CONTRIBUTION OF ATRIAL RESERVOIR FUNCTION TO VENTRICULAR FILLING IN HYPERTENSIVE PATIENTS - EFFECTS OF NIFEDIPINE ADMINISTRATION

We designed this study to assess the importance of left atrial functio n as a contributor to mitral flow velocity pattern in hypertensive pat ients. In hypertensive patients the early diastolic flow velocity and ratio of early to late diastolic flow velocity in the mitral flow velo city pattern increase in association with sublingual administration of nifedipine. These changes have been interpreted as signs of improved left ventricular diastolic function; however, the mitral flow velocity pattern is also affected by various other factors. Thus, the nifedipi ne-induced changes may not necessarily indicate the improvement of lef t ventricular diastolic function. Transthoracic Doppler echocardiograp hic parameters of mitral and pulmonary venous flow velocity patterns a nd left ventricular M-mode echograms were obtained in 16 untreated hyp ertensive patients before and after sublingual administration of nifed ipine (10 mg). Normal values of the parameters were determined in 50 a ge-matched healthy subjects. After nifedipine peak early diastolic mit ral flow velocity increased beyond the normal value, although the peak increasing rate of left ventricular inner dimension, another index of left ventricular diastolic function, did not recover to the normal va lue. Peak systolic velocity in the pulmonary venous flow velocity patt ern increased beyond the normal value, indicating improvement of the r eservoir function of the left atrium during systole. Nifedipine-induce d normalization of the mitral flow velocity pattern was associated wit h further abnormalities of the pulmonary venous flow velocity pattern, indicating enhanced left atrial reservoir function. Thus, nifedipine- induced normalization of the mitral flow velocity pattern should be ex plained not only by the normalization of left ventricular diastolic fu nction but also by another adaptive alteration in left atrial reservoi r function in hypertensive patients. Combined analysis of mitral and p ulmonary venous flow velocity patterns may be useful in avoiding the m isinterpretation of the mitral flow velocity pattern.