The relationship between nighttime dipping in blood pressure and cerebral hemodynamics in nonstroke patients

Inadequate dipping in nighttime blood pressure (BP) is associated with cerebrovascular disease. The authors aimed to determine whether inadequate nocturnal dipping was associated with abnormalities in cerebrovascular hemodynamics in individuals without stroke. Participants in this study underwent 24-hour ambulatory BP monitoring followed by morning transcranial Doppler measurements of blood flow velocities (BFVs) in the middle cerebral artery during supine rest, head-up tilt, hypocapnia, and hypercapnia. Nighttime BP decline by <10% was considered nondipping. Of the 102 nonstroke participants (mean age, 53.6 years), 35 (34%) were dippers. Although nondippers had similar BFV and cerebrovascular resistance (CVR) while supine, they had a lower BFV (P=.04) and greater CVR (P=.02) during head-up tilt compared with dippers. Moreover, greater nighttime dipping in both systolic BP (P=.006) and diastolic BP (P=.03) were associated with higher daytime BFV and lower CVR (P=.01 for systolic BP; P=.02 for diastolic BP). Inadequate nocturnal BP dipping is associated with lower daytime cerebral blood flow, especially during head-up tilt.     

Clinical trial of arotinolol in the treatment of hypertension: dippers vs. non-dippers.

To compare the effects of an alpha, beta blocker, arotinolol, in the treatment of essential hypertension between patients with a dipper and those with a non-dipper profile by means of 24-h ambulatory blood pressure monitoring (ABPM), a multicenter single blind parallel trial was carried out in five clinical centers. After a one-week single blind placebo run-in period, the patients underwent ABPM if their clinic diastolic blood pressure (DBP) ranged from 90-109 mmHg and their clinic systolic blood pressure (SBP) was <180 mmHg. They were divided into two groups according to the absence (non-dipper group, 24 cases) or presence (dipper group, 23 cases) of nocturnal BP reduction > or =10% of daytime BP. ABPM was measured again at the end of the active treatment phase. All patients were given Arotinolol 10-20 mg twice daily for 4 weeks. Twenty four-hour systolic and diastolic average BPs (MSBP, MDBP), 24-h systolic and diastolic blood pressure load (LS BP, LDBP), daytime systolic and diastolic average BPs (dMSBP, dMDBP), daytime systolic and diastolic blood pressure load (dLSBP, dLDBP), nighttime systolic and diastolic average BPs (nMSBP, nMDBP) and nighttime systolic and diastolic blood pressure load (nLSBP, nLDBP) were calculated. Arotinolol was effective in 78.2% of dippers and 54.2% of non-dippers, but the difference in effectiveness between these groups was not statistically significant. After treatment, SBP and DBP-including 24-h, daytime and nighttime systolic and diastolic BPs- were significantly reduced in both groups. During the daytime period, the systolic and diastolic blood pressures were significantly reduced in both dippers and non-dippers, while nighttime systolic and diastolic blood pressures were significantly reduced only in the non-dipper group. No significant changes were found in the dipper group over this period. In conclusion, Arotinolol, which can be dosed twice daily, is an effective antihypertensive agent which effectively lowers blood pressure during the day while reducing nighttime blood pressure more in non-dippers than in dippers, without excessive lowering blood pressure in the latter.     

Changes of nocturnal blood pressure dipping status in hypertensives by nighttime dosing of alpha-adrenergic blocker, doxazosin : results from the HALT study

