[Mechanism of presystolic intensification of mitral diastolic murmur in auricular fibrillation].

On the basis of a study of the sound pattern and of the data of right and left heart catheterization it has been established that the presystolic accentuation of the mitral diastolic murmur in atrial fibrillation is predisposed by the peculiarities of the dynamics of the left ventricular diastolic pressure. When the diastole is becoming shorter, the diastolic pressure does not grow gradually, as it happens under normal conditions, but progressively decreases during the whole period of the diastole which causes the appearence of a pressure gradient across the atrioventricular orifice, increasing during the diastole, an increasing diastolic blood flow rate through the mitral valve and, as a consequence, an accentuation of the mitral diastolic murmur during the diastole.