Risk of atrial fibrillation in dipper and nondipper sustained hypertensive patients

OBJECTIVE: The risk of atrial fibrillation (AF) in sustained hypertensive patients with different circadian blood pressure (BP) patterns is unknown. We investigated the risk of new onset AF in dipper and nondipper sustained hypertensive patients. METHODS: The occurrence of AF was evaluated in 1141 patients aged > or = 40 years with sustained hypertension (clinic BP > or = 140 and/or 90 mmHg and daytime BP > or = 135 and/or 85 mmHg). Among these patients, 783 had night-time systolic BP fall > or = 10% (dippers) and 358 had night-time BP decline <10% (nondippers). RESULTS: During the follow-up (6.1+/-3.2, range 0.5-12.9 years), AF occurred in 43 patients. The AF rate per 100 patient-years in dippers and nondippers was 0.38 and 1.13, respectively. AF free survival was significantly different between the groups (P=0.0002). After adjustment for other covariates, including left atrial enlargement or left ventricular hypertrophy (these variables were analyzed in separate models because of a strong association between them) and 24-h BP, Cox regression analysis showed that the risk of AF was significantly higher in nondippers than in dippers [nondippers vs. dippers, relative risk (RR) 2.02, 95% confidence interval (CI) 1.08-3.79, P=0.028 in the model including left atrial enlargement, and RR 1.97, 95% CI: 1.05-3.69, P=0.035 in the model including left ventricular hypertrophy]. CONCLUSION: This study shows that nondipper sustained hypertensive patients have a two-fold greater risk of developing AF than dipper ones. This aspect could partly contribute to explain the higher cardiovascular risk previously observed in nondipper hypertensive patients.     

Cardiac arrhythmias and left ventricular hypertrophy in dipper and nondipper patients with essential hypertension

To evaluate the behavior of cardiac arrhythmias in dipper and nondipper hypertensive patients, 48-h ambulatory blood pressure monitoring, 24-h Holter electrocardiogram recording and echocardiographic studies were performed in 56 untreated outpatients with essential hypertension. These patients were divided into 2 groups according to the presence (dipper, n=33) or absence (nondipper, n=23) of reduction of both systolic and diastolic blood pressure during nighttime by an average of more than 10% of daytime blood pressure. Mean 48-h systolic and diastolic blood pressures did not differ between the 2 groups. Nondipper patients had a significantly larger left atrial dimension (31.9+/-3.8 vs 35.6+/-3.7 mm; p<0.01), left ventricular mass index (114+/-26 vs 136+/-36 g/m2; p<0.05), as well as a larger number of total supraventricular (16+/-19 vs 89+/-197 beats; p<0.05) and ventricular ectopic beats (7+/-14 vs 47+/-96 beats; p<0.05) during daytime as compared with dippers. In conclusion, nondipper hypertensive patients are likely to experience supraventricular and ventricular arrhythmias more frequently than dippers. A blunted nocturnal blood pressure fall may be involved in the appearance of cardiac arrhythmias in patients with essential hypertension.     

Ventricular repolarization is prolonged in nondipper hypertensive patients: role of left ventricular hypertrophy and autonomic dysfunction

OBJECTIVE: The aim of this study was to investigate the influence of circadian behavior of blood pressure, left ventricular hypertrophy, and autonomic function on QTc interval duration in untreated hypertensive patients. DESIGN: Hypertensive patients underwent simultaneous blood pressure and ECG 24-h ambulatory monitoring. Patients were classified into two groups on the basis of a lack of nocturnal fall in blood pressure, as dippers and nondippers. A group of normotensive healthy subjects was studied as controls. METHODS: QT and QTc intervals were automatically computed and spectral analysis was applied to RR interval time series from the same electrocardiogram (ECG) recordings. Left ventricular mass index (LVMI) was computed by echocardiogram. RESULTS: No difference among the three groups was found concerning mean values and circadian pattern of heart rate; by contrast, QTc was significantly longer in nondippers compared to dippers or to normotensive subjects, particularly at night-time, whereas all groups exhibited similar circadian variations in heart rate. Compared to dippers, nondippers showed significantly higher LVMI, which positively correlated with QTc, and parasympathetic withdrawal, which negatively correlated with QTc. CONCLUSIONS: Nondippers show a prolonged ventricular repolarization throughout the 24-h period, absent either in dippers or normotensives. The association of left ventricular hypertrophy and vagal deactivation may lead to prolongation of QTc, potentially facilitating ventricular arrhythmias in nondipper hypertensive patients.     

