Effects of dipper and non-dipper status of essential hypertension on left atrial mechanical functions

Aim: This study was designed in order to investigate the effects of dipper and non-dipper status of hypertension on left atrial mechanical (reservoir, conduit and booster pump) functions with left atrial volume measurements by means of two-dimensional echocardiography in untreated systemic hypertensive patients. Method: A total of 27 untreated dipper hypertensive patients, group I (15 female, 12 male, mean age 57 +/- 12 years); 23 untreated non-dipper hypertensive patients, group II (12 female, 11 male, mean age: 53 +/- 18 years); and 25 voluntary healthy individuals, group II (13 female, 12 male, mean age 53 +/- 10 years) were included into the study. Twenty-four hour blood pressure (BP) measurement was performed by the cuff-oscillometric method to evaluate the nocturnal decrease of BP. The patients whose night time mean blood pressure measurements were found 10% or more lower compared to mean day time measurements were classified as dipper hypertensive patients, and the ones with a decrease of less than 10% were classified as non-dipper hypertensive patients. Left atrial (LA) volumes were measured echocardiographically according to biplane area-length method in apical four-chamber and two-chamber views. LA maximal volume (V-max) was recorded at the onset of mitral opening, LA minimal volume (V-min) was recorded at the onset of mitral closure and LA presystolic volume (V-p) was recorded at the beginning of the atrial systole (p wave on ECG). All volume measurements were corrected to body surface area, and following LA emptying functions parameters were calculated: LA passive emptying volume (LAPEV) = V-max - V-p, LA passive emptying fraction (LAPEF) = LAPEV/V-max, Conduit volume (CV) = left ventricular output volume - (V-max - V-min), LA active emptying volume (LAAEV) = V-p - V-min, LA active emptying fraction (LAAEF) = LAAEV/V-p, LA total emptying volume (LATEV) = V-max - V-min LA total emptying fraction (LATEF) = LATEV/V-max. Results: LA volume indexes, V-max, V-min, and V-p, were significantly increased in the hypertensive subgroups (groups I and II) than in controls (p < 0.001, p < 0.001, p < 0.001, respectively), but no significant difference was found in the V-p values between group I and group II. V-max and V-min were larger in non-dipper hypertensive group than in dipper hypertensive group (p < 0.05 and p < 0.05, respectively). LAPEV and LAPEF were observed to be significantly reduced in both dipper and non-dipper hypertensives than in control (p < 0.001 and p < 0.05, respectively), and this difference was more obvious in non-dipper than dipper cases (p < 0.001). Conduit volume was significantly lower in hypertensive groups than controls (p < 0.05). LA active emptying volume (p < 0.001) and LAA active emptying fraction (p < 0.001) were significantly greater in hypertensive cases than in controls. Furthermore, LA active emptying volume in non-dipper hypertensive subjects was significantly greater than dipper hypertensive cases (p < 0.05). Left atrial total emptying volume and left atrial total emptying fraction in both hypertensive groups were similar to control (p > 0.05). Conclusions: Atrial reservoir and booster pump functions increase in hypertensive patients, but this result is more prominent in non-dipper hypertensives than in dipper hypertensive patients. (C) 2003 Elsevier Ireland Ltd. All rights reserved.