Mitral valve calcification

Q13 Arterial emboli, which can block blood vessels and cause ischaemia or infarction in the tissues they affect, tend to originate in the left heart and are associated with valvular disease and dysrhythmias. Mitral stenosis is associated with abnormal atrial rhythm, particularly atrial fibrillation. Fibrillation and other rhythm abnormalities in the atria favour blood coagulation, resulting in production of thromboemboli which can move to distant parts of the circulation, such as the cerebral circulation. Thrombi could also form on surfaces of valves distorted by calcification and other abnormalities. In view of the risks of thromboembolism, it is usual to provide anticoagulant therapy to patients with mitral valve problems and atrial fibrillation. 

Calcification, and possibly sclerosis, of the aortic and mitral valves may be a cause of embolism of calcific or complicating thrombotic material. However, these degenerative disorders of heart valves are so common, particularly in the elderly, that it has been very difficult to associate them causally with stroke (Boon et al. 1996). 

Congestive heart failure is common and is related to fluid overload, hypertension, or atherosclerosis. Some workers have postulated a uremic cardiomyopathy. The enhancement by parathormone of cellular calcium uptake may contribute to myocardial calcification, degeneration, and fibrosis (M26). There is a higher incidence of calcification of the aortic and mitral valves, as well as of visceral and peripheral arteries in association with uremic hyperparathyroidism (M13). In addition to PTH, middle molecules (B19), phenols (L3), guanidino-succinic acid (K5), or cobalt (P6) may contribute to the observed cardiotoxicity in vitro of uremic serum. 

Boon, A., et al. Cardiac valve calcification characteristics of patients with calcification of the mitral annulns or aortic valve. Heart 78(5), 472—474 (1997)... 

Some other examples of animal models that are used in biotextile retrieval studies include implanting hernia repair meshes in the abdomen of piglets and mitral valve replacement in juvenile sheep or calves, and subcutaneous implants of valve materials in young rats for in vivo biocompatibility and calcification studies. 

Cardiovascular The incidence of mitral and aortic valve calcification has been studied in 1155 patients with atrial fibrillation, of whom 725 were taking warfarin [1 ]. There was a significant association between the use of warfarin and the risk of calcification (unadjusted OR = 1.71 95% Cl = 1.34, 2.18), and the association remained after adjustment for confounding factors. 

Inferior-or anterior-wall Ml, congenital abnormality, rheumab c fever, hypoxia, postoperative complication of mitral valve replacement, postprocedure complication of radiofiequency ablation in or near AV nodal tissue. Lev s disease (fibrosis and calcification that spreads from cardiac structures to the conductive tissue), and Lenegre s disease (conductive tissue fibrosk). 

The mechanisms of calcification and the methods of preventing calcification are active areas of current research [106]. The most common methods of studying calcification involve valve tissue implanted either subcutaneously in 3-week-old weanling rats, or valves implanted as mitral replacements, in young sheep or calves. Results of both types of studies show that bioprosthetic tissue calcifies in a fashion similar to clinical implant, but at a greatly accelerated rate. The subcutaneous implantation mode is a well-accepted, technically convenient, economical, and quantifiable model for investigating mineralization issues. It is also very useful for determining the potential of new antimineralization treatments. 

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