Cardiovascular Hemodynamic Changes Research Articles

Normobaric hypoxia and exercise training effects on cardiac biomarkers, left ventricular function and aerobic performance in patients after myocardial infarction

Abstract Background Chronic total occlusion (CTO) has a negative impact on the left ventricle function and long-term prognosis of the patients after myocardial infarction. Scientific evidence suggests that some patients with CTO develop collateral arteries which provide an alternative source of blood supply to myocardium and can help to preserve myocardial function. One of the factors influencing the formation of collateral circulation is hypoxia, which induces angiogenesis and arteriogenesis. Physical activity is the most effective stimulus for adaptive changes in cardiovascular hemodynamics. However, the use of hypoxia and endurance exercise training on hemodynamic parameters of the heart and angiogenic factors have not been thoroughly studied yet. The aim of the present study was to examine the effect of endurance training under normobaric hypoxia on cardiac-specific troponin T (cTnT), creatinine kinase-myocardial band (CK-MB), heart-type fatty acid binding protein (H-FABP), vascular endothelial growth factor (VEGF), cytokines and cardiovascular function in patients after myocardial infarction. Methods Patients aged 60.4 ± 4.4 years who had undergone angioplasty with stent implantation participated in the study. Due to high risk of the occurrence of side effects cause by normobaric hypoxia only patients with stable coronary diseases (participants of the second stage of cardiac rehabilitation program) were included. The training program included 3 weeks of endurance training in normobaric hypoxia (HypTr) corresponding to an altitude of 2000 m above the sea level (FiO2 = 15.0%; (HYP-123 Hypoxic Generator, LOWOXYGEN Technology GmbH, Germany). The training regimen comprised 5 sessions/week with 5 min of warm-up, 30 min of interval training (intensity 80% of HRpeak) and 5 min of cooling down. Spiroergometry (CORTEX METAMAX 3B analyzer ) was performed using the cardiopulmonary test Electrocardiography and cardiac biomarkers were evaluated before and after the three weeks of the training programme. Results An increase in average distance covered (622.7 ± 119.0 vs. 687.0 ± 126.7 m, p<0.01) and the test duration (10.4 ± 1.0 vs. 11.0 ± 1.7 m, p<0.05) were observed in response to exercise training in hypoxia. CK-MB (p<0.05) and cTnT (p<0.05) levels were lower post-training compared to the pre-training (p < 0.05). Training in hypoxia had a significant effect on hemoglobin (F=14.7 p<0.001), TNF β (F = 8.2 p<0.01) and VEGF (F = 7.4 p<0.1) levels. Left ventricular (LV) function was altered post-training and the alteration was characterized by favorable changes in end-diastolic and end-systolic dimensions and LV ejection fraction (p<0.05). Conclusions Exercise training in normobaric hypoxia had a significant positive effect on the left ventricular function and concentration of the specific cardiac biomarkers, therefore it may play a crucial role in the cardiovascular adaptive mechanisms in patients after myocardial infarction.

Blood flow restriction training activates the muscle metaboreflex during low-intensity sustained exercise.

Blood flow restriction training (BFRT) employs partial vascular occlusion of exercising muscle and has been shown to increase muscle performance while using reduced workload and training time. Numerous studies have demonstrated that BFRT increases muscle hypertrophy, mitochondrial function, and beneficial vascular adaptations. However, changes in cardiovascular hemodynamics during the exercise protocol remain unknown, as most studies measured blood pressure before the onset and after the cessation of exercise. With reduced perfusion to the exercising muscle during BFRT, the resultant accumulation of metabolites within the ischemic muscle could potentially trigger a large reflex increase in blood pressure, termed the muscle metaboreflex. At low workloads, this pressor response occurs primarily via increases in cardiac output. However, when increases in cardiac output are limited (e.g., heart failure or during severe exercise), the reflex shifts to peripheral vasoconstriction as the primary mechanism to increase blood pressure, potentially increasing the risk of a cardiovascular event. Using our chronically instrumented conscious canine model, we utilized a 60% reduction in femoral blood pressure applied to the hindlimbs during steady-state treadmill exercise (3.2 km/h) to reproduce the ischemic environment observed during BFRT. We observed significant increases in heart rate (+19 ± 3 beats/min), stroke volume (+2.52 ± 1.2 mL), cardiac output (+1.21 ± 0.2 L/min), mean arterial pressure (+18.2 ± 2.4 mmHg), stroke work (+1.93 ± 0.2 L/mmHg), and nonischemic vascular conductance (+3.62 ± 1.7 mL/mmHg), indicating activation of the muscle metaboreflex.NEW & NOTEWORTHY Blood flow restriction training (BFRT) increases muscle mass, strength, and endurance. There has been minimal consideration of the reflex cardiovascular responses that could be elicited during BFRT sessions. We showed that during low-intensity exercise BFRT may trigger large reflex increases in blood pressure and sympathetic activity due to muscle metaboreflex activation. Thus, we urge caution when employing BFRT, especially in patients in whom exaggerated cardiovascular responses may occur that could cause sudden, adverse cardiovascular events.

