Age and Sex Differences in the Contribution of Mean Arterial Pressure to Pulse Pressure Before Middle Age

INTRODUCTION

A lower ability to buffer pulse pressure (PP) in the face of increasing mean arterial pressure (MAP) may underlie the disproportionate increase in systolic blood pressure (SBP) in women from young adulthood through middle-aged relative to men.

AIM

To evaluate the contribution of MAP to the change in PP and pressure wave contour in men and women from young adulthood to middle age.

METHODS

Central pressure waveform was obtained from radial artery applanation tonometry in 312 hypertensive patients between 16 to 49 years (134 women, mean age 35 ± 9 years), 185 of whom were on antihypertensive treatment.

RESULTS

Higher MAP levels (≥ 100 mmHg) were significantly associated with higher brachial and central SBP (P < 0.001), PP (P < 0.001), incident wave (P = 0.005), AP (P < 0.001), and PWV (P < 0.001) compared to lower MAP levels. The relationship between MAP and brachial PP (P < 0.001), central PP (P < 0.001), incident wave (P < 0.001), and AP (P < 0.01), but not PWV, strengthens with age. The age-related increase in the contribution of MAP to brachial PP (P < 0.001), central PP (P < 0.001), and incident wave (P < 0.001) was more prominent in women than in men beginning in the fourth decade. In multiple regression analyses, MAP remained a significantly stronger predictor of central PP and incident wave in women than in men, independent of age, heart rate, and antihypertensive treatment. In turn, age remained a significantly stronger predictor of central PP and incident wave in women than in men, independent of MAP, heart rate, and antihypertensive treatment.

CONCLUSIONS

Women of reproductive age showed a steeper increase in PP with increasing MAP, despite comparable increases in arterial stiffness in both sexes. The difference was driven by a greater contribution of MAP to the forward component of the pressure wave in women.

Hemodynamic characterization of hypertensive patients with an exaggerated orthostatic blood pressure variation

Exaggerated orthostatic blood pressure variation (EOV) is a poorly understood phenomenon related to high cardiovascular risk. We aimed to determine whether hypertensive patients with EOV have a distinct hemodynamic pattern, assessed through impedance cardiography.

METHODS

In treated hypertensive patients, we measured the cardiac index (CI), systemic vascular resistance index (SVRI), blood pressure (BP), and heart rate (HR) in the supine and standing (after 3 minutes) positions, defining three groups according to BP variation: 1) Normal orthostatic BP variation (NOV): standing systolic BP (stSBP)-supine systolic BP (suSBP) between -20 and 20 mmHg and standing diastolic BP (stDBP)-supine diastolic BP (suDBP) between -10 and 10 mmHg; 2) orthostatic hypotension (OHypo): stSBP-suSBP≤-20 or stDBP-suDBP≤-10 mmHg; 3) orthostatic hypertension (OHyper): stSBP-suSBP≥20 or stDBP-suDBP≥10 mmHg. We performed multivariable analyses to determine the association of hemodynamic variables with EOV.

RESULTS

We included 186 patients. Those with OHyper had lower suDBP and higher orthostatic SVRI variation compared to NOV. In multivariable analyses, orthostatic HR variation (OR = 1.06 (95%CI 1.01-1.13), p = 0.03) and orthostatic SVRI variation (OR = 1.16 (95%CI 1.06-1.28), p = 0.002) were independently related to OHyper. No variables were independently associated with OHypo.

CONCLUSION

Patients with OHyper have a distinct hemodynamic pattern, with an exaggerated increase in SVRI and HR when standing.

Arterial Stiffness in Treated Hypertensive Patients With White-Coat Hypertension

Arterial stiffness, assessed through pulse wave velocity (PWV), independently predicts cardiovascular outcomes. In untreated persons, white-coat hypertension (WCH) has been related to arterial stiffness, but data in treated patients with WCH are scarce. The authors aimed to determine a possible association between WCH and arterial stiffness in this population. Adult treated hypertensive patients underwent home blood pressure monitoring and PWV assessment. Variables associated with PWV in univariable analyses were entered into a multivariable linear regression model. The study included 121 patients, 33.9% men, median age 67.9 (interquartile range 18.4) years, 5.8% with diabetes, and 3.3% with a history of cardiovascular or cerebrovascular disease. In multivariable analysis, WCH in treated hypertensive patients remained a determinant of PWV: β=1.1 (95% confidence interval, 0.1-2.1 [P=.037]; adjusted R² 0.49). In conclusion, WCH is independently associated with arterial stiffness in treated hypertensive patients. Whether this high-risk association is offset by antihypertensive treatment should be further investigated.