Abnormal nocturnal blood pressure (BP) dipping status may be partly determined by nocturnal sympathetic activity. We studied the effect of nighttime dosing of an alpha(1)-adrenergic blocker, doxazosin, on the BP dipping status of 118 hypertensives, all of whom underwent 24-hour ambulatory BP monitoring before and after treatment. The mean nighttime/daytime ratio of systolic BP was increased (0.91 after therapy versus 0.89 at baseline, P<0.05). The patients were initially divided into 4 groups on the basis of their dipping status at the baseline assessment: 18 (15%) were extreme dippers, with a nighttime systolic BP fall of at least 20% of daytime BP; 46 (39%) were dippers (fall between 10% and 20%); 48 (41%) were nondippers (fall between 0% and 10%); and 6 (5%) were risers (nocturnal increase of systolic BP). A shift in dipping status toward less nocturnal BP dipping was observed after doxazosin therapy (P<0.05). Dipping status was determined by nighttime more than by daytime BP, and this was not explained by differences in the number of daytime and nighttime readings. The effects of doxazosin on the mean nocturnal systolic BP changes were an increase of 4.3 mm Hg in extreme dippers and decreases of 0.7 mm Hg in dippers, 12 mm Hg in nondippers, and 18 mm Hg in risers; the reduction was only significant in the latter 2 groups (both P<0.01). To estimate the effects of regression to the mean on the changes in dipping status, we also defined dipping status with the average of the BPs before and after doxazosin and found no difference in the degree of nighttime BP reduction among each group. The reduction of daytime BP was now significantly greater in the subgroups with less dipping: 6. 4 mm Hg for extreme dippers and 16 mm Hg for risers (P<0.05). In conclusion, nighttime dosing with doxazosin markedly affects the nocturnal BP dipping status of hypertensives, but the apparently greater reduction in nighttime pressure in nondippers and risers may be, at least partly, due to the effect of regression to the mean. The most important determinants of the effect of doxazosin were the absolute BP levels, both day and night, rather than dipping status per se.     

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.     

Differential Effects of Amlodipine on Ambulatory Blood Pressure in Elderly Hypertensive Patients With Different Nocturnal Reductions in Blood Pressure

Previous studies have discovered that amlodipine given once daily can reduce blood pressure (BP) throughout the day and night. The effects of amlodipine on day and night BP have not been fully investigated in groups of hypertensives with different diurnal variations. In a prospective study, we performed 24-h ambulatory BP monitoring before and after once-daily use of amlodipine in three groups of asymptomatic elderly hypertensive patients with different nocturnal BP reductions, as follows: 10 extreme dippers with nocturnal reduction of systolic BP ≥ 20% of daytime systolic BP, 17 dippers (reduction by ≥ 10% to < 20%), and 23 nondippers (reduction by < 10%). At baseline, the office and the awake BP were similar in all three groups, whereas the nighttime BP was significantly higher in the nondippers than in the dippers and in the dippers than in the extreme dippers. After treatment, the office and the daytime BP were both equally reduced in all three groups. On the other hand, the nighttime BP was significantly reduced both in the nondippers and, to a lesser extent, in the dippers. In the extreme dippers, however, no further reductions of nocturnal BP were found. Significant positive correlations were found between baseline BP levels and the BP reduction after amlodipine therapy was begun. No BP reduction > 10 mm Hg was observed when the baseline systolic/diastolic BP was < 120/70 mm Hg. Multiple linear regression analysis disclosed that the nighttime BP reduction afforded by amlodipine was dependent on the baseline nighttime BP levels, but not on the baseline nocturnal fall of BP. Once-daily use of amlodipine reduced BP levels throughout the day and night in hypertensive patients who show minimal or mild nocturnal BP fall, but it had no effects on nocturnal BP in those who show a substantial nighttime BP reduction. Thus, when we controlled using daytime office BP, amlodipine might not further reduce nocturnal BP to the extent that it accelerates the brain ischemia in some hypertensive patients with marked nocturnal BP reduction.     

Efficacy and safety of combination therapy with losartan and hydrochlorothiazide in elderly hypertension

We examined the effect and safety of combination therapy with low-dose diuretics (hydrochlorothiazide: HCTZ) and angiotensin II receptor antagonist (losartan) in elderly cases of hypertension, using ambulatory blood pressure monitoring (ABPM). Elderly hypertensive patients (mean age 75 +/- 2 years) were treated with either losartan (25-50 mg/day) or HCTZ (12.5 mg/day) for at least 4 weeks, and then 24-hour blood pressure (BP) was measured by ABPM. Combination therapy with addition of other drug was initiated in 14 patients whose 24-hour systolic BP or daytime systolic BP was over 140 mmHg (160 mmHg for the patients of 80 years or older). After 4 weeks of the combination therapy, ABPM was repeated. Blood cell count and blood chemistry were also done before and after initiation of combination therapy. In the losartan-preceding group (n = 9), the combination therapy with HCTZ reduced 24-hour BP by 19.3 +/- 2.3/6.6 +/- 2.3 mmHg. Similarly, daytime and nighttime BP decreased by 21.4 +/- 4/8.4 +/- 2.8 mmHg and 15.2 +/- 4/4.2 +/- 2.4 mmHg, respectively. In the HCTZ-preceding group, the combination with losartan also decreased 24-hour BP by 12.2 +/- 4.8/3.4 +/- 1.4 mmHg. The decreases of daytime and nighttime BP were 13.8 +/- 6.6/4 +/- 1.1 mmHg and 10 +/- 4.7/3 +/- 2.4 mmHg, respectively. Heart rate did not change with combination therapy in the losartan-preceding group, while heart rate during daytime tended to decrease by addition of losartan in the HCTZ-preceding group (3.8 +/- 1.7/min). Serum electrolytes, uric acid, lipids, renal function and body weight did not change during the study period. Thus, combination therapy of losartan/hydrochlorothiazide seems useful in the treatment of elderly hypertension, showing additive BP lowering effect without metabolic adverse effects.     

