Simultaneous measurements of blood pressures in right and left brachial arteries.

Mendelson G, Nassimiha D, Aronow WS.

Shoham Geriatrics Center, Pardes Hanna, Israel.

The most recent guidelines do not mention which arm to use to measure blood pressure or interarm blood pressure differences. In 357 women and 171 men, mean age 79 +/- 10 years, 2 geriatricians simultaneously measured brachial artery blood pressure (BABP) with the patient in the sitting position. All blood pressure measurements were performed using the same 2 machines, which were calibrated and marked 1 and 2. The machines and cuffs were transferred to the opposite arm for a repeat measurement in all patients and the results of the 2 blood pressures averaged. Patients with conditions that may cause a disparity in blood pressure between the right and left arms were not included in this study. The right systolic BABP was >/= 10 mm Hg higher than the left systolic BABP in 35 of 528 patients (7%), and the left systolic BABP was >/= 10 mm Hg higher than the right systolic BABP in 35 of 528 patients (7%) (P = not significant). The right diastolic BABP was >/= 10 mm Hg higher than the left diastolic BABP in 16 of 528 patients (3%), and the left diastolic BABP was >/= 10 mm Hg higher than the right diastolic BABP in 12 of 528 patients (2%) (P = not significant). There was no significant difference in prevalence of hypertension, atherosclerotic vascular disease, diabetes mellitus, or hypercholesterolemia in patients with or without a >/= 10-mm Hg difference in right and left systolic BABP and in right and left diastolic BABP. Interarm differences of >/=10 mm Hg in systolic BABP were found in 14% of elderly patients and of >/= 10 mm Hg in diastolic BABP in 5% of elderly patients. The higher blood pressure should be used for the diagnosis of hypertension, and the blood pressure in that arm used for all follow-up blood pressure-evaluating therapy.

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[Ambulatory blood pressure monitoring in multicystic dysplastic kidney disease]

[Article in Spanish]

Pardo de la Vega R, Herrero Morin D, Ordonez Alvarez FA, Martinez Suarez V, Santos Rodriguez F, Malaga Guerrero S.

Seccion de Nefrologia Pediatrica. Departamento de Pediatria. Hospital Central de Asturias. Universidad de Oviedo. Espana. rpardo hcas.insalud.es

OBJECTIVE: To evaluate blood pressure in a group of patients with multicystic dysplastic kidney (MDK) disease through ambulatory blood pressure (ABP) monitoring. PATIENTS AND METHODS: ABP monitoring was performed in 16 patients with MDK disease using a Spacelabs 90207 monitor and an appropriately sized armband. The patients performed their normal daily activities except physical exercise. The activity period was 8:00 am to 8:00 pm and the resting period was midnight to 6:00 am. Patients with a percentage of correct readings of less than 70 % were excluded. The mean systolic and diastolic blood pressures for each period were calculated. Circadian variability was determined by the ratio between mean systolic and diastolic values in the active and resting periods, respectively. The results were compared with ABP values in healthy children. RESULTS: Fourteen patients (mean age 16 3.1 years, range: 6-27.6) were included. No patients with hypertension were found through casual measurement. One patient had daytime systolic hypertension. Five patients presented an abnormal drop in blood pressure during sleep. CONCLUSION: Blood pressure should be monitored in patients with MDK disease. ABP monitoring may detect alterations that can go unnoticed in casual determinations. Further studies with large samples are needed to establish the real prevalence of hypertension in these patients.

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Model of robust induction of glomerulosclerosis in mice: importance of genetic background.

Ma LJ, Fogo AB.

Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.

