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Current Cardiology Reviews 2022Invasive assessment of coronary physiology has radically changed the paradigm of myocardial revascularization in patients with coronary artery disease. Despite the... (Review)
Review
Invasive assessment of coronary physiology has radically changed the paradigm of myocardial revascularization in patients with coronary artery disease. Despite the prognostic improvement associated with ischemia-driven revascularization strategy, functional assessment of angiographic intermediate epicardial stenosis remains largely underused in clinical practice. Multiple tools have been developed or are under development in order to reduce the invasiveness, cost, and extra procedural time associated with the invasive assessment of coronary physiology. Besides epicardial stenosis, a growing body of evidence highlights the role of coronary microcirculation in regulating coronary flow with consequent pathophysiological and clinical and prognostic implications. Adequate assessment of coronary microcirculation function and integrity has then become another component of the decision-making algorithm for optimal diagnosis and treatment of coronary syndromes. This review aims at providing a comprehensive description of tools and techniques currently available in the catheterization laboratory to obtain a thorough and complete functional assessment of the entire coronary tree (both for the epicardial and microvascular compartments).
Topics: Coronary Angiography; Coronary Artery Disease; Coronary Stenosis; Fractional Flow Reserve, Myocardial; Humans; Microcirculation; Percutaneous Coronary Intervention
PubMed: 34521331
DOI: 10.2174/1573403X17666210908114154 -
Frontiers in Endocrinology 2021The pancreas is regarded as consisting of two separate organ systems, the endocrine and exocrine pancreas. While treatment of a disease with either an endocrine or... (Review)
Review
The pancreas is regarded as consisting of two separate organ systems, the endocrine and exocrine pancreas. While treatment of a disease with either an endocrine or exocrine pathogenesis may affect the function of the entire pancreas, the pancreatic diseases have been treated by clinicians in different medical disciplines, including endocrinologists and gastroenterologists. Islet microcirculation has long been considered to be regulated independently from that of the exocrine pancreas. A new model proposes that pancreatic islet blood flow is integrated with the surrounding exocrine capillary network. This recent model may provide revived or contrasting hypotheses to test, since the pancreatic microcirculation has critical implications for the regulation of islet hormones as well as acinar pancreas functions. In this mini-review, practical applications of and studies of islet microcirculation are described with a specific emphasis on large-scale data analysis to ensure sufficient sample size accounting for known islet heterogeneity. For small animal studies, intravital microscopy based on two-photon excitation microscopes is a powerful tool that enables capturing the flow direction and speed of individual fluorescent-labeled red blood cells. Complementarily, for structural analysis of blood vessels, the recent technical advancements of confocal microscopy and tissue clearing have enabled us to image the three-dimensional network structure in thick tissue slices.
Topics: Animals; Cytological Techniques; Hemodynamics; Humans; In Vitro Techniques; Islets of Langerhans; Microcirculation; Models, Biological
PubMed: 34040578
DOI: 10.3389/fendo.2021.602620 -
The International Journal of Lower... Jun 2023Dynamic optical coherence tomography (D-OCT) is a relatively new technique that may be used to study the substructures in the retina, in the skin and its... (Review)
Review
Dynamic optical coherence tomography (D-OCT) is a relatively new technique that may be used to study the substructures in the retina, in the skin and its microcirculation. Furthermore, D-OCT is a validated method of imaging blood flow in skin microcirculation. The skin around venous and mixed arterio-venous ulcers was imaged and found to have tortuous vessels assumed to be angiogenic sprouts, and classified as dots, blobs, coils, clumps, lines, and curves. When these images were analyzed and measurements of vessel density were made, it was observed that the prevalence of coils and clumps in wound borders was significantly greater compared with those at wound centers. This reinforced the belief of inward growth of vessels from wound edge toward wound center which, in turn, reposed confidence in following the wound edge to study healing. D-OCT imaging permits the structure and the function of the microcirculation to be imaged, and vessel density measured. This offers a new vista of skin microcirculation and using it, to better understand angiogenesis in chronic wounds.
