Tag: orthostatic intolerance

Phenylephrine Alters Phase Synchronization between Cerebral Blood Velocity and Blood Pressure in Chronic Fatigue Syndrome with Orthostatic Intolerance

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) with orthostatic intolerance (OI) is characterized by neuro-cognitive deficits perhaps related to upright hypocapnia and loss of cerebral autoregulation (CA). We performed N-back neurocognition testing and calculated the phase synchronization index (PhSI) between Arterial Pressure (AP) and cerebral blood velocity (CBV) as a time-dependent measurement of cerebral autoregulation in 11 control (mean age=24.1 years) and 15 ME/CFS patients (mean age=21.8 years). All ME/CFS patients had postural tachycardia syndrome (POTS).

A 10-minute 60⁰ head-up tilt (HUT) significantly increased heart rate (109.4 ± 3.9 vs. 77.2 ± 1.6 beats/min, P <0.05) and respiratory rate (20.9 ± 1.7 vs. 14.2 ± 1.2 breaths/min, P < 0.05) and decreased end-tidal CO2 (ETCO2; 33.9 ± 1.1 vs. 42.8 ± 1.2 Torr, P < 0.05) in ME/CFS vs. control. In ME/CFS, HUT significantly decreased CBV compared to control (-22.5% vs -8.7%, p<0.005).

To mitigate the orthostatic CBV reduction, we administered supplemental CO2, phenylephrine and acetazolamide and performed N-back testing supine and during HUT. Only phenylephrine corrected the orthostatic decrease in neurocognition by reverting % correct n=4 N-back during HUT in ME/CFS similar to control (ME/CFS=38.5±5.5 vs. ME/CFS+PE= 65.6±5.7 vs. Control 56.9±7.5). HUT in ME/CFS resulted in increased PhSI values indicating decreased CA. While CO2 and Acetazolamide had no effect on PhSI in ME/CFS, PE caused a significant reduction in PhSI (ME/CFS=0.80±0.03 vs ME/CFS+PE= 0.69±0.04, p< 0.05) and improved cerebral autoregulation. Thus, PE improved neurocognitive function in ME/CFS patients, perhaps related to improved neurovascular coupling, cerebral autoregulation and maintenance of CBV.

Source: Medow MS, Stewart JM. Phenylephrine Alters Phase Synchronization between Cerebral Blood Velocity and Blood Pressure in Chronic Fatigue Syndrome with Orthostatic Intolerance. Am J Physiol Regul Integr Comp Physiol. 2024 Apr 29. doi: 10.1152/ajpregu.00071.2024. Epub ahead of print. PMID: 38682242. https://journals.physiology.org/doi/abs/10.1152/ajpregu.00071.2024 (Full text available as PDF file)

Low Vasopressin in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (P4-4.006)

Abstract:

Objective: To shed light on the pathophysiology of water homeostasis in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), classified by WHO as a neurological disease (ICD 10 code G933).

Background: The complex symptomatology of ME/CFS includes signs suggesting abnormal water homeostasis and hypovolemia. Since many patients report polyuria-polydipsia, we conducted an observational series of plasma and urine osmolality as well as plasma levels of vasopressin (VP) in consecutive patients diagnosed with ME/CFS according to the Canadian Consensus Criteria.

Design/Methods: Plasma and urine osmolality (P-Osm and U-Osm, respectively) and plasma VP levels were measured in 111 patients after overnight fasting and 10-hour fluid deprivation. The clinical routine also included brain MRI and blood chemistry.

Results: Following the fluid deprivation P-Osm was above normal (>292 mOsm/kg) in 61 patients (55.0%) and U-Osm below normal (< 750 mOsm/kg) in 74 patients (66.7%). VP-levels were below the level of detection (<1.6 pg/mL) in 91 patients (82.0%). A normal level of VP in relation to their P-Osm was found in 11 patients (9.9 %). The state resembling a central type of diabetes insipidus (cDI) would in the absence of hypophyseal imaging findings and blood chemistry consistent with any other hypophyseal hormonal defect be classified as idiopathic.

