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Journal of Cardiothoracic and Vascular... Oct 2023Cardiogenic shock causes hypoperfusion within the microcirculation, leading to impaired oxygen delivery, cell death, and progression of multiple organ failure.... (Review)
Review
Cardiogenic shock causes hypoperfusion within the microcirculation, leading to impaired oxygen delivery, cell death, and progression of multiple organ failure. Mechanical circulatory support (MCS) is the last line of treatment for cardiac failure. The goal of MCS is to ensure end-organ perfusion by maintaining perfusion pressure and total blood flow. However, machine-blood interactions and the nonobvious translation of global macrohemodynamics into the microcirculation suggest that the use of MCS may not necessarily be associated with improved capillary flow. With the use of hand-held vital microscopes, it is possible to assess the microcirculation at the bedside. The paucity of literature on the use of microcirculatory assessment suggests the need for an in-depth look into microcirculatory assessment within the context of MCS. The purpose of this review is to discuss the possible interactions between MCS and microcirculation, as well as to describe the research conducted in this area. Regarding sublingual microcirculation, 3 types of MCS will be discussed: venoarterial extracorporeal membrane oxygenation, intra-aortic balloon counterpulsation, and microaxial flow pumps (Impella).
Topics: Humans; Microcirculation; Mouth Floor; Shock, Cardiogenic; Heart Failure; Hemodynamics; Heart-Assist Devices; Intra-Aortic Balloon Pumping
PubMed: 37330330
DOI: 10.1053/j.jvca.2023.05.028 -
Microcirculation (New York, N.Y. : 1994) Apr 2021The past few decades have seen an explosion in the development and use of methods for imaging the human microcirculation during health and disease. The confluence of... (Review)
Review
The past few decades have seen an explosion in the development and use of methods for imaging the human microcirculation during health and disease. The confluence of innovative imaging technologies, affordable computing power, and economies of scale have ushered in a new era of "translational" imaging that permit us to peer into blood vessels of various organs in the human body. These imaging techniques include near-infrared spectroscopy (NIRS), positron emission tomography (PET), and magnetic resonance imaging (MRI) that are sensitive to microvascular-derived signals, as well as computed tomography (CT), optical imaging, and ultrasound (US) imaging that are capable of directly acquiring images at, or close to microvascular spatial resolution. Collectively, these imaging modalities enable us to characterize the morphological and functional changes in a tissue's microcirculation that are known to accompany the initiation and progression of numerous pathologies. Although there have been significant advances for imaging the microcirculation in preclinical models, this review focuses on developments in the assessment of the microcirculation in patients with optical imaging, NIRS, PET, US, MRI, and CT, to name a few. The goal of this review is to serve as a springboard for exploring the burgeoning role of translational imaging technologies for interrogating the structural and functional status of the microcirculation in humans, and highlight the breadth of current clinical applications. Making the human microcirculation "visible" in vivo to clinicians and researchers alike will facilitate bench-to-bedside discoveries and enhance the diagnosis and management of disease.
Topics: Humans; Magnetic Resonance Imaging; Microcirculation; Positron-Emission Tomography; Tomography, X-Ray Computed; Ultrasonography
PubMed: 33524206
DOI: 10.1111/micc.12683 -
Seminars in Nephrology Mar 2015Endothelin (ET) is one of the most potent renal vasoconstrictors. Endothelin plays an essential role in the regulation of renal blood flow, glomerular filtration, sodium... (Review)
Review
Endothelin (ET) is one of the most potent renal vasoconstrictors. Endothelin plays an essential role in the regulation of renal blood flow, glomerular filtration, sodium and water transport, and acid-base balance. ET-1, ET-2, and ET-3 are the three distinct endothelin isoforms comprising the endothelin family. ET-1 is the major physiologically relevant peptide and exerts its biological activity through two G-protein-coupled receptors: ET(A) and ET(B). Both ET(A) and ET(B) are expressed by the renal vasculature. Although ET(A) are expressed mainly by vascular smooth muscle cells, ET(B) are expressed by both renal endothelial and vascular smooth muscle cells. Activation of the endothelin system, or overexpression of downstream endothelin signaling pathways, has been implicated in several pathophysiological conditions including hypertension, acute kidney injury, diabetic nephropathy, and immune nephritis. In this review, we focus on the effects of endothelin on the renal microvasculature, and update recent findings on endothelin in the regulation of renal hemodynamics.