BACKGROUND: Increasing evidence suggests that genetic background plays an important role in the development of progressive glomerulosclerosis. The remnant kidney model (RKM) of progressive renal disease has been used extensively in rats. However, C57BL/6 mice are resistant to glomerulosclerosis with RKM induced by either pole amputation or renal artery ligation. A pole resection protocol, applied in 129/Sv mice, induced only mild glomerulosclerosis. We present here a highly reproducible, modified RKM approach to successfully establish a glomerulosclerosis model in mice. METHODS: Male C57BL/6 (N = 17), 129/Sv (N = 20) and Swiss-Webster (N = 3) mice underwent RKM as follows: the lower branch of the left renal artery was ligated to produce about one third infarct; the upper pole of the left kidney (about one third kidney size) was removed by cautery and the right kidney was nephrectomized to induce a total 5/6 nephrectomy (Nx). In some C57BL/6 mice, 7/8 nephrectomy was induced by removing additional renal mass from the upper pole of the left kidney by cautery. Systolic blood pressure (BP) was measured in conscious mice using a tail-cuff blood pressure monitor and animals were sacrificed at 9, 12, 18, and 24 weeks after nephrectomy. Kidneys were harvested for morphologic analysis. RESULTS: BP in C57BL/6 mice increased slightly after 5/6 nephrectomy over time without significant difference compared to baseline blood pressure except at 8 weeks (blood pressure at week 0, 98 +/- 1 mm Hg; week 4, 105 +/- 2 mm Hg; week 8, 113 +/- 4 mm Hg; and week 12, 110 +/- 3 mm Hg). Blood presssure remained normal in C57BL/6 mice at 18 weeks after 7/8 nephrectomy (103 +/- 2 mm Hg). Blood pressure in 129/Sv mice increased significantly after 5/6 nephrectomy from 4 to 12 weeks (week 0, 112 +/- 3 mm Hg; week 4, 161 +/- 9 mm Hg; week 8, 166 +/- 5 mm Hg; and week 12, 176 +/- 5 mm Hg; P < 0.01 weeks 4, 8, and 12 vs. week 0 blood pressure). Urine protein excretion in C57BL/6 mice increased only at 4 weeks after 5/6 nephrectomy, and was back to normal at 8 and 12 weeks (week 0, 13.2 +/- 1.4 mg/24 hours; week 4, 20.5 +/- 1.8 mg/24 hours; week 8, 18.8 +/- 1.6 mg/24 hours; and week 12, 17.2 +/- 1.2 mg/24 hours, P < 0.05 week 4 vs. week 0). 129/Sv mice developed significant proteinuria 12 weeks after 5/6 nephrectomy compared to their baseline and to levels achieved in C57BL/6 mice (week 0, 17.2 +/- 1 mg/24 hours; week 4, 14.9 +/- 1.8 mg/24 hours; week 8, 23.8 +/- 6.7 mg/24 hours; and week 12, 36.3 +/- 6.6 mg/24 hours, P < 0.01 week 12 vs. week 0; P < 0.01 129/Sv vs. C57BL/6 at week 12). Mortality varied in response to nephrectomy injury in the different strains. Ten percent of C57BL/6 and 43% of 129/Sv died within 12 weeks after 5/6 nephrectomy. Although 50% of C57BL/6 mice died by 12 weeks after 7/8 nephrectomy, there was only mild glomerulosclerosis (<5%) in C57BL/6 mice even at 24 weeks after 5/6 nephrectomy or 18 weeks after 7/8 nephrectomy. In contrast, glomerulosclerosis was marked in both 129/Sv mice and Swiss-Webster mice as early as 9 weeks after 5/6 nephrectomy: 42% of glomeruli showed sclerosis in 129/Sv mice [average sclerosis index (SI), 0 to 4+ scale, 1.08] vs. 24% in Swiss-Webster mice (average SI, 0.57). Tubulointerstitial fibrosis developed in parallel with glomerulosclerosis in both 129/Sv and Swiss-Webster mice. CONCLUSION: We conclude that genetic background is one of the important factors determining the susceptibility to the development of glomerulosclerosis in mice. We speculate that the superior effects of renal artery ligation plus cautery to produce glomerulosclerosis may result from higher blood pressure responses due to local ischemia activating the renin-angiotensin system.

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Separating within and between effects in family studies: an application to the study of blood pressure in children.