Evaluation of the activity of the autonomic nervous system in "dipper" and "non dipper" essential hypertensives. Gender differences]

OBJECTIVES: 1) To compare the autonomic nervous system activity parameters obtained from a photoplethysmographic recording in dipper and non dipper hypertensive. 2) To look for an interaction between dipper/non dipper status and gender. METHODS: Prospective study involving 245 untreated hypertensives (51 +/- 13 years, 146 men, 99 women). All of the patients underwent a 24-hour ambulatory blood pressure measurement (ABPM) as well as an echocardiography for left ventricular mass index determination (LVMI) and a photoplethysmographic recording of blood pressure (BP). Nondippers were defined as those whose nocturnal decrease in systolic BP (SBP) and/or diastolic BP (DBP) was < 10% of daytime BP. Spectral powers were obtained from the photoplethysmographic recording using a fast Fourier transform over the low frequency band (LF) and the high frequency band (HF). Baroreflex sensitivity (BRS) was evaluated by the sequences method. RESULTS: Of the 245 patients, 159 were dippers (98 men, 61 women) and 86 were non dippers (48 men and 38 women). Clinic BP was significantly higher in non dippers than in dippers (168/101 vs 161/98 mmHg; p < 0.01 for SBP and p < 0.05 for DBP) whereas daytime ABPM and LVMI were not different, whatever the gender. LF spectral powers were significantly lower in non dippers than in dippers for SBP (respectively 25 +/- 11% vs 30 +/- 13%; p < 0.01) for DBP (respectively 35 +/- 14% vs 41 +/- 15%; p < 0.01) and for HR (respectively 34 +/- 15% vs 38 +/- 15%; p = 0.03). They showed a positive correlation with the nocturnal SBP fall (r = 0.21, p < 0.001 for SBP and DBP spectral powers, r = 0.19; p < 0.005 for HR spectral power) and with the nocturnal DBP fall, too (r = 0.19; p < 0.005 for SBP spectral power, r = 0.20; p < 0.002 for DBP spectral power, r = 0.19; p < 0.005 for HR spectral power). HF spectral powers tended to be higher in non dippers than in dippers but in a non significative way. BRS was roughly the same in dippers and non dippers (7.5 +/- 2.7 vs 7.0 +/- 3.1 ms/mmHg, NS). The interaction between non dipper/dipper status and sex was non significant whatever the LF spectral power. CONCLUSIONS: 1) The greater the nocturnal BP fall, the higher the sympathetic activity indexes. 2) This relationship was found both in males and females.     

A study on 24-hour ambulatory blood pressure in normotensive elderly, living in a local home for the aged]

Ambulatory blood pressure (BP) was non-invasively monitored in 124 normotensive elderly, living in an old people's home at the annual health examination. Cases were divided into 41 cases < 75 years (group A, mean age 70.6) and 83 cases > or = 75 years (group B, 82.7) for analysis of the office BP and 24-hour BP. Whole-day systolic BP in group B was significantly higher than those in the group A (p < 0.02) although no significant differences were observed in diastolic BP and pulse rate. Separated analysis of whole-day BP into daytime and nighttime revealed that the nighttime systolic BP in the group B was significantly higher than those in group A (132.2 +/- 17.4% vs. 123.8 +/- 18.6 mmHg, p < 0.02) whereas no significant difference was observed in day-time systolic BP between two groups (136.6 +/- 14.9 vs. 132.1 +/- 14.4 mmHg, n.s.). The day-night difference in systolic BP tended to be less in group B than in group A (4.5 +/- 11.6 vs. 8.2 +/- 12.2 mmHg, p < 0.10). The prevalence of non-dippers, who had a higher nighttime systolic BP than daytime systolic BP were 24.4% of the group A and 30.1% of the group B. It was concluded that systolic BP during the nighttime increased with the ageing process after age 60, although that during daytime did not change.     

