ABSTRACT
Introduction: The segment of epicardial coronary artery that traverses intramurally through the myocardium and bridged by a bunch of cardiac muscle fibers is called tunneled artery or intramural artery. The band of cardiac muscle fibers passing over the tunneled artery segment is named as myocardial bridge. During angiography milking effect is observed during systole due to the external pressure of muscle fibers on the tunneled artery that leads to narrowing of vessel lumen and further ischemia. Materials & Methods: It is a prospective study performed from 2012- 2015 in cardiac centers available around Tirupati, Andhra Pradesh, South India. A total number of 2015 adult patients who underwent diagnostic coronary angiography were evaluated to detect myocardial bridges. With the informed consent the relevant data was collected from the patients and analyzed. Results: The prevalence of myocardial bridges was 3.17%. Among the 2015 patients 70.7% are males and 29.2% are females. Among 64 myocardial bridge positive cases 62.5% were male and 37.5% were female patients. Regarding coronary dominance 84% were right dominant and 14.4% were left dominant and 1.6% are balanced. The percentage incidence of myocardial bridging according to dominance was 3.01% for right dominant patients, 4.12% for left dominant patients and 3.1% for balanced dominant patients. In all the myocardial bridge positive cases they were located on the left anterior descending artery (LAD). According to diagnosis the patients with normal coronaries were 22.6%, patients with MILD CAD were 17.9%, patients with single vessel disease were 23.4%, patients with two vessel disease were 14.7% and the patients with triple vessel disease were 21.3%. The 64 myocardial bridging cases were grouped in to three groups according to their age. Incidence of double bridges was observed in 3 cases of which 66.7% males & 33.3% in females. Conclusion: These results shows that Andhra Pradesh population are with high angiographic incidence of myocardial bridges (MB’s), when compared with other population in India. We observed more lengthy bridges which may cause luminal reduction of coronary vessel and myocardial ischemia (MI), we also observed higher incidence of MB’s in male patients but systolic luminal reduction is more in female patients then in males. These observations suggest that the risk of MI will be more for the female patients with MB’s.
ABSTRACT
Introduction: Myocardial bridging is the term used when a segment of major epicardial coronary artery runs intramuscularly under the tunnel formed by fibers of myocardium that bridges instead of it’s normal or routine epicardial path. In the literature there are varying reports on clinical implications of myocardial bridges from protection against atherosclerosis to myocardial ischemia, as well as leading to infarction and sudden cardiac death. Materials and Methods: 150 adult formalin fixed human hearts which were available in the department of Anatomy and Forensic Medicine, S.V.Medical College, Tirupati, Andhra Pradesh, India. These hearts were dissected and observed for the presence, location, type, number and direction of myocardial bridges and their association with coronary dominance. With the help of digital calipers morphometric parameters (length, width& thickness) of myocardial bridges and length of blood vessel underneath the myocardial bridge were measured, noted and photographs were taken. Results: The overall incidence of myocardial bridges was 20.6%( 31/150). Among these 18.6% (28/31) were on left anterior descending (LAD) artery and 2% (03/31) were on posterior interventricular (PIV) artery. The direction of muscle fibers in the bridges were oblique to the direction of the coronary vessels in majority of cases. Length, width and thickness of myocardial bridges were in the range of 12-69.7mm, 3.74-8.6mm and 1.3-3.87mm respectively. Conclusions: Myocardial bridges may be associated with wide range of clinical problems. Contraction of myocardial bridge may results in vascular compression and myocardial ischemia. Knowledge on morphology and morphometric details of myocardial bridges facilitates cardiologists in diagnosis, planning therapeutic strategies and prognostic predictions.