Mann V, De Stavola BL, Leon DA.

Medical Statistics Unit, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, UK. vera.mann lshtm.ac.uk

In epidemiology the analyses of family or twin studies do not always fully exploit the data, as information on differences between siblings is often used while between-families effect are not considered. We show how cross-sectional time-series linear regression analysis can be easily implemented to estimate within- and between-families effects simultaneously and how these effects can then be compared using the Hausman test. We illustrate this approach with data from the Uppsala family study on blood pressure in children with age ranging from 5.5 to 12.3 years for the younger and from 7.5 to 13.8 years for the older siblings. Comparing the effect of differences in birth weight on blood pressure within-family (in full siblings) and between-families (in unrelated children) allows us to study the contributions of fixed and pregnancy-specific maternal effects on birth weight and consequently on blood pressure. Our data showed a 0.88 mmHg decrease (95 per cent confidence interval: -1.7 to -0.03 mmHg) in systolic blood pressure for one standard deviation increase in birth weight between siblings within a family and 0.88 mmHg (95 per cent confidence interval: -1.6 to -0.2 mmHg) decrease in systolic blood pressure for one standard deviation increase in birth weight between unrelated children. These estimates were controlled for sex, age, pubertal stage, body size and pulse rate of the children at examination and for maternal body size and systolic blood pressure. The within- and between-families effects were not significantly different, p = 0.19, suggesting that fixed and pregnancy-specific factors have similar effects on childhood systolic blood pressure. Copyright 2004 John Wiley & Sons, Ltd.

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High-sodium intake prevents pregnancy-induced decrease of blood pressure in the rat.

Beausejour A, Auger K, St-Louis J, Brochu M.

Hopital Sainte-Justine, Department of Obstetrics and Gynecology, Universite de Montreal, Montreal, Quebec, Canada H3T 1C5.

Despite an increase of circulatory volume and of renin-angiotensin-aldosterone system (RAAS) activity, pregnancy is paradoxically accompanied by a decrease in blood pressure. We have reported that the decrease in blood pressure was maintained in pregnant rats despite overactivation of RAAS following reduction in sodium intake. The purpose of this study was to evaluate the impact of the opposite condition, e.g., decreased activation of RAAS during pregnancy in the rat. To do so, 0.9% or 1.8% NaCl in drinking water was given to nonpregnant and pregnant Sprague-Dawley rats for 7 days (last week of gestation). Increased sodium intakes (between 10- and 20-fold) produced reduction of plasma renin activity and aldosterone in both nonpregnant and pregnant rats. Systolic blood pressure was not affected in nonpregnant rats. However, in pregnant rats, 0.9% sodium supplement prevented the decreased blood pressure. Moreover, an increase of systolic blood pressure was obtained in pregnant rats receiving 1.8% NaCl. The 0.9% sodium supplement did not affect plasma and fetal parameters. However, 1.8% NaCl supplement has larger effects during gestation as shown by increased plasma sodium concentration, hematocrit level, negative water balance, proteinuria, and intrauterine growth restriction. With both sodium supplements, decreased AT1 mRNA levels in the kidney and in the placenta were observed. Our results showed that a high-sodium intake prevents the pregnancy-induced decrease of blood pressure in rats. Nonpregnant rats were able to maintain homeostasis but not the pregnant ones in response to sodium load. Furthermore, pregnant rats on a high-sodium intake (1.8% NaCl) showed some physiological responses that resemble manifestations observed in preeclampsia.

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[Spectral analysis of systolic blood pressure in atrial fibrillation]

[Article in Japanese]

Arai H, Sato H, Yamamoto M, Kirigaya H, Aizawa T, Fu LT.

Department of Radiology, Cardiovascular Institute Hospital, Roppongi 7-3-10, Minato-ku, Tokyo 106-0032.