Hypoxia-Evoked Spinal Adenosine Kinetics in Rats with Chronic Spinal Cord Injury

Therapeutic acute intermittent hypoxia (tAIH) is emerging as a simple and effective means of improving motor function after spinal cord injury (SCI) and ALS. For example, daily AIH applied one-week after C2 spinal hemisection (C2Hx) improves breathing in rats. Unfortunately, studies using the same protocol with chronic cSCI (>8 weeks) report less robust recovery, except when the rats are pretreated with an adenosine 2A receptor antagonist. Pro-inflammatory conditions, such as those experienced after SCI, increase CNS extracellular adenosine concentrations. Guided by increased understanding of adenosinergic signaling mechanisms constraining AIH-induced phrenic motor plasticity, we aimed to determine real-time in vivo dynamics of extracellular adenosine in response to hypoxia in the ventral cervical spinal cord in intact and spinally injured rats. We used enzyme-immobilized micro-biosensors for real time enzymatic detection of extracellular adenosine in the mid-cervical spinal cord of intact rats and rats with chronic C2Hx (>8 weeks post-injury) during 5-min 13% O2, 1-min 9% O2 and 1-min 9% O2 + 4% CO2. Extracellular adenosine exhibits rapid kinetics with a time-constant of seconds, regardless of condition. Rats with chronic C2Hx were classified post hoc into 2 groups: normotensive (systolic blood pressure > 120 mmHg) and hypotensive (systolic blood pressure < 120 mmHg). Normotensive C2Hx rats had baseline adenosine levels comparable to intact rats; hypoxia-induced increases in adenosine were slightly reduced versus intact rats. On the other hand, hypotensive C2Hx rats had elevated baseline adenosine levels and almost completely diminished hypoxia-evoked adenosine increases. Hypercapnic hypoxia had minimal impact on adenosine levels during exposures, but lowered adenosine following each hypercapnic hypoxic episode. These results suggest that changes in cardiovascular hemodynamics in chronic SCI rats can alter basal tissue adenosine levels, possibly undermining the therapeutic efficacy of tAIH in the condition of chronic SCI. Further, hypercapnic hypoxia appears to minimize inhibitory effects of adenosine on tAIH-induced phrenic/diaphragm motor plasticity. Supported by: NIH HL147554, HL148030 & OT2OD023854 and the University of Florida McKnight Brain Institute This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Super-resolution 4D flow MRI to quantify aortic regurgitation using computational fluid dynamics and deep learning

Changes in cardiovascular hemodynamics are closely related to the development of aortic regurgitation (AR), a type of valvular heart disease. Metrics derived from blood flows are used to indicate AR onset and evaluate its severity. These metrics can be non-invasively obtained using four-dimensional (4D) flow magnetic resonance imaging (MRI), where accuracy is primarily dependent on spatial resolution. However, insufficient resolution often results from limitations in 4D flow MRI and complex aortic regurgitation hemodynamics. To address this, computational fluid dynamics simulations were transformed into synthetic 4D flow MRI data and used to train a variety of neural networks. These networks generated super-resolution, full-field phase images with an upsample factor of 4. Results showed decreased velocity error, high structural similarity scores, and improved learning capabilities from previous work. Further validation was performed on two sets of in vivo 4D flow MRI data and demonstrated success in de-noising flow images. This approach presents an opportunity to comprehensively analyse AR hemodynamics in a non-invasive manner.

