The role of genetic and environmental factors in phenotypic variability of arterial pressure and body weight and their interconnection (a family study)

Contribution of genetic and environmental factors into phenotypic variability of blood pressure and body mass as well as into phenotypic correlation between these traits was defined. It was shown that additive genetic determinant is responsible for considerable level of blood pressure and body mass variability. Those common environmental factors are of importance which operate within the limits of one generation. Maternal effect of systolic and diastolic blood pressure variability is negligible. The correlation between systolic and diastolic blood pressure is determined both by environmental and genetic factors, whereas that between blood pressure and body mass is mediated by only environmental factors. The contribution of environmental factors into correlation between blood pressure and body mass lessens with age. The results obtained may be applied in development of population and individual programmes for preventing cardiovascular diseases.     

Assessment of the accuracy and role of self-recorded blood pressures in the management of hypertension.

Self-recording of the blood pressure by patients away from hospital or office ("home blood pressure") has been advocated as providing a better estimate of "true" blood pressure. The reliability of home blood-pressure recording has been assessed only by standard indirect methods which themselves are subject to considerable error and variability. The accuracy of self-recorded blood pressures was therefore assessed in 57 patients with essential hypertension by comparison with simultaneous measurements of clinic blood pressures and with intra-arterial blood pressures recorded at home and at hospital. Home systolic blood pressures showed good agreement with clinic and intra-arterial pressures, but home diastolic blood pressures overestimated intra-arterial pressures, as did clinic diastolic pressures. The clinic and home diastolic pressures showed good agreement. There was considerable variability in individual differences comparing the indirect and intra-arterial methods, though the two indirect methods showed much closer agreement. This study suggests that home blood pressures are as accurate as clinic readings but may be recorded more frequently and thus provide more useful information. Neither is likely to approximate the intra-arterial blood pressure.     

Factors Affecting Blood Pressure Variability: Lessons Learned from Two Systematic Reviews of Randomized Controlled Trials

Systematic reviews can often reveal much more than the original objective of the work. The objectives of this retrospective analysis were to answer three basic questions about blood pressure variability: 1) Does blood pressure entry criterion have an effect on baseline blood pressure variability? 2) Do thiazide diuretics have a significant effect on blood pressure variability? and 3) Does systolic blood pressure vary to the same degree as diastolic blood pressure? This analysis of blood pressure variability is based on resting standardized research setting BP readings from two systematic reviews evaluating blood pressure lowering efficacy of thiazide diuretics from double blind randomized controlled trials in 33,611 patients with primary hypertension. The standard deviation reported in trials was the focus of the research and the unit of analysis. When a threshold systolic or diastolic blood pressure value is used to determine entry into a trial, baseline variability is significantly decreased, systolic from 14.0 to 9.3 mmHg and diastolic from 8.4 to 5.3 mmHg. Thiazides do not change BP variability as the standard deviation and coefficient of variation of systolic blood pressure and diastolic blood pressure did not differ between thiazide and placebo groups at end of treatment. The coefficient of variation of systolic blood pressure was significantly greater than the coefficient of variation of diastolic blood pressure. Entry criterion decreases the baseline blood pressure variability. Treatment with a thiazide diuretic does not affect blood pressure variability. Systolic blood pressure varies to a greater degree than diastolic blood pressure.     

Heart rate reflex responses during gestation in normotensive and spontaneously hypertensive rats following angiotensin II and vasopressin

