An acute increase in Left Atrial volume and left ventricular filling pressure during Adenosine administered myocardial hyperaemia: CMR First-Pass Perfusion Study. To investigate whether left atrial (LA) volume and left ventricular filling pressure (LVFP) assessed by cardiovascular magnetic resonance (CMR) change during adenosine delivered myocardial hyperaemia as part of a first-pass stress
A comparison of subjective and objective conjunctival hyperaemia grading with AOS® Anterior software. This study evaluates a commercially available conjunctival hyperaemia grading system, providing validation of an important tool for ocular surface research and clinical trials. Bulbar conjunctival hyperaemia is a sign of ocular surface inflammation, and proper measurement is essential investigators graded the images with either a 0.1 or 0.5 unit scaling using a 0-4 Efron grading scale. Three of the investigators also imported the images into the AOS ® Anterior software and graded them objectively. All measurement techniques were assessed for repeatability and comparability to each other. Mean hyperaemia with the objective system (1.1 ± 0.7) was significantly less than the subjective
Near-infrared spectroscopy-derived total haemoglobin as an indicator of changes in muscle blood flow during exercise-induced hyperaemia. Blood flow changes in response to exercise have been attributed, among other factors, to the effect of vasodilators factors on the microvasculature, suggesting a close relationship between small blood vessels and conducting arteries. The main purpose
The effect of caffeine on cutaneous postocclusive reactive hyperaemia. Caffeine is reported to be the most widely used pharmacologically active substance. It causes mental stimulation and increases blood pressure. Acute systolic and diastolic blood pressure response to caffeine attenuates in the course of regular caffeine use; tolerance to cardiovascular responses develops in some people . For some hypertension-prone people coffee ingestion may be harmful, and for others it may be beneficial. The aim of our work was to evaluate the effect of caffeine on postocclusive reactive hyperaemia (PORH), a test of microvascular function, and at the same time to monitor the central effects of caffeine on blood pressure and heart rate. Heart rate, arterial pressure, and cutaneous laser-Doppler (LD
Evaluating a new objective grading software for conjunctival hyperaemia. Standardised numeric grading scales are used in ophthalmic practice to improve consistency between clinicians in recording the severity of ocular conditions and to facilitate the monitoring of such changes. We investigated the intra- and inter-observer grading reliability and the agreement between subjective Cornea and Contact Lens Research Unit (CCLRU) and Efron grading scales as well as a new Advanced Ophthalmic Systems (AOS) software which uses an objective approach to grading conjunctival hyperaemia. One experienced observer graded n = 30 bulbar and n = 26 palpebral conjunctival hyperaemia images to 0.1 increments. Masked grading of randomised images was undertaken for all three methods, on two separate occasions
Evidence of Flicker-Induced Functional Hyperaemia in the Smallest Vessels of the Human Retinal Blood Supply. Regional changes in blood flow are initiated within neural tissue to help fuel local differences in neural activity. Classically, this response was thought to arise only in larger arterioles and venules. However, recently, it has been proposed that a) the smallest vessels
Effects of hyperaemia on left ventricular longitudinal strain in patients with suspected coronary artery disease: AÂ first-pass stress perfusion cardiovascular magnetic resonance imaging study Myocardial perfusion imaging during hyperaemic stress is commonly used to detect coronary artery disease. The aim of this study was to investigate the relationship between left ventricular global enhancement imaging. Rest and stress HLA cine CMR images were analysed using feature-tracking software for the assessment of myocardial deformation. The presence of perfusion defects was scored on a binomial scale. In patients with hyperaemia-induced perfusion defects, rest global longitudinal strain GLS (-16.9 ± 3.7 vs. -19.6 ± 3.4; p-value = 0.02), E' (-86 ± 22 vs. -109 ± 38; p-value = 0.02), GLSR (69
Forearm vasodilator responses to environmental stress and reactive hyperaemia are impaired in young South Asian men Prevalence of cardiovascular disease (CVD) is greater in South Asians (SAs) than White Europeans (WEs). Endothelial dysfunction and blunted forearm vasodilatation to environmental stressors have been implicated in CVD. We investigated whether these features are present in young SA men. In 15 SA and 16 WE men (19-23 years), we compared changes in forearm blood flow, arterial blood pressure (ABP), forearm vascular conductance (FVC), heart rate, and electrodermal resistance (EDR; sweating) following release of arterial occlusion (reactive hyperaemia endothelium-dependent) and 5 single sounds at 5-10 min intervals (stressors). All were normotensive. Peak reactive hyperaemia
