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

Abstract

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 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. 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.