Topics: Humans; Tomography, Optical Coherence; Skin; Wound Healing; Microcirculation; Veins
PubMed: 33960852
DOI: 10.1177/15347346211017334 -
The Canadian Journal of Cardiology May 2020Large conduit arteries and the microcirculation participate in the mechanisms of elevation of blood pressure (BP). Large vessels play roles predominantly in older... (Review)
Review
Large conduit arteries and the microcirculation participate in the mechanisms of elevation of blood pressure (BP). Large vessels play roles predominantly in older subjects, with stiffening progressing after middle age leading to increases in systolic BP found in most humans with aging. Systolic BP elevation and increased pulsatility penetrate deeper into the distal vasculature, leading to microcirculatory injury, remodelling, and associated endothelial dysfunction. The result is target organ damage in the heart, brain, and kidney. In younger individuals genetically predisposed to high BP, increased salt intake or other exogenous or endogenous risk factors for hypertension, including overweight and excess alcohol intake, lead to enhanced sympathetic activity and vasoconstriction. Enhanced vasoconstrictor responses and myogenic tone become persistent when embedded in an increased extracellular matrix, resulting in remodelling of resistance arteries with a narrowed lumen and increased media-lumen ratio. Stimulation of the renin-angiotensin-aldosterone and endothelin systems and inflammatory and immune activation, to which gut microbiome dysbiosis may contribute as a result of salt intake, also participate in the injury and remodelling of the microcirculation and endothelial dysfunction. Inflammation of perivascular fat and loss of anticontractile factors play roles as well in microvessel remodelling. Exaggerated myogenic tone leads to closure of terminal arterioles, collapse of capillaries and venules, functional rarefaction, and eventually to anatomic rarefaction, compromising tissue perfusion. The remodelling of the microcirculation raises resistance to flow, and accordingly raises BP in a feedback process that over years results in stiffening of conduit arteries and systo-diastolic or predominantly systolic hypertension and, more rarely, predominantly diastolic hypertension. Thus, at different stages of life and the evolution of hypertension, large vessels and the microcirculation interact to contribute to BP elevation.
Topics: Arteries; Blood Pressure; Humans; Hypertension; Microcirculation; Phenotype; Vascular Remodeling; Vascular Stiffness
PubMed: 32389338
DOI: 10.1016/j.cjca.2020.02.003 -
Microvascular Research Jul 2023This study assessed the association between changes in sublingual microcirculation after a spontaneous breathing trial (SBT) and successful extubation. (Clinical Trial)
Clinical Trial
PURPOSE
This study assessed the association between changes in sublingual microcirculation after a spontaneous breathing trial (SBT) and successful extubation.
MATERIALS AND METHODS
Sublingual microcirculation was assessed using an incident dark-field video microscope before and after each SBT and before extubation. Microcirculatory parameters before the SBT, at the end of the SBT, and before extubation were compared between the successful and failed extubation groups.
RESULTS
Forty-seven patients were enrolled and analysed in this study (34 patients in the successful extubation group and 13 patients in the failed extubation group). At the end of the SBT, the weaning parameters did not differ between the two groups. However, the total small vessel density (21.2 [20.4-23.7] versus 24.9 [22.6-26.5] mm/mm), perfused small vessel density (20.6 [18.5-21.8] versus 23.1 [20.9-25] mm/mm), proportion of perfused small vessels (91 [87-96] versus 95 [93-98] %), and microvascular flow index (2.8 [2.7-2.9] versus 2.9 [2.9-3]) were significantly lower in the failed extubation group than in the successful extubation group. The weaning and microcirculatory parameters did not differ significantly between the two groups before the SBT.
CONCLUSIONS
More patients are required to investigate the difference between baseline microcirculation before a successful SBT and the change in microcirculation at the end of the SBT between the successful and failed extubation groups. Better sublingual microcirculatory parameters at the end of SBT and before extubation are associated with successful extubation.
Topics: Humans; Airway Extubation; Microcirculation; Ventilator Weaning
PubMed: 37207721
DOI: 10.1016/j.mvr.2023.104552 -
BMC Anesthesiology Dec 2022With recent advances in robot-assisted techniques, an increasing number of surgeries are being performed with pneumoperitoneum and head-down maneuver (HDM) that may...
BACKGROUND
With recent advances in robot-assisted techniques, an increasing number of surgeries are being performed with pneumoperitoneum and head-down maneuver (HDM) that may affect the cerebral microcirculation. For the first time, this study investigated the direct influence of pneumoperitoneum and HDM on the cerebral microvasculature in rabbits.
