Myocardial bridges: morphological and functional aspects.

Abstract

Objective-To assess the arrangement of myocardial bridges.Design-A necropsy study of 90 consecutive hearts (56 male, 34 female).Results-Myocardial bridges, either single or multiple, were seen in 50 (55-6%) of the 90 hearts. The left anterior descending artery was the most commonly affected artery. Thirty five of the 50 hearts which contained in total 41 muscle bridges were dissected further with a magnifying glass. Two different types of muscle bridges could be identified. Thirty one of these 41 myocardial bridges were superficial, crossing the artery transversely towards the apex of the heart at an acute angle or perpendicularly. The individual ages ranged from a stillbirth to 84 years and in none was there a history of preceding established cardiac disease and death was not referrable to cardiac causes. Myocardial bridges were identified in 50 hearts. Thirty five of these hearts were examined further by hand lens dissection. Thirteen of the remaining 15 hearts, in which the left anterior descending coronary artery was directly related to a muscle bundle, were assessed histologically. After fixation, five were embedded in paraffin and 10 gum sections were cut, and four were embedded in 8% celloidin and 100 gum sections were cut.The sections were then stained by azan and resorcin fuschin and the azan and Weigert method respectively to demonstrate connective and elastic tissue. Segments of four hearts which included muscle bridges were cut at 60 ,um in a cryostat and stained by Sudan III to assess the adipose tissue interposed between the artery and the muscle bridge. The remaining two hearts were set aside for ultrastructural investigation. STATISTICAL TESTSWe used Student's t test for paired and unpaired samples with Fisher tests for variance and multiple comparison analysis. P values < 0 05 were considered significant. ResultsThirty two of the 50 hearts that contained muscle bridges came from male subjects. In 35 hearts the bridges were single, affecting solely the left anterior descending coronary artery; 10 hearts contained two muscle bridges and five hearts contained three muscle bridges. These multiple muscle bridges affected either the same vessel or different coronary arteries or their branches. Significantly longer muscle bridges were seen in the 21-50 age group than in the hearts removed from subjects 0-20 years (table 1). There was no statistical difference between the length of myocardial bridges in male and female subjects (table 2). Shorter muscle bridges were more common (table 3 and fig 1).

Ponte miocárdica: evolução clínica e terapêutica

“…Its transient nature and the dynamics of the obstruction help the differential diagnosis of fixed coronary stenoses. The left ADA is the most commonly affected artery 15 and 100% of the patients in the present study presented the isolated form of left ADA involvement. However, other arteries can be involved, such as the left circumflex artery and the right coronary artery 4 .…”

Left Circumflex Coronary Artery Bridging.

“…There is a large difference between the incidence of MBs observed in pathological series and coronary angiography series. [8][9][10] While the incidence in autopsy series has been reported to be 15% to 85%, 11) the angiographic incidence has been reported to be 0.5% to 2.5%. 12) Most of the bridges seen in pathological examinations are invisible with angiography because only the deep type of bridges may be apparent angiographically.…”

Rescue coronary angioplasty in a patient with acute myocardial infarction and myocardial bridge

“…Channer et al 11 , after a consecutive review of 1,000 coronary angiographies, found an incidence of 1.4% for MB in the ADA. Autopsy studies have shown an incidence of MB as high as 85% 2,3 . The presence of MB, which is considered a benign condition, in the ADA would be protective because it prevents the development of significant atherosclerosis in the affected area 12 .…”