Circadian Blood Pressure Changes and Myocardial Ischemia in Hypertensive Patients With Coronary Artery Disease

Objectives. We sought to evaluate whether different circadian blood pressure (BP) changes could influence the occurrence of ischemic episodes in untreated and treated hypertensive patients with stable coronary artery disease (CAD).

Background. In hypertensive patients with CAD the occurrence of myocardial ischemia could be influenced by either high or low BP values. Ambulatory monitoring has shown that circadian BP profile is not uniform in hypertensive patients.

Methods. Twenty-one patients with a nighttime BP fall <10% (“nondippers”), 35 with a nighttime BP fall between >10% and <20% (“dippers”) and 14 with a nighttime BP fall >20% (“overdippers”) with CAD underwent simultaneous ambulatory BP and electrocardiographic monitoring before and during drug therapy with nitrates and atenolol or verapamil in a prospective, randomized, open, blinded end point design.

Results. Daytime BP was not significantly different among the groups both before and during therapy. Nighttime BP was different by definition. Treatment significantly reduced BP values in each group (p < 0.05). Daytime ischemic episodes did not differ among the groups either before or during therapy. Drug therapy significantly reduced daytime ischemia (p < 0.05). In untreated patients, nighttime ischemia was more frequent in nondippers than in dippers and overdippers (p < 0.05). Drug therapy significantly reduced nocturnal ischemia in nondippers (p < 0.05), had no significant effect in dippers and significantly increased nighttime ischemia in overdippers (p < 0.05). During treatment, nighttime ischemia was more frequent in overdippers than in dippers and nondippers (p < 0.05). The same results were achieved when ischemic episodes were defined with more restrictive criteria (ST segment depression ≥2 mm).

Conclusions. Circadian BP changes can influence the occurrence of myocardial ischemia in untreated and treated hypertensive patients with CAD. Nocturnal ischemia was found to be more frequent in nondippers among untreated patients and in overdippers among treated patients, potentially suggesting different therapeutic approaches based on circadian BP profile.     

Insulin resistance is associated with reduced nocturnal falls of blood pressure in normotensive, nonobese type 2 diabetic subjects

To assess the relationship between insulin resistance and ambulatory blood pressure (BP) pattern, we determined glucose infusion rate (GIR) as a marker of insulin resistance using a glucose clamp method, and measured 24-h BPs in 25 normotensive, nonobese type 2 diabetic subjects. They were divided into two groups: 11 dippers and 14 nondippers. Clinical characteristics were similar in the two groups except for orthostatic fall in systolic BP. The median GIR level was significantly lower in nondippers than in dippers (P < 0.05). Spearman's rank correlation revealed that the GIRs were negatively correlated with the systolic, diastolic and mean BPs during nighttime (P < 0.05 or less), but not with daytime or whole day BPs. Moreover, based on a logistic regression analysis, the GIR as well as orthostatic fall in systolic BP discriminated independently between dippers and nondippers. Thus, our results suggest that insulin resistance is associated with decreased nocturnal BP fall in type 2 diabetic subjects.     

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.     

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.     

Diurnal variation of hemodynamic indices in non-dipper hypertensive patients.