Conclusions: Our findings suggest that deficiency of vasopressin secretion is a fundamental measurable part of the disease mechanisms, which may underlie a number of symptoms in ME/CFS, including the common complaint of orthostatic intolerance.

Source: Helena Huhmar, Lauri Soinne, Per Sjögren, Bo Christer Bertilson, Per Hamid Ghatan, Björn Bragée, and Olli Polo. Low Vasopressin in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (P4-4.006) Neurology, April 9, 2024 issue 102 (17_supplement_1) https://doi.org/10.1212/WNL.000000000020576 https://www.neurology.org/doi/10.1212/WNL.0000000000205761

Characterization of subgroups of myalgic encephalomyelitis/chronic fatigue syndrome based on disease onset, symptoms and biomarkers

Abstract:

Myalgic encephalomyelitis, also called chronic fatigue syndrome (ME/CFS), is an acquired multisystem disease. The core symptoms include fatigue, exercise intolerance and pain as well as cognitive, autonomic and immunological manifestations. The diagnosis of ME/CFS is based on clinical criteria. Specific biomarkers do not currently exist, but studies suggest a role for soluble cluster of differentiation 26 (sCD26) and autoantibodies (AAK) against G protein-coupled receptors (GPCR). In many cases, the disease begins as a result of infections. 

The aim of this work was to determine the pathophysiological significance of potential biomarkers, assuming different development mechanisms in patients with infection-associated disease onset compared to those with other triggers. In a first study, sCD26, also called dipeptidyl peptidase-4 (DPP-4) due to its enzymatic activity, was analyzed and compared in the serum of 205 ME/CFS patients and 98 controls. This was followed by a comprehensive correlation analysis between sCD26 and clinical and laboratory parameters for ME/CFS patients, separated by type of disease onset. In addition, CD26 expression on lymphocyte subpopulations was determined for 12 patients and 12 controls. 

In another study, a correlation analysis was carried out between AAK against vasoregulatory GPCR and symptoms in 116 ME/CFS patients, separated by type of disease onset. It was shown that in ME/CFS patients with infection-associated disease onset, sCD26 correlated with numerous immunological and metabolic parameters, the changes of which have also been described in connection with DPP-4 inhibitors. In addition, there were inverse correlations with AAK against alpha1-adrenergic and M3-acetylcholine receptors. 

In this subgroup, the second study found correlations between numerous GPCR-AAK and the severity of fatigue, muscle pain and cognitive symptoms as well as greater functional impairment relevant to everyday life. None of these correlations were found in patients without infection-associated disease onset. 

Here, sCD26 correlated inversely with orthostatically induced heart rate increases and AAK against alpha- and beta-adrenergic receptors with the severity of orthostatic symptoms. Different correlation patterns between AAK against GPCR and symptoms allow us to assume that in patients with ME/CFS, an altered function of the AAK or its receptors or signaling pathways has occurred as a result of an infection. The association of sCD26 and GPCR-AAK also indicates the dysregulation of other parts of the immune system with potentially pathological consequences. The differences presented compared to patients with non-infectious genesis suggest two definable subgroups.

Source: Szklarski, Marvin. Characterization of subgroups of myalgic encephalomyelitis/chronic fatigue syndrome based on disease onset, symptoms and biomarkers. Charité – University Medicine Berlin, dissertation. https://refubium.fu-berlin.de/handle/fub188/40276

Augmentation of Anaerobic Pentose Phosphate Pathway Dysregulates Tetrahydrobiopterin Metabolism in Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS) Patients with Orthostatic Intolerance: A Pilot Study

Abstract:

Tetrahydrobiopterin (BH4), an essential cofactor of amino acid metabolism, was found to be strongly elevated in ME/CFS patients with Orthostatic intolerance (ME + OI). However, the molecular mechanism of BH4 upregulation is poorly understood in ME + OI patients. Here, we report that the activation of the non-oxidative pentose phosphate pathway (PPP) plays a critical role in the biosynthesis of BH4 in ME + OI patients.

