Search results for "Hemodynamics"
showing 10 items of 511 documents
Evaluation of regional haemodynamics and alterations of vascular wall of the lower limbs in hypertensive subjects
1995
This study was designed to analyse the relationship between arterial hypertension and changes in arterial blood flow and vascular wall damage of the lower limbs in hypertensive patients with various degrees of hypertension. Six hundred and fifty-four hypertensive patients (421 males and 233 females) aged 35 to 70 years and 88 healthy subjects (63 males and 25 females) aged 39 to 60 years were studied. Strain-gauge plethysmography of the lower limbs was used to calculate arterial calf blood flow (RF), arterial calf blood flow after post-ischaemic hyperaemia (PF), basal and minimal vascular resistances (BVR and MVR), time to reach peak flow (tPF), time until 50% reduction of peak flow (tT1/2)…
Subchronic Antidepressant Treatment with Venlafaxine or Imipramine and Effects on Blood Pressure and Heart Rate: Assessment by Automatic 24-Hour Moni…
1996
Venlafaxine is a new nontricyclic antidepressant inhibiting the reuptake of serotonin, noradrenaline, and, to a lesser extent, dopamine without antagonizing cholinergic, histaminergic, or noradrenergic receptors. Significantly, in a first placebo-controlled safety and efficacy study, high doses of venlafaxine increased blood pressure in some study subjects. In order to investigate further the effect of subchronic antidepressant drug treatment on blood pressure and heart rate, the effects of a conventional tricyclic (imipramine) and a structurally different phenethylamine antidepressant (venlafaxine) were compared. Sixteen inpatients with major depression (melancholic type) were treated for …
Instantaneous Transfer Entropy for the Study of Cardiovascular and Cardio-Respiratory Nonstationary Dynamics
2017
Objective: Measures of transfer entropy (TE) quantify the direction and strength of coupling between two complex systems. Standard approaches assume stationarity of the observations, and therefore are unable to track time-varying changes in nonlinear information transfer with high temporal resolution. In this study, we aim to define and validate novel instantaneous measures of TE to provide an improved assessment of complex nonstationary cardiorespiratory interactions. Methods: We here propose a novel instantaneous point-process TE (ipTE) and validate its assessment as applied to cardiovascular and cardiorespiratory dynamics. In particular, heartbeat and respiratory dynamics are characteriz…
Effects of gender on resting leg blood flow: implications for measurement of regional substrate oxidation.
1998
Jensen, Michael D., Tu T. Nguyen, A. Hernández Mijares, C. Michael Johnson, and Michael J. Murray. Effects of gender on resting leg blood flow: implications for measurement of regional substrate oxidation. J. Appl. Physiol. 84(1): 141–145, 1998.—These studies were designed to examine whether the respiratory quotient (RQ) of leg tissue (primarily skeletal muscle) would increase to a greater degree in women than in men during meal ingestion. We found that mean leg and systemic RQ values were similar in men under both basal and fed conditions, whereas the agreement was poor in women. In women, leg RQ values tended to be greater than the systemic RQ, whereas splanchnic RQ values tended to be l…
Association of Common Variants in NPPA and NPPB with Circulating Natriuretic Peptides and Blood Pressure
2009
We examined the association of common variants at the NPPA-NPPB locus with circulating concentrations of the natriuretic peptides, which have blood pressure-lowering properties. We genotyped SNPs at the NPPA-NPPB locus in 14,743 individuals of European ancestry, and identified associations of plasma atrial natriuretic peptide with rs5068 (P = 8 x 10(-70)), rs198358 (P = 8 x 10(-30)) and rs632793 (P = 2 x 10(-10)), and of plasma B-type natriuretic peptide with rs5068 (P = 3 x 10(-12)), rs198358 (P = 1 x 10(-25)) and rs632793 (P = 2 x 10(-68)). In 29,717 individuals, the alleles of rs5068 and rs198358 that showed association with increased circulating natriuretic peptide concentrations were a…
Influence of St John's wort on catecholamine turnover and cardiovascular regulation in humans
2004
BACKGROUND: St John's wort (Hypericum perforatum) is a popular over-the-counter antidepressant. Its antidepressive effect has been attributed in part to inhibition of monoamine transporters and monoamine oxidase, on the basis of in vitro studies. METHODS: In a double-blind, randomized, placebo-controlled, crossover study, 16 healthy subjects (11 men and 5 women; mean age, 31 +/- 5 years) ingested either St John's wort (300 mg three times daily) or placebo for 7 days. Imipramine treatment (50 mg three times daily) in 7 subjects served as a positive control. After treatment, physiologic and biochemical tests included cardiovascular reflex testing, graded head-up tilt testing, and plasma catec…
Nocturnal oxygen enrichment in sleep apnoea.
2000
We hypothesized that a modest oxygen enrichment, rather than 100% oxygen supplementation as used in previous trials, could result in improvement in ventilatory and cardiac symptoms, in patients with obstructive sleep apnoea (OSA), without jeopardizing the chemostimulant ventilatory drive. This hypothesis was tested in five male patients with OSA in a single-blinded trial consisting of one night spent sleeping in control room air (control night), followed by one night spent sleeping while exposed to air with a 9% enriched oxygen content (oxygen-enriched night). Oxygen enrichment resulted in a significant shift in the oxygen saturation profile towards values of ≥ 95% and to decrease desatura…
Associations of Birth Weight and Postnatal Weight Gain With Cardiometabolic Risk Parameters at 5 Years of Age
2014
The present prospective study assessed the impact of birth weight (BW) and postnatal weight gain on blood pressure and metabolic profile during the first 5 years of life. One hundred thirty-nine newborns (63 women) born at term after uncomplicated pregnancies and in the absence of perinatal illness were included. Subjects were divided according to size at birth in small, appropriate, and large for gestational age. After the initial evaluation on the second day of life, infants were followed up at 6 months and 2 and 5 years. Anthropometric parameters and blood pressure were measured at each visit and metabolic assessment was performed at 5 years of age. Among the BW groups, mothers did not d…
Hemodynamic Effects of Nonionic Contrast Bolus Injection and Oxygen Inhalation During Pulmonary Angiography in Patients With Chronic Major-Vessel Thr…
1996
Background Pulmonary angiography is the gold standard for the diagnosis of chronic thromboembolic pulmonary hypertension; however, major complications have been reported. This study evaluates the hemodynamic effects of direct pulmonary nonionic contrast bolus injection and oxygen inhalation in patients with chronic thromboembolic pulmonary hypertension. Methods and Results In 33 patients, hemodynamic parameters were measured after oxygen inhalation and during bolus injection of nonionic contrast medium in a control group (group 1, n=11), in a group of patients with moderately severe pulmonary hypertension (group 2, n=9), and in a group with severe pulmonary hypertension (group 3, n=13). Ox…
Improvement of tricuspid regurgitation after pulmonary thromboendarterectomy
2002
For patients with chronic thromboembolic pulmonary hypertension who undergo pulmonary thromboendarterectomy (PTE) it has not yet been systematically investigated how operation affects the severity of tricuspid regurgitation (TR). This study sought (1) to evaluate the extent of TR reversibility after operation, (2) to identify potential predictors of the reversibility of TR, and (3) to investigate the influence of geometric and hemodynamic alterations on the extent of TR severity.Thirty-nine patients (55+/-12 years) undergoing PTE without tricuspid valve repair were investigated before and 13+/-8 days after operation by Doppler color flow mapping. Geometry of the tricuspid valve as well as r…