Computational modeling of orthostatic intolerance for travel to Mars

Astronauts in a microgravity environment will experience significant changes in their cardiopulmonary system. Up until now, there has always been the reassurance that they have real-time contact with experts on Earth. Mars crew however will have gaps in their communication of 20 min or more. In silico experiments are therefore needed to assess fitness to fly for those on future space flights to Mars. In this study, we present an open-source controlled lumped mathematical model of the cardiopulmonary system that is able simulate the short-term adaptations of key hemodynamic parameters to an active stand test after being exposed to microgravity. The presented model is capable of adequately simulating key cardiovascular hemodynamic changes—over a short time frame—during a stand test after prolonged spaceflight under different gravitational conditions and fluid loading conditions. This model can form the basis for further exploration of the ability of the human cardiovascular system to withstand long-duration space flight and life on Mars.

Safety of sugammadex for reversal of neuromuscular block: A postmarketing study based on the World Health Organization pharmacovigilance database.

Residual neuromuscular blockade is a common complication after general anaesthesia. Sugammadex can reverse the action of aminosteroid neuromuscular blockers. This study aimed to explore sugammadex safety issues in the real world and determine the spectrum of adverse reactions. All sugammadex-related adverse events reported in VigiBase between 2010 and 2019 were classified by group queries according to the Medical Dictionary for Regulatory Activities. A disproportionality analysis of data was performed using the information component (IC); positive IC values were deemed significant. Overall, 16 219 410 adverse events were reported and 2032 were associated with sugammadex. The frequent reactions were recurrence of neuromuscular blockade (n = 54, IC 6.74, IC025 6.33), laryngospasm (n = 53, IC 6.05, IC025 5.64), bronchospasm (n = 119, IC 5.63, IC025 5.36) and bradycardia (n = 169, IC 5.13, IC025 4.90). Fatal cases were more likely among patients with cardiac disorders, especially those over 65 years. In addition, the common adverse drug reactions (ADRs) differed between different age groups (P < .01). ADRs were higher in the 0-17 years age group than in other age groups. The onset time of common ADRs was typically within 1day and 68.9% occurred within half an hour after sugammadex administration. Anaesthesiologists should carefully monitor the anaesthesia recovery period to correct the ADRs caused by sugammadex and recommend monitoring neuromuscular function throughout the anaesthesia process. Sugammadex should be used carefully in patients with cardiovascular diseases, and electrocardiography and hemodynamic changes should be monitored after medication.

Exaggerated pressor and sympathetic nerve responses during spontaneously‐occurring motor activity in decerebrate spontaneously hypertensive rats

Stimulation of the mesencephalic locomotor region (a putative component of the central command pathway) has been shown to elicit exaggerated pressor and sympathetic nerve responses in decerebrate spontaneously hypertensive rats (SHR) as compared to normotensive Wister-Kyoto rats. This finding suggests that central command activity and/or influence on caudal vasomotor centers may be augmented in hypertension. In the normotensive decerebrate rat model, mean arterial pressure (MAP) and sympathetic nerve activity are known to increase during intermittent bouts of spontaneous motor activity. Moreover, evidence suggests that simulated central command influences at the brainstem may evoke these pressor and sympathetic responses. However, it remains unknown whether these spontaneous changes in cardiovascular hemodynamics are altered with the pathogenesis of hypertension. Based on this background, we hypothesized that the pressor and sympathetic nerve responses during spontaneously-occurring motor activity are exaggerated in hypertension. MAP, renal sympathetic nerve activity (RSNA), and tibial nerve discharge were measured in decerebrate SHR (n=8) and normotensive Sprague-Dawley (SD) rats (n=6). The present study aimed to compare resting baroreflex changes in RSNA (in response to pharmacological alterations in MAP) and central command-evoked responses in MAP and RSNA during spontaneously-occurring motor activity between SHR and normotensive SD. Results demonstrated that the baroreflex-mediated RSNA response was not different between SHR and SD. In both SHR and SD, abrupt, spontaneous increases in RSNA were synchronized with tibial motor discharge and followed by a rise in MAP. These potentially central command-evoked increases in MAP and RSNA were greater in SHR than SD. Phenylephrine-induced elevations in MAP did not suppress the central command-induced RSNA increase in SHR, whereas it abolished the rise in RSNA in SD. Taken together, it is concluded that 1) the arterial baroreflex is operative during resting conditions in SHR as well as SD; 2) the pressor and sympathetic nerve responses during spontaneously-occurring motor activity are exaggerated in hypertensive rats; and 3) exaggerated RSNA responses in SHR may be induced along a central command pathway independent of the arterial baroreflex and/or as a result of central command-induced inhibition of the arterial baroreflex itself.

