Neurovascular and hemodynamic responses to mental stress and exercise in severe COVID-19 survivors.

Previous studies show that COVID-19 survivors have elevated muscle sympathetic nerve activity (MSNA), endothelial dysfunction, and aortic stiffening. However, the neurovascular responses to mental stress and exercise are still unexplored. We hypothesized that COVID-19 survivors, compared with age- and body mass index (BMI)-matched control subjects, exhibit abnormal neurovascular responses to mental stress and physical exercise. Fifteen severe COVID-19 survivors (aged: 49 ± 2 yr, BMI: 30 ± 1 kg/m2) and 15 well-matched control subjects (aged: 46 ± 3 yr, BMI: 29 ± 1 kg/m2) were studied. MSNA (microneurography), forearm blood flow (FBF), and forearm vascular conductance (FVC, venous occlusion plethysmography), mean arterial pressure (MAP, Finometer), and heart rate (HR, ECG) were measured during a 3-min mental stress (Stroop Color-Word Test) and during a 3-min isometric handgrip exercise (30% of maximal voluntary contraction). During mental stress, MSNA (frequency and incidence) responses were higher in COVID-19 survivors than in controls (P < 0.001), and FBF and FVC responses were attenuated (P < 0.05). MAP was similar between the groups (P > 0.05). In contrast, the MSNA (frequency and incidence) and FBF and FVC responses to handgrip exercise were similar between the groups (P > 0.05). MAP was lower in COVID-19 survivors (P < 0.05). COVID-19 survivors exhibit an exaggerated MSNA and blunted vasodilatory response to mental challenge compared with healthy adults. However, the neurovascular response to handgrip exercise is preserved in COVID-19 survivors. Overall, the abnormal neurovascular control in response to mental stress suggests that COVID-19 survivors may have an increased risk to cardiovascular events during mental challenge.

Sympathetic Neural Overdrive, Aortic Stiffening, Endothelial Dysfunction, and Impaired Exercise Capacity in Severe COVID-19 Survivors: A Mid-Term Study of Cardiovascular Sequelae.

BACKGROUND: COVID-19 has become a dramatic health problem during this century. In addition to high mortality rate, COVID-19 survivors are at increased risk for cardiovascular diseases 1-year after infection. Explanations for these manifestations are still unclear but can involve a constellation of biological alterations. We hypothesized that COVID-19 survivors compared with controls exhibit sympathetic overdrive, vascular dysfunction, cardiac morpho-functional changes, impaired exercise capacity, and increased oxidative stress. METHODS: Nineteen severe COVID-19 survivors and 19 well-matched controls completed the study. Muscle sympathetic nerve activity (microneurography), brachial artery flow-mediated dilation and blood flow (Doppler-Ultrasound), carotid-femoral pulse wave velocity (Complior), cardiac morpho-functional parameters (echocardiography), peak oxygen uptake (cardiopulmonary exercise testing), and oxidative stress were measured ~3 months after hospital discharge. Complementary experiments were conducted on human umbilical vein endothelial cells cultured with plasma samples from subjects. RESULTS: Muscle sympathetic nerve activity and carotid-femoral pulse wave velocity were greater and brachial artery flow-mediated dilation, brachial artery blood flow, E/e' ratio, and peak oxygen uptake were lower in COVID-19 survivors than in controls. COVID-19 survivors had lower circulating antioxidant markers compared with controls, but there were no differences in plasma-treated human umbilical vein endothelial cells nitric oxide production and reactive oxygen species bioactivity. Diminished peak oxygen uptake was associated with sympathetic overdrive, vascular dysfunction, and reduced diastolic function in COVID-19 survivors. CONCLUSIONS: Our study revealed that COVID-19 survivors have sympathetic overactivation, vascular dysfunction, cardiac morpho-functional changes, and reduced exercise capacity. These findings indicate the need for further investigation to determine whether these manifestations are persistent longer-term and their impact on the cardiovascular health of COVID-19 survivors.

Effects of Postprandial Lipemia Combined With Disturbed Blood Flow on the Flow-Mediated Dilation, Oxidative Stress, and Endothelial Microvesicles in Healthy Subjects.

Aims: Both postprandial lipemia (PPL) and disturbed blood flow (DBF) induce endothelial dysfunction. However, the interactive effect of these stimuli on endothelial function is currently unknown. In the present study, we tested whether PPL plus DBF causes a greater reduction in flow-mediated dilation (FMD) than PPL and if this response is associated with elevations in oxidative stress and endothelial microvesicles (EMVs). Methods: Eighteen individuals (aged 28 ± 1yrs, 3 females, and BMI 24.43 ± 0.8kg/m2) randomly underwent two experimental sessions: PPL and PPL plus DBF. FMD and venous blood samples were obtained at baseline and 30, 70, and 110 min after stimulation. PPL was induced by fat overload via mozzarella pizza ingestion and DBF by forearm cuff inflation to 75 mm Hg per 30 min. Lipidic profile, oxidative stress (thiobarbituric acid reactive substances, TBARS; ferric reducing/antioxidant power, FRAP; hydrogen peroxide, H2O2) and EMVs were measured in blood samples. Results: Hypertriglyceridemia was observed in both sessions. Retrograde shear rate and oscillatory index responses were significantly higher in the PPL plus DBF compared with PPL. PPL plus DBF evoked a greater reduction in FMD than did PPL and EMVs, NADPH oxidase, and H2O2 similarly increased in both sessions, but TBARS and FRAP did not change. Conclusion: These data indicate that the association of PPL plus DBF additively impairs endothelium-dependent function in 110 min after stimulus in healthy individuals, despite a similar increase in oxidative stress and EMVs. Further studies are needed to understand the mechanisms associated with the induced-endothelial dysfunction by association of PPL and DBF.