Evaluation of alterations on mitral annulus velocities, strain, and strain rates due to abrupt changes in preload elicited by parabolic flight

doi:10.1152/japplphysiol.00625.2006

Evaluation of alterations on mitral annulus velocities, strain, and strain rates due to abrupt changes in preload elicited by parabolic flight

E. G. Caiani,¹ L. Weinert,² M. Takeuchi,³ F. Veronesi,¹^,4 L. Sugeng,² C. Corsi,⁴ A. Capderou,⁵ S. Cerutti,¹ P. Vaïda,⁶ and R. M. Lang²

¹Dipartimento di Bioingegneria, Politecnico di Milano, Milan, Italy; ²Cardiac Imaging Center, University of Chicago, Chicago, Illinois; ³Tane General Hospital, Osaka, Japan; ⁴Dipartimento di Elettronica, Informatica e Sistemistica, Università di Bologna, Bologna, Italy; ⁵Université Paris Sud, Unité Propre de Recherche de l'Enseignement Supérieur Équipe d'Accueil 2397, Centre Chirurgical Marie-Lannelongue, Physiologie, Le Plessis Robinson, France; and ⁶Université Bordeaux 2, Unité Propre de Recherche de l'Enseignement Supérieur Équipe d'Accueil 518, Médecine Aérospatiale, Bordeaux, France

Submitted 5 June 2006 ; accepted in final form 9 January 2007

We tested the hypothesis that in normal subjects, cardiac tissuevelocities, strain, and strain rates (SR), measured by Dopplertissue echocardiography (DTE), are preload dependent. To accomplishit, immediately preceding image acquisition, reversible, repeatable,acute nonpharmacological changes in preload were induced byparabolic flight. DTE has been proposed as a new approach toassess left ventricular regional myocardial function by computingtissue velocities, strain, and SR. However, preload dependenceof these parameters in normal subjects still remains controversial.DTE images (Philips) were obtained in 10 normal subjects instanding upright position at normogravity (1 G_z), hypergravity(1.8 G_z), and microgravity (0 G_z) with and without –50mmHg lower body negative pressure (LBNP). Myocardial velocitycurves in the basal interventricular septum were reconstitutedoffline from DTE images, from which peak systolic (S'), early(E') and late (A') diastolic velocities, SR, and peak systolicstrain (PS ${varepsilon}$ ) were measured and averaged over four beats. At 1.8G_z (reduced venous return), S', E', and A' decreased by 21%,21%, and 26%, respectively, compared with 1-G_z values, whileat 0 G_z (augmented venous return), E', A', and PS ${varepsilon}$ increasedby 57%, 53%, and 49%, respectively. LBNP reduced E' and PS ${varepsilon}$ .In conclusion, our results were in agreement with those obtainedin animal models, in which preload was changed in a controlled,acute, and reversible manner, and image acquisition was performedimmediately following preload modifications. The hypothesisof preload dependence was confirmed for S', E', A', and PS ${varepsilon}$ ,while SR appeared to be preload independent, probably reflectingintrinsic myocardial properties.

Doppler tissue echocardiography; preload dependence; real-time three-dimensional echocardiography; weightlessness

Address for reprint requests and other correspondence: E. G. Caiani, Politecnico di Milano, Dipartimento di Bioingegneria, Piazza L. da Vinci, 32, 20133 Milano, Italy (e-mail: caiani{at}biomed.polimi.it)