2024
The metabolic and physiologic impairments underlying long COVID associated exercise intolerance
Leitner B, Joseph P, Quast A, Ramirez M, Heerdt P, Villalobos J, Singh I. The metabolic and physiologic impairments underlying long COVID associated exercise intolerance. Pulmonary Circulation 2024, 14: e70009. PMID: 39544193, PMCID: PMC11560803, DOI: 10.1002/pul2.70009.Peer-Reviewed Original ResearchPeak VO<sub>2</sub>Long COVID patientsCOVID patientsReduced peak VOSeverity of SARS-CoV-2 infectionSystemic oxygen extractionSARS-CoV-2 infectionLong COVIDArterial blood samplesQuantitative metabolomicsPeak VOVenous lactateCardiac outputImpaired mitochondrial ATP productionMild infectionExercise capacityPatientsMitochondrial ATP productionExercise intoleranceArteriovenous gradientBlood samplesOxygen extractionDependent mannerMetabolomicsPhysiological impairment
2023
Differential cardiopulmonary haemodynamic phenotypes in PASC-related exercise intolerance
Kahn P, Joseph P, Heerdt P, Singh I. Differential cardiopulmonary haemodynamic phenotypes in PASC-related exercise intolerance. ERJ Open Research 2023, 10: 00714-2023. PMID: 38348243, PMCID: PMC10860209, DOI: 10.1183/23120541.00714-2023.Peer-Reviewed Original ResearchInvasive cardiopulmonary exercise testingRight heart catheterizationPASC patientsExertional intoleranceCardiac outputPulmonary artery wedge pressurePeak VO 2Supranormal cardiac outputPeak exercise capacityCardiopulmonary exercise testingMaximal voluntary ventilationPost-acute sequelaeBody mass indexSystemic oxygen extractionMild acute illnessSARS-CoV-2Exercise hemodynamicsHFpEF patientsHFpEF phenotypeHeart catheterizationWedge pressureAcute illnessExercise capacityExercise testingHemodynamic abnormalities
2021
Persistent Exertional Intolerance After COVID-19 Insights From Invasive Cardiopulmonary Exercise Testing
Singh I, Joseph P, Heerdt PM, Cullinan M, Lutchmansingh DD, Gulati M, Possick JD, Systrom DM, Waxman AB. Persistent Exertional Intolerance After COVID-19 Insights From Invasive Cardiopulmonary Exercise Testing. CHEST Journal 2021, 161: 54-63. PMID: 34389297, PMCID: PMC8354807, DOI: 10.1016/j.chest.2021.08.010.Peer-Reviewed Original ResearchConceptsInvasive cardiopulmonary exercise testingCardiopulmonary exercise testingCardiopulmonary diseaseExercise testingControl participantsPeak VOExertional limitationCOVID-19Greater ventilatory inefficiencyPeak cardiac indexSex-matched control participantsCohort of patientsSystemic oxygen extractionDead space ventilationOnly mild symptomsExertional intoleranceCardiac indexPulmonary hemodynamicsAcute infectionVentilatory inefficiencyExercise intolerancePathophysiologic mechanismsMild symptomsHyperventilatory responseOxygen extraction
2020
Systemic vascular distensibility relates to exercise capacity in connective tissue disease
Singh I, Oliveira RKF, Naeije R, Oldham WM, Faria-Urbina M, Waxman AB, Systrom DM. Systemic vascular distensibility relates to exercise capacity in connective tissue disease. Rheumatology 2020, 60: 1429-1434. PMID: 33001175, DOI: 10.1093/rheumatology/keaa510.Peer-Reviewed Original ResearchConceptsCTD patientsSystemic oxygen extractionExercise capacityVascular distensibilityCardiopulmonary diseaseOxygen extractionDecreased exercise capacityStroke volume augmentationReduced exercise capacityCommon clinical manifestationsRadial arterial catheterConnective tissue diseaseAerobic exercise capacityPulmonary vascular distensibilityCardio-pulmonary diseasePressure-flow plotsPulmonary hypertensionCardiopulmonary exerciseHeart failureArterial catheterExercise intoleranceTissue diseaseClinical manifestationsNormal controlsPatients