Border zone geometry increases wall stress after myocardial infarction: contrast echocardiographic assessment

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 284; no. 2; pp. H475 - H479
• Main Authors: Jackson, Benjamin M, Gorman, Joseph H., III, Salgo, Ivan S, Moainie, Sina L, Plappert, Theodore, St. John-Sutton, Martin, Edmunds, L. Henry, Jr, Gorman, Robert C
• Format: Journal Article
• Language: English
• Published: United States 01.02.2003
• Subjects: Animals; Contrast Media; Echocardiography; Heart - physiopathology; Models, Cardiovascular; Myocardial Infarction - diagnostic imaging; Myocardial Infarction - physiopathology; Sheep; Stress, Mechanical
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00360.2002

1  Department of Surgery and the Harrison Department of Surgical Research and 2  Division of Cardiology, Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104; and 3  Philips Medical Systems, Andover, Massachusetts 01810 After myocardial infarction (MI), the border zone expands chronically, causing ventricular dilatation and congestive heart failure (CHF). In an ovine model ( n  = 4) of anteroapical MI that results in CHF, contrast echocardiography was used to image short-axis left ventricular (LV) cross sections and identify border zone myocardium before and after coronary artery ligation. In the border zone at end systole, the LV endocardial curvature ( K ) decreased from 0.86 ± 0.33 cm 1 at baseline to 0.35 ± 0.19 cm 1 at 1 h ( P  < 0.05), corresponding to a mean decrease of 55%. Also in the border zone, the wall thickness ( h ) decreased from 1.14   ± 0.26 cm at baseline to 1.01 ± 0.25 cm at 1 h ( P  < 0.05), corresponding to a mean decrease of 11%. By Laplace's law, wall stress is inversely proportional to the product K ·  h . Therefore, a 55% decrease in K results in a 122% increase in circumferential stress; a 11% decrease in h results in a 12% increase in circumferential stress. These findings indicate that after MI, geometric changes cause increased dynamic wall stress, which likely contributes to border zone expansion and remodeling. congestive heart failure; remodeled myocardium; coronary artery disease; perfusion echocardiography