| BackgroundHypertension is a well-known risk factor for stroke, atherosclerosis and heart failure. The cardiac effects of hypertension include increased left ventricle (LV) mass and hypertrophy, as well as deterioration of the atrial functions. It was suggested that electrocardiographic evidence of a left atrial (LA) abnormality be an early sign of hypertensive heart disease. Changes in LA size, structure and functions in patients with hypertension are well described, but studies on right atrial (RA) functions in these patients are limited. Actually, the right atrium is an important contributor to right ventricle (RV) stroke volume, and indirectly, LV filling and cardiac output. The three components of atrial function are as a reservoir, conduit and booster pump at different stages of the cardiac cycle, and the performance is complex. Among invasive and noninvasive methods to assess heart function, echocardiography is the most commonly used noninvasive technique to evaluate atrial performance. Several techniques used to assess LA performance include those measuring pulmonary venous systolic flow, transmitral flow peak velocity, as well as pulsed-wave Doppler and acoustic quantification (AQ) technique. In particular, AQ has been used as an adjunct to Doppler echocardiography to assess diastolic dysfunction in the left atrium in hypertensive patients and LA function with aging, but few studies have examined RA function with echocardiography in hypertensive patients. Gaynor et al evaluated RA reservoir and conduit functions using invasive methods to measure flow and pressure and RV pressure. Recently, certain angiotension H receptor blockers have been found to alleviate LV hypertrophy, improve diastolic function and play a role in cardiovascular protection. Olmesartan, the newest member of this family, appears to be superior, not only in lowering blood pressure but also in correcting the altered structure and endothelial dysfunction of resistant arteries, attenuating collagen deposition, and reversing LV and vascular hypertrophy. In this study, we evaluated the effect of olmesartan on alleviating LV hypertrophy and improving LA and RA structure and function in hypertensive patients by AQ and tissue Doppler echocardiography.Objectives The purpose of the present study was1. To investigate the characteristics of the structures and functions of LA and RA in the patients with hypertension by using AQ technique.2. To evaluate the effect of Olmesartan on left-and right-atrial functions in hypertensive patients.Subjects and MethodsWe recruited 50 (15 females,53.2±7.6 yr of age) outpatients who visited our hospital between December 2004 and June 2005. Inclusion criteria were as following: outpatients of either sex, aged from 18 to 65, with mild to moderate hypertension (diastolic BP≥95 mmHg and≤105 mmHg, systolic BP≥140 mmHg and<180 mmHg after a 2-week washout period on placebo). Patients with secondary or malignant hypertension, heart failure, cerebrovascular accident, myocardial infarction, angina pectoris, Diabetes mellitus, or severe liver or kidney diseases were excluded. Twenty healthy subjects (9 females,50.6±11.6 yr of age) without a history of cardiac disease or systemic hypertension and having normal findings on physical examination, chest roentgenography, electrocardiography, and echocardiography served as controls. The hypertensive participants meeting the entry criteria were treated with olmesartan 20 mg or 40 mg daily for 8 weeks.Echocardiography examination was carried out by the same expert operator using ultrasonography equipment (HP Sonos 5500 Philips Medical Systems, Andover, MA, USA) with a 1-to 3-MHz transducer. Tissue Doppler imaging was performed in the apical view (4-chamber) to assess the function of longitudinal and circumferential myocardial fibers. The automatic border detection system was activated and optimized by adjusting the total gain, time gain compensation, and lateral gain. A region of interest was then drawn around the left and right atria. The LA-and RA-area waveforms were displayed, with visual confirmation of consistent stable waveforms. Data on atrial area versus time data were saved to magneto-optical disk. All atrial waveforms were analysed off-line by use of custom software.Results1. Clinical characteristics of the control group and hypertensive group:There were no significant differences in age and gender between hypertensive group and control group. Compared with controls, BMI, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly higher in the patients with hypertension (P<0.05-0.001). Systolic and diastolic blood pressure were decreased after treatment with olmesartan (P<0.001).2. The interventricular septal thickness, LV mass index, RV anterior wall and left atrial dimension were significantly higher in hypertensive group than those in control group (P<0.05～0.001). After 8 weeks of olmesartan treatment, the interventricular septal thickness, LV mass index and RV anterior wall decreased significantly in hypertensive patients (P<0.001)3. The E1, E2 velocity, E1/A1 and E2/A2 ratio were lower and A1, A2 velocity were increased in hypertensive group than those in the controls(P all<0.001). After therapy with olmesartan, the E2/A2 ratio showed increased and A2 velocity decreased significantly (P all<0.001)4. In contrast to controls, The Em1, Em2, Em1/Am1 and Em2/Am2 ratio were all markedly decreased and the Am1, Am2 were increased in patients with hypertension (P<0.05-0.001). However, there was no significant difference in Sm1 and Sm2 velocity between the two groups. After 8 weeks of oral antihypertensive therapy, higher Em1, Em2, Em1/Am1 ratio, Em2/Am2 ratio and lower Am1 and Am2 were observed in hypertensive patients (P all<0.001)5. Compared with control subjects, significant increases were shown in ESV, EDV, reservoir volume and PFR (P<0.05-0.01), which reflected LA reservoir function. LA booster function, as assessed by AE, AEF, and PAER (P all<0.01), was increased in patients with hypertension. However, parameters of LA conduit function including REF, RE/AE ratio and PRER/PAER ratio were all significant decreased in hypertensives (P<0.01). The increase in RE/AE was reduced after therapy with olmesartan (P<0.05), and reservoir volume and PFR showed to decrease after therapy (P all<0.05).6. The interactions among AQ indexes in hypertensive population were confirmed by linear correlation analyses. There was a highly significant positive correlation between the OAEV and AE (r=0.762,P<0.001). The AEF negatively correlated significantly with REF, RE/AE ratio and PRER/PAER ratio (r value was-0.960,-0.862 and-0.699, respectively, P all<0.001). The RV showed statistically significant positive associations with OAEV and AE (r value was 0.480 and 0.608, respectively, P all<0.001)7. Significant increases were shown in reservoir volume, ESV, EDV and PFR (P all<0.01) for RA in hypertensive patients than those in controls. Compared with control subjects, The right atrium showed decreased RE and PRER/PAER in the hypertensive group (P<0.05-0.01), however, AE and PAER were increased (P<0.01). After 8 weeks of olmesartan treatment, PFR decreased significantly (P<0.05) in the right atrium.Conclusion1. Systemic hypertension is associated with impaired LA and RA functions contributing to hypertrophy of interventricular septal thickness and dysfunction of biventricular relaxation.2. Olmesartan might be useful to improve LA and RA functions in hypertensive patients. |
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