title: Isometric stress in cardiovascular magnetic resonance-a simple and easily replicable method of assessing cardiovascular differences not apparent at rest.
abstract: BACKGROUND
  Isometric exercise may unmask cardiovascular disease not evident at rest, and cardiovascular magnetic resonance (CMR) imaging is proven for comprehensive resting assessment. This study devised a simple isometric exercise CMR methodology and assessed the hemodynamic response evoked by isometric exercise.
  
  
  METHODS
  A biceps isometric exercise technique was devised for CMR, and 75 healthy volunteers were assessed at rest, after 3-minute biceps exercise, and 5-minute of recovery using: 1) blood pressure (BP) and 2) CMR measured aortic flow and left ventricular function. Total peripheral resistance (SVR) and arterial compliance (TAC), cardiac output (CO), left ventricular volumes and function (ejection fraction, stroke volume, power output), blood pressure (BP), heart rate (HR), and rate pressure product were assessed at all time points.
  
  
  RESULTS
  Image quality was preserved during stress. During exercise there were increases in CO (+14.9 %), HR (+17.0 %), SVR (+9.8 %), systolic BP (+22.4 %), diastolic BP (+25.4 %) and mean BP (+23.2 %). In addition, there were decreases in TAC (-22.0 %) and left ventricular ejection fraction (-6.3 %). Age and body mass index modified the evoked response, even when resting measures were similar.
  
  
  CONCLUSIONS
  Isometric exercise technique evokes a significant cardiovascular response in CMR, unmasking physiological differences that are not apparent at rest.
  
  
  CONCLUSIONS
  • Isometric exercise unmasks cardiovascular differences not evident at rest. • CMR is the reference standard for non-invasive cardiovascular assessment at rest. • A new easily replicable method combines isometric exercise with CMR. • Significant haemodynamic changes occur and differences are unmasked. • The physiological, isometric CMR stressor can be easily replicated.
authors.affiliation: UCL Centre for Cardiovascular MR, UCL Institute of Cardiovascular Science, Level 6 Old Nurses Home, Cardiorespiratory Unit, Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK. mortensen@doctors.org.uk.
authors.forename: Kristian H
authors.initials: KH
authors.lastname: Mortensen
authors.affiliation: UCL Centre for Cardiovascular MR, UCL Institute of Cardiovascular Science, Level 6 Old Nurses Home, Cardiorespiratory Unit, Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Jones
authors.affiliation: UCL Centre for Cardiovascular MR, UCL Institute of Cardiovascular Science, Level 6 Old Nurses Home, Cardiorespiratory Unit, Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Steeden
authors.affiliation: UCL Centre for Cardiovascular MR, UCL Institute of Cardiovascular Science, Level 6 Old Nurses Home, Cardiorespiratory Unit, Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Taylor
authors.affiliation: UCL Centre for Cardiovascular MR, UCL Institute of Cardiovascular Science, Level 6 Old Nurses Home, Cardiorespiratory Unit, Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK.
authors.forename: Vivek
authors.initials: V
authors.lastname: Muthurangu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001795:Blood Pressure Determination; D015992:Body Mass Index; D002302:Cardiac Output / Q000502:physiology; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012146:Rest / Q000502:physiology; D012737:Sex Factors; D013318:Stroke Volume / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology; D055815:Young Adult
keywords: Cardiac imaging technique; Cardiovascular physiological processes; Exercise test; Isometric exercise; Magnetic resonance imaging