scholarly journals Papillary Trunk Bifurcation Angles as Major Determinants of Ocular Perfusion: A Cross-Sectional Study

2020 ◽  
Vol 5 (6) ◽  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Minimum Energy ◽  
North India ◽  
Management Tool ◽  
Human Retina ◽  
Structural Factors ◽  
Digital Image Management ◽  
Retinal Microvasculature ◽  
Perfusion Defects

Background: Notable work has been done by Cecile and Murray in as early as 1926, on the structural and topological aspects of vasculature based on the concept that blood vessel size and arrangement is such that it provides blood flow with minimum energy loss. In the theoretical analysis of arterial networks, the existence of geometric optimisation for enabling functional adequacy has long been suggested, but observational studies have not yet fully corroborated these theories. Data on branching or bifurcation angles of retinal microvasculature is not only insufficient but also inconclusive. Aim: Attending to this gap in information, we compared the central retinal artery (CRA) branching angles of known diabetics with healthy subjects and explored their possible role in determining the circulatory adequacy of human retina. Methods: This study was done on North Indian subjects attending retina clinics of prominent tertiary centers of north India during 2019 through 2020. Fundus images were acquired through convenience sampling from 860 consecutive eyes of 430 subjects. Fluorescein fundus angiography was followed up for diabetics. CRA branching angles from digitalized fundus photographs of known diabetics and healthy subjects was analyzed through semi-automated digital image management tool and the readings were clinically correlated to note the occurrence and severity of retinopathic perfusion defects was Results: We found marked differences between CRA branching angles among diabetics and healthy subjects and a significant correlation between branching anless and the occurrence and severity of retinopathic perfusion defects. Discussion and Conclusion: The orientation of retinal blood vessels on the fundus plane is not merely ‘a matter of chance’ in the anatomic chronicle of the human body; rather, it has biological heralds and functional consequences. Direction, branching, angles; all determine the efficacy and abundance of blood flow in the human retina that hold indispensible relevance for optimal vision and might be subtle indicators of micro vascular damage in disease states. This study has elucidated retinal vascular geometrics of healthy and diseased Indians, a knowledge that can improve our understanding of ‘abnormal features’ and ‘natural variants’ in retinal vascular architecture. In this study, we quantified the ‘structural factors’ behind perfusion defects of the Diabetic retina.

Lutein Complex Supplementation Increases Ocular Blood Flow Biomarkers in Healthy Subjects

2019 ◽  
Vol 89 (1-2) ◽  
pp. 5-12
Author(s):  
Alon Harris ◽  
Brent Siesky ◽  
Amelia Huang ◽  
Thai Do ◽  
Sunu Mathew ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Diastolic Blood Pressure ◽  
Healthy Subjects ◽  
Ocular Blood Flow ◽  
Capillary Blood ◽  
Post Treatment ◽  
Capillary Blood Flow ◽  
Doppler Imaging ◽  
Retinal Capillary

Abstract. Introduction: To investigate the effects of a lutein complex supplementation on ocular blood flow in healthy subjects. Materials and Methods: Sixteen healthy female patients (mean age 36.8 ± 12.1 years) were enrolled in this randomized, placebo-controlled, double-blinded, two-period crossover study. Subjects received daily an oral dose of the lutein with synergistic phytochemicals complex (lutein (10 mg), ascorbic acid (500 mg), tocopherols (364 mg), carnosic acid (2.5 mg), zeaxanthin (2 mg), copper (2 mg), with synergistic effects in reducing pro-inflammatory mediators and cytokines when administered together in combination) and placebo during administration periods. Measurements were taken before and after three-week supplementation periods, with crossover visits separated by a three-week washout period. Data analysis included blood pressure, heart rate, intraocular pressure, visual acuity, contrast sensitivity detection, ocular perfusion pressure, confocal scanning laser Doppler imaging of retinal capillary blood flow, and Doppler imaging of the retrobulbar blood vessels. Results: Lutein complex supplementation produced a statistically significant increase in mean superior retinal capillary blood flow, measured in arbitrary units (60, p = 0.0466) and a decrease in the percentage of avascular area in the superior (−0.029, p = 0.0491) and inferior (−0.023, p = 0.0477) retina, as well as reduced systolic (−4.06, p = 0.0295) and diastolic (−3.69, p = 0.0441) blood pressure measured in mmHg from baseline. Data comparison between the two supplement groups revealed a significant decrease in systemic diastolic blood pressure (change from pre- to post-treatment with lutein supplement (mean (SE)): −3.69 (1.68); change from pre- to post-treatment with placebo: 0.31 (2.57); p = 0.0357) and a significant increase in the peak systolic velocity (measured in cm/sec) in the central retinal artery (change from pre- to post-treatment with lutein supplement: 0.36 (0.19); change from pre- to post-treatment with placebo: −0.33 (0.21); p = 0.0384) with lutein complex supplement; data analyses from the placebo group were all non-significant. Discussion: In healthy participants, oral administration of a lutein phytochemicals complex for three weeks produced increased ocular blood flow biomarkers within retinal vascular beds and reduced diastolic blood pressure compared to placebo.

