Dyspnea in Chronic Low Ventricular Preload States

Impact of body position on hemodynamic measurements during exercise: A tale of two bikes

The addition of exercise testing during right heart catheterization (RHC) is often required to accurately diagnose causes of exercise intolerance like early pulmonary vascular disease, occult left heart disease, and preload insufficiency. We tested the influence of body position (supine vs. seated) on hemodynamic classification both at rest and during exercise. We enrolled patients with exercise intolerance due to dyspnea who were referred for exercise RHC at the Cleveland Clinic. Patients were randomized (1:1) to exercise in seated or supine position to a goal of 60 W followed by maximal exercise in the alternate position. We analyzed 17 patients aged 60.3 ± 10.9 years, including 13 females. At rest in the sitting position, patients had significantly lower right atrial pressure (RAP), mean pulmonary artery pressure (mPAP), pulmonary artery wedge pressure (PAWP) and cardiac index (CI). In every stage of exercise (20, 40, and 60 W), the RAP, mPAP, and PAWP were lower in the sitting position. Exercise in the sitting position allowed the identification of preload insufficiency in nine patients. Exercise in either position increased the identification of postcapillary pulmonary hypertension (PH). Body position significantly influences hemodynamics at rest and with exercise; however, mPAP/CO and PAWP/CO were not positionally affected. Hemodynamic measurements in the seated position allowed the detection of preload insufficiency, a condition that was predominantly identified as no PH during supine exercise.

Association of Cardiac Autonomic Responses with Clinical Outcomes of Myasthenia Gravis: Short-Term Analysis of the Heart-Rate and Blood Pressure Variability

Introduction: The aim of the study was to assess cardiac and autonomic function in patients with myasthenia gravis (MG) and to explore its relationship with disease outcomes. Methods: Thirty-eight patients with an MG were enrolled (median age 40.5 years; median disease duration 5.5 years). Cardiovascular parameters, baroreflex sensitivity (BRS), spectral indices of short-term heart rate (HRV), and systolic blood pressure variability (SBPV) were compared with age- and gender-matched controls (n = 30). Cardiac autonomic function was assessed during the response to standing (tilt) and deep breathing tests (expiration/inspiration ratio-E/I). Results: HR and BP responses to the tilt test were similar in both groups. MG patients, as compared to controls, were characterized by altered SBPV at rest, significantly reduced HR response to the deep breathing test (p < 0.001), increased sympathovagal balance after tilt (delta LF/HF-RRI, p = 0.037), and lower values of BRS (p = 0.007) and hemodynamic parameters, i.e., cardiac index, index contractility, left ventricular work index, at rest and during tilt. There was no association between disease duration and autonomic parameters. Disease severity, as determined by MGFA (Myasthenia Gravis Foundation of America) corrected for age and sex, was an independent predictor of diminished vagal tone (E/I ratio) and increased sympathetic response to tilt (delta LF/HF-RRI) as measured with HRV. Lower BRS was associated with greater disease severity and older age. Hemodynamic parameters were predominantly predicted by age and sex. Conclusion: Our results confirm cardiac autonomic dysfunction among MG patients with predominant parasympathetic impairment. Clinicians should consider evaluation of autonomic balance in MG patients with, or at risk for, cardiovascular disease.

Autonomic dysfunction in SARS-COV-2 infection acute and long-term implications COVID-19 editor's page series

Abstract

The autonomic nervous system (ANS) is a complex network of nerves originating in the brain, brain stem, spinal cord, heart and extracardiac organs that regulates neural and physiological responses to internal and external environments and conditions. A common observation among patients with the 2019 Coronavirus (CoV) (SARS-severe acute respiratory syndrome CoV-2) (SARS-CoV-2) or COVID-19 [CO for corona, VI for virus, D for disease and 19 for when the outbreak was first identified (31 December 2019)] in the acute and chronic phases of the disease is tachycardia, labile blood pressure, muscular fatigue and shortness of breath. Because abnormalities in the ANS can contribute to each of these symptoms, herein a review of autonomic dysfunction in SARS-COV-2 infection is provided to guide diagnostic testing, patient care and research initiatives.

Graphic abstract

The autonomic nervous system is a complex network of nerves originating in the brain, brain stem, spinal cord, heart and extracardiac organs that regulates neural and physiological responses to internal and external environments and conditions. A common collection of signs and symptoms among patients with the 2019 Coronavirus (CoV) (SARS-severe acute respiratory syndrome CoV-2) (SARS-CoV-2) or COVID-19 [CO for corona, VI for virus, D for disease and 19 for when the outbreak was first identified (31 December 2019)] is tachycardia, labile blood pressure, muscular fatigue and shortness of breath. Abnormalities in the autonomic nervous system (ANS) can contribute to each of these identifiers, potentially offering a unifying pathobiology for acute, subacute and the long-term sequelae of SARS-CoV-2 infection (PASC) and a target for intervention.