Myocardial oxygenation during high work states in hearts with postinfarction remodeling

Citation
Y. Murakami et al., Myocardial oxygenation during high work states in hearts with postinfarction remodeling, CIRCULATION, 99(7), 1999, pp. 942-948
Citations number
27
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Journal title
CIRCULATION
ISSN journal
00097322 → ACNP
Volume
99
Issue
7
Year of publication
1999
Pages
942 - 948
Database
ISI
SICI code
0009-7322(19990223)99:7<942:MODHWS>2.0.ZU;2-T
Abstract
Background-Postinfarction left ventricular remodeling (LVR) is associated w ith reductions in myocardial high-energy phosphate (HEP) levels, which are more severe in animals that develop overt congestive heart failure (CHF). D uring high work states, further HEP loss occurs, which suggests demand-indu ced ischemia. This study tested the hypothesis that inadequate myocyte oxyg en availability is the basis for these HEP abnormalities. Methods and Results-Myocardial infarction was produced by left circumflex c oronary artery ligation in swine. Studies were performed in 20 normal anima ls, 14 animals with compensated LVR, and 9 animals with CHF. Phosphocreatin e (PCr)/ATP was determined with P-31 NMR and deoxymyoglobin (Mb-delta) with H-1 NMR in myocardium remote from the infarct, Basal PCr/ATP tended to be decreased in postinfarct hearts, and this was significant in animals with C HF. Infusion of dobutamine (20 mu g.kg(-1).min(-1) IV) caused doubling of t he rate-pressure product in both normal and LVR hearts and resulted in comp arable significant decreases of PCr/ATP in both groups. This decrease in PC r/ATP was not associated with detectable Mb-delta, In CHF hearts, rate-pres sure product increased only 40% in response to dobutamine; this attenuated response also was not associated with detectable Mb-delta. Conclusions-Thus, the decrease of PCr/ATP during dobutamine infusion is not the result of insufficient myocardial oxygen availability. Furthermore, in CHF hearts, the low basal PCr/ATP and the attenuated response to dobutamin e occurred in the absence of myocardial hypoxia, indicating that the HEP an d contractile abnormalities were not the result of insufficient oxygen avai lability.