Chapter 28 - Hemodynamics in acute stroke: Cerebral and cardiac complications

Hemodynamics is the study of blood flow, where parameters have been defined to quantify blood flow and the relationship with systemic circulatory changes. Understanding these perfusion parameters, the relationship between different blood flow variables and the implications for ischemic injury are outlined in the ensuing discussion. This chapter focuses on the hemodynamic changes that occur in ischemic stroke, and their contribution to ischemic stroke pathophysiology. We discuss the interaction between cardiovascular response and hemodynamic changes in stroke. Studying hemodynamic changes has a key role in stroke prevention, therapeutic implications and prognostic importance in acute ischemic stroke: preexisting hemodynamic and autoregulatory impairments predict the occurrence of stroke. Hemodynamic failure predisposes to the formation of thromboemboli and accelerates infarction due to impairing compensatory mechanisms. In ischemic stroke involving occlusion of a large vessel, persistent collateral circulation leads to preservation of ischemic penumbra and therefore justifying endovascular thrombectomy. Following thrombectomy, impaired autoregulation may lead to reperfusion injury and hemorrhage.

Exercise and caloric restriction improve cardiovascular and erectile function in rats with metabolic syndrome.

The aim of this study is to examine the possible benefits of exercise and caloric restriction (CR) on cardiovascular hemodynamics, erectile function, and antioxidant system in metabolic syndrome (MS). Sixty male Spraque-Dawley rats were divided into five groups; control, MS, MS + CR, MS + exercise (EXC), and MS + CR + EXC. To induce MS, 10% fructose solution was applied for 3 months. Thereafter, in CR groups calorie was restricted 40% and in EXC groups swimming was performed for 6 weeks. Body weight, blood glucose, and blood pressure (BP) levels were measured before and after MS induction and at the end of the experiment. After decapitation, tumor necrosis factor (TNF)-α, adiponectin (ADP), and plasminogen activator inhibitor (PAI)-1 levels were investigated in blood, oxidative stress parameters were examined in heart, aorta, and corpus cavernosum (CC) tissues. Isometric contraction in isolated tissue bath was studied in aorta and CC tissues. Animals subjected to exercise and CR had decreased BP and blood glucose levels. Impaired contraction-relaxation responses in MS group were improved with exercise and CR. MS-induced increase in TNF-α, PAI-1, malondialdehyde (MDA), and decrease in ADP, glutathione (GSH), and superoxide dismutase (SOD) were normalized with exercise and CR. Exercise and CR may be beneficial against changes in cardiovascular hemodynamics caused by MS.

Vascular Aging and Central Aortic Blood Pressure: From Pathophysiology to Treatment.

Large conductive arteries undergo to structural modifications by aging, eventually leading to increased vascular stiffness. As consequence, cardiovascular hemodynamic changes by increasing central blood pressure which may be also associated to the remodelling of peripheral resistance arteries that contribute to increase further the central vascular stiffness and blood pressure. These modifications resemble the ones that has been shown in essential hypertension, thus a condition of "early vascular aging" has been described in hypertensive patients. Since hypertension related target organs, particularly the heart, face aortic blood pressure rather than brachial blood pressure, it has been recently suggested that central blood pressure and other parameters of large arteries' stiffness, including pulse wave velocity (PWV), may better correlate with subclinical organ damage and might be useful to assess the cardiovascular risk of patients beyond the traditional risk factors. Different devices have been validated to measure central blood pressure and PWV, and are currently available for clinical use. The increasing application of these tools in clinical practice could improve the management of hypertensive patients by better defining the cardiovascular risk and address the antihypertensive therapy.