Comparative efficacy of aliskiren/valsartan vs valsartan in nocturnal dipper and nondipper hypertensive patients: a pooled analysis

This pooled analysis of ambulatory blood pressure (BP) monitoring data from two 8-week randomized controlled trials compared the antihypertensive efficacy and safety of combination aliskiren/valsartan vs valsartan alone in hypertensive patients (nocturnal dippers or nondippers). At study end, patients were taking aliskiren/valsartan 300/320 mg or valsartan 320 mg. In dippers (n=138) and nondippers (n=132), aliskiren/valsartan provided significantly (P<.05) greater reductions from baseline to week 8 than valsartan in 24-hour, daytime, and last-4-hour mean ambulatory systolic BP (maSBP). Treatment differences were more pronounced in nondippers. Nighttime maSBP reductions with aliskiren/valsartan were significantly greater vs valsartan in nondippers (-17.0 mm Hg vs -8.9 mm Hg; P<.05) but not dippers (-7.6 mm Hg vs -4.5 mm Hg; P=.16). In all time periods, combination therapy was generally associated with BP reductions that were greater in nondippers than dippers. Conversion from nondipper to dipper status was 32% vs 22% for aliskiren/valsartan vs valsartan (P=.48). Both treatments were similarly well tolerated. Although the addition of aliskiren to valsartan did not significantly alter dipper status, our data suggest an increased contribution of the renin-angiotensin-aldosterone system to the nondipper status of hypertensive patients.     

Adiponectin, insulin resistance, and left ventricular structure in dipper and nondipper essential hypertensive patients

BACKGROUND: Adiponectin is an adipocyte-derived protein with insulin-sensitizing and antiatherogenic properties. Failure to decrease blood pressure (BP) normally during night in hypertensive patients has been independently associated with left ventricular hypertrophy. METHODS: We examined the relationship between adiponectin levels, insulin sensitivity, and left ventricular structure in 40 newly diagnosed never-treated patients with essential hypertension, including 20 patients with a normal night-time pressure decrease (ie, dippers) and 20 patients with BP persistently elevated throughout the 24-h period (ie, nondippers). All subjects had grade 1-2 hypertension, aged 18 to 65 years, no diabetes mellitus, no obesity, no hyperlipidemia, and no cardiopulmonary, renal, or hepatic disease. RESULTS: The two groups of patients were similar for age, sex, body mass index, and had no differences for clinic, 24-h, and diurnal BP, and 24-h, diurnal, and nocturnal heart rate, as well as glucose, total cholesterol, and triglyceride levels. Plasma insulin and homeostasis model assessment (HOMA index) were higher (P < .01), and adiponectin levels were lower (P < .005) in nondippers than in dippers. Adiponectin correlated inversely with HOMA index and insulin levels (r = -0.58, and r = -0.62, respectively, P < .001) in the entire population. Nondippers showed left ventricular mass, relative wall thickness, and measure of early and late diastolic peak flow velocity ratio similar to those of dippers. CONCLUSIONS: In the absence of major cardiovascular risk factors, nondipper essential hypertensive patients show more prominent insulin resistance and lower adiponectin compared to dippers. Therapeutic modulation of adiponectin or insulin resistance might provide additional benefit to the conventional antihypertensive treatment.     