[Morning rise in home blood pressure and target organ damage in hypertensive patients]

The morning blood pressure (BP) rise entails a higher cardiovascular risk. Studies evaluating the association between home BP morning rise and target organ damage are scarce and almost exclusively based on Asians. The aim of our study was to characterize hypertensive patients with morning rise in home BP and to establish a possible association with left ventricular hypertrophy (LVH).

METHODS

treated hypertensive patients ≥ 18 years underwent home BP measurements (duplicate measurements for 4 days in the morning, afternoon and evening), and completed a questionnaire regarding risk factors and history of cardiovascular disease. Medical records were reviewed to extract data from grams. A morning rise in systolic home BP was defined as a difference between morning and evening systolic BP averages ≥15 mmHg. Subjects were considered to have LVH if the left ventricular mass index was >95 g/m2 in women and >115 g/m2 in men. Variables identified as relevant predictors of home BP morning rise were entered into a multivariable logistic regression analysis model.

RESULTS

216 patients were included, mean age 68 (+13.3), 69.4% women and 99.1% Caucasians. The prevalence of BP morning rise was 13.4% and independently associated factors were LVH (OR 3.5; 95%CI 1.1-11.4), age (OR 1.05; 95%CI 1.003-1.1) and a history of cerebrovascular disease (OR 3.9; 95%CI 1.1-14.2). In conclusion, a morning rise in systolic BP detected through home BP monitoring is independently associated with LVH, age and a history of cerebrovascular disease. The therapeutic implications of this observation need to be clarified in large-scale prospective studies.

Predictors of masked hypertension among treated hypertensive patients: an interesting association with orthostatic hypertension

BACKGROUND

Masked hypertension (MH) entails an increased cardiovascular risk. Therefore, it is important to identify those individuals who would benefit the most from out-of-office blood pressure (BP) measurement. We sought to determine the prevalence and identify predictors of MH among adult hypertensive patients under treatment.

METHODS

Treated hypertensive patients aged ≥ 18 years underwent office (duplicate sitting and standing BP in 1 visit) and home BP measurements (duplicate measurements for 4 days in the morning, afternoon, and evening; at least 16 measurements) and completed a questionnaire regarding risk factors and history of cardiovascular disease. MH was defined as normal office BP (<140/90mm Hg) with elevated home BP (≥135/85mm Hg, average of all readings discarding first day measurements). Patients with a systolic BP rise upon standing ≥5mm Hg were considered to have orthostatic hypertension (OHT). Variables indentified as relevant predictors of MH were entered into a multivariable logistic regression analysis model.

RESULTS

Three hundred and four patients were included (mean age = 66.7 ±13.8; 67.4% women). The prevalence of MH in the whole population was 12.4% and was 20.9% among patients with office-controlled hypertension. Factors independently associated with MH were age (odds ratio (OR) = 1.08, 95% confidence interval (CI) = 1.03-1.14), high-normal office systolic BP (OR = 5.61, 95% CI = 1.39-22.57), history of peripheral artery disease (PAD) (OR = 8.83, 95% CI = 1.5-51.84), moderate alcohol consumption (OR = 0.08, 95% CI = 0.01-0.73), and OHT (OR = 3.65, 95% CI = 1.27 to 10.51).

CONCLUSIONS

Easily measurable parameters such as age, office systolic BP, history of PAD, and OHT may help to detect a population at risk of MH that would benefit from home BP monitoring.

Prevalence and clinical profile of resistant hypertension among treated hypertensive subjects

We assessed prevalence and clinical characteristics of resistant hypertension (RH) and prevalence of false RH (white-coat effect [WCE] by home blood pressure [BP] monitoring), among a population of 302 treated hypertensive patients, mean age 66.6 (± 13.8), 67.5% women. Resistant hypertension was defined according to the American Heart Association criteria. Prevalence of RH was 10%, and the following five variables were independently associated with it: body mass index, diabetes, isolated systolic hypertension, orthostatic hypotension, and use of beta-blockers. Prevalence of WCE among subjects with office-RH was 27.6%. Our study identified easily measurable parameters related to RH. Standing BP should be systematically measured in individuals with RH.