COMPARISON OF VARIOUS TECHNIQUES FOR MANAGEMENT OF FISTULA-IN-ANO

INTRODUCTION: Cirrhosis is a condition that is defined histopathologically and has a variety of clinical manifestations and complications, some of which can be life-threatening. Patients with cirrhosis and portal hypertension exhibit characteristic cardiovascular & pulmonary hemodynamic changes. The cardiovascular complications include systolic dysfunction, diastolic dysfunction & electrochemical abnormalities like prolonged QT interval in Electrocardiogram (ECG), and Respiratory complications include Consolidation, Pleural Effusion & Pulmonary Arterial Hypertension, which may be due to Hepatopulmonary or Portopulmonary syndrome STUDY DESIGN: A two-year prospective observational study was conducted from July,2014 to June 2016 AIM: To study the different cardiac and pulmonary complications in the patients of Liver Cirrhosis. MATERIALS & METHODS: A two-year prospective observational study was conducted from July,2014 to June 2016 at a tertiary care hospital in Ahmedabad, Gujarat, India, including 30 patients (>12 years old), who were known cases of cirrhosis of liver as well as those newly diagnosed with it, with cardiopulmonary complications, developed after liver cirrhosis, in the absence of other etiological factors. Clinical profile with laboratory studies and diagnostic tests were studied. RESULTS: This study showed that cardiopulmonary complications in cirrhotic patients are more frequently seen in males than females, which commonly manifest during third & fourth decade. Dyspnoea is the most common symptom seen in the study. Among the pulmonary complications, Pneumonia & Hydrothorax are more common compared to hepatopulmonary & portopulmonary syndromes, and among cardiac complications, Diastolic dysfunction is a major complication in such patients, which increases with increasing severity of cirrhosis, as indicated by CP score. CONCLUSION: Among these patients, Cardiac and pulmonary complications have nearly the same incidences.

Poremećaji kardiovaskularne funkcije i ehokardiografskih parametara srca u manifestnom i subkliničkom hipotireoidizmu

Decreased thyroid function leads to changes in cardiovascular hemodynamics, changes in myocardial contractility and accelerated atherosclerosis. Peripheral circulation in hypothyroidism is characterized by increased vascular resistance and prolonged circulatory duration. Endothelial dysfunction that occurs in hypothyroid patients predisposes to the development of atherosclerosis, and increases arterial stiffness. The influence of subclinical hypothyroidism on the cardiovascular system is manifested through systolic and diastolic cardiac function, myocardial anatomy and effort endurance. Subclinical hypothyroidism in acute myocardial infarction increases cardiac mortality 3.6-fold and 2.3-fold overall mortality. Overt hypothyroidism is characterized by hypercholesterolemia, significantly elevated LDL cholesterol and apolipoprotein B. Subclinical hypothyroidism is associated with a small increase in LDL cholesterol, a decrease in HDL cholesterol, increasing the risk of developing atherosclerosis and coronary artery disease. Isovolumic relaxation time (IVRT) is significantly prolonged in hypothyroid patients, which indicates impaired passive relaxation of the left ventricle. Global right ventricular strain and right ventricular free wall strain are reduced in hypothyroid patients compared to healthy subjects. These changes are completely reversible after the application of thyroid replacement therapy and mostly after 6 months of L-thyroxine administration.

