This has relevance to the post on our companion images blog.
Myocardial bridging is a condition that occurs when the myocardium covers a part of the coronary artery; usually the LV covering part of the LAD, such that the artery runs through the myocardium and is subject to systolic reduction in calibre. An excellent image was published in NEJM in 2003.
The consensus regarding its significance is lacking, however there are anecdotal reports of patients with myocardial bridging presenting with acute coronary syndromes. Please see this report by Sciahbasi A et al and Low et al.
One study published by Teragawa H et al in Clinical Cardiology in 2003 shows that following intracoronary nitroglycerine, patients with bridging experience more incidents of spasm and the authors suggest that this may be a cause of related cardiac events in this group of patients.