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

• Published in: Journal of applied physiology (1985) Vol. 103; no. 1; pp. 80 - 87
• Main Authors: Caiani, E. G, Weinert, L, Takeuchi, M, Veronesi, F, Sugeng, L, Corsi, C, Capderou, A, Cerutti, S, Vaida, P, Lang, R. M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.07.2007; American Physiological Society
• Subjects: Adaptation, Physiological; Adult; Biological and medical sciences; Cardiology; Echocardiography, Doppler; Echocardiography, Doppler, Color; Feasibility Studies; Fundamental and applied biological sciences. Psychology; Heart; Heart Rate; Heart Septum - diagnostic imaging; Heart Septum - physiopathology; Heart Ventricles - diagnostic imaging; Heart Ventricles - physiopathology; Humans; Hypergravity; Hypotheses; Image Interpretation, Computer-Assisted; Lower Body Negative Pressure; Male; Middle Aged; Mitral Valve - diagnostic imaging; Mitral Valve - physiopathology; Myocardial Contraction; Reproducibility of Results; Research Design; Space Flight; Stress, Mechanical; Ultrasonic imaging; Ventricular Function, Left; Weightlessness; Weightlessness Simulation; preload dependence; Echocardiography; Flight; Rhythm; Doppler tissue echocardiography; Weightlessness; Real time; Velocity; Tissue; Vertebrata; Mammalia; real-time three-dimensional echocardiography; Dependence
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00625.2006

1 Dipartimento di Bioingegneria, Politecnico di Milano, Milan, Italy; 2 Cardiac Imaging Center, University of Chicago, Chicago, Illinois; 3 Tane General Hospital, Osaka, Japan; 4 Dipartimento di Elettronica, Informatica e Sistemistica, Università di Bologna, Bologna, Italy; 5 Université Paris Sud, Unité Propre de Recherche de l'Enseignement Supérieur Équipe d'Accueil 2397, Centre Chirurgical Marie-Lannelongue, Physiologie, Le Plessis Robinson, France; and 6 Université 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 tissue velocities, strain, and strain rates (SR), measured by Doppler tissue echocardiography (DTE), are preload dependent. To accomplish it, immediately preceding image acquisition, reversible, repeatable, acute nonpharmacological changes in preload were induced by parabolic flight. DTE has been proposed as a new approach to assess left ventricular regional myocardial function by computing tissue velocities, strain, and SR. However, preload dependence of these parameters in normal subjects still remains controversial. DTE images (Philips) were obtained in 10 normal subjects in standing upright position at normogravity (1 G z ), hypergravity (1.8 G z ), and microgravity (0 G z ) with and without –50 mmHg lower body negative pressure (LBNP). Myocardial velocity curves in the basal interventricular septum were reconstituted offline from DTE images, from which peak systolic (S'), early (E') and late (A') diastolic velocities, SR, and peak systolic strain (PS ) were measured and averaged over four beats. At 1.8 G z (reduced venous return), S', E', and A' decreased by 21%, 21%, and 26%, respectively, compared with 1-G z values, while at 0 G z (augmented venous return), E', A', and PS increased by 57%, 53%, and 49%, respectively. LBNP reduced E' and PS . In conclusion, our results were in agreement with those obtained in animal models, in which preload was changed in a controlled, acute, and reversible manner, and image acquisition was performed immediately following preload modifications. The hypothesis of preload dependence was confirmed for S', E', A', and PS , while SR appeared to be preload independent, probably reflecting intrinsic 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 )