Microarray-based gene screening followed by real-time PCR-based validation, ELISA assay, and finally enzyme kinetic studies of glucose-6-phosphate dehydrogenase (G6PDH), transaldolase (TALDO1), and transketolase (TK) enzymes revealed that the augmentation of anaerobic PPP is critical in the pathogenesis of ME + OI. Along with the upregulated anaerobic PPP enzymes, we observed that biopterin metabolites such as BH4 and dihydrobiopterin (BH2) are strongly upregulated suggesting the disruption of biopterin homeostasis in ME + OI patients.

To explore the molecular role of anaerobic PPP in biopterin metabolism, we devised a novel cell culture strategy to induce non-oxidative PPP by treating human microglial cells with ribose-5-phosphate (R5P) under a hypoxic condition of 85%N2/10%CO2/5%O2 followed by the analysis of BH4 and BH2 upregulation via ELISA, immunoblot and dual immunocytochemical analyses.

These results confirmed that the activation of non-oxidative PPP is indeed required for the upregulation of both BH4 and BH2. Moreover, the siRNA knocking down of the taldo1 gene strongly inhibited the expression of GTP cyclohydrolase 1 (GTPCH1) and subsequent production of BH4 and its metabolic conversion to BH2 in R5P-treated and hypoxia-induced C20 human microglia cells. To test the functional role of ME + OI plasma-derived biopterins, exogenously added plasma samples of ME + OI plasma with high BH4 upregulated inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in human microglial cells indicating that the non-oxidative PPP-induced-biopterins could stimulate inflammatory response in ME + OI patients.

Source: Sarojini Bulbule, Carl Gunnar Gottschalk, Molly E Drosen et al. Augmentation of Anaerobic Pentose Phosphate Pathway Dysregulates Tetrahydrobiopterin Metabolism in Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome (ME/CFS) Patients with Orthostatic Intolerance: A Pilot Study, 11 December 2023, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-3716093/v1] https://www.researchsquare.com/article/rs-3716093/v1 (Full text)

Dysregulations in hemostasis, metabolism, immune response, and angiogenesis in post-acute COVID-19 syndrome with and without postural orthostatic tachycardia syndrome: a multi-omic profiling study

Abstract:

Post-acute COVID-19 (PACS) are associated with cardiovascular dysfunction, especially postural orthostatic tachycardia syndrome (POTS). Patients with PACS, both in the absence or presence of POTS, exhibit a wide range of persisting symptoms long after the acute infection. Some of these symptoms may stem from alterations in cardiovascular homeostasis, but the exact mechanisms are poorly understood.

The aim of this study was to provide a broad molecular characterization of patients with PACS with (PACS + POTS) and without (PACS-POTS) POTS compared to healthy subjects, including a broad proteomic characterization with a focus on plasma cardiometabolic proteins, quantification of cytokines/chemokines and determination of plasma sphingolipid levels.

Twenty-one healthy subjects without a prior COVID-19 infection (mean age 43 years, 95% females), 20 non-hospitalized patients with PACS + POTS (mean age 39 years, 95% females) and 22 non-hospitalized patients with PACS-POTS (mean age 44 years, 100% females) were studied. PACS patients were non-hospitalized and recruited ≈18 months after the acute infection.

Cardiometabolic proteomic analyses revealed a dysregulation of ≈200 out of 700 analyzed proteins in both PACS groups vs. healthy subjects with the majority (> 90%) being upregulated. There was a large overlap (> 90%) with no major differences between the PACS groups. Gene ontology enrichment analysis revealed alterations in hemostasis/coagulation, metabolism, immune responses, and angiogenesis in PACS vs. healthy controls.

Furthermore, 11 out of 33 cytokines/chemokines were significantly upregulated both in PACS + POTS and PACS-POTS vs. healthy controls and none of the cytokines were downregulated. There were no differences in between the PACS groups in the cytokine levels. Lastly, 16 and 19 out of 88 sphingolipids were significantly dysregulated in PACS + POTS and PACS-POTS, respectively, compared to controls with no differences between the groups.

