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Source: Frontiers in Physiology
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Total 282 results found since Jan 2013.
Orthostatic Resiliency During Successive Hypoxic, Hypoxic Orthostatic Challenge: Successful vs. Unsuccessful Cardiovascular and Oxygenation Strategies
Discussion: Maintaining OR during SHHOC is reliant upon greater BMI, body weight, longer RRI, and lower HR at baseline, while increasing CI and SVI, minimizing peripheral 02 utilization and decreasing SVRI during hypoxia. During hypoxic LBNP, the ability to remain OR is dependent upon maintaining SAP, via CI increases rather than SVRI. Cerebral oxygenation parameters, beyond 02Hbc during P1 did not differ between groups, suggesting that the during acute hypoxia, an increase in cerebral 02 consumption, coupled with increased peripheral 02 utilization does seem to play a role in OI risk during SHHOC. However, cardiovascular ...
Source: Frontiers in Physiology - October 27, 2021 Category: Physiology Source Type: research
Development of a Collagen Fibre Remodelling Rupture Risk Metric for Potentially Vulnerable Carotid Artery Atherosclerotic Plaques
This study provides critical insights into the collagen fibre patterns required in carotid artery and plaque tissue to maintain plaque stability.
Source: Frontiers in Physiology - October 29, 2021 Category: Physiology Source Type: research
Effects of Cold Decompression on Hemodynamic Function and Decompression Sickness Risk in a Dry Diving Rat Model
Conclusion: During decompression, cardiac output (CO), and stroke volume (SV) decreased equally in cold rats and controls. CO and SV were temporarily re-established at the surface, before falling again in the cold rats. There was no difference in post-dive venous bubble grades. However, as the post-dive fall in CO and SV could be a sign of gas emboli obstructing the pulmonary circulation, we cannot conclude whether the DCS risk was increased. More sensitive bubble detection methods are needed to elucidate this point.
Source: Frontiers in Physiology - November 3, 2021 Category: Physiology Source Type: research
Virchow ’s Triad and the Role of Thrombosis in COVID-Related Stroke
In December 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as a virally transmitted disease. Three months later, SARS-CoV-2 became one of the largest pandemics in recent times, causing more than 235 million cases globally, and accounting for at least 4.8 million deaths to date. SARS-COV-2 infection was initially classified as a respiratory tract infection, but later was recognized as a multisystemic disease compromising gastrointestinal, hematological, cardiac, and neurological systems. With this Review, we aim to describe the epidemiology, risk factors, mechanisms, and management of cere...
Source: Frontiers in Physiology - November 10, 2021 Category: Physiology Source Type: research
Advances in Cardiac Pacing: Arrhythmia Prediction, Prevention and Control Strategies
Cardiac arrhythmias constitute a tremendous burden on healthcare and are the leading cause of mortality worldwide. An alarming number of people have been reported to manifest sudden cardiac death as the first symptom of cardiac arrhythmias, accounting for about 20% of all deaths annually. Furthermore, patients prone to atrial tachyarrhythmias such as atrial flutter and fibrillation often have associated comorbidities including hypertension, ischemic heart disease, valvular cardiomyopathy and increased risk of stroke. Technological advances in electrical stimulation and sensing modalities have led to the proliferation of me...
Source: Frontiers in Physiology - December 2, 2021 Category: Physiology Source Type: research
Closed-Loop Multiscale Computational Model of Human Blood Circulation. Applications to Ballistocardiography
Cardiac mechanical activity leads to periodic changes in the distribution of blood throughout the body, which causes micro-oscillations of the body’s center of mass and can be measured by ballistocardiography (BCG). However, many of the BCG findings are based on parameters whose origins are poorly understood. Here, we generate simulated multidimensional BCG signals based on a more exhaustive and accurate computational model of blood circulation than previous attempts. This model consists in a closed loop 0D-1D multiscale representation of the human blood circulation. The 0D elements include the cardiac chambers, cardiac ...
Source: Frontiers in Physiology - December 9, 2021 Category: Physiology Source Type: research
Central Hypovolemia Detection During Environmental Stress —A Role for Artificial Intelligence?
The first step to exercise is preceded by the required assumption of the upright body position, which itself involves physical activity. The gravitational displacement of blood from the chest to the lower parts of the body elicits a fall in central blood volume (CBV), which corresponds to the fraction of thoracic blood volume directly available to the left ventricle. The reduction in CBV and stroke volume (SV) in response to postural stress, post-exercise, or to blood loss results in reduced left ventricular filling, which may manifest as orthostatic intolerance. When termination of exercise removes the leg muscle pump fun...
