The relationship of myocardial bridges to coronary artery dominance in the adult human heart

Abstract

Myocardial bridging is recognized as an anatomical variation of the human coronary circulation in which an epicardial artery lies in the myocardium for part of its course. Thus, the vessel is 'bridged' by myocardium. The anterior interventricular branch of the left coronary artery has been reported as the most common site of myocardial bridges but other locations have been reported. The purpose of this study was to provide more definitive information on the vessels with myocardial bridges, the length and depth of the bridged segment, and the relationship between the presence of bridges and coronary dominance. Two hundred formalin-fixed human hearts were examined.Myocardial bridges were found in 69 (34.5%) of the hearts with a total of 81 bridges. One bridge was found in 59 of these hearts and multiple bridges were observed in ten (eight with double bridges and two with triple bridges).Bridges were most often found over the anterior interventricular artery (35 hearts). Bridges were also found over the diagonal branch of the left coronary artery (14), over the left marginal branch (five) and over the inferior interventricular branch of the left coronary artery (six). Bridges were also found over the right coronary artery (15 hearts), over the right marginal branch (four) and over the inferior interventricular branch of the right coronary artery (two). The presence of bridges appeared to be related to coronary dominance, especially in the left coronary circulation. Forty-six (66.6%) of the hearts with bridges were left dominant. Forty-two of these had bridges over the left coronary circulation and four over the right coronary circulation. Seventeen hearts (24.6%) were right dominant. Eleven of these had bridges over the right coronary circulation and six over the left coronary circulation.The remaining six hearts were co-dominant with four having bridges over the left coronary circulation and two over the right coronary circulation. The mean length of the bridges was 31 mm and the mean depth was 12 mm.The possible clinical implications of myocardial bridging may vary from protection against atherosclerosis to systolic vessel compression and resultant myocardial ischaemia.

Cardiac Vasculature: Development and Pathology

“…Myocardial bridging has been described as early as 1737 (Rayman, 1737) and have been described since with a wide range of frequencies reported. In one study of 200 adult human hearts collected from autopsies, myocardial bridges were found in 34.5% with a mean length of 31 mm and a mean depth of 12mm (Loukas et al, 2006). The most common site of myocardial bridging was over portions of the left anterior descending coronary artery (LAD).…”

Evaluation of coronary dominance in pigs; a comparative study with findings in human hearts

“…These differences are possibly due to the number of samples evaluated and to the divergence of criteria used by the authors to perform these characterizations. Diverse studies conducted in human hearts similarly report a wide range of occurrence of the right coronary dominance pattern: Lower incidences within a range of the 48-70% (Schlesinger, 1940;Cavalcanti et al, 1995;Ortale et al, 2004;Kaimkhani et al, 2005;Loukas et al, 2006), medium incidences within a range of 70-84% (Blunk and DiDio, 1971;DiDio and Wakefield, 1975;Hadziselimovic, 1981;Sahni and Jit, 1990;Kalpana, 2003;Pessa et al, 2004;Ballesteros et al, 2007) and high incidences between 85 and 90% (James, 1965;Penthe et al, 1976;Nerantzis et al, 1996). No studies have been conducted in swine to typify right dominance in depth; our series found that mild right dominance (subtype I) was most common, unlike common findings in humans, where a higher incidence of moderate right dominance is described.…”

“…Literature reports in humans present frequencies of between 7-26% (Polacek and Zechmeister, 1958;Zbigniew and Mikusek, 2000;Ortale et al, 2004;Loukas et al, 2006;Ballesteros et al, 2007). A balanced circulation expresses an equitable distribution of the irrigation of the diaphragmatic aspect of the heart by the coronary arteries and their branches.…”

“…The latter pattern has not been found in most investigations carried out with this animal species (Weaver et al, 1986;Kato et al, 1987;Crick et al, 1998;Sahni et al, 2008). Left dominance has been reported in humans within a range of 2.5-36% (Schlesinger, 1940;Ortale et al, 2004;Pessa et al, 2004;Loukas et al, 2006).…”

Morphologic Relationship Between the Coronary Arteries During Fetal Development

“…A dominant artery refers to the coronary artery providing the posterior interventricular branch (PIB) which supplies the posterior ventricular septum and frequently part of the posterolateral wall of the left ventricle (Pelter et al, 2011). The RCA is usually dominant with varying incidence ranging from 55 % to 89.6 % (Angelini et al, 2002;Kim et al, 2006;Loukas et al, 2006;Altin et al, 2015;Standring et al). and right ventricle (Drake et al, 2014).…”