The connection between heart rate variability (HRV), neurological health, and cognition: A literature review

The heart and brain have bi-directional influences on each other, including autonomic regulation and hemodynamic connections. Heart rate variability (HRV) measures variation in beat-to-beat intervals. New findings about disorganized sinus rhythm (erratic rhythm, quantified as heart rate fragmentation, HRF) are discussed and suggest overestimation of autonomic activities in HRV changes, especially during aging or cardiovascular events. When excluding HRF, HRV is regulated via the central autonomic network (CAN). HRV acts as a proxy of autonomic activity and is associated with executive functions, decision-making, and emotional regulation in our health and wellbeing. Abnormal changes of HRV (e.g., decreased vagal functioning) are observed in various neurological conditions including mild cognitive impairments, dementia, mild traumatic brain injury, migraine, COVID-19, stroke, epilepsy, and psychological conditions (e.g., anxiety, stress, and schizophrenia). Efforts are needed to improve the dynamic and intriguing heart-brain interactions.

The connection between heart rate variability (HRV), neurological health, and cognition: A literature review.

The heart and brain have bi-directional influences on each other, including autonomic regulation and hemodynamic connections. Heart rate variability (HRV) measures variation in beat-to-beat intervals. New findings about disorganized sinus rhythm (erratic rhythm, quantified as heart rate fragmentation, HRF) are discussed and suggest overestimation of autonomic activities in HRV changes, especially during aging or cardiovascular events. When excluding HRF, HRV is regulated via the central autonomic network (CAN). HRV acts as a proxy of autonomic activity and is associated with executive functions, decision-making, and emotional regulation in our health and wellbeing. Abnormal changes of HRV (e.g., decreased vagal functioning) are observed in various neurological conditions including mild cognitive impairments, dementia, mild traumatic brain injury, migraine, COVID-19, stroke, epilepsy, and psychological conditions (e.g., anxiety, stress, and schizophrenia). Efforts are needed to improve the dynamic and intriguing heart-brain interactions.

The Correlation between COVID-19 Hospitalizations and Emergency Medical Services Responses for Time-Sensitive Emergencies during the COVID-19 Pandemic.

OBJECTIVE: COVID-19 has had significant secondary effects on health care systems, including effects on emergency medical services (EMS) responses for time-sensitive emergencies. We evaluated the correlation between COVID-19 hospitalizations and EMS responses for time-sensitive emergencies in a large EMS system. METHODS: This was a retrospective study using data from the Los Angeles County EMS Agency. We abstracted data on EMS encounters for stroke, ST-elevation myocardial infarction (STEMI), out-of-hospital cardiac arrest (OHCA), and trauma from April 5, 2020 to March 6, 2021 and for the same time period in the preceding year. We also abstracted daily hospital admissions and censuses (total and intensive care unit [ICU]) for COVID-19 patients. We designated November 29, 2020 to February 27, 2021 as the period of surge. We calculated Spearman's correlations between the weekly averages of daily hospital admissions and census and EMS responses overall and for stroke, STEMI, OHCA, and trauma. RESULTS: During the study period, there were 70,616 patients admitted for confirmed COVID-19, including 12,467 (17.7%) patients admitted to the ICU. EMS responded to 899,794 calls, including 9,944 (1.1%) responses for stroke, 3,325 (0.4%) for STEMI, 11,207 (1.2%) for OHCA, and 114,846 (12.8%) for trauma. There was a significant correlation between total hospital COVID-19 positive patient admissions and EMS responses for all time-sensitive emergencies, including a positive correlation with stroke (0.41), STEMI (0.37), OHCA (0.78), and overall EMS responses (0.37); and a negative correlation with EMS responses for trauma (-0.48). ICU COVID-19 positive patient admissions also correlated with increases in EMS responses for stroke (0.39), STEMI (0.39), and OHCA (0.81); and decreased for trauma (-0.53). Similar though slightly weaker correlations were found when evaluating inpatient census. During the period of surge, the correlation with overall EMS responses increased substantially (0.88) and was very strong with OHCA (0.95). CONCLUSION: We found significant correlation between COVID-19 hospitalizations and the frequency of EMS responses for time-sensitive emergencies in this regional EMS system. EMS systems should consider the potential effects of this and future pandemics on EMS responses and prepare to meet non-pandemic resource needs during periods of surge, particularly for time-sensitive conditions.

Post-Acute Sequelae of SARS-COVID-2 Syndrome: Just the Beginning.

Viral diseases are some of the most common infections affecting humans. Despite the unpleasant symptoms, most people return to their normal lives without residual symptoms. Following the acute infectious phase of some viruses, however, in some individuals symptoms may linger to the extent they are unable to return to a normal lifestyle. Following coronavirus disease 2019 infection, significant numbers of patients continued to have symptoms that persisted for months after hospital discharge. Symptoms spanned many organ systems and were prominent in the pulmonary and cardiovascular systems. The exact mechanism is not clear. This group of patients represents a new challenge to our health care systems. An organized, multi-disciplinary approach and further research are warranted to be ready to deliver better care to these patients.

Emergency Medical Services Responses to Out-of-Hospital Cardiac Arrest and Suspected ST-Segment-Elevation Myocardial Infarction During the COVID-19 Pandemic in Los Angeles County.

