| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Hypertension. 2005;46:660.)
© 2005 American Heart Association, Inc.
Original Articles |
From the Research Center for Prevention and Health (M.H.O., T.W.H., S.R., T.J.), Glostrup University Hospital; Department of Cardiology (M.H.O., K.W.), Rigshospitalet; Department of Clinical Physiology and Nuclear Medicine (M.K.C.), Glostrup University Hospital; Department of Cardiology (F.G., P.H.), Frederiksberg University Hospital; Steno Diabetes Center (K.B.-J.), Gentofte; and Department of Internal Medicine (H.I.), Glostrup University Hospital, Denmark.
Correspondence to Dr Michael Hecht Olsen, Department of Clinical Physiology and Nuclear Medicine, Glostrup University Hospital, DK-2600 Glostrup, Denmark. E-mail mho{at}dadlnet.dk
| Abstract |
|---|
|
|
|---|
Key Words: risk factors albuminuria hypertrophy natriuretic peptides obesity
| Introduction |
|---|
|
|
|---|
Therefore, the aim of the present study was to evaluate the association of Nt-proBNP to metabolic and hemodynamic CV risk factors, including the metabolic syndrome, 24-hour ambulatory BP, LV hypertrophy, pulse wave velocity (PWV), and urine albumin/creatinine ratio (UACR) in 4 different age groups to control for age.
| Methods |
|---|
|
|
|---|
The metabolic syndrome was defined using the definition from the European Group for the Study of Insulin resistance (EGIR)12 as hyperinsulinemia (serum insulin
upper quartile of 44 pmol/L) together with
2 of the following: obesity (body mass index >30 kg/m2 or waistmen/women
94/80 cm), dyslipidemia (serum triglyceride >2.0 mmol/1 or serum HDL cholesterol <1.0 mmol/L), hyperglycemia (plasma glucose
6.1 mmol/L), or hypertension (systolic BP
140 mm Hg or diastolic BP
90 mm Hg).
Echocardiography
Studies were performed using M-mode and 2D echocardiographs. Studies were read by an experienced technician blinded for all other information. LV internal dimension and interventricular septal and posterior wall thicknesses (PWTs) were measured at end-diastole and end-systole according to American Society of Echocardiography (ASE) recommendation17 on up to 3 cycles. When optimal orientation of the LV could not be obtained by M-mode, correctly oriented 2D linear dimensions were made by the leading-edge convention according to ASE recommendation.18 End-diastolic ASE LV dimensions were used to calculate LV mass by a formula that yields values closely related (r=0.90; P<0.001) to necropsy LV weight20 and that showed excellent reproducibility (
=0.93; P<0.001) between 2 separate echocardiograms in 183 hypertensive patients.21 The ability to substitute ASE 2D LV measurements for M-mode measurements has resulted in yields of LV mass measurements of 91% to 98% in previous studies.14,2224 LV mass was considered as an unadjusted variable and also after traditional normalizations for body surface area (BSA).4,23 LV mass/BSA partition values of 116 g/m2 in men and 104 g/m2 in women were used as the upper gender-specific normal 95% confidence intervals, as described previously.4,15 Relative wall thickness (RWT) was calculated as 2x end-diastolic PWT/LV internal dimension.2,25 Increased RWT was present when this ratio exceeded 0.43, which represents the 97.5th percentile in previously described normal subjects.26 Normal geometry was present when LV mass/BSA and RWT were normal, whereas normal LV mass/BSA and increased RWT was classified as concentric remodeling. Increased LV mass/BSA but normal RWT identified eccentric LV hypertrophy, whereas increases in both variables identified concentric LV hypertrophy.2,27,28
LV internal dimension and wall thickness were measured at end-diastole and end-systole following ASE recommendations13 on
3 cardiac cycles. When optimal orientation of the M-mode cursor could not be obtained, correctly oriented linear dimension measurements were made using 2Dimensional imaging by the leading-edge ASE convention.13 End-diastolic LV dimensions were used to calculate LV mass, which was corrected for body size by dividing with BSA. Standard methods were used to calculate endocardial ejection fraction.
