Hemodynarnic Sequelae of Sustained Elevation of Left Atrial Pressure

SIMILJARITIES between mitral stenosis and left ventricular failure, regarding their effects upon the pulmonary circulation and the right heart, have been known long before cardiac catheterization permitted their direct assessment. The advent of mitral valve surgery, a decade ago, stimulated widespread interest in the hemodynamies of mitral stenosis. On the other hand, circulatory changes associated with cardiac failure have been studied in considerably less detail. In 1955, Harvey et al.' raised an important practical point regarding this similarity: are hemodynamnic changes caused by mechanical factors (mitral stenosis) and those caused by myoeardial factors (cardiac failure) distinctive enough to permit their differentiation? These authors answered this question in the affirmative, suggesting that venous catheterization of the heart is helpful in the selection of proper candidates for surgical treatment. The purely surgical aspect of this problem can now be approached in a more direct way, in that combined right and left heart catheterization permits the direct measurement of the diastolic gradient across the mitral valve. Other aspects of the similarity and dissimilarity between mitral stenosis and left ventricular failure are, however, of considerable importance, particularly in view of the increasing interest in the mechanism of pulmonary hypertension which may complicate these conditions. The current study was undertaken in an effort to compare circulatory dynamics of