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123 active trials for Blood Pressure

Optimal Nutrition for Prevention of Hypertension in Pregnancy

The aim of this study is to investigate the role of the 677C?T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene on blood pressure (BP) during pregnancy, and to examine the effect of intervention with riboflavin, alone or in combination with 5-methyltetrahydrofolate (5-MTHF), as a non-drug approach for managing BP in pregnancy in women with the variant TT genotype. In addition, we aim to examine the effect of maternal supplementation with riboflavin, alone or combined with 5-MTHF, on BP in the offspring in early infancy. Study design: A double-blind randomized controlled trial in pregnant women will be conducted. Women with a singleton pregnancy who are in their first trimester will be recruited from antenatal clinics in Northern Ireland and the Republic of Ireland. Women interested in the study will provide informed consent, complete a screening questionnaire and will provide a buccal swab to collect DNA to screen for the MTHFR 677C?T polymorphism. Women with multiple pregnancies, a previous NTD-affected pregnancy and those who are taking medication interfering with B-vitamin metabolism will be excluded from participation in the study. At approximately the 16th gestational week (GW), those with the variant TT genotype and age-matched heterozygous women (CT genotype) will be randomised to receive riboflavin (5 mg/day) alone, or in combination with 5-MTHF (400µg/day), or placebo, until the end of pregnancy. A non-fasting blood sample will be collected for biomarker assessment of B-vitamin status and other relevant variables from each participant before intervention and at the 36th GW. At the same time points, anthropometric and BP measurements will be taken. Women will also complete a health and lifestyle questionnaire and a 4-day dietary record. Samples of cord blood, umbilical cord and placenta will be collected after delivery and anthropometric parameters of the newborns will be retrieved postpartum. Maternal and infant BP will be measured 2-4 months after birth. In parallel with the intervention trial, age-matched pregnant women who do not carry the variant gene (CC genotype) and have not been randomized to treatment, will be monitored in order to control for any changes associated with normal pregnancy in the study outcome measurements. In the pilot phase, the feasibility and acceptability of the study procedures and treatment will be evaluated for clarification of the sample size and refinement of the study protocol.

Start: March 2017
Alternative Blood Pressure Measurements in OB Patients

The incidence of obesity has been increasing worldwide. In women with obesity, the anthropometric differences in the distribution of subcutaneous tissue can make accurate measurement of blood pressure difficult. A large upper arm circumference can prevent the use of a brachial artery blood pressure cuff and often prompts the use of alternative methods for blood pressure measurement, including measurements on the wrist or forearm. Outside of the obstetric population, there is evidence that if measurement of the blood pressure at the upper arm is not possible then measurement at the wrist can be used. Despite this evidence in non-pregnant patients, there is limited evidence in pregnancy regarding the accuracy of blood pressure measurements on the forearm or wrist. Accurate measurement of blood pressure is especially important in pregnancy to allow for prompt treatment of severe hypertension and for accurate diagnosis of hypertensive disorders of pregnancy. Error in measurement could lead to iatrogenic preterm birth or under treatment of severe hypertension, both which can lead to severe maternal and fetal morbidity and mortality. Additionally, it is biologically plausible that an increase in subcutaneous edema and vascular changes in pregnancy could lead to a larger discrepancy in blood pressure measurements between upper arm, forearm and wrist measurements. Due to the increasing epidemic of obesity and the increasing need for accurate alternative blood pressure measurements the investigators propose a prospective observational study of pregnant women ?18 years old admitted to labor and delivery for any indication or seen for prenatal care in OBGYN clinic. A total of 20 women in each BMI class (normal, overweight (25-29.9), class 1 (30-34.9), class 2 (35-39.9), class 3 (>40) will be enrolled (100 total). Participation will include a total of 9 blood pressure measurements, biometric measurements on the patient's upper arm, forearm, and wrist and a brief questionnaire. The investigators hypothesize that there will be a discrepancy between blood pressure measurements on the upper arm and forearm or wrist.

