الفهرس 
Physiiollogy and anattomy off tthe llefftt attriiumOnly 14 pages are availabe for public view
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Abstract
Mitral annular calcification (MAC) is a chronic non inflammatory degenerative process progressing with advancing age. The pathogenesis of (MAC) is largely unknown (Nestico PF et al., 1984).Mitral annular calcification has become an important pathological entity as one of degenerative valvular disease (Bonow R et al., 2005).
Previous studies have put forward that patients with MAC have a higher incidence of left atrial (LA) enlargement. Furthermore, MAC was proven to be associated with several conduction disorders, such as sinoatrial disease, atrial fibrillation (AF), atrioventricular block, left anterior hemiblock, and interventricular conduction defects, but the true incidence and the exact underlying mechanisms of AF were uncertain (Takamoto T., 1983).Our aim of this study is to investigate atrial conduction times, atrioventricular conduction times non invasively in patient with mitral annular calcification. The study include twenty five patients with MAC and twenty five controls, male in MAC group represent 64% and 60% in control group, All of these patients underwent conventional echocardiography Tissue Doppler Imaging, and 12 lead resting surface electrocardiography for measurement of atrial and atrioventricular conduction times. According to the results of this work there is a significant prolongation in the interatrial conduction time P = .048 and the intraatrial conduction time P =
.005 in patients with mitral annulus calcification (MAC).