Cutaneous reactive hyperaemia is unaltered by dietary nitrate supplementation in healthy humans. The purpose of this study was to determine whether nitrate supplementation augments cutaneous reactive hyperaemia. Seven participants were tested pre- and postnitrate supplementation (25 ml beetroot juice); participants consumed one shot per day for 3 days. Participants were instrumented with two microdialysis fibres: control (Ringer's solution) and NO synthase inhibition (20 mM L-NAME). Skin blood flow was measured via laser-Doppler flowmetry (LDF). A blood pressure cuff was placed on the experimental arm and inflated to 250 mmHg for 5 mins to occlude arterial inflow. The cuff was released, and the resultant reactive hyperaemia was measured. Blood pressure was continuously measured via
Reactive myocardial hyperaemia for functional assessment of coronary stenosis severity. Our aim was to compare functional assessment of coronary stenosis severity by fractional flow reserve (FFR) measurement, as induced by systemic adenosine, and by regional reactive myocardial hyperaemia. The primary study endpoints were coronary pressure-derived FFR values in response to intravenous adenosine infusion (140 µg/min/kg), and to a one-minute proximal coronary artery balloon occlusion (reactive hyperaemia) for the same stenosis of interest. The secondary study endpoint was coronary collateral flow index (CFI) during the same occlusion. CFI is the ratio between simultaneous mean arterial occlusive pressure and mean aortic pressure, both subtracted by central venous pressure. As a reference
Quantitative myocardial blush grade reserve during pharmacologic hyperaemia: a way to perform a real wireless fractional flow reserve measurement in patients with coronary artery disease and intermediate coronary lesions. We investigated the relation between myocardial blush grade reserve (MBGreserve) and fractional flow reserve (FFR) measures. FFR is a marker of inducible myocardial ischaemia , which could guide percutaneous coronary intervention (PCI) and stent placement. However, it requires a pressure wire and is associated with additional costs and potential hazards. The aim of our study was to investigate the ability of MBG for the evaluation of functional significance in intermediate coronary lesions during pharmacologic hyperaemia. Fifty-six patients who underwent routine cardiac
Effects of modest hyperoxia and oral vitamin C on exercise hyperaemia and reactive hyperaemia in healthy young men. We have argued that breathing 40 % O2 attenuates exercise hyperaemia by decreasing production of O2-dependent vasodilators. However, breathing 100 % O2 attenuated endothelium-dependent vasodilatation evoked by acetylcholine and this effect was prevented by vitamin C, implicating reactive oxygen species (ROS). We have therefore used vitamin C to test the hypothesis that 40 % O2 modulates exercise hyperaemia and reactive hyperaemia independently of ROS. In a cross-over study on 10 male subjects (21.1 ± 0.84 years), we measured forearm blood flow (venous occlusion plethysmography) and calculated forearm vascular conductance (FVC) at rest and following static handgrip at 60
Non-invasive endothelial function assessment using digital reactive hyperaemia correlates with three-dimensional intravascular ultrasound and virtual histology-derived plaque volume and plaque phenotype To study relationships between endothelial dysfunction (ED) and coronary atherosclerosis derived from intravascular ultrasound (IVUS) and virtual histology (VH). Endothelial dysfunction was examined by EndoPAT system (Itamar Medical) in 56 patients who underwent IVUS and VH (Volcano corp.). Reactive hyperaemia index (RHI) < 2 was used for definition of ED. IVUS sequences were divided into 5 mm-long non-overlapping and adjacent vessel segments. Plaque phenotype was determined for each frame and 5 mm vessel segment was labeled according to highest frame score (from 0 for "no lesion" to 5
Potassium inhibits nitric oxide and adenosine arteriolar vasodilatation via KIR and Na+/K+ATPase: implications for redundancy in active hyperaemia Redundancy, in active hyperaemia, where one vasodilator can compensate for another if the first is missing, would require that one vasodilator inhibits the effects of another; therefore, if the first vasodilator is inhibited, its inhibitory influence show that vasodilators relevant to muscle contraction can interact in a way that alters the effectiveness of other vasodilators. These data suggest that active hyperaemia may be the result of complex interactions between multiple vasodilators via a redundant control paradigm.