Cardiac & Pulmonary Complications Seen in Liver Cirrhosis-An Observational Study at a Tertiary Care Hospital

INTRODUCTION: Cirrhosis is a condition that is defined histopathologically and has a variety of clinical manifestations and complications, some of which can be life-threatening. Patients with cirrhosis and portal hypertension exhibit characteristic cardiovascular & pulmonary hemodynamic changes. The cardiovascular complications include systolic dysfunction, diastolic dysfunction & electrochemical abnormalities like prolonged QT interval in Electrocardiogram (ECG), and Respiratory complications include Consolidation, Pleural Effusion & Pulmonary Arterial Hypertension, which may be due to Hepatopulmonary or Portopulmonary syndrome STUDY DESIGN: A two-year prospective observational study was conducted from July,2014 to June 2016 AIM: To study the different cardiac and pulmonary complications in the patients of Liver Cirrhosis. MATERIALS & METHODS: A two-year prospective observational study was conducted from July,2014 to June 2016 at a tertiary care hospital in Ahmedabad, Gujarat, India, including 30 patients (>12 years old), who were known cases of cirrhosis of liver as well as those newly diagnosed with it, with cardiopulmonary complications, developed after liver cirrhosis, in the absence of other etiological factors. Clinical profile with laboratory studies and diagnostic tests were studied. RESULTS: This study showed that cardiopulmonary complications in cirrhotic patients are more frequently seen in males than females, which commonly manifest during third & fourth decade. Dyspnoea is the most common symptom seen in the study. Among the pulmonary complications, Pneumonia & Hydrothorax are more common compared to hepatopulmonary & portopulmonary syndromes, and among cardiac complications, Diastolic dysfunction is a major complication in such patients, which increases with increasing severity of cirrhosis, as indicated by CP score. CONCLUSION: Among these patients, Cardiac and pulmonary complications have nearly the same incidences.

Furosemide Pharmacodynamics and Cardiovascular Effects in Hemodialysis Patients

Furosemide is a drug that has not only a renal effect, but also a vascular one, resulting in decreased left atrial and ventricularfilling pressure accompanied by an increase in venous compliance, all of this with significant effects on central cardiac hemodynamics.In dialysis patients, it is still unclear the efficiency of furosemide, a diuretic drug that inhibits the Na+, K+, 2CL� cotransporter in the renal tubular system. Also, furosemide need to be used at much higher doses because of its pharmacokinetic changes in the context of impaired renal clearance.The aim of our study was to investigate whether furosemide induces changes in cardiovascular hemodynamics in end-stage renal disease (ESRD) patients, using standard echocardiography and Tissue Doppler Imaging (TDI).We foundcorrelations between furosemide useand improved cardiac parameters, assessed by multiple echocardiographic variables, and we consider that furosemide has complementary effects in dialysis patients with residual diuresis.

Cardiovascular Hemodynamic Changes After Antenatal Corticosteroids in Growth Restricted and Appropriate for GestationalAge Fetuses.

To investigate hemodynamic effects after antenatal corticosteroids (ACS) administration in appropriate for gestational age (AGA) and early growth restricted (GR) fetuses by measurement of Doppler cardiovascular function parameters. Prospective cohort study. AGA and GR singleton pregnancies receiving ACS for fetal lung maturation between 24 + 0-33 + 6 weeks were enrolled. Feto-placental vascular hemodynamics were studied by: umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, renal artery (RenA) PI. Cardiac function was evaluated by ductus venosus (DV) PI and by echocardiographic parameters: E to A wave ratios (E/A) and mitral and tricuspid annular plane systolic excursion (MAPSE and TAPSE) for diastolic function, left and right myocardial performance index (MPI) for overall (diastolic and systolic) function. A single operator performed all the measurements at 3 different time points (E): E0 before or within 4 hours of ACS administration (baseline examination), E1 24-48 hours after the first dose and E2 7 days after the second dose of ACS. The values were expressed as z-scores. Pairwise comparisons with paired t-test were performed to compare measurements before and after exposure to ACS. 25 AGA and 20 GR fetuses (mean gestational age: 31 + 1 and 30 + 6, respectively) were included in the analysis. In the AGA group ACS administration was associated with a significant reduction in UA PI. In the GR fetuses ACS temporarily (E0-E1) restored UA-end diastolic flow (EDF) in 6 of 9 fetuses with A/R-EDF ("Return of EDF phenomenon") and produced a significant increase (worsening) in right MPI (both in E1-E2 and in E0-E2). ACS administration is associated with UA vasodilation in both AGA and GR fetuses and with an increase in right MPI in the latter group. This suggests a worsening in cardiac function in GR fetuses.