[Reproducibility and reliability of a 4-day HBPM protocol with and without first day measurements]

HBPM guidelines state that morning and evening measurements should be recorded and, to improve stability, the first day of measurements should be discarded. Our objective was to assess the reproducibility and reliability of a 4-day HBPM protocol with and without first day measurements. We analyzed a retrospective cohort of ambulatory patients who required a HBPM for diagnostic purposes or evaluation of treatment efficacy. A 4-day protocol was implemented, with daily duplicate measurements in the morning, afternoon and evening, using an OMRON 705 CP validated equipment. HBPM reproducibility was quantified by test-re-test correlations and standard deviation of differences (SDD) between BP measurements obtained during the entire 4 days, with and without exclusion of the first day. The reliability criterion was the stabilization of the mean and standard deviation (SD). We included 353 subjects with a total of 8224 BP recordings (median of 24 recordings per patient). We found a strong test-re-test correlation between days 1 to 4, which improved when we excluded the first day (p<0.001). We also found a reduction of the mean BP when we increased the number of days and a reduction of SDD when we excluded day 1. Therefore, we conclude that the exclusion of the first day of measurements improves the reproducibility and reliability of a 4-day protocol, and such two factors are not affected by the inclusion of afternoon measurements.

Prevalence of hyperhomocysteinemia in an elderly population

BACKGROUND

Currently, total hyperhomocysteinemia (tHHcy) is a well-known condition linked to a higher risk of vascular disease. Prevalence of HHcy increases in elderly persons as the risk associated with it persists. Because factors can be potentially reduced in the elderly, it is important to carry out epidemiologic studies of HHcy.

PROCEDURE

Previously we described the prevalence of hypertension control in an elder population; now, in an observational cross-sectional simple blind study, total homocysteine (tHcy) concentration was determined in 196 of 400 patients from the original cohort.

RESULTS

Mean Hcy concentration was 13.2 ,amol/L (95% confidence interval 12.4-14.0; range, 5.0 to 48.9); 15.0 ,imol/L for men and 12.3 pAmol/L for women. Mean serum folic acid levels were 4.9 + 3.1 ng/mL (range, 2.0 to 20.0 ng/mL), and vitamin B12 levels were 384.8 314.1 pg/mL (range, 48.0 to 1500.0 pg/mL). Taking into account the reference values established by the Third National Health and Nutrition Examination Survey III study, HHcy was detected in 69.8% of all the subjects evaluated. The study showed that 76.2% of the men and 66.4% of the women had high Hcy levels.

CONCLUSIONS

The very high prevalence of tHHcy in the elderly population, and the consequent risks associated with it suggest that although there are no trials that effectively prove the benefit of tHcy decrease, nutritional intervention is still justified.

Ambulatory blood pressure monitoring after recovery from hemolytic uremic syndrome

The outcome of acute renal failure due to diarrhea-associated hemolytic uremic syndrome (D+ HUS) is generally predicted to be good. However, there are only a few long-term observations with detailed reports on long-term sequelae. Specifically, adequate long-term blood pressure (BP) evaluations are scarce. The present study evaluated BP in pediatric patients after childhood D+ HUS. The study group comprised 28 patients (20 males) aged 6-23.5 years (median 10.1 years). All patients had a history of D+ HUS at a median age of 1.1 years (range 0.5-6 years). Based on the duration of oliguria and/or anuria, the primary disease was classified as mild (n=6), moderate (n=6), or severe (n=16). The BP in these patients was studied at a median time of 8.4 years (range 2.3-22.9 years) after manifestation of D+ HUS by means of office BP measurements and 24-h ambulatory BP monitoring (ABPM) using a Spacelabs 90207 oscillometric monitor. Measurements were compared with normal values of published standards for healthy children and adolescents. Conventional office BP measurements were above the 95th percentile in 1 patient. By ABPM, 2 patients were diagnosed to have mean systolic daytime and nighttime values in the hypertensive range, and systolic and diastolic hypertension was confirmed in the first patient. All these patients had a severe form of D+ HUS in the past. By applying ABPM, BP anomalies were detected in 5 additional patients. Elevated systolic BP loads were found in 4 patients, and daytime systolic and diastolic hypertension in the other 1. At the time of the study, 2 of them were classified as "recovered." The late outcome of D+ HUS may be worse than anticipated. BP anomalies as long-term sequelae of D+ HUS could be identified by ABPM but not by office BP measurements. These findings may represent an isolated sign of residual renal disturbance.

Hyperhomocysteinemia in stable pediatric, adolescents, and young adult renal transplant recipients

BACKGROUND

High total plasma homocysteine (tHcy) levels are accompanied by an increased risk for premature development of atherosclerosis and atherothrombosis. Adult renal transplant recipients have elevated tHcy levels. Corresponding data in pediatric, adolescent, and young adult renal transplant recipients are scarce. We investigated whether tHcy levels were elevated in stable renal transplant recipients who received kidney grafts before age 18.

