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Medicina (Kaunas, Lithuania) Dec 2023Coronary microvascular dysfunction (CMD) is a clinical entity linked with various risk factors that significantly affect cardiac morbidity and mortality. Hypertension,... (Review)
Review
Coronary microvascular dysfunction (CMD) is a clinical entity linked with various risk factors that significantly affect cardiac morbidity and mortality. Hypertension, one of the most important, causes both functional and structural alterations in the microvasculature, promoting the occurrence and progression of microvascular angina. Endothelial dysfunction and capillary rarefaction play the most significant role in the development of CMD among patients with hypertension. CMD is also related to several hypertension-induced morphological and functional changes in the myocardium in the subclinical and early clinical stages, including left ventricular hypertrophy, interstitial myocardial fibrosis, and diastolic dysfunction. This indicates the fact that CMD, especially if associated with hypertension, is a subclinical marker of end-organ damage and heart failure, particularly that with preserved ejection fraction. This is why it is important to search for microvascular angina in every patient with hypertension and chest pain not associated with obstructive coronary artery disease. Several highly sensitive and specific non-invasive and invasive diagnostic modalities have been developed to evaluate the presence and severity of CMD and also to investigate and guide the treatment of additional complications that can affect further prognosis. This comprehensive review provides insight into the main pathophysiological mechanisms of CMD in hypertensive patients, offering an integrated diagnostic approach as well as an overview of currently available therapeutical modalities.
Topics: Humans; Microvascular Angina; Coronary Circulation; Myocardial Ischemia; Coronary Artery Disease; Hypertension; Cardiomyopathies; Microcirculation; Coronary Vessels
PubMed: 38138252
DOI: 10.3390/medicina59122149 -
Best Practice & Research. Clinical... Dec 2016Over the last decade, there has been an increased interest in the use of goal-directed therapy (GDT) in patients undergoing high-risk surgery, and various haemodynamic... (Review)
Review
Over the last decade, there has been an increased interest in the use of goal-directed therapy (GDT) in patients undergoing high-risk surgery, and various haemodynamic monitoring tools have been developed to guide perioperative care. Both the complexity of the patient and surgical procedure need to be considered when deciding whether GDT will be beneficial. Ensuring optimum tissue perfusion is paramount in the perioperative period and relies on the coherence between both macrovascular and microvascular circulations. Although global haemodynamic parameters may be optimised with the use of GDT, microvascular impairment can still persist. This review will provide an overview of both haemodynamic optimisation and microvascular assessment in the perioperative period.
Topics: Hemodynamics; Humans; Microcirculation; Patient Care Planning; Perioperative Care
PubMed: 27931648
DOI: 10.1016/j.bpa.2016.10.007 -
Best Practice & Research. Clinical... Dec 2016The ultimate goal of fluid therapy is to improve the oxygenation of cells by improving the cardiac output, thus improving microcirculation by optimizing... (Review)
Review
The ultimate goal of fluid therapy is to improve the oxygenation of cells by improving the cardiac output, thus improving microcirculation by optimizing macrocirculation. This haemodynamic coherence is often altered in patients with haemorrhagic shock and sepsis. The loss of haemodynamic coherence is associated with adverse outcomes. It may be influenced by the mechanisms of the underlying disease and properties of different fluids used for resuscitation in these critically ill patients. Monitoring microcirculation and haemodynamic coherence may be an additional tool to predict the response to fluid administration. In addition, microcirculatory analysis may support the clinician in his decision to not administer fluids when microcirculatory blood flow is preserved. In future, the indication, guidance and termination of fluid therapy may be assessed by bedside microvascular analysis in combination with standard haemodynamic monitoring.
Topics: Critical Illness; Fluid Therapy; Hemodynamics; Humans; Microcirculation; Sepsis
PubMed: 27931645
DOI: 10.1016/j.bpa.2016.11.003 -
Revista Brasileira de Terapia Intensiva 2017Parameters related to macrocirculation, such as the mean arterial pressure, central venous pressure, cardiac output, mixed venous saturation and central oxygen... (Review)
Review
Parameters related to macrocirculation, such as the mean arterial pressure, central venous pressure, cardiac output, mixed venous saturation and central oxygen saturation, are commonly used in the hemodynamic assessment of critically ill patients. However, several studies have shown that there is a dissociation between these parameters and the state of microcirculation in this group of patients. Techniques that allow direct viewing of the microcirculation are not completely disseminated, nor are they incorporated into the clinical management of patients in shock. The numerous techniques developed for microcirculation assessment include clinical assessment (e.g., peripheral perfusion index and temperature gradient), laser Doppler flowmetry, tissue oxygen assessment electrodes, videomicroscopy (orthogonal polarization spectral imaging, sidestream dark field imaging or incident dark field illumination) and near infrared spectroscopy. In the near future, the monitoring and optimization of tissue perfusion by direct viewing and microcirculation assessment may become a goal to be achieved in the hemodynamic resuscitation of critically ill patients.