Pulse Wave Velocity
Two transducers connected to a printer were placed over the common carotid artery and the femoral artery. PWV was calculated as the distance between the 2 transducers divided by the calculated time delay for the pulse wave between the 2 transducers.14
Ambulatory BP
Immediately after recording of office BP, an automatic BP device measuring ambulatory BP (BP) by the cuff-oscillometric method (Takeda TM-2421; A&D Co. Ltd.)15 was applied and worn for 24 hours. BP recordings were made every 15 minutes between 7 AM and 11 PM, and every 30 minutes between 11 PM and 7 AM. Means of 24-hour ambulatory BP were computed with weights according to the time interval between successive readings.
Assays
Urine albumin concentration was determined by standard methods16 using a turbidimetric method (Hitachi 717 analyzer; Roche Diagnostics)17 on a single urine specimen taken in the morning. Urine creatinine was analyzed using the Jaffé reaction without deproteinizing and then quantified by a photometric method (Hitachi 717 analyzer; Roche Diagnostics). UACR was calculated.
Serum was frozen immediately at 20°C to be examined in July 2003. To assess the stability of Nt-proBNP in the frozen samples, we plotted serum Nt-proBNP as a function of the time the samples had been frozen, which varied from 8.5 to 10.5 years, and found no association between Nt-proBNP level and the time from which the sample was obtained. Ruling out a systemic change in Nt-proBNP over this time interval, together with findings by others,18 suggests that the peptide is likely to be stable when preserved as described in the present protocol. Serum Nt-proBNP concentration was determined using Elecsys proBNP sandwich immunoassay on an Elecsys 2010 (Roche Diagnostics). The analytical range extended from 5.1 to 34 927 pg/mL. Between-assay coefficients of variation in low and high ranges of Nt-proBNP are reported to be 4.8% and 2.7%.19
Fasting concentrations of serum insulin and lipids were measured using well-established methods.20 Plasma glucose concentrations were measured using a Beckman glucose analyzer (Beckman Instruments Inc.) and a glucose oxidase method.
Statistics
Data management and analysis were performed using SPSS 12.0 (SPSS) software. Data are presented as mean±SD for continuous variables with normal distribution, median, and interquartile range for continuous variables without normal distribution and proportions for categorical variables. Variables with skewed distributions underwent logarithmic transformation to create normal distributions. Unpaired Students t test was used to determine differences in continuous variables between groups. Pearsons
2 test or Fishers exact test was used to determine differences in categorical variables between groups. Using multiple regression analyses, correlations were adjusted for age and gender, lifestyle (daily exercise, alcohol consumption, and smoking status), body composition (body mass index and waist circumference), metabolic CV risk factors (glucose, insulin, and lipid levels), hemodynamic CV risk factors (heart rate, clinic BP, 24-hour systolic BP), and subclinical CV damage (LV mass index, LV ejection fraction, UACR, and PWV), calculating the standardized regression quotient (ß). Only variables with P values <0.10 entered the final multiple regression models, in which we performed by stepwise, backward selection. The 4 age groups were described by a categorical variable assigned a value from 1 to 4. Two-tailed P<0.05 indicated statistical significance.
| Results |
|---|
|
|
|---|
|
|
|
Nt-proBNP in Relation to Other CV Risk Factors
Median Nt-proBNP was elevated in subjects with elevated BP (Table 1), and higher Nt-proBNP was associated with higher clinic (r=0.17; P<0.001) and higher 24-hour ambulatory systolic BP (r=0.07; P<0.05) as well as higher clinic (r=0.30) and higher 24-hour ambulatory pulse pressure (r=0.19; both P<0.001). Both relationships were modulated by age (P<0.001) and were much stronger in the older age groups (r=0.19 and r=0.29 both P<0.001 versus r=0.07 and r=0.07 both P<0.05). The metabolic syndrome did not modulate the relation to pulse pressure. However, the metabolic syndrome shifted the positive relationship between pulse pressure and Nt-proBNP to the right (P<0.001), allowing subjects with the metabolic syndrome to have higher pulse pressure for a given level of Nt-proBNP (Figure 3). The relationship between Nt-proBNP and pulse pressure as well as systolic BP were also shifted to the right in subjects with hyperinsulinemia (Figure 4) and dyslipidemia (Figure 5).