METHODS
Adult male rabbits were randomly allocated to the following groups (n = 7 each): control, pneumoperitoneum alone (P), and pneumoperitoneum with HDM (P + HDM) for 120 min. A closed cranial window was installed above the parietal bone to visualize the pial microvasculature. Pial arteriolar diameter and hemodynamic and blood gas parameters were measured during the 140-min observation period. Brain edema was assessed by evaluation of the brain water content at the end of the experiment.
RESULTS
Rabbits in the P and P + HDM groups exhibited a similar degree of immediate pial arteriolar dilation following the initiation of both P and P + HDM (P: 1.11 ± 0.03, p = 0.0044 and P + HDM: 1.07 ± 0.02, p = 0.0004, relative changes from the baseline value by defining the baseline as one). In the P + HDM group, pial arteriole diameter returned to the baseline level following the discontinuation of pneumoperitoneum and HDM (1.05 ± 0.03, p = 0.0906, vs. baseline). In contrast, the pial arterioles remained dilated as compared to the baseline level in the P group after discontinuation of pneumoperitoneum. There were no changes in pial arteriole diameter in the animals in the control group. Heart rate, blood gas parameters, and brain water content were not significantly different between the groups.
CONCLUSION
The pial arterioles dilated immediately after pneumoperitoneum with or without HDM. The pial arterioles remained dilated 20 min after discontinuation of pneumoperitoneum alone but constricted upon discontinuation of pneumoperitoneum plus HDM. Pneumoperitoneum and HDM for 2 h did not cause brain edema.
Topics: Male; Animals; Rabbits; Pneumoperitoneum; Brain Edema; Injections, Intraperitoneal; Microvessels; Microcirculation
PubMed: 36457106
DOI: 10.1186/s12871-022-01911-2 -
VASA. Zeitschrift Fur Gefasskrankheiten Apr 2020The term "microcirculation" refers to the terminal vascular network of the body, which includes arterioles, capillaries, venules as well as initial lymphatic vessels....
The term "microcirculation" refers to the terminal vascular network of the body, which includes arterioles, capillaries, venules as well as initial lymphatic vessels. Additionally, it insinuates to their unique function in thermoregulation, fluid balance, maintenance of cellular exchange, and metabolism. Disturbances of microvascular function were identified to precede macrovascular involvement in the presence of cardiovascular risk factors and is the hallmark of terminal disease stages like critical limb or acral ischemia. Nevertheless, despite its obvious significance in vascular medicine assessment of microvascular function became increasingly neglected in the clinical institutions during the last decades and seems to play a subordinary role in medical education. We therefore provide an overview over relevant and clinically practicable methods to assess microcirculation in vascular medicine with critical estimations of their pros and cons and their perspectives in the future.
Topics: Arterioles; Capillaries; Humans; Microcirculation; Vascular Diseases; Venules
PubMed: 32040388
DOI: 10.1024/0301-1526/a000851 -
Anesthesia and Analgesia Jan 2021
Review
Topics: Critical Care; Hemodynamics; Humans; Microcirculation; Resuscitation
PubMed: 33177325
DOI: 10.1213/ANE.0000000000005272 -
JACC. Cardiovascular Imaging Jul 2022
Topics: Coronary Circulation; Heart; Humans; Microcirculation; Predictive Value of Tests
PubMed: 35798396
DOI: 10.1016/j.jcmg.2022.03.020 -
Cardiology Clinics Feb 2024Ischemic heart disease (IHD) affects more than 20 million adults in the United States. Although classically attributed to atherosclerosis of the epicardial coronary... (Review)
Review
Ischemic heart disease (IHD) affects more than 20 million adults in the United States. Although classically attributed to atherosclerosis of the epicardial coronary arteries, nearly half of patients with stable angina and IHD who undergo invasive coronary angiography do not have obstructive epicardial coronary artery disease. Ischemia with nonobstructive coronary arteries is frequently caused by microvascular angina with underlying coronary microvascular dysfunction (CMD). Greater understanding the pathophysiology, diagnosis, and treatment of CMD holds promise to improve clinical outcomes of patients with ischemic heart disease.
Topics: Adult; Humans; Coronary Artery Disease; Microcirculation; Coronary Angiography; Microvascular Angina; Coronary Vessels; Coronary Circulation
PubMed: 37949533
DOI: 10.1016/j.ccl.2023.07.003