Coronary artery anomaly
Normally, the initial portion of coronary arteries lies onto the external surface of the heart (epicardium) where fat deposits tend to form during life.
[2] Anomalous origin of a coronary artery from the opposite sinus are relevant on a clinical level due to a significant association with sudden cardiac death, if they are accompanied by intramural course.
[citation needed] Autonomic and/or endothelial dysfunction may occur and induce spasm and/or thrombosis at anomalous sites (and critical ischemia), although intracoronary clotting has been rarely observed.
Coronary narrowing is most likely the main process implied in ACAOS, and it may result in symptoms such as chest pain (“angina pectoris”), dyspnea (shortness of breath), palpitations, cardiac arrhythmias (heart rhythm disorders), syncope (fainting).
L-ACAOS-IM (intramural) is seen in 0.1% of young children and, among coronary anomalies, it has the highest probability of clinical repercussions, being consistently associated with sudden cardiac death following physical exercise.
Several more varieties of L-ACAOS are described: - prepulmonic (L-ACAOS-PP): origin of the LCA (or only the LAD) from the right sinus of Valsalva (RSV) with an epicardial course (on the surface of the heart) anterior to the pulmonary outflow tract - this does not usually cause stenosis nor requires intervention (benign anomaly, unless spasm occurs); - subpulmonary, infundibular or intraseptal (L-ACAOS-SP): the LCA (or only the LAD) originates from the RSV, initially runs inter-arterially (outside the aortic wall) then intramyocardially inside in the ventricular septum and finally epicardially in the anterior interventricular groove - this anomaly is considered benign since it is not associated with significant fixed degree of stenosis (but it could cause spasm); - retroaortic (L-ACAOS-RA): origin of the LCA or the only LCx from the RSV or from the RCA, running behind the aortic root and at the central fibrous mitro-aortic septum – this is considered as a benign anomaly (but it could cause spasm); - retrocardiac (L-ACAOS-RC) – LCA originates from the RCA at the atrioventricular groove - or wrap-around the apex (L-ACAOS-WA) – generally benign, unless spasm occurs.
[5] Anomalies at the mid segments include myocardial bridges, affecting >1% of the clinical population, and characterized by an intramyocardial course of coronary arteries within the muscle fibers.
Smaller fistulas are usually benign, and only severe cases can be complicated by aneurysmatic dilatation with potential thrombosis and distal embolization, volume overload or “blood steal” from arterial circulation and subsequent ischemia.
Cardiac magnetic resonance (CMR) is an excellent tool to identify coronary artery anomalies with a significantly higher diagnostic accuracy than standard echocardiography.
Assessment of severity of stenosis is best achieved by intravascular ultrasound (IVUS) imaging and it should be considered in known carriers of ACAOS-IM or that have symptoms or positive stress test results or are involved in competitive exercises.
[citation needed] Criteria for intervention in ACAOS-IM are: - symptoms of effort-related chest pain, shortness of breath, syncope or aborted sudden cardiac death (Class I, Level of Evidence A/B) and/or high-risk professional lifestyle.
- positive treadmill stress test, ideally by nuclear technology, in the correct dependent myocardial territory, in the presence of intramural course (Class I, Level of Evidence B) For special populations, e.g. athletes, treatment may be indicated with specific advice of medical experts, in the absence of the previously mentioned criteria.
PCI of R-ACAOS-IM is feasible and quite successful, but further experience is needed in L-ACAOS-IM since few cases have been treated percutaneously, while surgery is the recommended treatment in this subpopulation, at this time.
