Morphological analysis of myocardial bridges and coronary arterial dominance in northeast Brazil.

BACKGROUND: Coronary arterial dominance and myocardial bridges have clinical implications, since a left dominant pattern associated to the presence of myocardial bridges is often associated to a higher incidence of arteriosclerosis and higher mortality by myocardial infarction. OBJECTIVE: To determine the presence and position of myocardial bridges and their relation with coronary arterial dominance. METHODS: Fifty-seven human cadaveric hearts were analyzed into three groups, as follows: right dominance; left dominance; codominance. Each group was then divided into two subgroups: with or without myocardial bridges. Finally, each subgroup with myocardial bridges was classified according to the position of the myocardial bridge according to the main axis of the heart (proximal, middle and distal third). RESULTS: The right dominance occurred in most hearts (30 hearts-52,6%). Twenty-three myocardial bridges (40,3%) were identified and mostly occurred on left dominant hearts (22,8%). The pattern of coronary dominance presented a statistically significant correlation with the presence of myocardial bridges (P=0.048). The middle third of the heart axis showed the highest occurrence of myocardial bridges. CONCLUSION: These findings suggest there is a clear relationship between the presence of myocardial bridges and left dominant pattern. Middle third of the heart axis present the higher occurrence of myocardial bridges. Knowledge of the myocardial bridges morphology is of great clinical significance, improving patient care.

Anatomical relationship between mitral valve annulus and circumflex artery and its surgical implications.

BACKGROUND: Performing surgical procedures around the mitral valve (MV) annulus can cause iatrogenic lesions on the circumflex artery (Cx). The risk of this iatrogenesis comes from the proximity between this vessel and the MV annulus. OBJECTIVE: To evaluate the relation between the MV annulus and the Cx at different spots of its path and highlight the risks of its damage. METHODS: Fifty cadaveric adult human hearts were studied. Each heart was categorized depending on coronary dominance, and Cx was classified in type 1 (Cx giving off only the left posterior ventricular artery) and type 2 (Cx reaching the crux cordis and giving off the posterior interventricular branch). Three reference spots were chosen: A- when Cx begins to run across the coronary sulcus; B- immediately before the left posterior ventricular artery emerges and C- in the midpoint of the two previous points; to measure the diameter of the Cx and the MV annulus. Values of P<0.05 were considered significant. RESULTS: A total of 43 (86%) hearts were classified in type 1. These hearts showed that the diameter of the Cx in spot A is bigger than in the B and C spots (P=0.001). The 7 hearts (14%) classified in type 2 did not exhibit a difference in the diameter of the Cx in the A, B and C spots (NS). Also, the thickness of the fibrous annulus, in type 1 and type 2 hearts were not different between the three spots (NS). CONCLUSION: The present study showed that the diameter of the Cx varies depending on the heart type. This knowledge might improve the success rate of cardiac surgeries and decrease the rates of iatrogenic Cx lesions.