Booster pump function of the left atrium in hypertensive patients

We evaluated the left atrial function in 45 hypertensive patients using echocardiography and the backward method of ECG-gated equilibrium radionuclide angiocardiography. The following parameters were measured : 1) AV/EDV = (LV volume at end-diastole-LV volume at the beginning of atrial contraction)/LV volume at end-diastole (in LV echocardiogram) 2) peak AF rate = (maximum dv/dt in atrial filling)/(end-diastolic counts) (in RI angiocardiography) 3) A dip : the depth from the beginning of active atrial shortening (in interatrial septal echocardiogram obtained with right subcostal approach) 4) LAD' : the left atrial dimension at the beginning of atrial active contraction (in aortic root echocardiogram) 5) IVST : interventricular septal thickness at the top of R wave of ECG (in LV echocardiogram). As a result, AV/EDV, peak AF rate and A dip were directly proportional to IVST within the range of IVST ≤ 13 mm. But these indices were inversely proportional to IVST within the range of IVST > 13 mm. LAD' was poorly correlative to IVST (r = 0.483, p < 0.01). In conclusion it seems to be possible that the booster pump function of the left atrium begins to deteriorate in the hypertensive patients beyond the critical LV wall thickness. (author)