Oxidative Stress Impairs Endothelial Function in Nondipper Hypertensive Patients

Aims: Essential hypertension, as well as other established cardiovascular risk factors, is associated with endothelial dysfunction. Hypertensive patients with a nondipper circadian pattern have a greater risk of cerebrovascular and cardiovascular complications in comparison with those with a dipper circadian pattern. In this study, we evaluated the association between nondipper pattern and endothelial function in patients with essential hypertension. Methods: We evaluated the forearm blood flow (FBF) response to intraarterial acetylcholine (ACh), an endothelium‐dependent vasodilator, and sodium nitroprusside (SNP), an endothelium‐independent vasodilator, infusions in 190 hypertensive patients stratified according to dipper and nondipper status. The FBF was measured by strain‐gauge plethysmography. Effects of oxidative stress on FBF were evaluated by intraarterial infusion of vitamin C. Ambulatory BP monitorings were obtained by a validated oscillometric device (SpaceLabs 90207 Monitor Inc., Issaquah, WA, USA). Results: Systolic and diastolic blood pressures were higher during daytime and lower during night‐time in dipper subjects than in nondippers. The peak percent increase in ACh‐stimulated FBF was higher in dippers than in nondippers (473% vs. 228%, P < 0.001). The FBF responses to SNP were similar in dipper and nondipper patients. The FBF response to ACh during coinfusion of vitamin C was higher in nondippers rather than in dipper hypertensives. Conclusions: Present data demonstrate that endothelium‐dependent vasodilation is impaired in patients who have nondipper hypertension. The effects of vitamin C on impaired ACh‐stimulated vasodilation support the hypothesis that oxidative stress contributes to endothelial dysfunction of nondipper hypertensive patients.     

Lack of correlation between QTc dispersion and morning blood pressure surge in recently diagnosed essential hypertensive patients.

BACKGROUND: Cardiovascular events are known to occur more frequently in patients with a high morning surge in blood pressure (BP), but the correlation between a morning BP surge and corrected QT dispersion (QTc) has not been confirmed to date. METHODS AND RESULTS: The correlation between the morning BP surge and QTc was studied in 82 patients recently diagnosed with high BP (47 males, 35 females). Twenty-four-hours BP monitoring was conducted to classify patients into dipper (n=45) or nondipper (n=37) groups according to the degree of nocturnal BP reduction. QTc was found to be significantly longer in the nondippers compared with the dippers (36.1+/-17.2 vs 47.6+/-20.7, p<0.001). In addition, there was a significant increase in the end-diastolic interventricular septum thickness (IVSd), left ventricular posterior wall thickness in diastole (PWT) and left ventricular mass index (LVMI) in the nondippers vs the dippers (respectively, 0.93+/-0.09 vs 1.03+/-0.05, p<0.001, 0.94+/-0.09 vs 1.01+/-0.04, p<0.01, 109.7+/-12.8 vs 129.1+/-20.9, p<0.001). QTc had a significant positive correlation with nighttime BP, IVSd, PWT, and LVMI, but negatively correlated with the nocturnal BP reduction rate. These results were maintained even after adjusting for age and gender. However, a significant correlation between the morning BP surge and QTc was not confirmed. CONCLUSION: In the present nondipper hypertensive patients, QTc, nighttime BP, LVMI, and wall thickness were significantly greater than in the dipper patients. However, there was no significant correlation between the morning BP surge and QTc.     