Predicting Cardiovascular Hemodynamics in Cold and Warm Environments at Rest with Skin and Core Temperature

Many occupations require workers to be exposed to extreme heat or cold. During prolonged exposure to extreme environments, the cardiovascular system plays a critical role in thermal homeostasis, by adjusting blood flow in peripheral and central vascular beds. Importantly, exposure to either environment, and the concordant blood‐volume redistribution, increases morbidity and mortality from the additional [and often significant] stress on the cardiovascular system. To gain insight on how to predict cardiovascular stress during exposure to extreme environments at rest, this study attempted to build a regression model to examine the influence of progressive, whole‐body skin and core cooling and heating on cardiovascular hemodynamics. Seventeen participants (12 males, 22.9 ± 3.58 years, 174.2 cm ± 7.85 cm, 12.8 ± 6.20 kg fat mass, and 59.3 ± 9.49 kg fat free mass) wearing shorts and a t‐shirt participated in two laboratory sessions: i) progressive heating (22°C to 40°C); and ii) progressive cooling (22°C to 5°C); each aimed to independently influence skin and core temperatures. Cardiovascular hemodynamics data was collected via thoracic electrical bioimpedance, while metabolic and cardiorespiratory variables were assessed via indirect calorimetry. Mean weighted skin (Tsk) and core (Tc) temperature were measured via portable data loggers and a thermocouple, respectively. Mean weighted skin temperatures ranged from 22.7°C to 37.4°C and Tc ranged from 35.5°C to 37.9°C. A stepwise multiple linear regression analysis was conducted using Tsk, Tc, fat free mass, fat mass, sex and age as predictors for cardiovascular hemodynamics changes under thermal stress. The present model explained 24.4% of changes in stroke volume, 27.9% of heart rate, 15.9% of cardiac output and 49.5% of oxygen consumption. Although changes in Tsk and Tc temperature induced by whole‐body cooling and heating at rest accounted for changes in cardiovascular hemodynamics in the model, a significant portion of the variation remained unexplained. Further research is needed to develop a more accurate model to represent changes in cardiovascular hemodynamics under thermal stress.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A comparative study of cardiovascular autonomic function tests between second trimester pregnant women and non-pregnant women

Background: Normal pregnancy has been documented to be accompanied by marked alteration in maternal circulation during the first and second trimesters. For adapting the cardiovascular hemodynamic changes during normal pregnancy, a well-controlled interaction between the sympathetic and parasympathetic system is very essential, failure of which may result in pregnancy-related complications. Aims and Objectives: To evaluate and compare the cardiovascular autonomic function tests (AFTs) between the second trimester pregnant women and controls. Materials and Methods: A cross‑sectional study was conducted by random selection of 67 s trimester pregnant women and 67 controls in the age group of 19–29 years. The cardiovascular AFTs were carried out. The statistical analysis was done using unpaired t-test. Results: During isometric handgrip exercise, the maximum rise in diastolic blood pressure (DBP), and during cold pressor test, the maximum rise in systolic BP and maximum rise in DBP were significantly less in the second trimester of pregnancy than controls. There was significantly less increase in 30:15 ratio and E: I ratio of the second trimester pregnant women when compared to controls. Conclusion: The cardiovascular autonomic nervous activity was decreased in the second trimester of pregnancy when compared to controls.

