The effect of a myocardial infarction on the normalized time-varying elastance curve

• Published in: Journal of applied physiology (1985) Vol. 102; no. 3; pp. 1123 - 1129
• Main Authors: Jegger, David, Mallik, Ajit S, Nasratullah, Mohammed, Jeanrenaud, Xavier, Silva, Rafaela da, Tevaearai, Hendrik, von Segesser, Ludwig K, Stergiopulos, Nikolaos
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.03.2007; American Physiological Society
• Subjects: Anesthesia; Animals; Biological and medical sciences; Blood pressure; Blood Pressure - physiology; Cardiac Volume - physiology; Cardiology; Clinical outcomes; Clinical trials; Coronary vessels; Elasticity; Fundamental and applied biological sciences. Psychology; Heart attacks; Male; Myocardial Infarction - pathology; Myocardial Infarction - physiopathology; Myocardium - pathology; Rats; Rats, Sprague-Dawley; Rodents; Time Factors; Ventricular Function, Left - physiology; Myocardial infarction; Contractility; conductance volumetry; ventricular function; Cardiovascular disease; Myocardial disease; Elastance; Vertebrata; Mammalia; Ischemia; Heart disease; compliance; Hemodynamics
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00976.2006

1 Laboratory of Haemodynamics and Cardiovascular Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne; 2 Department of Cardiovascular Surgery, Centre Hospitalier Universitaire Vaudois, Lausanne; 3 Department of Cardiovascular Surgery, Inselspital, Bern; and 4 Department of Cardiology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland Submitted 4 September 2006 ; accepted in final form 4 December 2006 It has been suggested that the shape of the normalized time-varying elastance curve [E n ( t n )] is conserved in different cardiac pathologies. We hypothesize, however, that the E n ( t n ) differs quantitatively after myocardial infarction (MI). Sprague-Dawley rats ( n = 9) were anesthetized, and the left anterior descending coronary artery was ligated to provoke the MI. A sham-operated control group (CTRL) ( n = 10) was treated without the MI. Two months later, a conductance catheter was inserted into the left ventricle (LV). The LV pressure and volume were measured and the E n ( t n ) derived. Slopes of E n ( t n ) during the preejection period ( PEP ), ejection period ( EP ), and their ratio ( = EP / PEP ) were calculated, together with the characteristic decay time during isovolumic relaxation ( ) and the normalized elastance at end diastole (E min n ). MI provoked significant LV chamber dilatation, thus a loss in cardiac output (–33%), ejection fraction (–40%), and stroke volume (–30%) ( P < 0.05). Also, it caused significant calcium increase (17-fold), fibrosis (2-fold), and LV hypertrophy. End-systolic elastance dropped from 0.66 ± 0.31 mmHg/µl (CTRL) to 0.34 ± 0.11 mmHg/µl (MI) ( P < 0.05). Normalized elastance was significantly reduced in the MI group during the preejection, ejection, and diastolic periods ( P < 0.05). The slope of E n ( t n ) during the PEP and were significantly altered after MI ( P < 0.05). Furthermore, and end-diastolic E min n were both significantly augmented in the MI group. We conclude that the E n ( t n ) differs quantitatively in all phases of the heart cycle, between normal and hearts post-MI. This should be considered when utilizing the single-beat concept. compliance; ischemia; contractility; ventricular function; hemodynamics; conductance volumetry Address for reprint requests and other correspondence: D. Jegger, Laboratory of Haemodynamics and Cardiovascular Technology, Swiss Federal Institute of Technology, Batiment AAB.026, 1015 Lausanne, Switzerland (e-mail: David.Jegger{at}epfl.ch )