Influence of diurnal blood pressure rhythm on aortic elastic properties in hypertensive subjects

OBJECTIVE: The aim of this study was to evaluate whether there is a relationship between aortic elastic properties and diurnal blood pressure rhythm in hypertensive subjects. METHODS AND RESULTS: This study included 41 hypertensive patients who were taking medical treatment and had undergone ambulatory blood pressure monitoring (ABPM). The patients were classified according to their night mean systolic blood pressure (Nm-SBP) fall. On the basis of Nm-SBP fall: 10 (24.4%) patients were dippers (with 10% but < 20% fall), 19 (46.3%) patients were nondippers (with 0% but <0% fall) and 12 (29.3%) patients were reverse dippers (with <0%). All subjects underwent echocardiographic examination. Internal aortic root diameters were measured at 3 cm above the aortic valve by the use of two-dimensional guided M-mode transthoracic echocardiography, and arterial blood pressure was measured simultaneously from the brachial artery by sphygmomanometry. Two indexes of the aortic elastic properties were measured which are aortic distensibility and aortic stiffness index. After subgroup analysis of the hypertensive patients, the highest aortic stiffness index value was found in reverse dipper patients (5.8 +/- 3.4) followed by nondipper patients (4.87 +/- 3.5) and the lowest in dipper patients (3.5 +/- 1.3) although clinical blood pressure values of hypertensive patients were similar. The aortic stiffness index value of reverse dippers and nondippers (5.6 +/- 3.4) was higher than in the (3.5 +/- 1.3) dippers group. CONCLUSION: In this study, we found a relation between diurnal blood pressure patterns and aortic elastic properties.     

Cardiovascular abnormalities in never-treated hypertensives according to nondipper status

Ambulatory blood pressure monitoring allows a better understanding of blood pressure fluctuations over 24 h than simple clinic measurements. In this way the diagnosis of “white coat” versus “sustained” hypertension and that of “dipper” (patient with blood pressure fall during nighttime > 10% of daytime levels) versus “nondipper” status were made possible. This pilot study has been undertaken to investigate whether patients with recently discovered, never-treated, mild, sustained hypertension have cardiovascular abnormalities according to their dipper/nondipper status. Patients with long-standing (n = 123) and newly discovered (n = 56) sustained hypertension were classified according to their nighttime blood pressure fall, and compared with normotensive controls. Ambulatory blood pressure monitoring was performed noninvasively. Parameters of left ventricular structure, cardiac systolic and diastolic function, and carotid anatomy were determined noninvasively by echographic methods. Significant increases in parameters of cardiac structure as well as abnormalities in diastolic function were observed in patients with long-standing hypertension, regardless of their dipper status. In the group with newly discovered hypertension, left atrium (3.4 ± 0.3, 3.7 ± 0.5, 3.2 ± 0.4 cm in dippers, nondippers, and controls, respectively), end-diastolic diameter index (2.9 ± 0.3, 3.0 ± 0.2, 2.8 ± 0.2 cm/m), and atrial filling fraction (0.50 ± 0.07, 0.52 ± 0.05, 0.42 ± 0.04) were significantly altered only in the nondipper subgroup, in comparison with controls. Significant changes in cardiac structure and diastolic function were observed in nondipper patients with recently discovered hypertension, who, at variance with dippers, show changes similar to those in patients with long-standing hypertension. Hypertensives with the observed abnormalities may benefit from active antihypertensive treatment, which appears, therefore, justified even in an early phase of mild hypertension, in terms of potential reduction of end-organ complications as well as cost-effectiveness.     