Liver Blood Flow as a Major Determinant of the Clearance of Recombinant Human Tissue-Type Plasminogen Activator

1992 ◽  
Vol 67 (01) ◽  
pp. 083-087 ◽  
Author(s):  
A de Boer ◽  
C Kluft ◽  
J M Kroon ◽  
F J Kasper ◽  
H C Schoemaker ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rat Liver ◽  
Healthy Subjects ◽  
Liver Blood Flow ◽  
Major Determinant ◽  
Tissue Type ◽  
Perfused Rat Liver ◽  
Liver Model ◽  
Type Plasminogen Activator ◽  
Proportional Change

SummaryThe influence of changes in liver blood flow on the clearance of rt-PA was studied both in healthy subjects and in a perfused rat liver model. Liver blood flow in healthy subjects was documented indirectly by the clearance of indocyanine green (ICG). Exercise reduced liver blood flow on average by 57% with a 95% confidence interval (95% Cl) ranging from 51% to 62% (n = 5) and increased plasma levels of rt-PA activity (after an i. v. infusion of 18 mg of rt-PA over 120 min) by 119% (95% Cl, 58% - 203%) and rt-PA antigen by 91% (95% Cl, 30% - 140%). In the perfused rat liver model it was shown that halving or doubling of the physiological flow rate of a perfusate, containing rt-PA caused a proportional change in the clearance of rt-PA, while the extraction of rt-PA by the liver remained similar. In conclusion, liver blood flow is a major determinant of the clearance of rt-PA. This may have important implications for dosage of rt-PA in patients with myocardial infarction.

scholarly journals SWE and SMI ultrasound techniques for monitoring needling treatment of ankylosing spondylitis: study protocol for a single-blinded randomized controlled trial

Trials ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Mengyu Wang ◽  
Wen Fu ◽  
Lingcui Meng ◽  
Jia Liu ◽  
Lihua Wu ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Blood Flow ◽  
Ankylosing Spondylitis ◽  
Outcome Measures ◽  
Healthy Subjects ◽  
Acupuncture Group ◽  
Musculoskeletal Ultrasound ◽  
Sham Control ◽  
Post Intervention