Background Public health emergencies may significantly impact emergency medical services responses to cardiovascular emergencies. We compared emergency medical services responses to out-of-hospital cardiac arrest (OHCA) and ST-segment‒elevation myocardial infarction (STEMI) during the 2020 COVID-19 pandemic to 2018 to 2019 and evaluated the impact of California's March 19, 2020 stay-at-home order. Methods and Results We conducted a population-based cross-sectional study using Los Angeles County emergency medical services registry data for adult patients with paramedic provider impression (PI) of OHCA or STEMI from February through May in 2018 to 2020. After March 19, 2020, weekly counts for PI-OHCA were higher (173 versus 135; incidence rate ratios, 1.28; 95% CI, 1.19‒1.37; P<0.001) while PI-STEMI were lower (57 versus 65; incidence rate ratios, 0.87; 95% CI, 0.78‒0.97; P=0.02) compared with 2018 and 2019. After adjusting for seasonal variation in PI-OHCA and decreased PI-STEMI, the increase in PI-OHCA observed after March 19, 2020 remained significant (P=0.02). The proportion of PI-OHCA who received defibrillation (16% versus 23%; risk difference [RD], -6.91%; 95% CI, -9.55% to -4.26%; P<0.001) and had return of spontaneous circulation (17% versus 29%; RD, -11.98%; 95% CI, -14.76% to -9.18%; P<0.001) were lower after March 19 in 2020 compared with 2018 and 2019. There was also a significant increase in dead on arrival emergency medical services responses in 2020 compared with 2018 and 2019, starting around the time of the stay-at-home order (P<0.001). Conclusions Paramedics in Los Angeles County, CA responded to increased PI-OHCA and decreased PI-STEMI following the stay-at-home order. The increased PI-OHCA was not fully explained by the reduction in PI-STEMI. Field defibrillation and return of spontaneous circulation were lower. It is critical that public health messaging stress that emergency care should not be delayed.

Cardiovascular Health and Disease in the Context of COVID-19.

First documented in China in early December 2019, the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly and continues to test the strength of healthcare systems and public health programs all over the world. Underlying cardiovascular disease has been recognized as a risk factor for coronavirus disease 2019 (COVID-19)-related morbidity and mortality since the early days of the pandemic. In addition, evidence demonstrates cardiac and endothelial damage in somewhere between one-third and three-quarters of individuals with COVID-19, regardless of symptom severity. This damage is thought to be mediated by direct viral infection, immunopathology and hypoxemia with the additional possibility of exacerbation via medication-induced cardiotoxicity. Clinically, the cardiovascular consequences of COVID-19 may present as myocarditis with or without arrhythmia, endothelial dysfunction and thrombosis, acute coronary syndromes and heart failure. Presentation can vary widely and may or may not be typical of the condition in an individual without COVID-19. There is evidence to support the prognostic utility of cardiac biomarkers (e.g., cardiac troponin) and imaging studies (e.g., echocardiography, cardiac magnetic resonance imaging) in the context of COVID-19 and building evidence suggests that cardiovascular screening may be warranted even among those with asymptomatic or mild infection and those without traditional cardiovascular risk factors. In addition, evidence suggests the potential for long-term cardiovascular consequences for those who recover from COVID-19 with implications for the field of cardiology long into the future. Even among those without COVID-19, disruption of infrastructure and changes in human behavior as a result of the pandemic also have an upstream role in cardiovascular outcomes, which have already been documented in multiple locations. This review summarizes what is currently known regarding the pathogenic mechanisms of COVID-19-related cardiovascular injury and describes clinical cardiovascular presentations, prognostic indicators, recommendations for screening and treatment, and long-term cardiovascular consequences of infection. Ultimately, medical personnel must be vigilant in their attention to possible cardiovascular symptoms, take appropriate steps for clinical diagnosis and be prepared for long-term ramifications of myocardial injury sustained as a result of COVID-19.

Viral myocarditis: 1917-2020: From the Influenza A to the COVID-19 pandemics.

Myocarditis is common during viral infection with cases described as early as the influenza pandemic of 1917, and the current COVID-19 pandemic is no exception. The hallmark is elevated troponin, which occurs in 36% of COVID patients, with electrocardiogram, echocardiogram, and cardiac magnetic resonance being valuable tools to assist in diagnosis. Cardiac inflammation may occur secondary to direct cardiac invasion with the virus, or to intense cytokine storm, often encountered during the course of the disease. Angiotensin converting enzyme inhibitors, angiotensin receptor blockers, and judicious use of beta-blockers are beneficial in management of myocarditis. Corticosteroids may be avoided during the very early phase of viral replication, but can be of clear benefit in hospitalized, critically ill patients. Statins are beneficial to shorten the course of the disease and may decrease mortality.

E-cigarette or Vaping Product Use-Associated Lung Injury Produced in an Animal Model From Electronic Cigarette Vapor Exposure Without Tetrahydrocannabinol or Vitamin E Oil.

E-cigarette or vaping product use-associated lung injury was recognized in the United States in the summer of 2019 and is typified by acute respiratory distress, shortness of breath, chest pain, cough, and fever, associated with vaping. It can mimic many of the manifestations of coronavirus disease 2019 (COVID-19). Some investigators have suggested that E-cigarette or vaping product use-associated lung injury was due to tetrahydrocannabinol or vitamin E acetate oil mixed with the electronic cigarette liquid. In experimental rodent studies initially designed to study the effect of electronic cigarette use on the cardiovascular system, we observed an E-cigarette or vaping product use-associated lung injury-like condition that occurred acutely after use of a nichrome heating element at high power, without the use of tetrahydrocannabinol, vitamin E, or nicotine. Lung lesions included thickening of the alveolar wall with foci of inflammation, red blood cell congestion, obliteration of alveolar spaces, and pneumonitis in some cases; bronchi showed accumulation of fibrin, inflammatory cells, and mucus plugs. Electronic cigarette users should be cautioned about the potential danger of operating electronic cigarette units at high settings; the possibility that certain heating elements may be deleterious; and that E-cigarette or vaping product use-associated lung injury may not be dependent upon tetrahydrocannabinol, vitamin E, or nicotine.