Limitations
Our population was young and verified to be without cardiac disease and despite this 11 patients were excluded mainly due to insufficient image quality. Only participants with analysable image quality were included. The imaging protocol was arduous, however the findings (threshold values for EF and GLS / continuous augmentation of S’) would allow simplification in future studies that would also be more clinically achievable. Non invasive blood pressure was measured as part of the protocol, however the sampling from the automatic detection devices was consistently poor resulting in less than 50% evaluable data. Analysis requiring blood pressure was therefore not performed. These findings may not apply to a disease population or those from other age groups. TVI measurements were optimised for perpendicular septal measurements. Lateral wall TVI may have been off axis which can introduce error. Transmitral Doppler was not recorded because of the technical challenge of obtaining these values at high rate show complete E/A fusion making detection of the true Doppler E wave and hence an unreliable E/E’. The GLS measured by speckle tracking may not be accurate at the higher heart rate. Our data would have permitted the evaluation of myocardial work, but this did not form part of the original protocol and is vendor specific, therefore this analysis has not been undertaken.