|
|
|
After adjusting for age and gender using multiple regression analyses, higher log(Nt-proBNP) was unrelated to lifestyle measures but associated with better metabolic profile and higher BP (Table 2). In multiple regression analyses, higher log(Nt-proBNP) was after adjustment for age (ß=0.33), and female gender (ß=0.33) related to higher clinic pulse pressure (ß=0.20), lower serum total cholesterol (ß=0.16; all P<0.001), lower log(serum insulin) (ß=0.07), lower log(plasma glucose) (ß=0.06; both P<0.01), lower log(serum triglyceride) (ß=0.06), lower body mass index (ß=0.05), lower heart rate (ß=0.05; all P<0.05; adjusted R2=0.34; P<0.001).
|
Nt-proBNP in Relation Subclinical CV Damage
After adjusting for age, female gender, and metabolic and hemodynamic CV risk factors, log(Nt-proBNP) was correlated independently to LV ejection fraction (ß=0.08; P<0.001), logUACR (ß=0.04; P<0.05) and log(LV mass index) (ß=0.04; P<0.07; adjusted R2=0.35; P<0.001) in multiple regression analyses. Because of a significant modulation by age on the relationship between log(Nt-proBNP), logUACR, and log(LV mass index) (P<0.001), we divided the population in younger subjects 41 or 51 years of age and older subjects 61 or 71 years of age. Only in the older group, log(Nt-proBNP) was positively related to log(LV mass index) (ß=0.10) and logUACR (ß=0.09; both P<0.01; adjusted R2=0.29) after adjusting for CV risk factors, suggesting that high Nt-proBNP was related to subclinical CV damage independently of BP in subjects 61 or 71 years of age.
| Discussion |
|---|
|
|
|---|
In accordance with others, we found that Nt-proBNP increased with age and was higher in women.32 The gender difference decreased with age, probably because of a higher number of subjects with unrecognized CV disease with high Nt-proBNP independently of gender in the older age group.
Nt-proBNP in Relation to Subclinical CV Damage
After adjustment for age, gender, and pulse pressure, high serum Nt-proBNP was related to reduced LV systolic function, LV mass index, and UACR but not to PWV, indicating that the previously demonstrated relationship between high serum Nt-proBNP and LV hypertrophy6 and albuminuria7,8 do not just reflect parallel age- or load-related changes. This BP-independent relationship was especially clear in the older age group and may reflect subclinical coronary artery disease.3 In hypertension, the relationship between serum Nt-proBNP and CV damage is not limited to old patients, probably because they all have increased cardiac load attributable to high BP.5 This may indicate that the heart has to be stressed beyond a threshold before the secretion of BNP in the heart is activated.1 Thereafter, the secretion is related to the stress load on the heart best reflected by pulse pressure. The relationship between higher serum Nt-proBNP and stiffer arteries was not independent of age and gender. The relative weak relationship between serum Nt-proBNP and LV hypertrophy as well as LV ejection fraction supports the limited use of serum Nt-proBNP in screening for LV hypertrophy and dysfunction in the general population demonstrated by Vasan et al.33
Clinical Implications
The fact that Nt-proBNP was unrelated to lifestyle measures but related to subclinical CV damage almost independently of traditional CV risk factors indicates that Nt-proBNP is a superior marker of subclinical CV damage and therefore suitable to detect subclinical disease before it develops into clinical disease.4 However, the inverse relationship between Nt-proBNP and established metabolic CV risk factors may be a problem when defining cutoff values for Nt-proBNP in patients with varying levels of obesity, dyslipidemia, or hyperinsulinemia. Longitudinal studies are required to address whether traditional cutoff levels for Nt-proBNP can be used in patients with high body mass index, dyslipidemia, or hyperinsulinemia. Using BNP does not solve the problem because the same inverse relationship has been demonstrated for BNP as well.9,21
Limitations
Because data on previous CV disease was self-reported, we chose a conservative but probably accurate definition using only previous myocardial infarction or previous stoke as previous CV disease. Therefore, some of the subjects may have unrecognized CV disease. We did not have a direct measure of kidney function, but the correlations did not change significantly after excluding the 2% to 3% of the subjects with microalbuminaria or macroalbuminuria to ensure normal kidney function. The stability of Nt-proBNP in frozen serum over a period of 10 years has never been tested. However, we documented stability of Nt-proBNP between serum samples for 8.5 to 10.5 years and demonstrated that the expected relationships between Nt-proBNP and age and gender and BP were preserved, supporting the assumption of stability of Nt-proBNP throughout the whole period.