Start: March 2020
BP Variability on the Outcomes of Hemodialysis Vascular Access

Hemodialysis vascular access dysfunction continues to be a major source of morbidity and mortality in patients with ESRD. Thrombosis is the most common cause of secondary vascular access failure Although intimal hyperplasia at the outflow vein is the most common cause of thrombosis, 20-40% of thrombosis may develop secondary without underlying anatomic abnormalities. Low-flow states secondary to low BP have been proposed to precipitate access thrombosis. In previous studies, lower pre- and post- dialysis SBP are associated with a higher rate of access thrombosis. Nonetheless, high blood pressure is also a well-known risk factor for arteriosclerosis, intimal hyperplasia, and thrombotic vascular events. In dialysis patients, the relation between blood pressure and thrombosis seems to be more complex, and few studies have delineated the effect of blood pressure in a systematic manner. In addition to the static component of blood pressure, blood pressure variability (BPV) is increasingly accepted as a novel risk factors for vascular disease. BPV is categorized as either long or short term. In dialysis patients, long-term BPV is typically defined on the basis of BP measurements taken at the start of hemodialysis (inter-dialysis BPV); short-term BPV is usually considered in terms of variability during hemodialysis (intra-dialysis BPV). BP variability is increased in ESRD patients and is associated with adverse outcomes. To the best of our knowledge, only one study by Cheung et al focused on intra-dialytic BPV, which found intradialytic hypotension to be a risk factor for access thrombosis. Nonetheless, access thrombotic events rarely occur during the dialysis session. It remained unclear that if inter-dialysis BPV is a more relevant factor for access thrombosis. Answer to this question is of clinical significance because the optimal BP target after PTA remained unknown. In this study, we aimed to investigate the effect of BP variability on the outcomes of hemodialysis vascular access, major cardiovascular events in maintenance hemodialysis patients. We also aimed to evaluate the determinants of BPV in hemodialysis patients, including medication, frailty, fluid status and autonomic function. The impact of autonomic function and frailty on the outcomes of vascular access and cardiovascular events will be evaluated as well.

Start: January 2018
Nicotinamide Riboside Supplementation for Treating Arterial Stiffness and Elevated Systolic Blood Pressure in Patients With Moderate to Severe CKD

Risk of cardiovascular diseases (CVD) is significantly elevated in patients with chronic kidney disease (CKD); however, this increased risk is only partially explained by traditional CV risk factors. Arterial dysfunction is an important nontraditional CV risk factor gaining increased recognition in the field of nephrology. This process is best represented, both physiologically and pathophysiologically, by increases in the gold standard measure of arterial stiffening, carotid to femoral artery pulse wave velocity (CFPWV), which reflects, in particular, increases in aortic stiffness. Aortic stiffening with CKD is mediated by structural and functional (increased vascular smooth muscle tone) changes in the arterial wall stimulated by oxidative stress and chronic low-grade inflammation. Caloric restriction (CR) is a promising strategy for prevention of CKD-associated arterial dysfunction and CVD. However, long-term adherence to chronic CR regimens with optimal nutrition is very difficult to achieve. Research has shown that boosting NAD+ bioavailability to stimulate SIRT-1, a "CR mimetic" approach, reduces CFPW and oxidative stress in old mice, and this lab recently took the first step in translating these findings in a study of adults with normal kidney function and elevated systolic blood pressure (SBP). The data found that supplementation with nicotinamide riboside, a natural, commercially available precursor of NAD+ and novel CR mimetic, increased NAD+ bioavailability and reduced CFPWV and SBP. A randomized, placebo-controlled, double-blind, single-site phase IIa clinical trial to assess the safety and efficacy of oral nicotinamide riboside (500 mg capsules 2x/day; NIAGEN®; ChromaDex Inc.) for 3 months vs. placebo for decreasing aortic stiffness and SBP in patients (35-80 years) with stage III and IV CKD is being proposed. It is hypothesized that treatment will reduce CFPWV and SBP, as related to increases in systemic NAD+ bioavailability and reductions in oxidative stress, and inflammation. Aim 1: To measure CFPWV (primary outcome) before/after nicotinamide riboside vs. placebo treatment; Aim 2: To measure casual and 24h-ambulatory SBP (secondary outcome) before and after treatment; Aim 3: To determine the safety and tolerability of treatment with nicotinamide riboside vs. placebo; Aim 4: To measure systemic NAD+ and NAD+-related metabolite concentrations, as well as circulating markers of oxidative stress, inflammation, and vasoconstriction factors before and after treatment.

Start: November 2019