OBJECTIVES: Power spectral analysis was used to analyze fluctuations of systolic blood pressure and heart rate. METHODS: Non-invasive finger plethysmography and electrocardiography were performed in 20 patients with chronic atrial fibrillation and in 10 age-matched healthy subjects with normal sinus rhythm. The impulse train was stored on a personal computer and the power spectrum of R-R interval and systolic blood pressure were obtained by Fourier analysis (0.01-0.03 Hz). The power spectrum (log power vs log frequency) characteristically revealed a linear regression as 1/f beta. RESULTS: The R-R interval spectrum during atrial fibrillation showed a white noise-like flat spectrum when plotted as log power against log frequency, whereas the systolic blood pressure spectrum during atrial fibrillation showed a 1/f noise-like negative slope linear pattern. The spectrum exponent of systolic blood pressure in patients with atrial fibrillation was significantly lower than that in subjects with normal sinus rhythm (2.3 +/- 0.1 vs 1.3 +/- 0.1, p < 0.0001). CONCLUSIONS: Systolic blood pressure fluctuation in patients with atrial fibrillation has a fractal component and is more complex than that of healthy subjects with normal sinus rhythm.

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Adolescent pain sensitivity is associated with cardiac autonomic function and blood pressure over 8 years.

Campbell TS, Ditto B, Seguin JR, Sinray S, Tremblay RE.

Department of Psychology, McGill University, Montreal, Quebec, H3A 1B1, Canada.

Low pain sensitivity has been reported in hypertensive subjects as well in groups deemed to be at increased risk of development of the disorder. However, it is uncertain whether individual differences in pain sensitivity are associated prospectively with increases in blood pressure. In the current study, 24-hour blood pressure and heart rate variability were recorded in 110, 22-year-old men previously assessed at age 14 years for casual blood pressure and pain sensitivity (mechanical finger pressure). Significant correlations were observed between pain tolerance in 14-year-olds and current 24-hour systolic blood pressure (r=0.37, P<0.01) and diastolic blood pressure (r=0.36, P<0.01). Hierarchical multiple regression analyses indicated that information regarding pain tolerance improved prediction of systolic and diastolic blood pressure at age 22 years beyond that afforded by differences in blood pressure, parental history of hypertension, and body mass index at age 14 years. Similar analyses revealed that average pain sensitivity at age 14 was also associated with 24-hour high-frequency heart rate variability (r=0.28, P<0.01) and low-frequency/high-frequency heart rate variability at age 22 (r=-0.35, P<0.01), suggesting increased sympathetic and reduced parasympathetic tone among individuals less sensitive to pain. These results provide further evidence that blood pressure related hypoalgesia might be related to processes involved in blood pressure regulation as well as in the development of sustained high blood pressure.

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Patients' views of high blood pressure, its treatment and risks.

Taylor C, Ward A.

Department of General Practice, University of Western Australia.

OBJECTIVE: To examine the understanding and beliefs of a sample of Australian patients about high blood pressure and its therapy, and to examine the accuracy of their assessment of their own risk. METHOD: A cross sectional study in two general practices in Perth, Western Australia. Interviews were conducted with 55 consecutive patients aged 40-80 years of age with uncomplicated hypertension. Qualitative and quantitative data were collected on patients' beliefs about the nature, symptoms, causes and treatment of high blood pressure as well as their adherence to antihypertensive medications during the preceding month. Patients also estimated their own risk of stroke or myocardial infarction. RESULTS: Two-thirds of the patients (65%) described high blood pressure within an appropriate biomedical definition. Forty-five percent attributed a variety of symptoms to their high blood pressure while 55% believed that stress was a cause of their high blood pressure. Three-quarters (73%) were fully adherent to their medications in the preceding month. Seventy-one percent and 62% of patients were aware that stroke and heart attack respectively are possible consequences of high blood pressure. They significantly overestimated their risk of stroke and myocardial infarction. CONCLUSION: One-third of treated hypertensive patients are poorly informed about the causes and effects of hypertension, and overestimate their risk of both stroke and heart attack, as well as the benefit derived from treatment.

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