MITRAL VALVE DISEASE COMPLICATED BY LEFT-TO-RIGHT SHUNT AT ATRIAL LEVEL.

Abstract

The clinical features and the changes in hemodynamics are described before and after operation in two patients with mitral valve disease associated with left-to-right shunt at atrial level. The first patient had severe rheumatic mitral stenosis, which masked the associated moderate shunt. Since the interatrial communication was small, there was a moderate gradient in pressure between the two atria. Thus, the finding of an elevated left atrial or pulmonary artery wedge pressure in a patient with mitral stenosis and an increase in the saturation of blood at atrial level does not eliminate the possibility of a small interatrial communication. The second patient had severe mitral regurgitation due to a structurally abnormal valve with ruptured chordae tendineae, and had also functional pulmonary and tricuspid valve regurgitation. These lesions also masked the associated large left-to-right shunt. Electrocardiographic and angiocardiographic criteria were used to exclude the possibilities of persistent atrioventricular canal defect and of left ventricle-right atrium shunt. After operation, cardiac catheterization demonstrated a return of the hemodynamic changes toward normal in both patients. There was also a striking clinical improvement. In both, the interatrial communication was situated in the fossa ovalis. It appeared to be a foramen ovale that had become patent due to stretching of the walls of the left atrium, rather than a true atrial septal defect. Although left-to-right shunting may occur through a patent foramen ovale in infants with mitral or aortic valve atresia, we are unaware of previous hemodynamic or surgical evidence of a similar phenomenon developing as a consequence of severe mitral valve disease in adults.