Topics: Endothelins; Glomerular Filtration Rate; Humans; Microcirculation; Renal Circulation
PubMed: 25966346
DOI: 10.1016/j.semnephrol.2015.02.004 -
Revista Portuguesa de Cardiologia Jan 2020
Topics: Blood Viscosity; Coronary Artery Disease; Hemorheology; Humans; Microcirculation; Microvascular Angina
PubMed: 32156447
DOI: 10.1016/j.repc.2020.02.004 -
Biomedicine & Pharmacotherapy =... Aug 2023Coronary microvascular dysfunction (CMD) is a high-risk factor for a variety of cardiovascular events. Due to its complex aetiology and concealability, knowledge of the... (Review)
Review
Coronary microvascular dysfunction (CMD) is a high-risk factor for a variety of cardiovascular events. Due to its complex aetiology and concealability, knowledge of the pathophysiological mechanism of CMD is still limited at present, which greatly restricts its clinical diagnosis and treatment. Studies have shown that CMD is closely related to a variety of cardiovascular diseases, can aggravate the occurrence and development of cardiovascular diseases, and is closely related to a poor prognosis in patients with cardiovascular diseases. Improving coronary microvascular remodelling and increasing myocardial perfusion might be promising strategies for the treatment of cardiovascular diseases. In this paper, the pathogenesis and functional assessment of CMD are reviewed first, along with the relationship of CMD with cardiovascular diseases. Then, the latest strategies for the treatment of CMD and cardiovascular diseases are summarized. Finally, urgent scientific problems in CMD and cardiovascular diseases are highlighted and future research directions are proposed to provide prospective insights for the prevention and treatment of CMD and cardiovascular diseases in the future.
Topics: Humans; Cardiovascular Diseases; Coronary Circulation; Myocardial Ischemia; Microcirculation
PubMed: 37321056
DOI: 10.1016/j.biopha.2023.115011 -
Function (Oxford, England) 2023When exercising humans increase their oxygen uptake (V̇O) 20-fold above rest the numbers are staggering: Each minute the O transport system - lungs, cardiovascular,... (Review)
Review
When exercising humans increase their oxygen uptake (V̇O) 20-fold above rest the numbers are staggering: Each minute the O transport system - lungs, cardiovascular, active muscles - transports and utilizes 161 sextillion (10 ) O molecules. Leg extension exercise increases the quadriceps muscles' blood flow 100-times; transporting 17 sextillion O molecules per kilogram per minute from microcirculation (capillaries) to mitochondria powering their cellular energetics. Within these muscles, the capillary network constitutes a prodigious blood-tissue interface essential to exchange O and carbon dioxide requisite for muscle function. In disease, microcirculatory dysfunction underlies the pathophysiology of heart failure, diabetes, hypertension, pulmonary disease, sepsis, stroke and senile dementia. Effective therapeutic countermeasure design demands knowledge of microvascular/capillary function in health to recognize and combat pathological dysfunction. Dated concepts of skeletal muscle capillary (from the Latin meaning 'hair') function prevail despite rigorous data-supported contemporary models; hindering progress in the field for future and current students, researchers and clinicians. Following closely the 100th anniversary of August Krogh's 1920 Nobel Prize for capillary function this Evidence Review presents an anatomical and physiological development of this dynamic field: Constructing a scientifically defensible platform for our current understanding of microcirculatory physiological function in supporting blood-mitochondrial O transport. New developments include: 1. Putative roles of red blood cell aquaporin and rhesus channels in determining tissue O diffusion. 2. Recent discoveries regarding intramyocyte O transport. 3. Developing a comprehensive capillary functional model for muscle O delivery-to-V̇O matching. 4. Use of kinetics analysis to discriminate control mechanisms from collateral or pathological phenomena.
Topics: Humans; Oxygen; Microcirculation; Capillaries; Oxygen Consumption; Muscle, Skeletal; Mitochondria
PubMed: 37168497
DOI: 10.1093/function/zqad013 -
Disease Markers 2022Bulbar conjunctival microcirculation is a microvascular system distributed in the translucent bulbar conjunctiva near the corneal limbus. Multiple ocular diseases lead... (Review)
Review
Bulbar conjunctival microcirculation is a microvascular system distributed in the translucent bulbar conjunctiva near the corneal limbus. Multiple ocular diseases lead to bulbar conjunctival microcirculation alterations, which means that bulbar conjunctival microcirculation alterations would be potential screening and diagnostic indicators for these ocular diseases. In recent years, with the emergence and application of a variety of noninvasive observation devices for bulbar conjunctiva microcirculation and new image processing technologies, studies that explored the potential of bulbar conjunctival microcirculation alterations in the diagnosis of ocular diseases have been emerging. However, the potential of bulbar conjunctival microcirculation alterations as indicators for ocular diseases has not been exploited to full advantage. The observation devices, image processing methods, and algorithms are not unified. And large-scale research is needed to concrete bulbar conjunctival microcirculation alterations as indicators for ocular diseases. In this paper, we provide an update on the progress of bulbar conjunctival microcirculation alterations in the diagnosis of ocular diseases in recent five years (from January 2017 to March 2022). Relevant ocular diseases include contact lens wearing, dry eye, conjunctival malignant melanoma, conjunctival nevus, and diabetic retinopathy.
