Anomalous origin and course of the coronary arteries

Coronary Artery Anomalies in Animals

Coronary artery anomalies represent a disease spectrum from incidental to life-threatening. Anomalies of coronary artery origin and course are well-recognized in human medicine, but have received limited attention in veterinary medicine. Coronary artery anomalies are best described in the dog, hamster, and cow though reports also exist in the horse and pig. The most well-known anomaly in veterinary medicine is anomalous coronary artery origin with a prepulmonary course in dogs, which limits treatment of pulmonary valve stenosis. A categorization scheme for coronary artery anomalies in animals is suggested, dividing these anomalies into those of major or minor clinical significance. A review of coronary artery development, anatomy, and reported anomalies in domesticated species is provided and four novel canine examples of anomalous coronary artery origin are described: an English bulldog with single left coronary ostium and a retroaortic right coronary artery; an English bulldog with single right coronary ostium and transseptal left coronary artery; an English bulldog with single right coronary ostium and absent left coronary artery with a prepulmonary paraconal interventricular branch and an interarterial circumflex branch; and a mixed-breed dog with tetralogy of Fallot and anomalous origin of all coronary branches from the brachiocephalic trunk. Coronary arterial fistulae are also described including a coronary cameral fistula in a llama cria and an English bulldog with coronary artery aneurysm and anomalous shunting vessels from the right coronary artery to the pulmonary trunk. These examples are provided with the intent to raise awareness and improve understanding of such defects.

The clinical anatomy of high take-off coronary arteries

A number of criteria are used in the literature to describe high take-off coronary arteries, which can in part, explain the divide in the literature on the pathological significance of this anomaly. This study presents the anatomical variations of high take-off coronary arteries to draw attention to the possible clinical implications they may cause during angiography and other surgical procedures. The English Literature was searched to review high take-off coronary arteries. A high take-off coronary artery arising at least 1 cm in adults or 20% the depth of the sinus in children above the sinutubular junction, is considered of greater clinical relevance and was included in our meta-analysis. High take-off coronaries by other criteria was also included as part of the comprehensive review. Exclusion criteria were reports made in case studies or case reviews. The prevalence of high take-off coronary arteries in our study was 26 of 12,899 (0.202%). High take-off coronary arteries were found to originate up to 5 cm above the sinutubular junction. Right coronary arteries made up 84.46% of high take-off coronary arteries reported in the literature. Three (0.023%) cases that originated more than one centimeter above the sinutubular junction was associated with sudden cardiac death. This is a higher reported association than in studies that used other criteria for classification. It is important for clinicians to recognize the importance of correctly diagnosing high take-off coronary arteries in patients with coexisting cardiac morbidities so that suitable management plans can be developed.

Congenital coronary artery anomalies for the pathologist

Congenital coronary artery anomalies are rare. Pathologists are exposed to those in mainly two settings; in association with sudden death and usually extreme exercise in young adults, and in association with complex congenital heart disease in the pediatric and perinatal population. Pediatric pathologists, other pathologists and pathologists' assistants performing pediatric or forensic autopsies therefore need to be familiar with coronary artery anomalies.

Understanding coronary arterial anatomy in the congenitally malformed heart

With the development of three-dimensional techniques for imaging, such as computed tomography and magnetic resonance imaging, it is now possible to demonstrate the precise sinusal origin and epicardial course of the coronary arteries with just as much accuracy as can be achieved by the morphologist holding the heart in his or her hands. At present, however, there is no universally accepted convention for categorising the various patterns found when the heart is congenitally malformed. In this review, we show how, to provide such a convention, it is necessary to take note not only of the sinusal origin of the three major coronary arteries, but also the relationship of the aortic root relative to the cardiac base. We summarise the evidence showing how the proximal portions of the developing coronary arteries grow into the aortic valvar sinuses subsequent to the separation of the aortic root from the subpulmonary infundibulum. We also discuss the evidence showing that the subpulmonary myocardium is impervious to the passage of epicardial coronary arteries, and suggest that the process of septation itself plays an integral role in guiding the arteries into the two aortic sinuses that are adjacent to the pulmonary root. We then show how marriage of convenience between the epicardial coronary arteries and the aortic valvar sinuses provides a good explanation for the known variations found in the setting of transposition. We point out that it is the absence of septation that likely governs the patterns seen in the setting of a common arterial trunk.

Can we better understand the known variations in coronary arterial anatomy?

Coronary arterial anatomy is remarkably diverse. Identification of surgical risk factors, however, requires description in a uniform fashion. Such description mandates that account be given of both aortic sinusal origin and variability in aortopulmonary relationships. Currently, however, it is rare to find all this information provided either in clinical reports or published reviews. In this review, therefore, we summarize why both these features are important, emphasizing the marriage of convenience between the aortic root position within the cardiac base and the arrangement of the epicardial coronary arteries. The inductive approach accounts for all potential variations.

The prevalence of coronary artery variations on coronary computed tomography angiography

BACKGROUND

Coronary computed tomography angiography (CCTA) can delineate the coronary artery anatomy precisely. Basic knowledge of the normal coronary artery anatomy and familiarity with its common variations are essential in order to assess CCTA accurately.

PURPOSE

To determine the prevalence of coronary artery variations detected by 64-slice mutidetector CT.

MATERIAL AND METHODS

CCTA images of 2096 patients were evaluated retrospectively. Relatively unusual coronary artery morphological features that were seen in greater than 1% of the study population were classified as variations.

RESULTS

Coronary artery circulation was right dominant in 86.6%, left dominant in 9.6%, and balanced in 3.8% of patients. The conus artery arose from the right coronary artery in 83%, or directly from the aorta with a separate ostium in 17% of cases which was much more common in men than women. The sinoatrial node artery originated from the right coronary artery (65.6%) or the circumflex artery (33.7%). The atrioventricular node artery originated from the right coronary artery in 86.4% or the circumflex artery in 13.6% of cases. The left main coronary artery was shorter than 0.5 cm in 4.7% of cases and trifurcated into the intermediate artery in 31.3% of cases. A myocardial bridge was observed in 21.6%, coronary ectasia-aneurysm in 2%, dual left anterior descending artery (LAD) type 1 in 1.38%, and a variant of type 1 in 0.1% of cases. The presence of coronary atherosclerosis was higher in patients with coronary ectasia-aneurysm than the patients who did not have coronary ectasia-aneurysm (90.5% vs. 72.2%, P = 0.000).

CONCLUSION

CCTA is a non-invasive imaging modality for the depiction of variations of the coronary arteries. The incidence of coronary artery variations is high and various, and readers should be familiar and looking for these conditions during interpretation of CCTA examinations.