Influence of afterload on left ventricular radial and longitudinal systolic functions: a two-dimensional strain imaging study.
Résumé
AIMS: This study aimed to assess the influence of afterload alteration on radial (R) and longitudinal (L) left ventricular (LV) systolic regional functions. METHODS AND RESULTS: We analysed systolic myocardial function by two-dimensional strain (2D-S) and sonomicrometry (SS) in an experimental pig model of aortic banding. Both radial and longitudinal functions were analysed in six open-chest pigs under various loading conditions: baseline and graded aortic banding (subsequent increase in LV pressure of 10, 20, and 40 mmHg). Both systolic 2D-S(long) and 2D-S(rad) were significantly correlated with SS(long) and SS(rad) (r = 0.63, P < 0.001 and r = 0.65, P < 0.01, respectively). At a low increase in LV afterload, 2D-S(rad) was still preserved whereas 2D-S(long) significantly decreased. When LV afterload was subsequently increased, both 2D-S(rad) and 2D-S(long) significantly decreased. Difference in dependence to wall stress might explain these different behaviours. CONCLUSION: 2D-S shows a different response in longitudinal and radial functions to increased afterload. Longitudinal function is early impaired, whereas radial function remains preserved. This finding justifies the combined assessment of both radial and longitudinal regional myocardial functions to characterize myocardial dysfunction and might help to better identify the transition to heart failure in pressure-overload cardiomyopathy.