高血压患者血压和心率昼夜节律变化与左心室肥厚的关系

目的探讨原发性高血压患者血压和心率24h昼夜节律变化与左心室肥厚的关系。方法对初发未治疗高血压患者296例进行动态血压监测分析,根据患者夜间血压和心率均值较白天平均值下降是否超过10%,将患者分为4组:杓型血压和心率组(血压和心率均杓型,n=163)、非杓型血压组(血压非杓型,心率杓型,n=62)、非杓型心率组(血压杓型,心率非杓型,n=42)、非杓型血压和心率组(血压和心率均非杓型,n=29)。对4组间相关临床资料、超声心动图结果进行比较。结果高血压患者收缩压和舒张压非杓型率分别为25%和27%,非杓型心率的比例为24%。非杓型血压和心率组、非杓型血压组、非杓型心率组左心房内径(LAD)、左心室舒张末期内径(LVEDD)、室间隔厚度(IVST)和左心室质量指数(LVMI)明显高于杓型血压和心率组(均P<0.05),其中非杓型血压和心率组上述指标明显高于其他3组(均P<0.05),非杓型血压组、非杓型心率组之间差异无统计学意义。Logistic回归分析显示,年龄、24h平均收缩压、24h平均舒张压、夜间平均收缩压、夜间平均舒张压、非杓型血压、非杓型心率与左心室肥厚的发生密切相关。经调整相关指标后,非杓型血压和非杓型心率使左心室肥厚发生风险分别增加56%和32%。结论高血压患者血压和心率昼夜节律变化与左心室肥厚明显相关。     

Role of insulin resistance in nondipper essential hypertensive patients.

In hypertensive patients, diminished nocturnal blood pressure (BP) fall is associated with poor prognosis for cardiovascular events. However, the relation of insulin resistance with the etiology of nondipper essential hypertension remains unclear. The aim of the present study was to assess the role of insulin resistance in diminished nocturnal BP fall, left ventricular hypertrophy (LVH), and increased plasma atrial (ANP) and brain natriuretic peptides (BNP) in essential hypertensive patients. One hundred and three patients with essential hypertension were divided into dippers (n = 57; age: 57 +/- 5 years, mean +/- SD) or age-matched nondippers (n = 46; 57 +/- 4 years), based on ambulatory BP (ABP) monitoring. Although the systolic and diastolic ABP values were similar during the day, those at night were higher in nondippers than in dippers ( p < 0.0001 for each). Echocardiographic findings revealed that the left ventricular mass index (LVMI) was higher in nondippers (p < 0.0001). Plasma ANP and BNP were also higher in nondippers (p < 0.0001 for each). Fasting plasma concentrations of glucose and insulin (p < 0.0001 for each) and the homeostasis model assessment (HOMA) index (p < 0.0001) were also higher in nondippers. Multivariate analysis revealed that systolic ABP at night was a significant factor for LVMI, ANP and BNP. In addition, the HOMA index was a significant factor for LVMI and BNP. These observations suggest that diminished nocturnal BP fall is closely related to the development of LVH with concomitant increase in BNP in essential hypertensive patients, and that insulin resistance may play a key role in these processes.     

Disruption of ultradian and circadian rhythms of blood pressure in nondipper hypertensive patients

Ultradian rhythms in blood pressure (BP) are known to exist, but their modification in hypertension is largely unknown. The present study was undertaken to assess the integrity of ultradian and 24-hour BP rhythms in dipper (n=100) and nondipper (n=20) hypertensive patients compared with 44 dipper normotensive individuals. Fourier analysis was used to fit ultradian (12, 8, and 6 hour) and 24-hour rhythms in BP and heart rate (HR). Mesor, amplitude, and acrophase were calculated for individual and overall rhythm curves. All subjects showed significant ultradian or 24-hour BP and HR rhythms. Systolic and diastolic BP mesor was higher in hypertensive patients compared with normotensive patients. The percentage of variability in ambulatory BP that could be explained by fitting ultradian and 24-hour rhythms was reduced in nondippers compared with normotensives or dippers. Amplitude of ultradian and 24-hour rhythms in BP increased in dippers and decreased in nondippers. Ultradian and 24-hour rhythms in HR did not differ among the 3 groups examined. Results indicate that in nondippers, blunted ultradian and 24-hour rhythm amplitude in BP was accompanied by a loss of rhythm integrity.     