Short-Term Changes in Cardiovascular Hemodynamics in Response to Bariatric Surgery and Weight Loss Using the Nexfin® Non-invasive Continuous Monitoring Device: a Pilot Study

Compared to healthy individuals, obese have significantly higher systolic and diastolic blood pressure, mean arterial pressure, heart rate, and cardiac output. The aim of this study was to evaluate cardiovascular hemodynamic changes before and 3months after bariatric surgery. Patients scheduled for bariatric surgery between the 29th of September 2016 and 24th of March 2016 were included and compared with 24 healthy individuals. Hemodynamic measurements were performed preoperatively and 3months after surgery, using the Nexfin® non-invasive continuous hemodynamic monitoring device (Edwards Lifesciences/BMEYE B.V., Amsterdam, the Netherlands). Eighty subjects were included in this study, respectively, 56 obese patients scheduled for bariatric surgery and 24 healthy individuals. Baseline hemodynamic measurements showed significant differences in cardiac output (6.5±1.6 versus 5.7±1.6l/min, p=0.046), mean arterial pressure (107±19 versus 89±11mmHg, p=0.001), systolic (134±24 versus 116±18mmHg, p=0.001) and diastolic blood pressure (89±17 versus 74±10mmHg, p=0.001), and heart rate (87±12 versus 76±14bpm, p=0.02) between obese and healthy subjects. Three months after surgery, significant changes occurred in mean arterial pressure (89±17mmHg, p=0.001), systolic (117±24mmHg, p=0.001) and diastolic blood pressure (71±15mmHg, p=0.001), stroke volume (82.2±22.4ml, p=0.03), and heart rate (79±17bpm, p=0.02) CONCLUSIONS: Three months after bariatric surgery, significant improvements occur in hemodynamic variables except cardiac output and cardiac index, in the patient group.

Diurnal blood pressure parameters in normal tension glaucoma, primary open angle glaucoma, and healthy subjects.

Objective:The pathophysiology of glaucoma is still undisclosed. Cardiovascular hemodynamic changes are hypothesized to contribute to glaucoma. This study aimed to determine the differences in the diurnal blood pressure (BP) of patients with normal tension glaucoma (NTG), primary open angle glaucoma (POAG), and controls without glaucoma.Methods:A total of 129 patients were included in this study. The day–night average systolic and diastolic BPs, the day–night average pulse pressures (PPs), the day–night average heart rates, and the percentage of BP decline at night were obtained from the Holter devices and compared. Study design: Prospective, randomized, case-control study.Results:This study included 43 NTG patients (Group 1), 44 POAG patients (Group 2), and 42 healthy subjects without glaucoma (Group 3). The age (p=0.138) and sex (p=0.216) distributions between the groups were similar. The average day–night PP values of Group 1 were 49.17±9.90 and 46.07±10.84 mm Hg, respectively, while their total average PP was 48.48±9.60, their total average systolic BP was 120.02±12.65, and their night average systolic BP was 111.93±15.87 mm Hg. In Group 2, the average day and night PP values were 54.83±10.35 and 51.73±9.10 mm Hg, respectively, their total average PP was 54.00±9.87, their total average systolic BP was 126.75±11.50, and their night average systolic BP was 119.21±12.38 mm Hg. These differences were statistically significant and the corresponding p values were 0.040, 0.040, 0.037, 0.033, and 0.038.Conclusion:NTG patients have low diurnal BP parameters, which may reduce their optic nerve perfusion and may be responsible for their glaucomatous visual field damage.

Effects of Obesity on Cardiovascular Hemodynamics, Cardiac Morphology, and Ventricular Function.

Obesity produces a variety of hemodynamic alterations that may cause changes in cardiac morphology which predispose to left and right ventricular dysfunction. Various neurohormonal and metabolic alterations commonly associated with obesity may contribute to these abnormalities of cardiac structure and function. These changes in cardiovascular hemodynamics, cardiac morphology, and ventricular function may, in severely obese patients, predispose to heart failure, even in the absence of other forms of heart disease (obesity cardiomyopathy). In normotensive obese patients, cardiac involvement is commonly characterized by elevated cardiac output, low peripheral vascular resistance, and increased left ventricular (LV) end-diastolic pressure. Sleep-disordered breathing may lead to pulmonary arterial hypertension and, in association with left heart failure, may contribute to elevation of right heart pressures. These alterations, in association with various neurohormonal and metabolic abnormalities, may produce LV hypertrophy; impaired LV diastolic function; and less commonly, LV systolic dysfunction. Many of these alterations are reversible with substantial voluntary weight loss.