Topics: Critical Illness; Hemodynamics; Humans; Microcirculation; Monitoring, Physiologic; Point-of-Care Systems; Resuscitation
PubMed: 28977264
DOI: 10.5935/0103-507X.20170033 -
Development (Cambridge, England) Aug 2020Blood vessels have long been considered as passive conduits for delivering blood. However, in recent years, cells of the vessel wall (endothelial cells, smooth muscle... (Review)
Review
Blood vessels have long been considered as passive conduits for delivering blood. However, in recent years, cells of the vessel wall (endothelial cells, smooth muscle cells and pericytes) have emerged as active, highly dynamic components that orchestrate crosstalk between the circulation and organs. Encompassing the whole body and being specialized to the needs of distinct organs, it is not surprising that vessel lining cells come in different flavours. There is calibre-specific specialization (arteries, arterioles, capillaries, venules, veins), but also organ-specific heterogeneity in different microvascular beds (continuous, discontinuous, sinusoidal). Recent technical advances in the field of single cell biology have enabled the profiling of thousands of single cells and, hence, have allowed for the molecular dissection of such angiodiversity, yielding a hitherto unparalleled level of spatial and functional resolution. Here, we review how these approaches have contributed to our understanding of angiodiversity.
Topics: Animals; Blood Vessels; Endothelial Cells; Humans; Microcirculation; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle
PubMed: 32792338
DOI: 10.1242/dev.146621 -
Clinical Hemorheology and... 2017The endothelial glycocalyx (EG) lining the endoluminal surface of the capillaries has been proposed as a key component of the microcirculation and a major player in...
The endothelial glycocalyx (EG) lining the endoluminal surface of the capillaries has been proposed as a key component of the microcirculation and a major player in microvascular pathology. Recent advances in the understanding of its physiological role and clinical significance have been made upon the development of methods allowing EG assessment in clinical medicine. Laboratory methods can assess the amount of EG damage by measuring levels of its degradation products (e.g. syndecan-1, heparan sulphate and hyaluronan sulphate), mostly in the plasma, however, their physiological turnover disqualifies them from being the reliable index of EG damage. At the bedside, in vivo video microscopy tools technologies (e.g. Side-stream Dark Field imaging technology) allow indirect assessment of EG thickness in sublingual microcirculation by measuring the penetration extent (called Perfused Boundary Region) of flowing red blood cells into the EG.
Topics: Glycocalyx; Humans; Microcirculation
PubMed: 28922148
DOI: 10.3233/CH-179235 -
Expert Review of Medical Devices Nov 2020Coronary artery disease affecting myocardial perfusion continues to be the leading cause of cardiovascular morbidity and mortality worldwide. While invasive evaluation... (Review)
Review
INTRODUCTION
Coronary artery disease affecting myocardial perfusion continues to be the leading cause of cardiovascular morbidity and mortality worldwide. While invasive evaluation based on coronary angiography and flow measurements still is considered the reference technique for assessing myocardial perfusion, technological evolutions in noninvasive imaging techniques resulted in them playing a more important role in assessing myocardial perfusion influencing therapeutic decision-making and prognostication.
AREAS COVERED
Different imaging modalities are used to evaluate coronary perfusion, including echocardiography, coronary computerized tomography scan, magnetic resonance imaging, and nuclear myocardial perfusion imaging. Through a combination of different techniques, it is possible to describe coronary artery anatomy and the diameter of the epicardial vessels but more recently also of the coronary microcirculation. Quantification of myocardial perfusion is feasible both at baseline and during pharmacological or physiological stress.
EXPERT OPINION
The objective of this state-of-the-art paper is to review the recent evolutions in imaging methods to estimate myocardial perfusion and to discuss the diagnostic strengths and limitations of the different techniques. The new ultrasound technologies and the hybrid approaches seem to be the future is these fields.
