Myocardial bridging of the coronary arteries

Myocardial bridging is a common congenital anomaly of the coronary arteries ¹ where a coronary artery courses through the myocardium. 

Epidemiology

It is found approximately in approximately in 20-30% of adult population on autopsy studies. Incidence in in coronary angiograms is between 2-15%.

Pathology

Normally major coronary arteries follow an epicardial course course throughout their length, but in some cases segments of coronary arteries may course intramurally intramurally into the myocardium (tunnelled artery). 

Myocardial bridging may be described as:

• superficial (incomplete)
• deep (complete)

Location

Bridging is typically described for left anterior descending artery (LAD), with the mid LAD considered the most common location ⁵, however, other major coronary arteries can also be involved².

Clinical presentation

Myocardial bridging does not produce any symptoms in the majority majority of patients. However, deeper bridging (>2 mm) may cause symptoms like angina or ischemia in some patients.

Radiographic features

CT and angiography

• LAD myocardial bridging can be detected by both angiography and coronary artery MDCT
  • angiographic diagnosis is by demonstrating indirect sign called milking effect
  • coronary artery MDCT directly shows a a portion of the artery which is interamyocardialintramyocardial
  • coronary artery MDCT is often better at detecting RCA myocardial bridging
• the bridged segment often appears to be free of atherosclerosis ⁵

Treatment and prognosis

There are some reports suggesting efficacy with calcium channel blockers for symptomatic patients ³.