The influence of ambulatory blood pressure profile on global and regional functions of the left and the right ventricles in orderly treated hypertensive patients

BACKGROUND: The association between nondipping profile and adverse cardiovascular outcome is still controversial. Tissue Doppler imaging (TDI), a new and useful addition to standard echocardiographic imaging techniques, permits a quantitative assessment of both global and regional function and timing of myocardial velocities. In this study, we aimed to assess whether a reduced nocturnal fall in blood pressure (BP) in orderly treated hypertensive patients with satisfactory BP control is related to more prominent structural and functional alterations of the ventricles. METHOD AND RESULTS: Sixty-nine hypertensive patients with adequate BP control were divided into two groups with respect to ambulatory BP profiles as dippers and nondippers. In addition to conventional echocardiographic parameters, in septal and lateral segments of left ventricle and free wall of right ventricle, peak systolic velocity (Sm), early (Em), and late (Am) diastolic velocities, isovolumic contraction time (ICTm), isovolumic relaxation time (IRTm), and ejection times (ETm) were measured, and modified myocardial performance index (MPIm) was calculated. Left ventricular (LV) and atrial dimensions, ejection fraction, transmitral early to late diastolic flow ratio, LV mass index, and LV hypertrophy ratio did not differ between groups. Both regional and mean LV Sm, Em/Am, MPIm and right ventricular Sm and MPIm were similar in both groups. CONCLUSION: In treated hypertensive patients with satisfactory BP control, there was no significant difference in cardiac structural and functional abnormalities among dipper and nondipper subjects.     

Adrenergic, metabolic, and reflex abnormalities in reverse and extreme dipper hypertensives

Limited information is available on whether and to what extent the different patterns of the nocturnal blood pressure profile reported in hypertension are characterized by differences in sympathetic drive that may relate to, and account for, the different day-night blood pressure changes. In 34 untreated middle-aged essential hypertensive dippers, 17 extreme dippers, 18 nondippers, and 10 reverse dippers, we assessed muscle sympathetic nerve traffic, heart rate, and beat-to-beat arterial blood pressure at rest and during baroreceptor deactivation and stimulation. Measurements were also performed in 17 age-matched dipper normotensives. All patients displayed reproducible blood pressure patterns at 2 different monitoring sessions. The 4 hypertensive groups did not differ by gender or 24-hour or daytime blood pressure. Muscle sympathetic nerve traffic was significantly higher in nondipper, dipper, and extreme dipper hypertensives than in normotensive controls (58.6+/-1.8, 55.6+/-0.9, and 53.3+/-0.8 versus 43.5+/-1.4 bursts/100 heartbeats, respectively; P<0.01 for all), a further significant increase being detected in reverse dippers (76.8+/-3.1 bursts/100 heartbeats; P<0.05). Compared with normotensives, baroreflex-heart rate control was similarly impaired in all the 4 hypertensive states, whereas baroreflex-sympathetic control was preserved. The day-night blood pressure difference correlated inversely with sympathetic nerve traffic (r=-0.76; P<0.0001) and homeostasis model assessment index (r=-0.32; P<0.005). Thus, the reverse dipping state is characterized by a sympathetic activation greater for magnitude than that seen in the other conditions displaying abnormalities in nighttime blood pressure pattern. The present data suggest that in hypertension, sympathetic activation represents a mechanism potentially responsible for the day-night blood pressure difference.     

Urinary albumin excretion among nondipper hypertensive patients is closely related with the pattern of nondipping

The relationship between 24-hour urinary albumin excretion (UAE) rate and the pattern of nondipping (isolated systolic nondipping, isolated diastolic nondipping, and both systolic and diastolic nondipping) is not known. Medical history, physical examination, laboratory analysis, and office and ambulatory blood pressure measurements were performed. Twenty-four hour urine specimens were collected to determine creatinine clearance and UAE. In total, 158 essential hypertensive patients (104 dippers, 54 nondippers) were included. Fourteen patients were isolated systolic nondippers, 7 patients were isolated diastolic nondippers, and 33 patients were both systolic and diastolic nondippers. Among nondipper patients, 17 had microalbuminuria and, among dipper patients, 9 had microalbuminuria (P < .0001). The median UAE of dippers was lower when compared with nondippers (5.25 mg/day vs.23 mg/day, P < .0001). The median UAE of isolated systolic nondippers, isolated diastolic nondippers, and both systolic and diastolic nondippers were 8.45 mg/day, 7.7 mg/day, and 25.5 mg/day, respectively (P = .001). Subgroup comparison of patients revealed that UAE was higher in patients with both systolic and diastolic nondippers when compared with dippers (P < .0001), isolated systolic nondippers (P = .001), and isolated diastolic nondippers (P =  .017). Not only nondipping itself, but nondipping profile may be related with UAE in essential hypertensive patients.     

