiography

Coronary artery dilatations-aneurysms and ectasia-are an uncommon and frequently unrecognized incidental finding in patients with coronary artery disease. Aneurysms and ectasia are associated with a vast group of disorders, and the evaluation and characterization of coronary aneurysms and ectasia represent a great diagnostic task with clinical and therapeutic implications. The underlying etiology is variable and includes degenerative, congenital, inflammatory, infectious, toxic, and traumatic causes. Unlike aneurysms, ectasia is more frequently seen in association with atherosclerosis or as a compensatory mechanism in those cases in which a proximal stenosis is noted in the opposite coronary artery; ectasia is also seen in some coronary artery anomalies, such as anomalous origin from the pulmonary artery, or as a result of a high-flow state, as seen in coronary artery fistulas. The diagnostic approach depends on the clinical scenario, and nowadays, noninvasive evaluation with multidetector computed tomography is possible. Imaging assessment should include evaluation of (a) the distribution, (b) maximal diameter, (c) presence or absence of intraluminal thrombi, (d) number, (e) extension, and (f) associated complications such as myocardial infarction. This article presents an overview of the definition, classification, etiology, clinical manifestations, and potential complications of coronary artery aneurysms and ectasia.

The parallel left anterior descending coronary artery

The left anterior descending artery (LADA) is defined as the vessel that travels in the anterior interventricular sulcus (AIVS) supplying septal branches to the anterior interventricular septum. Duplication of the LADA entails that two vessels are located in the AIVS. This report presents some comments regarding a case of the so called "parallel LADA" which has been erroneously recognized as dual LADA.

Identification of unexpected nonatherosclerotic cardiovascular disease with coronary CT angiography

OBJECTIVES

The aim of this study was to assess, in a general cardiology cohort screened for obstructive coronary artery disease (CAD), the effectiveness and frequency with which multidetector computed tomography (MDCT) angiography unexpectedly imaged and identified other nonatherosclerotic cardiovascular diseases.

BACKGROUND

MDCT angiography is a novel imaging strategy employed primarily to diagnose CAD that, in the course of these studies, can also potentially identify other important but previously unrecognized cardiovascular abnormalities.

METHODS

Consecutive 64-slice MDCT angiography studies were obtained in 4,543 patients with suspected atherosclerotic CAD at the Minneapolis Heart Institute, over a 29-month period (2005 to 2007).

RESULTS

Nonatherosclerotic-related cardiovascular abnormalities judged to be of potential clinical relevance were identified in 201 patients (4.4%). In 50 of these patients (1.1% of 4,543) the abnormality was previously unrecognized despite other imaging studies performed in 40%. Most common among the 50 patients were: congenital coronary artery anomalies (38%; largely right coronary artery from the left aortic sinus); ascending aortic aneurysms > or = 45 mm (22%); hypertrophic cardiomyopathy with apical left ventricular (LV) wall thickening (14%); valvular heart diseases (8%), congenital heart diseases, including ventricular septal defect (6%); pulmonary embolus (6%); as well as LV noncompaction, left atrial myxoma, and LV apical aneurysm (2% each). As a consequence of MDCT angiography findings, new management strategies were instituted in 15 of 50 patients (30%), including surgical correction of coronary artery anomalies of wrong sinus origin, ascending aneurysm graft repair, thrombolytic therapy for pulmonary embolism, and myxoma resection.

CONCLUSIONS

Approximately 1% of patients undergoing MDCT angiography for suspicion of CAD proved to have otherwise unsuspected, but clinically relevant, cardiovascular abnormalities unrelated to coronary atherosclerosis. Almost one-third of these patients had cardiovascular diseases with major clinical implications for subsequent therapy. These findings underscore the value of MDCT angiography and the importance of careful assessment of scans for the recognition of a variety of cardiovascular abnormalities.

Anomalous right coronary artery from the left coronary sinus with an interarterial course: is it really dangerous?

Anomalous origin of the right or left coronary artery from the contralateral sinus of Valsalva is often asymptomatic, but many patients, particularly young ones, present with sudden death or myocardial ischemia without symptoms. The mechanism of sudden death in this entity is unclear and has not been fully evaluated. These anomalies are rare, and many cardiologists and radiologists are unfamiliar with them. Surgical repair is recommended, especially with anomalous origin of the left coronary artery (LCA). However, there is controversy concerning the treatment of anomalous right coronary artery (RCA) with interarterial course due to its relatively high incidence and the fact that it leads to few, if any, clinical problems.

Right coronary artery arising from pulmonary trunk: assessment with conventional coronary angiography and multislice computed tomography coronary angiography

We present a case of a 59-year-old man who was admitted to the hospital because of atypical chest pain and dyspnea. Conventional coronary angiography showed an anomalous origin of the right coronary artery from the pulmonary trunk. The patient underwent multislice computed tomography in order to clarify the origin and course of the anomalous vessel. The aim of this report is to emphasize the role of multislice computed tomography as an accurate noninvasive imaging tool in the evaluation of coronary artery anomalies.

Separate origin of left anterior descending artery and left circumflex artery from left aortic sinus of Valsalva: visualization by multislice computed tomography before and after coronary artery bypass graft

A 59-year-old woman was admitted to our hospital because of atypical chest pain. Stress ECG test was inconclusive. The patient underwent contrast-enhanced 16-slice computed tomography which demonstrated the absence of left main, and separate but adjacent ostia of the left anterior descending artery (LAD) and the left circumflex artery (CX) from the left coronary aortic sinus of Valsalva and severe narrowing of their proximal tracts. Conventional coronary angiography confirmed the diagnosis. Some time later, the patient underwent coronary artery bypass graft by left internal mammary artery graft to the LAD and Y-saphenous vein bypass to the obtuse marginal branch of CX. Multislice computed tomography (MSCT) scan, 1 year later, revealed the patency of grafts. MSCT, with the aid of postprocessing techniques, is an accurate and precise, noninvasive tool for the visualization of coronary artery anatomy, identification of coronary stenoses and evaluation of coronary artery bypass grafts.

Coronary artery anomalies and clinically important anatomy in patients with congenital heart disease: multislice CT findings

In patients with congenital heart disease, coronary artery anomalies are common and have different clinical importance from individuals with structurally normal hearts. Visibility of the coronary arteries by CT has markedly improved due to high temporal resolution and ECG-synchronized data acquisition. In this article we describe current multislice CT techniques for coronary artery imaging and illustrate coronary artery anomalies and clinically important coronary artery anatomy from the point of view of congenital heart disease.