Distinctive changes in end-diastolic wall thickness and postsystolic thickening in viable and infarcted myocardium.
OBJECTIVE
In this study, we sought to compare the magnitude of changes in end-diastolic wall thickness (WT(ed)) and postsystolic thickening (PST) in a swine model of stunning and reperfused acute myocardial infarction, and to explore the relationship between WT(ed) and PST.


METHODS
Twenty-six pigs were subjected to left anterior descending coronary artery occlusion followed by reperfusion to induce stunning (n = 6), nontransmural (n = 8), or transmural (n = 12) myocardial infarction. Myocardial wall thickness was measured using intracardiac echocardiography. Transmural extent of necrosis (TEN) was quantified by triphenyltetrazolium chloride technique.


RESULTS
During the first minutes of reperfusion, a marked increase in WT(ed) occurred in the myocardial walls with nontransmural and transmural infarct (42% and 102%, respectively) but less in those with stunning (19%). PST persisted at reperfusion in walls with stunning and nontransmural infarct (23% and 26%, respectively). In transmurally infarcted walls, PST progressively decreased either during occlusion (5/12 pigs) or shortly after reperfusion (7/12 pigs). PST at reperfusion was virtually absent when TEN was >70%. Both PST and the increase in WT(ed) at reperfusion correlated well with TEN (P <.0001 for both). Changes in PST at reperfusion were weakly correlated with changes in WT(ed).


CONCLUSIONS
A marked increase in WT(ed) after reperfusion and absence of PST indicate transmural myocardial infarction. Presence of PST at reperfusion indicates viable tissue in more than 30% of wall thickness. The results suggest that amplitude of PST is modulated predominantely by factors related to the severity of ischemia and, to a smaller extent, by changes in wall thickness.
Pislaru
Cristina
C
Mayo Clinic College of Medicine, Ultrasound Research Laboratory, Rochester, MN 55905, USA. Pislaru.Cristina@mayo.edu
Bruce
Charles J
CJ
Seward
James B
JB
Greenleaf
James F
JF
D000704:Analysis of Variance; D000818:Animals; D003971:Diastole; D004195:Disease Models, Animal; D004452:Echocardiography; D006439:Hemodynamics; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D017682:Myocardial Stunning / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology*; D009336:Necrosis; D012044:Regression Analysis; D013552:Swine; D013599:Systole; D013997:Time Factors