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

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.

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 III (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).

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).

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.