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

Jegger, David; Mallik, Ajit S; Nasratullah, Mohammed; Jeanrenaud, Xavier; da Silva, Rafaela; Tevaearai, Hendrik; von Segesser, Ludwig K; Stergiopulos, Nikolaos (2007). The effect of a myocardial infarction on the normalized time-varying elastance curve. Journal of applied physiology, 102(3), pp. 1123-9. Bethesda, Md.: American Physiological Society 10.1152/japplphysiol.00976.2006

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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 (alpha(PEP)), ejection period (alpha(EP)), and their ratio (beta = alpha(EP)/alpha(PEP)) were calculated, together with the characteristic decay time during isovolumic relaxation (tau) 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/microl (CTRL) to 0.34 +/- 0.11 mmHg/microl (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 alpha(PEP) and beta were significantly altered after MI (P < 0.05). Furthermore, tau 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.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Cardiovascular Disorders (DHGE) > Clinic of Heart Surgery
UniBE Contributor:	Tevaearai, Hendrik
ISSN:	8750-7587
ISBN:	17158245
Publisher:	American Physiological Society
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:56
Last Modified:	27 Feb 2024 14:29
Publisher DOI:	10.1152/japplphysiol.00976.2006
PubMed ID:	17158245
Web of Science ID:	000244722400042
URI:	https://boris.unibe.ch/id/eprint/23983 (FactScience: 45569)