Topics: Coronary Angiography; Coronary Vessels; Echocardiography; Fractional Flow Reserve, Myocardial; Humans; Microcirculation; Myocardial Perfusion Imaging
PubMed: 33044100
DOI: 10.1080/17434440.2020.1834844 -
Current Opinion in Critical Care Jun 2016Prone positioning is recommended as a rescue therapy to improve arterial oxygenation in patients with severe acute respiratory distress syndrome (ARDS). In this review,... (Review)
Review
PURPOSE OF REVIEW
Prone positioning is recommended as a rescue therapy to improve arterial oxygenation in patients with severe acute respiratory distress syndrome (ARDS). In this review, we summarize the macro and the microcirculatory effects of prone positioning and emphasize which hemodynamic variables can be monitored when this therapy is applied.
RECENT FINDINGS
Early and prolonged prone positioning sessions significantly decrease the mortality of patients with severe ARDS. Prone positioning increases cardiac preload and decreases right ventricular afterload in patients with ARDS under protective ventilation and maximal lung recruitment. This results in an increase in cardiac output only in patients with preload reserve, emphasizing the important role of preload in the hemodynamic effects of prone positioning. Prone positioning might also exert some effects on regional and/or local blood flows, which mainly result from the increase in intra-abdominal pressure. Because prone positioning does not produce a significant increase in intra-abdominal pressure, it does not exert deleterious effects on the microcirculation of intra-abdominal organs.
SUMMARY
Prone positioning generally exerts beneficial macrocirculatory effects, which can result in increased cardiac output in patients with preload reserve without negatively altering regional circulations.
Topics: Cardiac Output; Hemodynamics; Humans; Microcirculation; Prone Position; Respiratory Distress Syndrome
PubMed: 27101363
DOI: 10.1097/MCC.0000000000000308 -
Shock (Augusta, Ga.) Jan 2018Far from traditional "vital signs," the field of hemodynamic monitoring (HM) is rapidly developing. However, it is also easy to misunderstand hemodynamic therapy as... (Review)
Review
Far from traditional "vital signs," the field of hemodynamic monitoring (HM) is rapidly developing. However, it is also easy to misunderstand hemodynamic therapy as merely HM and some concrete bundles or guidelines for circulation support. Here, we describe the concept of "critical hemodynamic therapy" and clarify the concepts of the "therapeutic target" and "therapeutic endpoint" in clinical practice. Three main targets (oxygen delivery, blood flow, perfusion pressure) for resuscitation are reviewed in critically ill patients according to the sepsis guidelines and hemodynamic consensus. ScvO2 at least 70% has not been recommended as a directed target for initial resuscitation, and the directed target of mean arterial pressure (MAP) still is 65 mmHg. Moreover, the individual MAP target is underlined, and using flow-dependent monitoring to guide fluid infusion is recommended. The flow-directed target for fluid infusion might be a priority, but it remains controversial in resuscitation. The interpretation of these targets is necessary for adequate resuscitation and the correction of tissue hypoxia. The incoherence phenomenon of resuscitation (macrocirculation and microcirculation, tissue perfusion, and cellular oxygen utilization) is gaining increased attention, and early identification of these incoherences might be helpful to reduce the risk of over-resuscitation.
Topics: Arterial Pressure; Hemodynamics; Humans; Microcirculation; Oxygen; Resuscitation
PubMed: 28650929
DOI: 10.1097/SHK.0000000000000929 -
Microcirculation (New York, N.Y. : 1994) Jan 2018Arterial tone is tightly regulated by a variety of potassium (K ) permeable ion channels at the sarcolemma of vascular smooth muscle cells. In particular, several types...
Arterial tone is tightly regulated by a variety of potassium (K ) permeable ion channels at the sarcolemma of vascular smooth muscle cells. In particular, several types of K channels provide a significant hyperpolarizing influence and serve to oppose pressure and agonist-induced membrane depolarization to promote smooth muscle relaxation and augmentation of vascular diameter and blood flow. In recent years, a number of studies have underscored previously unknown roles for particular K subunits, new modes of channel regulation, and distinct cellular functions for these channels during physiological and pathological conditions. In this overview, we highlight articles contained in this Special Topics Issue that focus on the latest, most exciting advancements in the field of K channels in the microcirculation. The collection of articles aims to highlight important new discoveries and controversies in the field of vascular K channels as well as to shed light on key questions that require additional investigation.
Topics: Animals; Humans; Microcirculation; Muscle, Smooth, Vascular; Potassium Channels, Voltage-Gated
PubMed: 29239491
DOI: 10.1111/micc.12435