Abstract Background Ankylosing spondylitis (AS) is a high-incidence disease in young men that interferes with patients’ physical and mental wellbeing and overall quality of life (QoL). It is often accompanied by arthralgia, stiffness, and limited lumbar flexibility. Acupuncture is safe and effective for reducing the symptoms of AS, but the underlying mechanisms by which it does so are not fully understood. Therefore, to objectively assess acupuncture efficacy, which is critical for patients making informed decisions about appropriate treatments, we will use shear-wave elastography (SWE) and superb microvascular imaging (SMI) ultrasound techniques to evaluate elasticity of lumbar paraspinal muscles and blood flow to the sacroiliac joint (SIJ) in AS. Methods We will recruit a total of 60 participants diagnosed with AS and 30 healthy subjects. Participants will be randomly allocated 1:1 to either an acupuncture group or a sham control acupuncture group. Primary-outcome measures will be musculoskeletal ultrasound, Ankylosing Spondylitis Quality of Life Scale (ASQoL), Bath Ankylosing Spondylitis Metrology Index (BASMI), and the Visual Analogue Scale (VAS) for pain. Secondary outcome measures will be the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Function Index (BASFI), and Fatigue Scale-14 (FS-14). We will monitor the effect of acupuncture or sham acupuncture on blood flow and SIJ inflammation using SMI, lumbar-muscle stiffness using SWE and the lumbar paraspinal-muscle cross-sectional area (CSA) using a two-dimensional (2D) grayscale imaging. QoL, physical function, and fatigue will be assessed using an evaluation scale or questionnaire developed for this study, with outcomes measured by the ASQoL, BASMI, BASDAI, BASFI, and FS-14. Healthy subjects will not receive acupuncture but undergo only musculoskeletal ultrasound at baseline. Acupuncture and sham control acupuncture interventions will be conducted for 30 min, 2–3 times/week for 12 weeks. Musculoskeletal ultrasound will be conducted at baseline and post-intervention, while other outcomes will be measured at baseline, 6 weeks, and post-intervention. The statistician, outcome assessor, and participants will be blinded to treatment allocation. Discussion The results of this single-blinded, randomized trial with sham controls could help demonstrate the efficacy of acupuncture and clarify whether musculoskeletal ultrasound could be used to evaluate AS. Trial registration ClinicalTrials.gov ChiCTR2000031476. Registered 3 April 2020.

scholarly journals Four-Dimensional Flow MRI of Abdominal Veins: A Systematic Review

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 767
Author(s):  
Simon O. Haarbye ◽  
Michael B. Nielsen ◽  
Adam E. Hansen ◽  
Carsten A. Lauridsen
Keyword(s):  
Systematic Review ◽  
Blood Flow ◽  
Portal Hypertension ◽  
Healthy Subjects ◽  
Visual Quality ◽  
Sampling Strategies ◽  
4D Flow Mri ◽  
4D Flow ◽  
Dimensional Flow ◽  
Flow Mri

The aim of this systematic review is to provide an overview of the use of Four-Dimensional Magnetic Resonance Imaging of vector blood flow (4D Flow MRI) in the abdominal veins. This study was composed according to the PRISMA guidelines 2009. The literature search was conducted in MEDLINE, Cochrane Library, EMBASE, and Web of Science. Quality assessment of the included studies was performed using the QUADAS-2 tool. The initial search yielded 781 studies and 21 studies were included. All studies successfully applied 4D Flow MRI in abdominal veins. Four-Dimensional Flow MRI was capable of discerning between healthy subjects and patients with cirrhosis and/or portal hypertension. The visual quality and inter-observer agreement of 4D Flow MRI were rated as excellent and good to excellent, respectively, and the studies utilized several different MRI data sampling strategies. By applying spiral sampling with compressed sensing to 4D Flow MRI, the blood flow of several abdominal veins could be imaged simultaneously in 18–25 s, without a significant loss of visual quality. Four-Dimensional Flow MRI might be a useful alternative to Doppler sonography for the diagnosis of cirrhosis and portal hypertension. Further clinical studies need to establish consensus regarding MRI sampling strategies in patients and healthy subjects.

scholarly journals Use of quantitative cardiovascular magnetic resonance myocardial perfusion mapping for characterization of ischemia in patients with left internal mammary coronary artery bypass grafts

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Andreas Seraphim ◽  
Kristopher D. Knott ◽  
Anne-Marie Beirne ◽  
Joao B. Augusto ◽  
Katia Menacho ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiovascular Magnetic Resonance ◽  
Coronary Artery ◽  
Magnetic Resonance ◽  
Myocardial Perfusion ◽  
Myocardial Blood Flow ◽  
Coronary Artery Bypass ◽  
Artery Bypass ◽  
Internal Mammary ◽  
Perfusion Defects

