446 research outputs found
Blood pressure changes after renal denervation at 10 European expert centers
We did a subject-level meta-analysis of the changes (Δ) in blood pressure (BP) observed 3 and 6 months after renal denervation (RDN) at 10 European centers. Recruited patients (n=109; 46.8% women; mean age 58.2 years) had essential hypertension confirmed by ambulatory BP. From baseline to 6 months, treatment score declined slightly from 4.7 to 4.4 drugs per day. Systolic/diastolic BP fell by 17.6/7.1 mm Hg for office BP, and by 5.9/3.5, 6.2/3.4, and 4.4/2.5 mm Hg for 24-h, daytime and nighttime BP (P0.03 for all). In 47 patients with 3- and 6-month ambulatory measurements, systolic BP did not change between these two time points (P0.08). Normalization was a systolic BP of <140 mm Hg on office measurement or <130 mm Hg on 24-h monitoring and improvement was a fall of 10 mm Hg, irrespective of measurement technique. For office BP, at 6 months, normalization, improvement or no decrease occurred in 22.9, 59.6 and 22.9% of patients, respectively; for 24-h BP, these proportions were 14.7, 31.2 and 34.9%, respectively. Higher baseline BP predicted greater BP fall at follow-up; higher baseline serum creatinine was associated with lower probability of improvement of 24-h BP (odds ratio for 20-μmol l(-1) increase, 0.60; P=0.05) and higher probability of experiencing no BP decrease (OR, 1.66; P=0.01). In conclusion, BP responses to RDN include regression-to-the-mean and remain to be consolidated in randomized trials based on ambulatory BP monitoring. For now, RDN should remain the last resort in patients in whom all other ways to control BP failed, and it must be cautiously used in patients with renal impairment
Blood pressure response to renal denervation is correlated with baseline blood pressure variability: a patient-level meta-analysis
Background: Sympathetic tone is one of the main
determinants of blood pressure (BP) variability and
treatment-resistant hypertension. The aim of our study was
to assess changes in BP variability after renal denervation
(RDN). In addition, on an exploratory basis, we investigated
whether baseline BP variability predicted the BP changes
after RDN.
Methods: We analyzed 24-h BP recordings obtained at
baseline and 6 months after RDN in 167 treatmentresistant
hypertension patients (40% women; age, 56.7
years; mean 24-h BP, 152/90 mmHg) recruited at 11 expert
centers. BP variability was assessed by weighted SD [SD
over time weighted for the time interval between
consecutive readings (SDiw)], average real variability (ARV),
coefficient of variation, and variability independent of the
mean (VIM).
Results: Mean office and 24-h BP fell by 15.4/6.6 and 5.5/
3.7 mmHg, respectively (P < 0.001). In multivariable-adjusted
analyses, systolic/diastolic SDiw and VIM for 24-h
SBP/DBP decreased by 1.18/0.63 mmHg (P 0.01) and
0.86/0.42 mmHg (P 0.05), respectively, whereas no
significant changes in ARV or coefficient of variation
occurred. Furthermore, baseline SDiw (P ¼ 0.0006), ARV
(P ¼ 0.01), and VIM (P ¼ 0.04) predicted the decrease in
24-h DBP but not 24-h SBP after RDN.
Conclusion: RDN was associated with a decrease in BP
variability independent of the BP level, suggesting that
responders may derive benefits from the reduction in BP
variability as well. Furthermore, baseline DBP variability
estimates significantly correlated with mean DBP decrease
after RDN. If confirmed in younger patients with less
arterial damage, in the absence of the confounding effect
of drugs and drug adherence, baseline BP variability may
prove a good predictor of BP response to RDN
Nonergodicity transitions in colloidal suspensions with attractive interactions
The colloidal gel and glass transitions are investigated using the idealized
mode coupling theory (MCT) for model systems characterized by short-range
attractive interactions. Results are presented for the adhesive hard sphere and
hard core attractive Yukawa systems. According to MCT, the former system shows
a critical glass transition concentration that increases significantly with
introduction of a weak attraction. For the latter attractive Yukawa system, MCT
predicts low temperature nonergodic states that extend to the critical and
subcritical region. Several features of the MCT nonergodicity transition in
this system agree qualitatively with experimental observations on the colloidal
gel transition, suggesting that the gel transition is caused by a low
temperature extension of the glass transition. The range of the attraction is
shown to govern the way the glass transition line traverses the phase diagram
relative to the critical point, analogous to findings for the fluid-solid
freezing transition.Comment: 11 pages, 7 figures; to be published in Phys. Rev. E (1 May 1999
Quantitative estimation of tissue blood flow rate
The rate of blood flow through a tissue (F) is a critical parameter for assessing the functional efficiency of a blood vessel network following angiogenesis. This chapter aims to provide the principles behind the estimation of F, how F relates to other commonly used measures of tissue perfusion, and a practical approach for estimating F in laboratory animals, using small readily diffusible and metabolically inert radio-tracers. The methods described require relatively nonspecialized equipment. However, the analytical descriptions apply equally to complementary techniques involving more sophisticated noninvasive imaging. Two techniques are described for the quantitative estimation of F based on measuring the rate of tissue uptake following intravenous administration of radioactive iodo-antipyrine (or other suitable tracer). The Tissue Equilibration Technique is the classical approach and the Indicator Fractionation Technique, which is simpler to perform, is a practical alternative in many cases. The experimental procedures and analytical methods for both techniques are given, as well as guidelines for choosing the most appropriate method
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