Gestation in the human and in rats is accompanied by a decrease in blood pressure and a reduction of the pressor response to vasoconstrictor agents. In humans, the decreased vascular reactivity to angiotensin II (AII) may occur simultaneously with a state of increased baroreceptor sensitivity. We have consequently evaluated the heart rate response to elevation of blood pressure following administration of either AII or arginine8-vasopressin (AVP) in conscious unrestrained, nonpregnant, or term-pregnant normotensive rats (Sprague-Dawley, SDR; Wistar-Kyoto, WKR) and in spontaneously hypertensive rats (SHR). The decrease in heart rate in response to increase in blood pressure by AII in nonpregnant animals was similar in SDR and SHR, but much greater in WKR. The heart rate response to increase in blood pressure by AVP was similar in all three strains of cycling rats. Gestation (20th day) did not change the heart rate response to increase in blood pressure by AII in normotensive animals, but increased slightly the reflex responses in SHR, as shown by a significant increase of the slope of the relationship of the decrement in heart rate versus the increment of blood pressure. The heart rate response to increase in blood pressure by AVP was greater during gestation in normotensive SDR and WKR, but not in SHR. These results show that the heart rate responses to an increase in blood pressure by vasoconstrictor peptides is dependent on the strain of animals used and suggest that the baroreceptor reflexes play a minor role in the blunted effect of vasconstrictor agens at the end of gestation in normotensive and spontaneously hypertensive rats.     

Effects of elements on blood pressure

This article presents a comprehensive review of all known elements involved in blood pressure control. Data source was by computerized literature searches. A total of 28 elements have been documented as being involved in blood pressure control. The individual elements react directly and indirectly in a variety of metabolic and structural activities known to participate in blood pressure regulation. Reports from both experimental animal and human subjects are presented. The role of certain elements in blood pressure control is controversial. Conversely, important established functions of dosage, absorption, storage, and excretion of individual elements are known and are described in relation to blood pressure control. Some elements are pressor, whereas others are depressor in action, and this article demonstrates the important role elements play in the control of blood pressure.     

Association between Ambient Temperature and Blood Pressure and Blood Pressure Regulators: 1831 Hypertensive Patients Followed Up for Three Years

Several studies have suggested an association between ambient air temperature and blood pressure. However, this has not been reliably confirmed by longitudinal studies. Also, whether the reaction to temperature stimulation is modified by other factors such as antihypertensive medication is rarely investigated. The present study explores the relationship between ambient temperature and blood pressure, without and with antihypertensive medication, in a study of 1,831 hypertensive patients followed up for three years, in two or four weekly check ups, accumulating 62,452 follow-up records. Both baseline and follow-up blood pressure showed an inverse association with ambient temperature, which explained 32.4% and 65.6% of variation of systolic blood pressure and diastolic blood pressure (P<0.05) respectively. The amplitude of individual blood pressure fluctuation with temperature throughout a year (a 29 degrees centigrade range) was 9.4/7.3 mmHg. Medication with angiotensin converting enzyme inhibitor benazepril attenuated the blood pressure fluctuation by 2.4/1.3 mmHg each year, though the inverse association of temperature and blood pressure remained. Gender, drinking behavior and body mass index were also found to modify the association between temperature and diastolic blood pressure. The results indicate that ambient temperature may negatively regulate blood pressure. Hypertensive patients should monitor and treat blood pressure more carefully in cold days, and it could be especially important for the males, thinner people and drinkers.     

Food restriction reduces the blood pressure of the spontaneously hypertensive rat

Spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKy) and Sprague-Dawley (S-D) rats were fed a normal diet on an $\text{ad}$$\text{libitum}$ basis or the normal diet was reduced by 35 per cent prior to, during, and after high blood pressure became established in SHR. Weight loss occurred in all animals at all ages and was associated with effective inhibition of the acute rise in blood pressure and the exacerbation of pre-existing elevated blood pressure. Weight loss after high blood pressure had become well established also caused reduction in blood pressure. The purported normotensive WKy rats developed high blood pressure. Weight loss was not as effective in reducing blood pressure in WKy as in SHR. These findings are construed to mean that reduced body weight will ameliorate the inexorable rise in the genetically-programmed high blood pressure of SHR if instituted prior to, during, but not after high blood pressure has become well established.     

Heterogeneity of Prognostic Studies of 24-Hour Blood Pressure Variability: Systematic Review and Meta-Analysis

In addition to mean blood pressure, blood pressure variability is hypothesized to have important prognostic value in evaluating cardiovascular risk. We aimed to assess the prognostic value of blood pressure variability within 24 hours. Using MEDLINE, EMBASE and Cochrane Library to April 2013, we conducted a systematic review of prospective studies of adults, with at least one year follow-up and any day, night or 24-hour blood pressure variability measure as a predictor of one or more of the following outcomes: all-cause mortality, cardiovascular mortality, all cardiovascular events, stroke and coronary heart disease. We examined how blood pressure variability is defined and how its prognostic use is reported. We analysed relative risks adjusted for covariates including the appropriate mean blood pressure and considered the potential for meta-analysis. Our analysis of methods included 24 studies and analysis of predictions included 16 studies. There were 36 different measures of blood pressure variability and 13 definitions of night- and day-time periods. Median follow-up was 5.5 years (interquartile range 4.2–7.0). Comparing measures of dispersion, coefficient of variation was less well researched than standard deviation. Night dipping based on percentage change was the most researched measure and the only measure for which data could be meaningfully pooled. Night dipping or lower night-time blood pressure was associated with lower risk of cardiovascular events. The interpretation and use in clinical practice of 24-hour blood pressure variability, as an important prognostic indicator of cardiovascular events, is hampered by insufficient evidence and divergent methodologies. We recommend greater standardisation of methods.     

Blood pressure control by home monitoring: meta-analysis of randomised trials

Objective To determine the effect of home blood pressure monitoring on blood pressure levels and proportion of people with essential hypertension achieving targets.Design Meta-analysis of 18 randomised controlled trials.Participants 1359 people with essential hypertension allocated to home blood pressure monitoring and 1355 allocated to the “control” group seen in the healthcare system for 2-36 months.Main outcome measures Differences in systolic (13 studies), diastolic (16 studies), or mean (3 studies) blood pressures, and proportion of patients achieving targets (6 studies), between intervention and control groups.Results Systolic blood pressure was lower in people with hypertension who had home blood pressure monitoring than in those who had standard blood pressure monitoring in the healthcare system (standardised mean difference 4.2 (95% confidence interval 1.5 to 6.9) mm Hg), diastolic blood pressure was lower by 2.4 (1.2 to 3.5) mm Hg, and mean blood pressure was lower by 4.4 (2.0 to 6.8) mm Hg. The relative risk of blood pressure above predetermined targets was lower in people with home blood pressure monitoring (risk ratio 0.90, 0.80 to 1.00). When publication bias was allowed for, the differences were attenuated: 2.2 (-0.9 to 5.3) mm Hg for systolic blood pressure and 1.9 (0.6 to 3.2) mm Hg for diastolic blood pressure.Conclusions Blood pressure control in people with hypertension (assessed in the clinic) and the proportion achieving targets are increased when home blood pressure monitoring is used rather than standard blood pressure monitoring in the healthcare system. The reasons for this are not clear. The difference in blood pressure control between the two methods is small but likely to contribute to an important reduction in vascular complications in the hypertensive population.     

The importance of penile blood pressure in cases of impotence

It appears that the normal penile systolic blood pressure, as measured by a spectroscopic method, is equal to or greater than the calculated brachial mean blood pressure. A pressure definitely lower than this in impotent patients indicates obstruction to blood flow in the main vessels supplying the penis. On this basis, obstruction to blood flow was identified as a cause of impotence in patients with little other evidence of peripheral vascular disease.     

Systems engineering analysis of aortic root blood pressure

This paper describes the aortic blood pressure as a function of aortic blood flow and the parameters of the blood and circulatory system. The method of performance involves the analogue of a multi-branched electrical to hydraulic transmission line applying graphical convolution to the blood flow-transform impedance relationship resulting in a theoretical pressure curve for the infinite aorta. The difference between the single pressure pulse and the computed adjusted infinite aorta pressure curve is described as the reflected wave. This reflected wave is then shown to be of reasonable configuration in time and velocity. The blood pressure is thus finally described completely by the physical parameters of the blood and the circulatory system and the blood flow.     

Arterial Blood Pressure and Modernization in Brazil

The relationship between individual modernization and elevated arterial blood pressure was examined in a study in urban Brazil. We hypothesized that elevated blood pressure would result from the discrepancy between an individual's style of life and his or her economic resources; specifically, we suggested that when modern life-style acquisition exceeded economic resources, a circumstance referred to as "life-style stress," blood pressure would be elevated. This factor was related to diastolic, but not systolic, blood pressure, independently of a variety of biologic, dietary, and sociocultural confounding factors. The perceived change associated with life events also predicted diastolic, but not systolic, blood pressure. Other predictors of diastolic blood pressure were calcium intake, fat intake, race, age, and the body mass index. We argue that sociocultural risk factors emerge in the modernization process as a result of social structural imbalances generated by economic development and represent independent risk factors for elevated arterial blood pressure.     

Hemodynamic effects of metalloporphyrin catalytic antioxidants: structure-activity relationships and species specificity

Superoxide plays a role in blood pressure regulation in certain vascular diseases, however, its involvement in regulating basal blood pressure is uncertain. Vascular superoxide concentrations are limited by extracellular superoxide dismutase (EC-SOD), which is highly expressed in the vasculature of most animal species. Metalloporphyrins are low molecular weight, synthetic, redox-active, catalytic antioxidants that act as SOD mimetics. We evaluated the effects of metalloporphyrins on blood pressure in different animal species. The metalloporphyrin AEOL10113 (5–10 μg/kg iv), but not native or polyethylene glycol-CuZnSOD, caused a dose-dependent reduction in blood pressure in anesthetized rats. AEOL10113 had no effect on blood pressure in mice (wild-type or EC-SOD knockouts), guinea pigs, dogs, or baboons at doses up to 5 mg/kg iv Structure-activity studies indicated that metalloporphyrins with high SOD activity were more effective in lowering rat blood pressure than low-activity analogs. The blood pressure effect of AEOL10113 was not attributable to the release of manganese, nor was it affected by inhibitors of nitric oxide synthase (L-NAME) and guanylate cyclase (ODQ, 8-bromo-cGMP, and methylene blue) or nitric oxide scavengers (HbA_o). Chlorpheniramine attenuated the effect, suggesting that the blood pressure response in rats is related to histamine release rather than the protection of nitric oxide.     

基于卷积神经网络-长短期记忆神经网络模型利用光学体积描记术重建动脉血压波信号

目的 直接动脉血压（arterial blood pressure,ABP）连续监测是侵入式的,传统袖带式的间接血压测量法无法实现连续监测。既往利用光学体积描记术（photoplethysmography,PPG）实现了连续无创血压监测,但其为收缩压和舒张压的离散值,而非ABP波的连续值,本研究期望基于卷积神经网络-长短期记忆神经网络（CNN-LSTM）利用PPG信号波重建ABP波信号,实现连续无创血压监测。方法 构建CNN-LSTM混合神经网络模型,利用重症监护医学信息集（medical information mart for intensive care,MIMIC）中的PPG与ABP波同步记录信号数据,将PPG信号波经预处理降噪、归一化、滑窗分割后输入该模型,重建与之同步对应的ABP波信号。结果 使用窗口长度312的CNN-LSTM神经网络时,重建ABP值与实际ABP值间误差最小,平均绝对误差（mean absolute error,MAE）和均方根误差（root mean square error,RMSE）分别为2.79 mmHg和4.24 mmHg,余弦相似度最大,重建ABP值与实际ABP值一致性和相关性情况良好,符合美国医疗器械促进协会（Association for the Advancement of Medical Instrumentation,AAMI）标准。结论 CNN-LSTM混合神经网络可利用PPG信号波重建ABP波信号,实现连续无创血压监测。     

Autonomic nervous system and blood pressure regulation in RGS2-deficient mice

Regulator of G protein signaling (RGS2) deletion in mice prolongs signaling by G protein-coupled vasoconstrictor receptors and increases blood pressure. However, the exact mechanism of the increase in blood pressure is unknown. To address this question we tested autonomic nervous system function and blood pressure regulation in RGS2-deficient mice (RGS2-/-). We measured arterial blood pressure and heart rate (HR) with telemetry, computed time and frequency-domain measures for blood pressure and HR variability (HRV) as well as baroreflex sensitivity [BRS-low frequency (LF)], and assessed environmental stress sensitivity. Mean arterial blood pressure (MAP) was approximately 10 mmHg higher in RGS2-/-compared with RGS2+/+mice, while HR was not different between the groups, indicating a resetting of the baroreceptor reflex. Atropine increased MAP more in RGS2-/-than in RGS2+/+mice while HR responses were not different. Urinary norepinephrine excretion was higher in RGS2-/-than in RGS2+/+mice. The blood pressure decrease following prazosin was more pronounced in RGS2-/-mice than in RGS2+/+mice. The LF and high-frequency (HF) power of HRV were reduced in RGS2-/-compared with controls while BRS-LF and SBP-LF were not different. Atropine and atropine+metoprolol markedly reduced the HRV parameters in the time (RMSSD) and frequency domain (LF, HF, LF/HF) in both strains. Environmental stress sensitivity was increased in RGS2-/-mice compared with controls. We conclude that the increase in blood pressure in RGS2-/-mice is not solely explained by peripheral vascular mechanisms. A central nervous system mechanism might be implicated by an increased sympathetic tone. This state of affairs could lead to a baroreceptor-HR reflex resetting, while BRS remains unimpaired.     

The correlation of skin blood flow with age, total cholesterol, hematocrit, blood pressure, and hemoglobin

Normal skin blood flow at the deltoid region in 55 men whose ages ranged from 20 to 72 years was measured by the xenon-133 clearance method. In addition, the correlation of skin blood flow with age, systolic blood pressure, total cholesterol, hematocrit, hemoglobin, and total protein was analyzed by multiple regression analysis. The following results were obtained. Normal skin blood flow was found to decrease with increase in age, total cholesterol, and systolic blood pressure and showed a tendency to increase with elevation in hematocrit and hemoglobin values. Of the six parameters examined in the present study, the parameter that showed the strongest correlation with skin blood flow at the deltoid region was age, followed in decreasing order by total cholesterol, hematocrit, systolic blood pressure, and hemoglobin. It could therefore be concluded that age is the most reliable factor in clinically estimating skin blood flow. Furthermore, inasmuch as total cholesterol, hematocrit, systolic blood pressure and hemoglobin values also were correlated with skin blood flow, these values also should be taken in account in the synthetic evaluation of skin blood flow. It was skin blood flow at the deltoid region that was strongly correlated with age. This was followed by systolic blood pressure, hematocrit, and hemoglobin. Total cholesterol showed a weak correlation with age, but total protein did not demonstrate any correlation with skin blood flow and age. The results of the present study show that skin blood flow would be poor in the elderly and in patients with arteriosclerosis, hypertension, and anemia. Since it is suggested that the wound-healing process is delayed in such patients, utmost care should be exercised in treating their wounds.     

Relation of low diastolic blood pressure to coronary heart disease death in presence of myocardial infarction: the Framingham Study.

OBJECTIVE--To examine the hypothesis that a J curve relation between blood pressure and death from coronary heart disease is confined to high risk subjects with myocardial infarction. DESIGN--Cohort longitudinal epidemiological study with biennial examinations since 1950. SETTING--Framingham, Massachusetts, USA. SUBJECTS--5209 subjects in the Framingham study cohort followed up by a person examination approach. MAIN OUTCOME MEASURES--Coronary heart disease deaths and non-cardiovascular disease deaths in men and women with or without myocardial infarction relative to blood pressure. RESULTS--Among subjects without myocardial infarction non-cardiovascular disease deaths were twice to three times as common as coronary heart disease deaths. Furthermore, there was no significant relation between non-cardiovascular disease death and diastolic or systolic blood pressure. Also coronary heart disease deaths were linearly related to diastolic and systolic blood pressures. Among high risk patients (that is, people with myocardial infarction but free of congestive heart failure) death from coronary heart disease was more common than non-cardiovascular disease death. There was a significant U shaped relation between coronary heart disease death and diastolic blood pressure. Although there was an apparent U shaped relation between coronary heart disease death and systolic blood pressure, it did not attain statistical significance when controlling for age and change in systolic blood pressure from the pre-myocardial infarction level. None of the above conclusions changed when adjustments were made for risk factors such as serum cholesterol concentration, antihypertensive treatment, and left ventricular function. The U shaped relation between diastolic blood pressure and high risk subjects existed for both those given antihypertensive treatment and those not. CONCLUSIONS--These data suggest that an age and sex independent U curve relation exists for diastolic blood pressure and coronary heart disease deaths in patients with myocardial infarction but not for low risk subjects without myocardial infarction. The relation seems to be independent of left ventricular function and antihypertensive treatment.     

Failure to realise growth potential in utero and adult obesity in relation to blood pressure in 50 year old Swedish men.

OBJECTIVES: To clarify the type of fetal growth impairment associated with increased blood pressure in adult life, and to establish whether this association is influenced by obesity and is mediated through impairment of insulin action. DESIGN: Cross sectional survey with retrospective ascertainment of size at birth from obstetric archives. SUBJECTS: 1333 men resident in Uppsala, Sweden, who took part in a 1970 study of coronary risk factors at age 50 and for whom birth weight was traced. MAIN OUTCOME MEASURES: Systolic and diastolic blood pressure at age 50. RESULTS: In the full study population for a 1000g increase in birth weight there was a small change in systolic blood pressure of -2.2mmHg (95% confidence interval -4.2 to - 0.3mmHg) and in diastolic blood pressure of -1.0mmHg (-2.2 to 0.1mmHg). Much stronger effects were observed among men who were born at term and were in the top third of body mass index at age 50, for whom a 1000g increase in birth weight was associated with a change of -9.1mmHg (-16.4 to-1.9mmHg) systolic and -4.2mmHg (-8.3 to -0.1mmHg) diastolic blood pressure. Men who were light at birth (<3250g) but were above median adult height had particularly high blood pressure. Adjustment for insulin concentrations reduced the associations of birth weight with systolic and diastolic blood pressure. CONCLUSIONS: A failure to realise growth potential in utero (as indicated by being light at birth but tall as an adult) is associated with raised adult blood pressure. Impaired fetal growth may lead to substantial increases in adult blood pressure among only those who become obese. Metabolic disturbances, possibly related to insulin resistance, may provide a pathway through which fetal growth affects blood pressure.     

Estimating absolute aortic pressure using MRI and a one-dimensional model

Aortic blood pressure is a strong indicator to cardiovascular diseases and morbidity. Clinically, pressure measurements are done by inserting a catheter in the aorta. However, imaging techniques have been used to avoid the invasive procedure of catheterization. In this paper, we combined MRI measurements to a one-dimensional model in order to simulate blood flow in an aortic segment. Absolute pressure was estimated in the aorta by using MRI measured flow as boundary conditions and MRI measured compliance as a pressure law for solving the model. Model computed pressure was compared to catheter measured pressure in an aortic phantom. Furthermore, aortic pressure was estimated in vivo in three healthy volunteers.     

Blood pressure monitoring during hospital convalescence

Blood pressure ambulatory monitoring has provided numerous and interesting informations on the clinical as well as investigational setting of arterial hypertension. The vast majority of data have been obtained registering blood pressure during the normal daily activities of the patients and surprisingly few studies have been undertaken to evaluate blood pressure behaviour in inpatients. We observed the 24 hours pattern of blood pressure in hypertensive and normotensive inpatients, using an automated sphygmomanometer (Omega 1400), whose performance was previously evaluated by us. The results demonstrate that blood pressure monitoring in inpatients could be a useful tool in managing hypertensive patients.