The purpose of this study was to elucidate the underlying mechanisms of blunted nocturnal blood pressure reduction in non-dipper hypertensive patients. We studied the diurnal variations in systemic hemodynamic indices and baroreflex sensitivity. In 45 subjects with essential hypertension (24 men; mean age, 49+/-1 years), intra-arterial pressure was monitored telemetrically. Non-dippers were defined as those with a nocturnal reduction of systolic blood pressure of less than 10% of daytime systolic blood pressure. Stroke volume was determined using Wesseling's pulse contour method, calibrated with indocyanine green dilution. Baroreflex sensitivity was calculated as deltapulse interval/deltasystolic blood pressure on spontaneous variations. The mean values of the hemodynamic parameters were calculated every 30 min. Twenty-six subjects were classified as non-dippers. Daytime blood pressure was not significantly different between dippers (149+/-4/87+/-3 mmHg) and non-dippers (147+/-3/82+/-2 mmHg), while the nighttime blood pressure was significantly reduced in dippers (131+/-3/77+/-2 mmHg) but not in non-dippers (145+/-3/80+/-2 mmHg). Nocturnal decreases in both cardiac index and stroke index were smaller in non-dippers (-12.0+/-1.2% and 1.5+/-1.0%) than in dippers (-17.5+/-1.4% and -2.2+/-1.1%). Baroreflex sensitivity significantly increased at nighttime both in dippers (6.5+/-0.6 to 8.0+/-0.7 ms/mmHg) and in non-dippers (5.1+/-0.3 to 6.4+/-0.4 ms/mmHg). Neither daytime nor nighttime baroreflex sensitivity was significantly different between the groups. We conclude that the hemodynamics of non-dipper essential hypertension are characterized by an inadequate nocturnal decrease in cardiac index and stroke index, suggestive of relative volume expansion or malsuppressed sympathetic activity.     

Clinical impact of dipping and nocturnal blood pressure patterns in newly diagnosed,never-treated patients with essential hypertension

The significance of nondipping and increased nighttime systolic blood pressure (SBP) in established hypertension is well defined. We investigated whether these factors alone or combined correlate with vascular damage in early-stage hypertension. Newly diagnosed, untreated hypertensives were classified as dippers and nondippers according to ambulatory blood pressure (BP). Twenty-four–hour urinary albumin excretion and markers of arterial stiffness (pulse wave velocity, augmentation index, central and peripheral pulse pressure, central BP) and atherosclerosis (carotid intima-media thickness) were assessed. Serum asymmetric dimethylarginine, an index of endothelial dysfunction, was measured in a study subgroup; 10-year cardiovascular risk was calculated. Among 222 hypertensives, only urinary albumin excretion was increased in nondippers, compared to dippers (P = .026). When dippers were further stratified according to nighttime SBP (<120 or ≥120 mm Hg), the first group demonstrated the lowest levels of office, aortic, 24-hour, daytime and nighttime BP, compared to dippers with elevated nighttime SBP and nondippers. Although vascular measurements and asymmetric dimethylarginine were comparable between these groups, dippers with normal nighttime SBP exhibited the lowest cardiovascular risk score (P = .050). In early-stage hypertension, nondipping was accompanied by microvascular, yet not macrovascular and endothelial dysfunction. Dippers with elevated nighttime SBP appear as a distinct group with increased hemodynamic pressure load and cardiovascular risk.     

Early alterations of blood pressure in normotensive and normoalbuminuric Type 1 diabetic patients

With the objective to examine patterns of blood pressure (BP) in normotensive and normoalbuminuric Type 1 diabetic patients during 24 h ambulatory blood pressure monitoring (ABPM) we studied 28 Type 1 diabetic patients aged 27+/-7.1 years with a disease duration of 9+/-6.6 years, and 28 non-diabetic normotensive subjects aged 25+/-6.5 years matched to the diabetic group for age, gender, skin color, weight, height, body mass index, clinic BP and absence of microalbuminuria. Systolic BP (sBP) and diastolic BP (dBP) were recorded for 24 h, daytime and nighttime. SBP and dBP burden, night/day BP ratios and percent nighttime BP fall were determined. Subjects with a nocturnal fall in either sBP or dBP of less than 10% of daytime values were classified as non-dippers. Both sBP (111+/-7.1 vs. 104+/-9 mmHg; P=0.003) and dBP nighttime (66+/-6.1 vs. 61+/-5.3 mmHg; P=0.001) were higher in diabetic patients than non-diabetic subjects. Night/day ratios for sBP (0.93+/-0.04 vs. 0.89+/-0.05; P=0.006) and dBP (0.86+/-0.06 vs. 0.82+/-0.06; P=0.007) were higher in diabetics. The loss of a fall in sBP was more prevalent in diabetic subjects (78 vs. 39%; P=0.007). Non-dippers for sBP and dBP in the diabetic group had higher BP burden during the nighttime (21.4+/-16.6 vs. 3.2+/-3.9%; P=0.01 and 21.9+/-10 vs. 3.7+/-5.5%; P<0.001, respectively). Our data demonstrate higher sBP and dBP during the nighttime and loss of the nocturnal fall in BP in Type 1 diabetic patients. Further prospective studies are needed to define if high BP burden in diabetic non-dippers during the night could represent a risk for nephropathy and cardiovascular disease.     

