title: Quantitation of myocardial borderzone using reconstructive 3-D echocardiography after chronic infarction in rats: incremental value of low-dose dobutamine.
abstract: Myocardial remodeling determines the degree of left ventricular dysfunction and mortality after transmural chronic myocardial infarction (CMI). Noninvasive characterization and quantitation of myocardial borderzone and collagenous scar are therefore parameters of clinical interest. The aims of this study were (i) to measure accuracy of reconstructive 3-D echocardiography (3DE) in scar and myocardial borderzone size assessment and (ii) to investigate the incremental value of low-dose dobutamine stress. 3DE was performed in 14 immunodeficient rats (rnu-rnu, 180-200 g) with anterior CMI 25 d after coronary ligation. Briefly, consecutive parallel short-axis cineloops were obtained electrocardiogram-gated starting from base to the apex. Morphology (mass, surface) and function (contractility, contractile reserve) of different compartments were assessed and correlated with 3-D histomorphometry. Histology was done using picrosirius red for collagen staining. 3DE left ventricular mass correlated closely with histomorphometry (y = 0.89x + 155, p < 0.0001, r = 0.80). Hypo- and akinetic myocardial surface correlated well with borderzone myocardium (y = 0.34x + 17, p = 0.009, r = 0.62) and collagenous scar (y = 1.9x + 4.4, p < 0.0001, r = 0.79), respectively. Extent of abnormal wall motion was closely related to borderzone and scar tissue area (y = 0.82x + 7, p < 0.0001, r = 0.77). 3DE quantitation of borderzone myocardium, but not collagenous scar, was more closely correlated to histomorphometry during inotropic stimulation. Global contractile reserve is positively associated with the size of myocardial borderzone. Regional contractile reserve of borderzone myocardium is not negatively associated with its collagen content. 3DE allows precise quantitation of myocardial borderzone and identification of transmural scar tissue noninvasively. Assessment of contractile reserve improves characterization and estimation of myocardial borderzone after CMI.
authors.affiliation: Department of Medicine/Cardiology, University of Bonn, Bonn, Germany. ghanem@uni-bonn.de
authors.forename: Alexander
authors.initials: A
authors.lastname: Ghanem
authors.forename: Clemens
authors.initials: C
authors.lastname: Troatz
authors.forename: Naziha
authors.initials: N
authors.lastname: Elhafi
authors.forename: Oliver
authors.initials: O
authors.lastname: Dewald
authors.forename: Christopher
authors.initials: C
authors.lastname: Heeschen
authors.forename: Georg
authors.initials: G
authors.lastname: Nickenig
authors.forename: Joerg
authors.initials: J
authors.lastname: Stypmann
authors.forename: Klaus
authors.initials: K
authors.lastname: Tiemann
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000008:administration & dosage; D002921:Cicatrix / Q000000981:diagnostic imaging / Q000473:pathology; D004195:Disease Models, Animal; D004280:Dobutamine / Q000008:administration & dosage; D005240:Feasibility Studies; D005260:Female; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D011923:Rats, Nude; D014463:Ultrasonography; D020257:Ventricular Remodeling
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine