Myocardial Edema After Ischemia/Reperfusion Is Not Stable and Follows a Bimodal Pattern

• Published in: Journal of the American College of Cardiology Vol. 65; no. 4; pp. 315 - 323
• Main Authors: Fernández-Jiménez, Rodrigo, MD, Sánchez-González, Javier, PhD, Agüero, Jaume, MD, García-Prieto, Jaime, BSc, López-Martín, Gonzalo J., Tech, García-Ruiz, José M., MD, Molina-Iracheta, Antonio, DVM, Rosselló, Xavier, MD, Fernández-Friera, Leticia, MD, PhD, Pizarro, Gonzalo, MD, García-Álvarez, Ana, MD, PhD, Dall'Armellina, Erica, MD, DPhil, Macaya, Carlos, MD, PhD, Choudhury, Robin P., DM, Fuster, Valentin, MD, PhD, Ibáñez, Borja, MD, PhD
• Format: Journal Article
• Language: English
• Published: New York Elsevier Inc 03.02.2015; Elsevier Limited
• Subjects: Cardiology; Cardiovascular; CMR; Content analysis; Heart attacks; Hogs; Internal Medicine; Ischemia; Laboratory animals; MRI; myocardial infarction; pig; Studies; Veins & arteries; water content; NEX; T2 weighted; repetition time; MRI; myocardial infarction; CMR; FOV; field of view; STIR; I/R; ROI; pig; ischemia/reperfusion; TE; number of excitations; region of interest; echo time; water content; T2W; short-tau inversion recovery; cardiac magnetic resonance; T2; TR
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/j.jacc.2014.11.004

Abstract Background It is widely accepted that edema occurs early in the ischemic zone and persists in stable form for at least 1 week after myocardial ischemia/reperfusion. However, there are no longitudinal studies covering from very early (minutes) to late (1 week) reperfusion stages confirming this phenomenon. Objectives This study sought to perform a comprehensive longitudinal imaging and histological characterization of the edematous reaction after experimental myocardial ischemia/reperfusion. Methods The study population consisted of 25 instrumented Large-White pigs (30 kg to 40 kg). Closed-chest 40-min ischemia/reperfusion was performed in 20 pigs, which were sacrificed at 120 min (n = 5), 24 h (n = 5), 4 days (n = 5), and 7 days (n = 5) after reperfusion and processed for histological quantification of myocardial water content. Cardiac magnetic resonance (CMR) scans with T2-weighted short-tau inversion recovery and T2-mapping sequences were performed at every follow-up stage until sacrifice. Five additional pigs sacrificed after baseline CMR served as controls. Results In all pigs, reperfusion was associated with a significant increase in T2 relaxation times in the ischemic region. On 24-h CMR, ischemic myocardium T2 times returned to normal values (similar to those seen pre-infarction). Thereafter, ischemic myocardium-T2 times in CMR performed on days 4 and 7 after reperfusion progressively and systematically increased. On day 7 CMR, T2 relaxation times were as high as those observed at reperfusion. Myocardial water content analysis in the ischemic region showed a parallel bimodal pattern: 2 high water content peaks at reperfusion and at day 7, and a significant decrease at 24 h. Conclusions Contrary to the accepted view, myocardial edema during the first week after ischemia/reperfusion follows a bimodal pattern. The initial wave appears abruptly upon reperfusion and dissipates at 24 h. Conversely, the deferred wave of edema appears progressively days after ischemia/reperfusion and is maximal around day 7 after reperfusion.