Basal hyperaemia is the primary abnormality of perfusion in Takotsubo cardiomyopathy: a quantitative cardiac perfusion positron emission tomography study. Takotsubo cardiomyopathy (TTC) is characterized by acute completely reversible regional left ventricle (LV) akinesia and decreased tracer uptake in the akinetic region on semi-quantitative perfusion imaging. The latter may be due
Single bolus intravenous regadenoson injection versus central venous infusion of adenosine for maximum coronary hyperaemia in fractional flow reserve measurement. The aim of this study was to compare the hyperaemic effect of a single bolus regadenoson injection to a central venous adenosine infusion for inducing hyperaemia in the measurement of fractional flow reserve (FFR). One hundred patients scheduled for FFR measurement were enrolled. FFR was first measured by IV adenosine (140 µg/kg/min), thereafter by IV bolus regadenoson injection (400 µg), followed by another measurement by IV adenosine and bolus injection of regadenoson. The regadenoson injections were randomised to central or peripheral intravenous. Hyperaemic response and duration of steady state maximum hyperaemia were studied
Prolonged (9 hours) poikilocapnic hypoxia (12% O2) augments cutaneous thermal hyperaemia in healthy humans. The primary aim of this study was to investigate the effect of systemic poikilocapnic hypoxia on forearm cutaneous thermal hyperaemia. A secondary aim was to examine the relationship between the individual susceptibility to oxygen desaturation and cutaneous vasodilator capacity. Twelve = 0.01) and plateau phase of thermal hyperaemia (P = 0.01). Prolonged poikilocapnic hypoxia causes robust increases in CVC during both phases of thermal hyperaemia that are dependent on the oxygen saturation of the individual.
Functional coronary stenosis severity assessed from the mean pressure gradient-velocity relationship obtained by contrast medium-induced submaximal hyperaemia. First, to establish the diagnostic performance of the pressure gradient at a standardised mean velocity (dPv) as derived from the cycle-averaged stenosis pressure gradient-velocity (dP-v) relationship obtained by administration of adenosine and, second, to determine whether dPv can be assessed from contrast medium-induced submaximal hyperaemia. Distal coronary pressure and velocity were simultaneously recorded in 64 patients during the response to intracoronary injection of adenosine. dPv was assessed at velocities between 20 and 50 cm/s. The pressure gradient at a mean flow velocity of 30 cm/s (dPv30) yielded an excellent
Cerebral hyperaemia after isoflurane anaesthesia for craniotomy of patients with supratentorial brain tumour. Few studies look into cerebral blood flow (CBF) changes during emergence from general anaesthesia for craniotomy. The purpose of this study was to assess CBF changes during emergence from general anaesthesia for craniotomy, through monitoring blood oxygen saturation of jugular vein bulb extubation. While Vmca of the right side changed only slightly (63.6 ± 7.7 cm/s vs. 61.8 ± 8.1 cm/s, P < 0.01) but significantly at extubation in group A. SjvO2 increased significantly (81.4% ± 7.4% vs. 60.9% ± 3.7%, P < 0.01) at extubation in group C, and remained above baseline significantly for 2 h. There was no significant correlation between Vmca and MAP at any time. Cerebral hyperaemia occurs after