INSULIN RESISTANCE IS ASSOCIATED WITH REDUCED NOCTURNAL FALLS OF BLOOD PRESSURE IN NORMOTENSIVE,NONOBESE TYPE 2 DIABETIC SUBJECTS

To assess the relationship between insulin resistance and ambulatory blood pressure (BP) pattern, we determined glucose infusion rate (GIR) as a marker of insulin resistance using a glucose clamp method, and measured 24-h BPs in 25 normotensive, nonobese type 2 diabetic subjects. They were divided into two groups: 11 dippers and 14 nondippers. Clinical characteristics were similar in the two groups except for orthostatic fall in systolic BP. The median GIR level was significantly lower in nondippers than in dippers (P < 0.05). Spearman's rank correlation revealed that the GIRs were negatively correlated with the systolic, diastolic and mean BPs during nighttime (P < 0.05 or less), but not with daytime or whole day BPs. Moreover, based on a logistic regression analysis, the GIR as well as orthostatic fall in systolic BP discriminated independently between dippers and nondippers. Thus, our results suggest that insulin resistance is associated with decreased nocturnal BP fall in type 2 diabetic subjects.     

Prognostic Value of Subdivisions of Nighttime Blood Pressure Fall in Hypertensives Followed Up for 8.2 Years. Does Nondipping Classification Need to Be Redefined?

J Clin Hypertens(Greenwich). 2010;12:508–515. © 2010 Wiley Periodicals, Inc. To evaluate the long-term prognostic significance of different ranges of the percentage fall in nighttime blood pressure (BP) of the nondipping pattern, 1200 hypertensive patients (645 women, age 51±12 years) underwent ambulatory BP monitoring under stabilized therapy. The occurrence of cardiovascular (CV) events was followed for 9833 patient-years and analyzed by the Cox hazard model. There were 152 CV fatal/nonfatal events (79 strokes, 51 coronary events, 22 others) during the 15.2 years of follow-up. According to nighttime BP fall (%) the authors noted: <0% (reverse-dippers [RD], n=83); 0%–4.9% (nondippers 1 [ND1], n=207); 5%–9.9% (nondippers 2 [ND2], n=311), 10%–19.9% (dippers [D], n=523); and ≥20% (extreme dippers [ED], n=76). After adjustment for confounding variables, hazard ratios (95% confidence interval) of CV event and stroke in RD vs D were 2.29 (1.31–3.99) and 2.46 (1.11–5.49); of ND1 vs D were 1.42 (1.12–1.79) and 1.62 (1.17–2.23); and of ND1 vs ND2 were 2.24 (1.33–3.75) and 2.30 (1.15–4.58). No differences were found in RD vs ND1 and ND2 vs D. Nondippers have a higher CV risk than dippers but only for a nighttime BP fall <5% suggesting that the limits for nondipping should be redefined for a stratification of CV risk.     

Ambulatory blood pressure monitoring in haemodialysis and continuous ambulatory peritoneal dialysis (CAPD) patients

The aim of this study was to compare the results of the 44-h ambulatory blood pressure monitoring (ABPM) data between haemodialysis (HDp) and CAPD patients and to investigate the relation of circadian rhythm in blood pressure (BP) with development of left ventricular hypertrophy. Twenty-two HDp (11 male, 11 female, mean age: 50 +/- 17 years) and 24 CAPDp (11 male, 13 female, mean age: 47 +/- 15 years) were included. Echocardiographic measurements and ABPM were performed in all study groups. ABPM of the first and second days were analysed separately and compared with CAPDp. Left ventricular hypertrophy was detected in 17 of the 22 HDp (77%) and 17 of the 24 CAPDp (71%). There was no significant differences between HD and CAPDp in respect to 44-h, daytime and night-time systolic and diastolic BP values. Although the course of BP in CAPDp was stable during the 44-h period, systolic and diastolic BP levels on the second day were significantly higher than those of on the first day in HDp (P < 0.001 for both). Daytime systolic and diastolic BP levels on the first day in HD group were recorded lower than those of the CAPD group. On the second day, night-time BP readings (both systolic and diastolic BP) were measured significantly higher in the HD group compared with the CAPD group. Twenty-one of the 24 (88%) CAPD patients were dippers, whereas only four of the 22 (18%) HDp were dippers (P < 0.001). Dipper patients had significantly lower left ventricular mass index (LVMI) than non-dipper patients (131 +/- 29 g/m(2) vs 153 +/- 40 g/m(2), P = 0.03). In 44-h ABPM, there were no differences in daytime and night-time systolic and diastolic blood pressures between HD and CAPD patients. Non-dipper patients had increased LVMI as compared with dipper patients. Abnormalities in circadian rhythm of the blood pressure might be one of the implicated factors for development of left ventricular hypertrophy.     