| Conclusion |
|---|
|
|
|---|
| Acknowledgments |
|---|
Received April 22, 2005; first decision May 9, 2005; accepted July 14, 2005.
| References |
|---|
|
|
|---|
2. Maeda K, Tsutamoto T, Wada A, Mabuchi N, Hayashi M, Tsutsui T, Ohnishi M, Sawaki M, Fujii M, Matsumoto T, Kinoshita M. High levels of plasma brain natriuretic peptide and interleukin-6 after optimized treatment for heart failure are independent risk factors for morbidity and mortality in patients with congestive heart failure. J Am Coll Cardiol. 2000; 36: 15871593.
3. de Lemos JA, Morrow DA, Bentley JH, Omland T, Sabatine MS, McCabe CH, Hall C, Cannon CP, Braunwald E. The prognostic value of B-type natriuretic peptide in patients with acute coronary syndromes. N Engl J Med. 2001; 345: 10141021.
4. Wang TJ, Larson MG, Levy D, Benjamin EJ, Leip EP, Omland T, Wolf PA, Vasan RS. Plasma natriuretic peptide levels and the risk of cardiovascular events and death. N Engl J Med. 2004; 350: 655663.
5. Olsen MH, Wachtell K, Tuxen C, Fossum E, Bang LE, Hall C, Ibsen H, Rokkedal J, Devereux RB, Hildebrandt P. N-terminal pro-brain natriuretic peptide predicts cardiovascular events in patients with hypertension and left ventricular hypertrophy: a LIFE study. J Hypertens. 2004; 22: 15971604.[CrossRef][Medline] [Order article via Infotrieve]
6. Schirmer H, Omland T. Circulating N-terminal pro-atrial natriuretic peptide is an independent predictor of left ventricular hypertrophy in the general population. The Tromso Study. Eur Heart J. 1999; 20: 755763.
7. Siebenhofer A, Ng LL, Plank J, Berghold A, Hodl R, Pieber TR. Plasma N-terminal pro-brain natriuretic peptide in Type 1 diabetic patients with and without diabetic nephropathy. Diabet Med. 2003; 20: 535539.[CrossRef][Medline] [Order article via Infotrieve]
8. Yano Y, Katsuki A, Gabazza EC, Ito K, Fujii M, Furuta M, Tuchihashi K, Goto H, Nakatani K, Hori Y, Sumida Y, Adachi Y. Plasma brain natriuretic peptide levels in normotensive noninsulin-dependent diabetic patients with microalbuminuria. J Clin Endocrinol Metab. 1999; 84: 23532356.
9. Wang TJ, Larson MG, Levy D, Benjamin EJ, Leip EP, Wilson PW, Vasan RS. Impact of obesity on plasma natriuretic peptide levels. Circulation. 2004; 109: 594600.
10. Kanda H, Kita Y, Okamura T, Kadowaki T, Yoshida Y, Nakamura Y, Ueshima H. What factors are associated with high plasma B-type natriuretic peptide levels in a general Japanese population? J Hum Hypertens. 2005; 19: 165172.[CrossRef][Medline] [Order article via Infotrieve]
11. McCord J, Mundy BJ, Hudson MP, Maisel AS, Hollander JE, Abraham WT, Steg PG, Omland T, Knudsen CW, Sandberg KR, McCullough PA. Relationship between obesity and B-type natriuretic peptide levels. Arch Intern Med. 2004; 164: 22472252.