Collectively, these observations suggest a clear and distinct dysregulation in the proteome, cytokines/chemokines, and sphingolipid levels in PACS patients compared to healthy subjects without any clear signature associated with POTS. This enhances our understanding and might pave the way for future experimental and clinical investigations to elucidate and/or target resolution of inflammation and micro-clots and restore the hemostasis and immunity in PACS.

Source: Mahdi, A., Zhao, A., Fredengren, E. et al. Dysregulations in hemostasis, metabolism, immune response, and angiogenesis in post-acute COVID-19 syndrome with and without postural orthostatic tachycardia syndrome: a multi-omic profiling study. Sci Rep 13, 20230 (2023). https://doi.org/10.1038/s41598-023-47539-1 https://www.nature.com/articles/s41598-023-47539-1 (Full study)

Case report: Recurrent cervical spinal stenosis masquerading as myalgic encephalomyelitis/chronic fatigue syndrome with orthostatic intolerance

Abstract:

Introduction: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex, chronic, multi-system disorder that is characterized by a substantial impairment in the activities that were well tolerated before the illness.

In an earlier report, we had described three adult women who met criteria for ME/CFS and orthostatic intolerance, and had congenital or acquired cervical spinal stenosis. All three experienced substantial global improvements in their ME/CFS and orthostatic intolerance symptoms after recognition and surgical treatment of the cervical stenosis. After a several year period of improvement, one of the individuals in that series experienced a return of ME/CFS and orthostatic intolerance symptoms.

Main Symptoms and Clinical Findings: Radiologic investigation confirmed a recurrence of the ventral compression of the spinal cord due to a shift of the disc replacement implant at the involved cervical spinal level.

Therapeutic Intervention: Decompression of the spinal cord with removal of the implant and fusion at the original C5-C6 level was once again followed by a similar degree of improvement in function as had been observed after the first operation.

This recapitulation of the outcomes after surgical management of cervical stenosis provides further evidence in support of the hypothesis that cervical spinal stenosis can exacerbate pre-existing or cause new orthostatic intolerance and ME/CFS. Especially for those with refractory symptoms and neurological signs, surgical interventions may offer relief for selected patients with this complex condition.

Source: Charles C. Edwards III, Charles C. Edwards II, Scott Heinlein, Peter C. Rowe. Case report: Recurrent cervical spinal stenosis masquerading as myalgic encephalomyelitis/chronic fatigue syndrome with orthostatic intolerance. Frontiers in Neurology, Volume-14- 2023. https://www.frontiersin.org/articles/10.3389/fneur.2023.1284062/abstract

Ivabradine effects on COVID-19-associated postural orthostatic tachycardia syndrome: a single center prospective study

Abstract:

Background: A wide range of cardiac arrhythmias were reported in the setting of active infection or as a complication of COVID-19. The main pathophysiology can be attributed to dysautonomia or autonomic nervous system dysfunction. Postural orthostatic tachycardia syndrome (POTS) is a complex, multisystemic disorder affecting usually younger age with tachycardia at rest or with minimal effort being the main symptom. Data regarding the safety and efficacy of ivabradine in POTS treatment is limited to small studies and case reports.

Methods: This prospective observational study included a total of 55 COVID-19-associated POTS patients after the exclusion of other causes of tachycardia. Ivabradine 5 mg twice daily was initiated. Re-assessment of patients’ symptoms, heart rate, and heart rate variability (HRV) parameters’ changes after 3 days of ivabradine therapy was done.

Results: The mean age of the included patients was 30.5±6.9 years with 32 patients being males (58.2%). 43 of 55 (78%) of the included patients reported significant improvement of the symptoms within 7 days of ivabradine therapy. 24-hour heart rate (minimum, average, and maximum) was significantly lower (p-value < 0.0001*, = 0.001*, < 0.0001* consecutively) with a significant difference in HRV time-domain parameters (SDNN, rMSSD) (p-value < 0.0001*) after ivabradine therapy.