METHODS

This cross-sectional study was conducted during routine posttransplantation follow-up. Fasting tHcy levels, serum creatinine, and lipoprotein profile were measured in 38 clinically stable renal transplant recipients with different degrees of renal function. No patient was receiving B vitamin or folic acid supplementation. Estimated glomerular filtration rate (GFR) was assessed according to Schwartz's formula. All patients followed a triple-drug immunosuppressive regimen, with the exception of three patients (deflazacort and azathioprine). Forty-one apparently healthy subjects constituted the control group. tHcy levels were determined by fluorescence polarization immunoassay in an IMx analyzer.

RESULTS

Mean tHcy levels in transplant recipients were significantly higher than in controls (16.8+/-8.7 micromol/L and 9.5+/-2.3 micromol/L, respectively; P<0.01). A significant positive correlation between tHcy and serum creatinine levels was observed for both transplant recipients (rS=0.70, P<0.01) and controls (rS=0.54, P<0.01). In transplant recipients, tHcy correlated negatively with estimated GFR (rS=[minus]0.47, P<0.05). Fasting tHcy levels in excess of 14.6 micromol/L (>95th percentile in controls) were present in 19 (50%) patients; 14 of these patients had an estimated GFR<60 ml/min per 1.73 m2. When the renal transplant recipients were analyzed by renal function, mean tHcy was significantly higher in patients with an estimated GFR<60 ml/min per 1.73 m2 compared with patients with an estimated GFR> or =60 ml/min per 1.73 m2 (20.5+/-9.9 vs. 13.2+/-5.8 micromol/L, P<0.01). Both groups were significantly different from controls (P<0.01). No relationship was found between tHcy level and either cumulative cyclosporine or cumulative methylprednisone doses. No differences were observed in tHcy levels or lipoprotein profile between patients who were receiving deflazacort and those on methylprednisone.

CONCLUSIONS

Hyperhomocysteinemia in renal transplant recipients is a common condition. Testing for fasting tHcy level might be a useful tool to identify patients at increased risk for development of vascular disease.

Contribution of stroke volume to the change in pulse pressure pattern with age

This study investigated the effect of age on pulse pressure and its underlying mechanisms in unmedicated hypertensive men with the same level of mean arterial pressure. We included 77 men 17 to 76 years old with daytime mean arterial pressure between 95 and 114 mm Hg. In the supine position, pulse pressure showed a significant widening in young (<30 years) and older (>/=60 years) patients. Pulse pressure decreased in parallel with stroke index from age >30 to 40 to 49 years. Upright posture, however, eliminated this difference through a larger orthostatic fall in stroke index and pulse pressure in the youngest patients. After age 50 years, pulse pressure exhibited a progressive widening despite the further age-related decrease in stroke index. Supine, upright, and 24-hour pulse pressure fitted a curvilinear correlation with age (r=0.55, 0.56, and 0.68, respectively, P<0.001), with a transition at age 50 years. Before age 50 years, 24-hour pulse pressure correlated positively with stroke volume (r=0.5, P<0.001) and negatively with arterial compliance (SV/PP ratio, r=-0.37, P<0.01). In contrast, in men >/=50 years old, 24-hour pulse pressure correlated negatively with the SV/PP ratio (r=-0.5; P<0.01), without significant influence of stroke volume. Thus, in hypertensive men, the age-related change in stroke volume significantly accounted for the change in clinic and ambulatory pulse pressure during young adulthood, but its contribution decreased after the fifth decade.

Lack of effective blood pressure control among an elder hypertensive population in Buenos Aires

Our purpose was to determine the level of awareness, treatment, and control of hypertension in a population of subjects aged 65 or more. We studied a random sample from the national health care program in Buenos Aires. Letters were mailed to 1000 selected individuals. Among those eligible, 41.4% (n = 414) were enrolled. The mean age was 73.8 years and 68% were women. Prevalence of hypertension in our sample was 77.5% (n = 321). Awareness of hypertension was 60.7% (n = 195). Fifty-four percent (n = 173) of the hypertensive subjects were receiving pharmacologic treatment and only 18.5% (n = 32) of them were controlled. These results show that there is a low level of awareness, pharmacologic treatment, and control of hypertension in the studied elderly subjects.