12. Balkau B, Charles MA. Comment on the provisional report from the WHO consultation. European Group for the Study of Insulin Resistance (EGIR). Diabet Med. 1999; 16: 442443.[CrossRef][Medline] [Order article via Infotrieve]
13. Schiller NB, Shah PM, Crawford M, DeMaria A, Devereux R, Feigenbaum H, Gutgesell H, Reichek N, Sahn D, Schnittger I. Recommendations for quantitation of the left ventricle by two-dimensional echocardiography. American Society of Echocardiography Committee on Standards, Subcommittee on Quantitation of Two-Dimensional Echocardiograms. J Am Soc Echocardiogr. 1989; 2: 358367.[Medline] [Order article via Infotrieve]
14. Hansen TW, Jeppesen J, Rasmussen S, Ibsen H, Torp-Pedersen C. Relation between insulin and aortic stiffness: a population-based study. J Hum Hypertens. 2004; 18: 17.[CrossRef][Medline] [Order article via Infotrieve]
15. OBrien E, Waeber B, Parati G, Staessen J, Myers MG. Blood pressure measuring devices: recommendations of the European Society of Hypertension. BMJ. 2001; 322: 531536.
16. Rowe DJ, Dawnay A, Watts GF. Microalbuminuria in diabetes mellitus: review and recommendations for the measurement of albumin in urine. Ann Clin Biochem. 1990; 27: 297312.[Medline] [Order article via Infotrieve]
17. Borch-Johnsen K, Wenzel H, Viberti GC, Mogensen CE. Is screening and intervention for microalbuminuria worthwhile in patients with insulin dependent diabetes? BMJ. 1993; 306: 17221725.
18. Mueller T, Gegenhuber A, Dieplinger B, Poelz W, Haltmayer M. Long-term stability of endogenous B-type natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP) in frozen plasma samples. Clin Chem Lab Med. 2004; 42: 942944.[CrossRef][Medline] [Order article via Infotrieve]
19. Yeo KT, Wu AH, Apple FS, Kroll MH, Christenson RH, Lewandrowski KB, Sedor FA, Butch AW. Multicenter evaluation of the Roche NT-proBNP assay and comparison to the Biosite Triage BNP assay. Clin Chim Acta. 2003; 338: 107115.[CrossRef][Medline] [Order article via Infotrieve]
20. Drivsholm T, Ibsen H, Schroll M, Davidsen M, Borch-Johnsen K. Increasing prevalence of diabetes mellitus and impaired glucose tolerance among 60-year-old Danes. Diabet Med. 2001; 18: 126132.[CrossRef][Medline] [Order article via Infotrieve]
21. Mehra MR, Uber PA, Park MH, Scott RL, Ventura HO, Harris BC, Frohlich ED. Obesity and suppressed B-type natriuretic peptide levels in heart failure. J Am Coll Cardiol. 2004; 43: 15901595.
22. Rocchini AP, Key J, Bondie D, Chico R, Moorehead C, Katch V, Martin M. The effect of weight loss on the sensitivity of blood pressure to sodium in obese adolescents. N Engl J Med. 1989; 321: 580585.[Abstract]
23. Licata G, Volpe M, Scaglione R, Rubattu S. Salt-regulating hormones in young normotensive obese subjects. Effects of saline load. Hypertension. 1994; 23: I20I24.[Medline] [Order article via Infotrieve]
24. De Pergola G, Garruti G, Giorgino F, Cospite MR, Corso M, Cignarelli M, Giorgino R. Reduced effectiveness of atrial natriuretic factor in pre-menopausal obese women. Int J Obes Relat Metab Disord. 1994; 18: 9397.[Medline] [Order article via Infotrieve]
25. Dessi-Fulgheri P, Sarzani R, Serenelli M, Tamburrini P, Spagnolo D, Giantomassi L, Espinosa E, Rappelli A. Low calorie diet enhances renal, hemodynamic, and humoral effects of exogenous atrial natriuretic peptide in obese hypertensives. Hypertension. 1999; 33: 658662.
26. Nannipieri M, Seghieri G, Catalano C, Prontera T, Baldi S, Ferrannini E. Defective regulation and action of atrial natriuretic peptide in type 2 diabetes. Horm Metab Res. 2002; 34: 2652670.[CrossRef][Medline] [Order article via Infotrieve]
27. Sarzani R, Paci VM, Zingaretti CM, Pierleoni C, Cinti S, Cola G, Rappelli A, Dessi-Fulgheri P. Fasting inhibits natriuretic peptides clearance receptor expression in rat adipose tissue. J Hypertens. 1995; 13: 12411246.[CrossRef][Medline] [Order article via Infotrieve]
28. Dessi-Fulgheri P, Sarzani R, Tamburrini P, Moraca A, Espinosa E, Cola G, Giantomassi L, Rappelli A. Plasma atrial natriuretic peptide and natriuretic peptide receptor gene expression in adipose tissue of normotensive and hypertensive obese patients. J Hypertens. 1997; 15: 16951699.[CrossRef][Medline] [Order article via Infotrieve]