Ambulatory pulse pressure, left ventricular hypertrophy and function in arterial hypertension

BACKGROUND: A wide pulse pressure (PP) can provide important risk assessment information about myocardial infarction, carotid artery atherosclerosis, and global cardiovascular risk. Ambulatory pulse pressure (APP) does not have a well-known prognostic value in hypertensive patients. METHODS:To evaluate the relationship among high APP, atrial volumes, and cardiac function, an observational study was performed on 108 untreated non-elderly hypertensive patients (mean age 54.23 +/- 7.12). Twenty-four-hour ambulatory blood pressure monitoring, Doppler and echocardiographic measurements of systolic, diastolic function, left and right atrial volumes, left ventricular mass index and dimensions, were performed in subjects with both clinic and APP > 60 mmHg (APP1 Group). A control group of hypertensive selected subjects with both clinic and APP < 60 mmHg was chosen (APP 2 Group). RESULTS: The APP1 group showed left atrial volume enlargement, high left ventricular mass index, and impaired diastolic function. A positive correlation was found in the APP1 group results among left ventricular end diastolic diameter (r = 0.39, P < 0.01), left atrial volume (0.38, P < 0.05), and left ventricular mass index (r = 0.33, P < 0.05); clinic PP showed a statistically significant correlation with left atrial volume, left ventricular end diastolic diameter, and left ventricular mass index only in the APP1 group. CONCLUSIONS: These results suggest that elevated APP can be considered an effective predictor of cardiovascular risk in hypertensive subjects. In these patients echocardiographic evaluation of left ventricular function and morphology can increase the prognostic value of PP.     

QT Dispersion in Dipper- and Nondipper-Type Hypertension

The aim of this study was to identify the relationship of QT dispersion on 12-lead electrocardiograms and left ventricular mass index on echocardiograms associated with the circadian rhythm of blood pressure (BP). Heart rate and BP were monitored every 30 min for 48 h in 62 patients with essential hypertension using an ambulatory BP monitoring device. The patients were divided into four groups according to gender and circadian BP pattern (nocturnal BP dipper or nondipper). The patients were classified as dippers if their daytime BP decreased by at least 10% during the night and all the other subjects were classified as nondippers. Age, body mass index, and 48-h mean BP were similar among the four groups. During the night-rest period, the systolic and diastolic BP were significantly decreased in dipper-type hypertensives. The maximum QT_c interval and QT_c dispersion were longer in nondippers than in dippers. Left ventricular mass index (LVMI) had a tendency to increase in nondippers. The nocturnal reduction of BP significantly correlated with QT_c dispersion and LVMI. The QT_c dispersion significantly correlated with LVMI and interventricular septum thickness.     

Hypertension and sudden death: Increased ventricular ectopic activity in left ventricular hypertrophy

The present study was designed to detect and quantify cardiac arrhythmias in hypertensive patients with left ventricular hypertrophy. Continuous ambulatory electrocardiographic tracings and arterial pressure were recorded for 24 hours in 14 normotensive subjects, 10 patients with established essential hypertension without left ventricular hypertrophy, and 16 hypertensive patients with left ventricular hypertrophy by electrocardiographic criteria. Urinary excretion of norepinephrine was simultaneously measured over four successive four-hour and one eight-hour period. Patients with left ventricular hypertrophy had significantly more ventricular (but not atrial) premature contractions than those without left ventricular hypertrophy or than normotensive subjects. Five patients with left ventricular hypertrophy had episodes of more than 30 premature ventricular contractions per minute. Higher-grade ventricular ectopic activity such as coupled premature ventricular contractions was seen in two, and multifocal premature ventricular contractions were seen in three in the group with left ventricular hypertrophy. No difference in urinary catecholamine excretion rates among the three groups was seen. Left ventricular hypertrophy has been shown to be an independent risk factor for sudden death and acute myocardial infarction. Electrocardiographic monitoring of patients with left ventricular hypertrophy allows identification of those who have the highest risk and, therefore, require the most aggressive therapeutic intervention.     

Associations between nondipping of nocturnal blood pressure decrease and cardiovascular target organ damage in strictly selected community-dwelling normotensives

BACKGROUND: In hypertensives, nondippers are more likely than dippers to suffer silent, as well as overt, hypertensive target organ damage. In this study, we investigated whether a nondipper status was associated with target organ damage in normotensives. METHODS: We performed ambulatory blood pressure (BP) monitoring, echocardiography, and carotid ultrasonography and measured natriuretic peptides and urinary albumin (UAE) in 74 normotensive subjects with the following criteria: 1) clinical BP <140/90 mm Hg; 2) average 24-h ambulatory BP <125/80 mm Hg. RESULTS: The left ventricular mass index (LVMI) and the relative wall thickness (RWT) measured by echocardiography were greater in nondippers than dippers (LVMI: 103 +/- 26 v 118 +/- 34 g/m(2), P <.05; RWT: 0.38 +/- 0.07 v 0.43 +/- 0.09, P <.01). Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were higher in nondippers than dippers (ANP: 14 +/- 10 v 36 +/- 63 pg/mL, P <.01; BNP: 16 +/- 12 v 62 +/- 153 pg/mL, P <.05). There were no significant differences in UAE and intima-media thickness measured by carotid ultrasonography. CONCLUSIONS: Normotensive nondipping may not reflect renal damage, but may have a predominant effect on cardiac damage. Nondipping of nocturnal BP seems to be a determinant of cardiac hypertrophy and remodeling, and may result in a cardiovascular risk independent of ambulatory BP levels in normotensives.     

Age-Related Differences in the Mechanism of Nondipping Among Patients with Obstructive Sleep Apnea Syndrome

The frequency of nondipper (those lacking the normal drop in nocturnal blood pressure [BP]) is high in patients with obstructive sleep apnea syndrome (OSAS). The objective of this study is to investigate age-related differences in the nocturnal BP profile of patients with OSAS. The study subjects included 214 patients with polysomnography-diagnosed OSAS. The status of dipper or nondipper was determined by 24-hour ambulatory BP measurements. We divided the subjects into three groups by age (younger, middle-aged, and elderly) and compared the frequency and sleep profiles of nondippers in the different age groups. The prevalence of nondippers was significantly higher in the elderly OSAS group than in the younger and middle-aged OSAS groups (69% vs. 45%, 47%; P < .05). In the younger OSAS group, nondippers, when compared with dippers, were characterized by higher apnea–hypopnea index (AHI, 48.2 ± 27.1 vs. 37.4 ± 23.0 times/h, P < .05), whereas in the middle-aged and elderly OSAS groups, the AHI of nondippers was almost identical to that of dippers. On the other hand, in the elderly OSAS group, nondippers, when compared with dippers, had shorter periods of slow wave sleep as measured by nonrapid eye movement stage 3–4, whereas nondippers and dippers in the other two age groups were not different in terms of slow wave sleep. These results indicate age-related differences in major mechanisms leading to nondipping. Severe apnea causes nondipping only in young OSAS patients, whereas disturbance of sleep quality plays a more important role in elderly OSAS patients.