Topics: Conjunctiva; Humans; Microcirculation
PubMed: 36072898
DOI: 10.1155/2022/4046809 -
Arteriosclerosis, Thrombosis, and... Jan 2020
Topics: Coronary Stenosis; Humans; Microcirculation; Myocardial Ischemia
PubMed: 31869270
DOI: 10.1161/ATVBAHA.119.313579 -
Journal of Applied Physiology... Jan 2016After shock, persistent oxygen extraction deficit despite the apparent adequate recovery of systemic hemodynamic and oxygen-derived variables has been a source of... (Review)
Review
After shock, persistent oxygen extraction deficit despite the apparent adequate recovery of systemic hemodynamic and oxygen-derived variables has been a source of uncertainty and controversy. Dysfunction of oxygen transport pathways during intensive care underlies the sequelae that lead to organ failure, and the limitations of techniques used to measure tissue oxygenation in vivo have contributed to the lack of progress in this area. Novel techniques have provided detailed quantitative insight into the determinants of microcirculatory and mitochondrial oxygenation. These techniques, which are based on the oxygen-dependent quenching of phosphorescence or delayed luminescence are briefly reviewed. The application of these techniques to animal models of shock and resuscitation revealed the heterogeneous nature of oxygen distributions and the alterations in oxygen distribution in the microcirculation and in mitochondria. These studies identified functional shunting in the microcirculation as an underlying cause of oxygen extraction deficit observed in states of shock and resuscitation. The translation of these concepts to the bedside has been enabled by our development and clinical introduction of hand-held microscopy. This tool facilitates the direct observation of the microcirculation and its alterations at the bedside under the conditions of shock and resuscitation. Studies identified loss of coherence between the macrocirculation and the microcirculation, in which resuscitation successfully restored systemic circulation but did not alleviate microcirculatory perfusion alterations. Various mechanisms responsible for these alterations underlie the loss of hemodynamic coherence during unsuccessful resuscitation procedures. Therapeutic resolution of persistent heterogeneous microcirculatory alterations is expected to improve outcomes in critically ill patients.
Topics: Animals; Hemodynamics; Humans; Hypoxia; Microcirculation; Mitochondria; Resuscitation; Sepsis; Shock
PubMed: 26066826
DOI: 10.1152/japplphysiol.00298.2015 -
Journal of Cerebral Blood Flow and... Oct 2023Temporal lobe epilepsy (TLE) is increasingly associated with blood-brain barrier dysfunction and microvascular alterations, yet the pathophysiological link is missing....
Temporal lobe epilepsy (TLE) is increasingly associated with blood-brain barrier dysfunction and microvascular alterations, yet the pathophysiological link is missing. An important barrier function is exerted by the glycocalyx, a gel-like layer coating the endothelium. To explore such associations, we used intraoperative videomicroscopy to quantify glycocalyx and microcirculation properties of the neocortex and hippocampus of 15 patients undergoing resective brain surgery as treatment for drug-resistant TLE, and 15 non-epileptic controls. Fluorescent lectin staining of neocortex and hippocampal tissue was used for blood vessel surface area quantification. Neocortical perfused boundary region, the thickness of the glycocalyx' impaired layer, was higher in patients (2.64 ± 0.52 µm) compared to controls (1.31 ± 0.29 µm), 0.01, indicative of reduced glycocalyx integrity in patients. Moreover, erythrocyte flow velocity analysis revealed an impaired ability of TLE patients to (de-)recruit capillaries in response to changing metabolic demands ( = 0.75, 0.01), indicating failure of neurovascular coupling mechanisms. Blood vessel quantification comparison between intraoperative measurements and resected tissue showed strong correlation ( = 0.94, 0.01). This is the first report on assessment of glycocalyx and microcirculation properties in TLE patients, confirming the pivotal role of cerebrovascular changes. Further assessment of the cerebral microcirculation in relation to epileptogenesis might open avenues for new therapeutic targets for drug-resistant epilepsy.
Topics: Humans; Epilepsy, Temporal Lobe; Glycocalyx; Microcirculation; Blood-Brain Barrier; Capillaries
PubMed: 37231664
DOI: 10.1177/0271678X231179413