Abstract Background Quantitative myocardial perfusion mapping using cardiovascular magnetic resonance (CMR) is validated for myocardial blood flow (MBF) estimation in native vessel coronary artery disease (CAD). Following coronary artery bypass graft (CABG) surgery, perfusion defects are often detected in territories supplied by the left internal mammary artery (LIMA) graft, but their interpretation and subsequent clinical management is variable. Methods We assessed myocardial perfusion using quantitative CMR perfusion mapping in 38 patients with prior CABG surgery, all with angiographically-proven patent LIMA grafts to the left anterior descending coronary artery (LAD) and no prior infarction in the LAD territory. Factors potentially determining MBF in the LIMA–LAD myocardial territory, including the impact of delayed contrast arrival through the LIMA graft were evaluated. Results Perfusion defects were reported on blinded visual analysis in the LIMA–LAD territory in 27 (71%) cases, despite LIMA graft patency and no LAD infarction. Native LAD chronic total occlusion (CTO) was a strong independent predictor of stress MBF (B = − 0.41, p = 0.014) and myocardial perfusion reserve (MPR) (B = − 0.56, p = 0.005), and was associated with reduced stress MBF in the basal (1.47 vs 2.07 ml/g/min; p = 0.002) but not the apical myocardial segments (1.52 vs 1.87 ml/g/min; p = 0.057). Extending the maximum arterial time delay incorporated in the quantitative perfusion algorithm, resulted only in a small increase (3.4%) of estimated stress MBF. Conclusions Perfusion defects are frequently detected in LIMA–LAD subtended territories post CABG despite LIMA patency. Although delayed contrast arrival through LIMA grafts causes a small underestimation of MBF, perfusion defects are likely to reflect true reductions in myocardial blood flow, largely due to proximal native LAD disease.

Blood Flow Velocities in the Vertebral Veins of Healthy Subjects: A Duplex Sonographic Study

1999 ◽  
Vol 9 (4) ◽  
pp. 198-200 ◽  
Author(s):  
Olaf Hoffmann ◽  
Markus Weih ◽  
Thomas von Münster ◽  
Stephan Schreiber ◽  
Karl Max Einhäupl ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Blood Flow Velocities ◽  
Flow Velocities

scholarly journals Renal arterial blood flow measurement by breath-held MRI: Accuracy in phantom scans and reproducibility in healthy subjects

2010 ◽  
Vol 63 (4) ◽  
pp. 940-950 ◽  
Author(s):  
Samuel Dambreville ◽  
Arlene B. Chapman ◽  
Vicente E. Torres ◽  
Bernard F. King ◽  
Ashley K. Wallin ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Flow Measurement ◽  
Arterial Blood Flow ◽  
Blood Flow Measurement ◽  
Arterial Blood

Noninvasive measurement of forearm blood flow and oxygen consumption by near-infrared spectroscopy

1994 ◽  
Vol 76 (3) ◽  
pp. 1388-1393 ◽  
Author(s):  
R. A. De Blasi ◽  
M. Ferrari ◽  
A. Natali ◽  
G. Conti ◽  
A. Mega ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Healthy Subjects ◽  
Near Infrared ◽  
Forearm Blood Flow ◽  
Vascular Occlusion ◽  
Venous Occlusion ◽  
The Subject

We applied near-infrared spectroscopy (NIRS) for the simultaneous measurement of forearm blood flow (FBF) and oxygen consumption (VO2) in the human by inducing a 50-mmHg venous occlusion. Eleven healthy subjects were studied both at rest and after hand exercise during vascular occlusion. FBF was also measured by strain-gauge plethysmography. FBF measured by NIRS was 1.9 +/- 0.8 ml.100 ml-1.min-1 at rest and 8.2 +/- 2.9 ml.100 ml-1.min-1 after hand exercise. These values showed a correlation (r = 0.94) with those obtained by the plethysmography. VO2 values were 4.6 +/- 1.3 microM O2 x 100 ml-1.min-1 at rest and 24.9 +/- 11.2 microM O2 x 100 ml-1.min-1 after hand exercise. The scatter of the FBF and VO2 values showed a good correlation between the two variables (r = 0.93). The results demonstrate that NIRS provides the particular advantage of obtaining the contemporary evaluation of blood flow and VO2, allowing correlation of these two variables by a single maneuver without discomfort for the subject.

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