Background Strain is a relative deformation and has three dimensions, in the left ventricle (LV) usually longitudinal (εL), transmural (εT) and circumferential (εC) strain. All three components can be measured generically by the basic systolic and diastolic dimension measures of LV wall length, wall thickness and diameter. In this observational study we aimed to study the relations of normal generic strains to age, body size and gender, as well as the interrelations between the three strain components.
Methods Generic strains derived from dimension measures by longitudinal and cross-sectional M-mode in all three dimensions were measured in 1266 individuals without heart disease from the Nord-Trøndelag Health Study.
Results The mean εL was −16.3%, εC was −22.7% and εT was 56.5%. Normal values by age and gender are provided. There was a gradient of εC from the endocardial, via the midwall to the external level, lowest at the external. All strains decreased in absolute values by increasing body surface area (BSA) and age, relations were strongest for εL. Gender differences were mainly a function of BSA differences. The three strain components were strongly interrelated through myocardial incompressibility.
Conclusions Global systolic strain is the total deformation of the myocardium; the three strain components are the spatial coordinates of this deformation, irrespective of the technology used for measurement. Normal values are method-dependent and not normative across methods. Interrelation of strains indicates a high degree of myocardial incompressibility and that longitudinal strain carries most of the total information.
- cardiac function
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Contributors AS and HD participated in the study design. HD has done the actual acquisitions. HD and HEM have done the measurements. AS has done the data analysis, interpretation and draft of the paper. All three authors participated in critical revision and approved the final manuscript. All authors accept responsibility for the final content.
Funding The study was fully sponsored by the Norwegian University of Science and Technology as a PhD grant, as well as the HUNT Study providing the infrastructure for the echocardiography in the HUNT3 Study.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval All subjects gave written consent to participate in the study and the study was approved by the ethical committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.
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