Conclusion: In a prospective study that evaluated the effects of ivabradine in post-COVID-19 POTS, patients treated with ivabradine reported improvement of their symptoms within 7 days of ivabradine treatment with a significant reduction of 24-hour average, minimum, and maximum heart rate, and improvement of HRV time domains parameters. Ivabradine might be a useful option to relieve symptoms of tachycardia in COVID-19 POTS. Further research is required to confirm the safety and efficacy of ivabradine in POTS treatment.

Source: Abdelnabi M, Saleh Y, Ahmed A, Benjanuwattra J, Leelaviwat N, Almaghraby A. Ivabradine effects on COVID-19-associated postural orthostatic tachycardia syndrome: a single center prospective study. Am J Cardiovasc Dis. 2023 Jun 25;13(3):162-167. PMID: 37469536; PMCID: PMC10352820. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10352820/ (Full text)

Cognitive impairment in post-acute sequelae of COVID-19 and short duration myalgic encephalomyelitis patients is mediated by orthostatic hemodynamic changes

Introduction: Cognitive impairment is experienced by people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-acute sequelae of COVID-19 (PASC). Patients report difficulty remembering, concentrating, and making decisions. Our objective was to determine whether orthostatic hemodynamic changes were causally linked to cognitive impairment in these diseases.

Methods: This prospective, observational cohort study enrolled PASC, ME/CFS, and healthy controls. All participants underwent clinical evaluation and assessment that included brief cognitive testing before and after an orthostatic challenge. Cognitive testing measured cognitive efficiency which is defined as the speed and accuracy of subject’s total correct responses per minute. General linear mixed models were used to analyze hemodynamics and cognitive efficiency during the orthostatic challenge. Additionally, mediation analysis was used to determine if hemodynamic instability induced during the orthostatic challenge mediated the relationship between disease status and cognitive impairment.

Results: Of the 276 participants enrolled, 256 were included in this study (34 PASC, 71 < 4 year duration ME/CFS, 69 > 10 year ME/CFS duration, and 82 healthy controls). Compared to healthy controls, the disease cohorts had significantly lower cognitive efficiency scores immediately following the orthostatic challenge. Cognitive efficiency remained low for the >10 year ME/CFS 2 and 7 days after orthostatic challenge. Narrow pulse pressure less than 25% of systolic pressure occurred at 4 and 5 min into the orthostatic challenge for the PASC and ME/CFS cohorts, respectively. Abnormally narrow pulse pressure was associated with slowed information processing in PASC patients compared to healthy controls (−1.5, p = 0.04). Furthermore, increased heart rate during the orthostatic challenge was associated with a decreased procedural reaction time in PASC and < 4 year ME/CFS patients who were 40 to 65 years of age.

Discussion: For PASC patients, both their disease state and hemodynamic changes during orthostatic challenge were associated with slower reaction time and decreased response accuracy during cognitive testing. Reduced cognitive efficiency in <4 year ME/CFS patients was associated with higher heart rate in response to orthostatic stress. Hemodynamic changes did not correlate with cognitive impairment for >10 year ME/CFS patients, but cognitive impairment remained. These findings underscore the need for early diagnosis to mitigate direct hemodynamic and other physiological effects on symptoms of cognitive impairment.

Source: Day Heather, Yellman Brayden, Hammer Sarah, Rond Candace, Bell Jennifer, Abbaszadeh Saeed, Stoddard Greg, Unutmaz Derya, Bateman Lucinda, Vernon Suzanne D. Cognitive impairment in post-acute sequelae of COVID-19 and short duration myalgic encephalomyelitis patients is mediated by orthostatic hemodynamic changes. Frontiers in Neuroscience, VOLUME=17, 2023. DOI=10.3389/fnins.2023.1203514. ISSN=1662-453X. https://www.frontiersin.org/articles/10.3389/fnins.2023.1203514 (Full text)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Comorbidities: Linked by Vascular Pathomechanisms and Vasoactive Mediators?