Nighttime blood pressure dipping in young adults and coronary artery calcium 10-15 years later: the coronary artery risk development in young adults study

Nighttime blood pressure (BP) dipping can be quantified as the ratio of mean nighttime (sleep) BP to mean daytime (awake) BP. People whose dipping ratio is ≥ 0.90 have been referred to as nondippers, and nondipping is associated with cardiovascular disease events. We examined the relationship between systolic nighttime BP dipping in young adults and the presence of coronary artery calcium (CAC) 10 to 15 years later using data from the ambulatory BP monitoring substudy of the Coronary Artery Risk Development in Young Adults Study. Among 239 participants with adequate measures of both nighttime and daytime readings and coronary artery calcium, the systolic BP dipping ratio ranged from 0.72 to 1.24 (mean, 0.88; SD, 0.06), and CAC was present 10 to 15 years later in 54 participants (22.6%). Compared with those whose systolic BP dipping ratio ranged from 0.88 to 0.92 (quartile 3), the 57 participants (23.9%) with less pronounced or absent dipping (ratio, 0.92-1.24; quartile 4) had an unadjusted odds ratio of 4.08 (95% CI, 1.48-11.2) for the presence of CAC. The 60 participants (25.1%) with a more pronounced dipping (ratio, 0.72-0.85; quartile 1) also had greater odds for presence of CAC (odds ratio, 4.76 [95% CI, 1.76-12.9]). When modeled as a continuous predictor, a U-shaped relationship between systolic BP dipping ratio and future CAC was apparent and persisted after adjustment for multiple potential confounders (P<0.001 for quadratic term). Both failure of systolic BP to dip sufficiently and "overdipping" during nighttime may be associated with future subclinical coronary atherosclerosis.     

A possible relationship of nocturnal blood pressure variability with coronary artery disease in diabetic nephropathy

Evidence suggests a relationship between short-term blood pressure (BP) variability and cardiovascular target-organ damage. Although a blunted nocturnal decrease in BP and reduced heart rate variability have been shown to be associated with cardiovascular morbidity in diabetic patients, little information is available on short-term BP variability. In this study, short-term BP variability was assessed in 36 subjects with type 2 diabetes and overt nephropathy who underwent ambulatory BP monitoring, and the factors that correlated with short-term BP variability were examined. The incidence of coronary artery disease (CAD) was significantly greater in the patients with increased 24-h systolic BP variability (67% versus 11%; p < 0.0005), while that of cerebrovascular disease was not significantly affected (61% versus 50%). Multiple stepwise regression analysis revealed that serum cholesterol (cholesterol) and plasma norepinephrine (p-NE) were significant and independent contributors to nighttime systolic BP variability (partial R2 = 0.490, p < 0.001; partial R2 = 0.470, p < 0.001) and demonstrated that body mass index and p-NE were primary determinants of nighttime diastolic BP variability (partial R2 = 0.539, p < 0.0005; partial R2 = 0.304, p < 0.05). Diabetic nephropathy patients with CAD had significantly increased daytime systolic (17.8 mmHg versus 13.1 mmHg, p < 0.0005), nighttime systolic (17.4 mmHg versus 10.5 mmHg, p < 0.0001), and nighttime diastolic (10.4 mmHg versus 7.2 mmHg, p < 0.05) BP variability. Furthermore, logistic regression analysis demonstrated that nighttime systolic BP variability was an independent risk factor for CAD (odds ratio 3.13 [95% CI 1.02-9.61]; p < 0.05). The increase in nighttime BP variability is associated with a proportional sympathetic activation in diabetic nephropathy. Elevated short-term BP variability combined with relative sympathetic prevalence during the night might represent an important risk factor for cardiovascular events in the diabetic population.