Extension of borderzone myocardium in postinfarction dilated cardiomyopathy
BM Jackson, JH Gorman, SL Moainie, TS Guy… - Journal of the American …, 2002 - jacc.org
BM Jackson, JH Gorman, SL Moainie, TS Guy, N Narula, J Narula, MG St. John-Sutton…
Journal of the American College of Cardiology, 2002•jacc.orgObjectives: This study tests the hypothesis that hypocontractile, borderzone myocardium
adjacent to an expanding infarct becomes progressively larger and more hypocontractile as
remodeling continues. Background: Early infarct expansion following anteroapical
myocardial infarction (MI) is associated with progressive ventricular dilation and heart
failure. The contribution of perfused, hypocontractile, borderzone myocardium to this
process is unknown. Methods: Using a sheep model of anteroapical infarction …
adjacent to an expanding infarct becomes progressively larger and more hypocontractile as
remodeling continues. Background: Early infarct expansion following anteroapical
myocardial infarction (MI) is associated with progressive ventricular dilation and heart
failure. The contribution of perfused, hypocontractile, borderzone myocardium to this
process is unknown. Methods: Using a sheep model of anteroapical infarction …
Objectives
This study tests the hypothesis that hypocontractile, borderzone myocardium adjacent to an expanding infarct becomes progressively larger and more hypocontractile as remodeling continues.
Background
Early infarct expansion following anteroapical myocardial infarction (MI) is associated with progressive ventricular dilation and heart failure. The contribution of perfused, hypocontractile, borderzone myocardium to this process is unknown.
Methods
Using a sheep model of anteroapical infarction, sonomicrometry array localization and serial microsphere injections were used to track changes in regional myocardial contractility, geometry, and perfusion. Eight sheep were studied before and after infarction and two, five, and eight weeks later. Thirty intertransducer chord lengths were analyzed to measure regional contractility and serial changes in regional geometry at end systole.
Results
Beginning as a narrow band of fully perfused hypocontractile myocardium adjacent to the infarction, borderzone myocardium extends to involve additional contiguous myocardium that progressively loses contractile function as the heart remodels. Three distinct myocardial zones develop as a result of transmural MI: infarct, borderzone (perfused but hypocontractile), and remote (perfused and normally functioning).
Conclusions
This study demonstrates that hypocontractile, fully perfused borderzone myocardium extends to involve contiguous normal myocardium during postinfarction remodeling. This borderzone myocardium is a unique type of perfused, hypocontractile myocardium, which is distinct from hibernating or stunned myocardium. Preventing extension of borderzone myocardium by medical or surgical means offers the prospect of preventing late-onset heart failure following transmural expanding MIs.
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