Diastolic pressure underestimates age-related hemodynamic impairment

It has been hypothesized that as large arteries become more rigid with age, the pattern of hypertension changes from diastolic to systolic. Thus, diastolic blood pressure (DBP) may lose its ability to reflect the increase in vascular resistance with age. To assess this, we studied the age-related changes in blood pressure pattern and its steady-state and pulsatile determinants. We performed an epidemiological analysis based on a national survey of 10,462 subjects from Argentina. A hemodynamic analysis (impedance cardiography) was then carried out in 636 consecutive hypertensive patients (age, 25 to 74 years). Whereas the rate of increment in the prevalence of mild to moderate hypertension (MMH) reached a plateau after the sixth decade, isolated and borderline systolic forms of hypertension began a steep and sustained rise. Among patients with MMH, DBP remained stable from the third to the seventh decade, whereas SBP maintained a sustained increase. Despite similar DBP, the systemic vascular resistance index increased 47% (P<.01) and the cardiac index decreased 27% (P<.01), whereas the ratio of stroke volume to pulse pressure, an index of arterial compliance, decreased 45% (P<.01). However, there were no significant differences between older patients with MMH and those with isolated systolic hypertension in the level of SBP, vascular resistance, stroke volume, and cardiac index. Compared with age-matched normotensive control subjects, the ratio of stroke volume to pulse pressure was much more reduced in isolated systolic hypertension (48%) than in MMH (30%). In summary, the present study, carried out in a large sample of hypertensive subjects with a wide age range, showed a simultaneous impairment in vascular resistance and arterial compliance associated with aging in different patterns of hypertension. The magnitude of these changes, with opposite effects on DBP but additive effects on SBP, suggests that a hemodynamic mechanism could determine the transition in the prevalence of diastolic hypertension toward a systolic pattern of hypertension with aging. Also, the results suggest that SBP, but not DBP, is a reliable indicator of the underlying hemodynamic abnormalities (high resistance and low arterial compliance) in the elderly.

Hemodynamic effects of transdermal estradiol alone and combined with norethisterone acetate

A 24 weeks, randomized, two-period, placebo controlled study was conducted to compare the effects of continuous transdermal 17 beta-estradiol replacement therapy (0.05 mg/day once a week) with placebo on systemic hemodynamics and blood pressure in postmenopausal women. Twenty-nine postmenopausal women (47-62 years) free of hormone replacement therapy were randomized in two groups; group 1 received estradiol patches for the first 12 weeks and placebo patches for the second, and group 2 received the same treatments in the reverse order. The effect of combined estradiol plus oral norethisterone acetate (NETA) 1 mg was also evaluated in the subset of women with intact uteri (n = 24). Crossover analysis showed that stroke volume and cardiac output were significantly higher (P < 0.05) and blood pressure was significantly lower (P < 0.05) with estradiol, irrespective of the order in which the treatments were administered. Although correlations between plasma estradiol levels during active treatment and hemodynamic changes were not significant, hemodynamic changes were significantly greater above 63 pg/ml than below this level (P < 0.05). Oral norethisterone acetate administration either during transdermal placebo or estradiol arms tended to modify systemic hemodynamics in the same direction than estradiol but the changes did not attained statistical significance. In summary compared with placebo, transdermal 17 beta-estradiol, replacement to postmenopausal women, increased cardiac output and decreased blood pressure. Although the average magnitude of changes was small, the results suggest that plasma estradiol levels could be a source of individual variability in the hemodynamic response. Oral NETA administration tended to enhance rather than reverse the estradiol-induced changes.

Relationship between systemic hemodynamics and ambulatory blood pressure level are sex dependent

Sex-related differences in systemic hemodynamics were analyzed by means of cardiac index and systemic vascular resistance according to the level of daytime ambulatory blood pressure. In addition, we assessed the relations between ambulatory blood pressure measurements and systemic hemodynamics in male and female patients. We prospectively included 52 women and 53 men referred to our unit for evaluation of arterial hypertension. Women and men were grouped according to the level of daytime mean arterial pressure: < 110 or > or = 110 mm Hg. Patients underwent noninvasive evaluation of resting hemodynamics (impedance cardiography) and 24-hour ambulatory blood pressure monitoring. Compared with women men with lower daytime blood pressure had a 12% higher systemic vascular resistance index (P = NS) and a 14% lower cardiac index (P < .02), whereas men with higher daytime blood pressure had a 25% higher vascular resistance (P < .003) and a 21% lower cardiac index (P < .0004). Furthermore, in men systemic vascular resistance correlated positively with both daytime and nighttime systolic and diastolic blood pressures, whereas cardiac index correlated negatively only with daytime diastolic blood pressure. In contrast, women did not exhibit any significant correlation between hemodynamic parameters and ambulatory blood pressure measurements. In conclusion, sex-related differences in systemic hemodynamics were more pronounced in the group with higher daytime hypertension. The relations between systemic hemodynamics and ambulatory blood pressure level depended on the sex of the patient. In men a progressive circulatory impairment underlies the increasing level of ambulatory blood pressure, but this was not observed in women.