29. Hall C. Essential biochemistry and physiology of (NT-pro)BNP. Eur J Heart Fail. 2004; 6: 257260.
30. Moro C, Polak J, Richterova B, Sengenes C, Pelikanova T, Galitzky J, Stich V, Lafontan M, Berlan M. Differential regulation of atrial natriuretic peptide- and adrenergic receptor-dependent lipolytic pathways in human adipose tissue. Metabolism. 2005; 54: 122131.[CrossRef][Medline] [Order article via Infotrieve]
31. Sarzani R, Strazzullo P, Salvi F, Iacone R, Pietrucci F, Siani A, Barba G, Gerardi MC, Dessi-Fulgheri P, Rappelli A. Natriuretic peptide clearance receptor alleles and susceptibility to abdominal adiposity. Obes Res. 2004; 12: 351356.[Medline] [Order article via Infotrieve]
32. Raymond I, Groenning BA, Hildebrandt PR, Nilsson JC, Baumann M, Trawinski J, Pedersen F. The influence of age, sex and other variables on the plasma level of N-terminal pro brain natriuretic peptide in a large sample of the general population. Heart. 2003; 89: 745751.
33. Vasan RS, Benjamin EJ, Larson MG, Leip EP, Wang TJ, Wilson PW, Levy D. Plasma natriuretic peptides for community screening for left ventricular hypertrophy and systolic dysfunction: the Framingham Heart Study. J Am Med Assoc. 2002; 288: 12521259.
This article has been cited by other articles:
![]() |
J. Ybarra, F. Planas, and J. M Pou Aminoterminal pro-brain natriuretic peptide (NT-proBNP) and sleep-disordered breathing in morbidly obese females: a cross-sectional study Diabetes and Vascular Disease Research, March 1, 2008; 5(1): 19 - 24. [Abstract] [PDF] |
||||
![]() |
M. Y. Rady B-Type Natriuretic Peptide and Sepsis: It Is Not Just the Heart J Intensive Care Med, November 1, 2007; 22(6): 386 - 388. [PDF] |
||||
![]() |
M. Schou, F. Gustafsson, C. N. Kistorp, P. Corell, A. Kjaer, and P. R. Hildebrandt Effects of Body Mass Index and Age on N-Terminal Pro Brain Natriuretic Peptide Are Associated with Glomerular Filtration Rate in Chronic Heart Failure Patients Clin. Chem., November 1, 2007; 53(11): 1928 - 1935. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Ingelsson, M. J. Pencina, G. H. Tofler, E. J. Benjamin, K. J. Lanier, P. F. Jacques, C. S. Fox, J. B. Meigs, D. Levy, M. G. Larson, et al. Multimarker Approach to Evaluate the Incidence of the Metabolic Syndrome and Longitudinal Changes in Metabolic Risk Factors: The Framingham Offspring Study Circulation, August 28, 2007; 116(9): 984 - 992. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. M. Richards Natriuretic Peptides: Update on Peptide Release, Bioactivity, and Clinical Use Hypertension, July 1, 2007; 50(1): 25 - 30. [Full Text] [PDF] |
||||
![]() |
M. H. Olsen, T. W. Hansen, M. K. Christensen, F. Gustafsson, S. Rasmussen, K. Wachtell, H. Ibsen, C. Torp-Pedersen, and P. R. Hildebrandt N-terminal pro-brain natriuretic peptide, but not high sensitivity C-reactive protein, improves cardiovascular risk prediction in the general population Eur. Heart J., June 1, 2007; 28(11): 1374 - 1381. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. J. Wang, M. G. Larson, M. J. Keyes, D. Levy, E. J. Benjamin, and R. S. Vasan Association of Plasma Natriuretic Peptide Levels With Metabolic Risk Factors in Ambulatory Individuals Circulation, March 20, 2007; 115(11): 1345 - 1353. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Hypertension Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 2005 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |