Variant Hemodynamic Patterns in Mitral Stenosis

Of a total group of 86, 11 cases of proved significant mitral stenosis with cardiovascular hemodynamic data are presented. Four had normal pulmonary wedge and pulmonary artery pressures at rest and low cardiac index at rest and after mild exercise. It is postulated that such persons respond to mitral valve obstruction primarily by lowering cardiac output. The cardiac index in seven was normal at rest and after mild exercise. Thus there was no evidence that alteration of blood flow had occurred in response to the lesion. The values for pulmonary arteriolar resistance in three of these were qualitatively normal when flow was increased. These are considered to be examples of absent or inadequate changes in pulmonary vascular reactivity. The existence in a significant percentage of patients with mitral stenosis of a low cardiac output with normal resting pulmonary, arteriolar, and wedge pressures, or normal cardiac output despite elevation of these pressures infers that potent flow-regulating factors tors can operate independently of the obstructive lesion.