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is often associated with various other syndromes or conditions including mast cell activation (MCA), dysmenorrhea and endometriosis, postural tachycardia (POTS) and small fiber neuropathy (SFN). The causes of these syndromes and the reason for their frequent association are not yet fully understood.

We previously published a comprehensive hypothesis of the ME/CFS pathophysiology that explains the majority of symptoms, findings and chronicity of the disease. We wondered whether some of the identified key pathomechanisms in ME/CFS are also operative in MCA, endometriosis and dysmenorrhea, POTS, decreased cerebral blood flow and SFN, and possibly may provide clues on their causes and frequent co-occurrence.

Our analysis indeed provides strong arguments in favor of this assumption, and we conclude that the main pathomechanisms responsible for this association are excessive generation and spillover into the systemic circulation of inflammatory and vasoactive tissue mediators, dysfunctional β2AdR, and the mutual triggering of symptomatology and disease initiation. Overall, vascular dysfunction appears to be a strong common denominator in these linkages.

Source: Wirth KJ, Löhn M. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Comorbidities: Linked by Vascular Pathomechanisms and Vasoactive Mediators? Medicina. 2023; 59(5):978. https://doi.org/10.3390/medicina59050978  https://www.mdpi.com/1648-9144/59/5/978 (Full text)

ME/CFS Pathophysiology Investigated by Invasive Cardiopulmonary Exercise Testing and Autonomic Function Testing

Abstract

Introduction: Mechanisms underlying exercise and orthostatic intolerance in myalgic encephalomyelitis/chronic
fatigue syndrome (ME/CFS) have been uncovered by invasive cardiopulmonary exercise testing (iCPET) and
autonomic function testing (AFT), but the relationships between the two are not known. This study aims to determine
if there is overlap of cardiovascular and respiratory pathophysiology in patients who have undergone both
tests.

Methods: Between January 2017 and April 2022, 62 patients were identified with a contemporary iCPET and
AFT. Key variables from the iCPET included peak oxygen uptake (pVO2), cardiac output (pQc), right atrial pressure
(pRAP), and systemic oxygen extraction (Ca-vOy/Hgb) at peak exercise. Key variables from the autonomic testing
included epidermal and sweat gland small fiber neurite density, electrochemical skin conductance, and change in
heart rate (AH) and end tidal carbon dioxide (AETCO2) from supine to upright during the tilt table test
(TTT).

Results: All 62 patients demonstrated preload failure (pRAP < 6.5mmHg). Of this group, 54 patients (87.1%) fulfilled NAM criteria for ME/CFS, with 32 testing positive (59.3%) for small fiber neuropathy (SFN) using either morphological and/or functional testing. Significant correlations were found between pVOg and both AH (r=-0.439. P<0.05) and AETCO, (r=0.474, P<0.05) during TTT. The same tilt table variables were found to be significantly correlated with pQc (r=-0.365, P<0.05 and r=0.351, P<0.05) from the iCPET. It should be noted that 8 of the ME/CFS SFN patients (25%) fulfilled diagnostic criteria for postural orthostatic tachycardia syndrome (POTS) based on the tilt table test.

Conclusion: Decreased oxygen uptake and cardiac output at peak exercise during iCPET correlated with a greater change in heart rate and ETCO from supine to upright during TTT. There appears to be significant overlap of cardiopulmonary pathophysiology in ME/CFS underlying exercise and orthostatic symptoms.

Source: J. Squires, K. Wichmann Madsen, M.C. Stovall, S. Al-Zayer, W. Xiao, C.-J. Chang, P. Novak, D.M. Systrom. ME/CFS Pathophysiology Investigated by Invasive Cardiopulmonary Exercise Testing and Autonomic Function Testing. American Journal of Respiratory and Critical Care Medicine 2023;207:A2996. https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A2996