Left atrial size and atrial fibrillation in mitral stenosis. Factors influencing their relationship

In a series of 135 patients with mitral valvular stenosis, three groups were identified: those in sinus rhythm, those with intermittent atrial fibrillation, and those with longstanding, established atrial fibrillation. Examination of the relationships between atrial fibrillation, hemodynamic findings and radiologic data in mitral stenosis was undertaken. Analysis of clinical and hemodynamic factors in the three groups revealed that: 1) age is an etiological factor in the production of atrial fibrillation, as suggested by the age distribution among the three groups; 2) left atrial enlargement may be the result, rather than the cause, of atrial fibrillation; and 3) severity of mitral stenosis is not invariably related to the incidence of atrial fibrillation. Hemodynamic measurements were not significantly different among the three groups, with the single exception of lower cardiac outputs found in patients with established atrial fibrillation. Since no single consequence of mitral stenosis always produces atrial fibrillation, it is suggested that several factors in different combinations can initiate the self-perpetuating process of atrial fibrillation and that the classic form of the arrhythmia may lead secondarily to left atrial enlargement.

High-yield method for dispersing simian kidneys for cell cultures

A technique for dispersion of animal tissue cells is described. The proposed technique is based on the concomitant use of trypsin and disodium ethylenediamine tetraacetate (EDTA). The use of the two dispersing agents (trypsin and disodium EDTA) markedly enhances cell yield as compared with the standard cell dispersion methods. Moreover, significant reduction in the amount of time required for complete tissue dispersal, presence of a very low number of nonviable cells, less cell clumping, and more uniform monolayer formation upon cultivation compare favorably with the results usually obtained with the standard trypsinization technique.