Isometric stress in cardiovascular magnetic resonance—a simple and easily replicable method of assessing cardiovascular differences not apparent at rest
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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.
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.
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.
Isometric exercise technique evokes a significant cardiovascular response in CMR, unmasking physiological differences that are not apparent at rest.
• 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.
KeywordsMagnetic resonance imaging Cardiovascular physiological processes Cardiac imaging technique Isometric exercise Exercise test
Abbreviations and acronyms
Cardiovascular magnetic resonance
Left ventricular end-diastolic volume
Left ventricular end-systolic volume
Left ventricular stroke volumes
Total peripheral resistance
Total arterial compliance
Systolic blood pressure
Diastolic blood pressure
Mean blood pressure
Rate pressure product
Left ventricular power output
Body mass index
We would like to thank Rod Jones, Wendy Norman and Anne Layther for their help with recruitment and imaging.
The scientific guarantor of this publication is Dr Vivek Muthurangu. The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article. This study has received funding by the British Heart Foundation. One of the authors has significant statistical expertise. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects in this study.
Methodology: prospective, observational, performed at one institution.
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