Source: Frontiers in Physiology - December 15, 2021 Category: Physiology Source Type: research
Hypoxic Regulation of the Large-Conductance, Calcium and Voltage-Activated Potassium Channel, BK
Hypoxia is a condition characterized by a reduction of cellular oxygen levels derived from alterations in oxygen balance. Hypoxic events trigger changes in cell-signaling cascades, oxidative stress, activation of pro-inflammatory molecules, and growth factors, influencing the activity of various ion channel families and leading to diverse cardiovascular diseases such as myocardial infarction, ischemic stroke, and hypertension. The large-conductance, calcium and voltage-activated potassium channel (BK) has a central role in the mechanism of oxygen (O2) sensing and its activity has been related to the hypoxic response. BK ch...
Source: Frontiers in Physiology - December 22, 2021 Category: Physiology Source Type: research
Post-exercise Hypotension in Patients With Coronary Artery Disease
Conclusion: These findings indicate that in coronary artery patients, the recovery phase after exercise is characterized by PEH which is mediated mainly by a generalized peripheral vasodilation and appears to influence BP behavior throughout the daily life. Finally, the cardiac component of the arterial baroreflex seems to contribute indirectly to BP reduction occurring after exercise.
Source: Frontiers in Physiology - December 22, 2021 Category: Physiology Source Type: research
Reversed Apico-Basal Myocardial Relaxation Sequence During Exercise in Long QT Syndrome Mutations Carriers With History of Previous Cardiac Events
ConclusionLQTS patients show reversed longitudinal relaxation sequence, which worsens with exercise, particularly in those with previous cardiac events.
Source: Frontiers in Physiology - February 7, 2022 Category: Physiology Source Type: research
Cardiovascular Response to Posture Changes: Multiscale Modeling and in vivo Validation During Head-Up Tilt
In spite of cardiovascular system (CVS) response to posture changes have been widely studied, a number of mechanisms and their interplay in regulating central blood pressure and organs perfusion upon orthostatic stress are not yet clear. We propose a novel multiscale 1D-0D mathematical model of the human CVS to investigate the effects of passive (i.e., through head-up tilt without muscular intervention) posture changes. The model includes the main short-term regulation mechanisms and is carefully validated against literature data and in vivo measures here carried out. The model is used to study the transient and steady-sta...
Source: Frontiers in Physiology - February 17, 2022 Category: Physiology Source Type: research
mt tRFs, New Players in MELAS Disease
MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) is an OXPHOS disease mostly caused by the m.3243A>G mutation in the mitochondrial tRNALeu(UUR) gene. Recently, we have shown that the mutation significantly changes the expression pattern of several mitochondrial tRNA-derived small RNAs (mt tsRNAs or mt tRFs) in a cybrid model of MELAS and in fibroblasts from MELAS patients versus control cells. Among them are those derived from mt tRNA LeuUUR containing or not the m.3243A>G mutation (mt 5′-tRF LeuUUR-m.3243A>G and mt 5′-tRF LeuUUR), whose expression levels are, respectively, in...
Source: Frontiers in Physiology - February 22, 2022 Category: Physiology Source Type: research
On the Impact of Left Upper Lobectomy on the Left Atrial Hemodynamics
The left atrium (LA) functions to transport oxygenated blood from the pulmonary veins (PVs) to the left ventricle (LV). LA hemodynamics has received much attention because thrombosis in the LA in pathological states, such as atrial fibrillation, is a major factor leading to thromboembolic stroke. In the last 5 years, multiple cohort studies have revealed that left upper lobectomy (LUL) with PV resection risks thrombus formation in the PV stump even in the normal LA without a history of cardiac disease; the causal mechanism is, however, an open question. The present study investigated the potential effect of an LUL on LA he...
Source: Frontiers in Physiology - February 24, 2022 Category: Physiology Source Type: research
Muscle Fatigue and Swimming Efficiency in Behind and Lateral Drafting
Drafting in swimming is a tactic in which an athlete (drafter) swims in the wave of another athlete (leader). Our aim was to compare the effects of this tactic on the drafter, as far as muscle fatigue, muscle activity, and swimming efficiency are concerned. Fifteen drafters performed three 200 m front crawl trials at a controlled submaximal pace in three configurations: Behind Drafting (BD), Lateral Drafting (LD), and Free Swimming (FS). Muscle fatigue, muscle activity, and swimming efficiency were obtained by surface electromyography (EMG) and video analysis from flexor carpi radialis, triceps brachii, latissimus dorsi,...
Source: Frontiers in Physiology - March 3, 2022 Category: Physiology Source Type: research
Differences in Cardiac Output and Aerobic Capacity Between Sexes Are Explained by Blood Volume and Oxygen Carrying Capacity
In conclusion, sex differences in cardiac output and aerobic capacity are not present in experimental conditions matching BV and O2 carrying capacity between healthy young women and men.
Source: Frontiers in Physiology - March 17, 2022 Category: Physiology Source Type: research
