TY - JOUR
T1 - Effect of Adjustable Passive Constraint on the Failing Left Ventricle
T2 - A Finite-Element Model Study
AU - Jhun, Choon-Sik
AU - Wenk, Jonathan F.
AU - Zhang, Zhihong
AU - Wall, Samuel T.
AU - Sun, Kay
AU - Sabbah, Hani N.
AU - Ratcliffe, Mark B.
AU - Guccione, Julius M.
N1 - Funding Information:
This work was supported by grants 5R01 HL077921 (J.M.G.), 5R01 HL063348 (Mark B. Ratcliffe), and P41 RR08605 from the National Institutes of Health .
PY - 2010/1
Y1 - 2010/1
N2 - Background: Passive constraint is used to prevent left ventricular dilation and subsequent remodeling. However, there has been concern about the effect of passive constraint on diastolic left ventricular chamber stiffness and pump function. This study determined the relationship between constraint, diastolic wall stress, chamber stiffness, and pump function. We tested the hypothesis that passive constraint at 3 mm Hg reduces wall stress with minimal change in pump function. Methods: A three-dimensional finite-element model of the globally dilated left ventricle based on left ventricular dimensions obtained in dogs that had undergone serial intracoronary microsphere injection was created. The model was adjusted to match experimentally observed end-diastolic left ventricular volume and midventricular wall thickness. The experimental results used to create the model were previously reported. A pressure of 3, 5, 7, and 9 mm Hg was applied to the epicardium. Fiber stress, end-diastolic pressure-volume relationship, end-systolic pressure-volume relationship, and the stroke volume-end-diastolic pressure (Starling) relationship were calculated. Results: As epicardial constraint pressure increased, fiber stress decreased, the end-diastolic pressure-volume relationship shifted to the left, and the Starling relationship shifted down and to the right. The end-systolic pressure-volume relationship did not change. A constraining pressure of 2.3 mm Hg was associated with a 10% reduction in stroke volume, and mean end-diastolic fiber stress was reduced by 18.3% (inner wall), 15.3% (mid wall), and 14.2% (outer wall). Conclusions: Both stress and cardiac output decrease in a linear fashion as the amount of passive constraint is increased. If the reduction in cardiac output is to be less than 10%, passive constraint should not exceed 2.3 mm Hg. On the other hand, this amount of constraint may be sufficient to reverse eccentric hypertrophy after myocardial infarction.
AB - Background: Passive constraint is used to prevent left ventricular dilation and subsequent remodeling. However, there has been concern about the effect of passive constraint on diastolic left ventricular chamber stiffness and pump function. This study determined the relationship between constraint, diastolic wall stress, chamber stiffness, and pump function. We tested the hypothesis that passive constraint at 3 mm Hg reduces wall stress with minimal change in pump function. Methods: A three-dimensional finite-element model of the globally dilated left ventricle based on left ventricular dimensions obtained in dogs that had undergone serial intracoronary microsphere injection was created. The model was adjusted to match experimentally observed end-diastolic left ventricular volume and midventricular wall thickness. The experimental results used to create the model were previously reported. A pressure of 3, 5, 7, and 9 mm Hg was applied to the epicardium. Fiber stress, end-diastolic pressure-volume relationship, end-systolic pressure-volume relationship, and the stroke volume-end-diastolic pressure (Starling) relationship were calculated. Results: As epicardial constraint pressure increased, fiber stress decreased, the end-diastolic pressure-volume relationship shifted to the left, and the Starling relationship shifted down and to the right. The end-systolic pressure-volume relationship did not change. A constraining pressure of 2.3 mm Hg was associated with a 10% reduction in stroke volume, and mean end-diastolic fiber stress was reduced by 18.3% (inner wall), 15.3% (mid wall), and 14.2% (outer wall). Conclusions: Both stress and cardiac output decrease in a linear fashion as the amount of passive constraint is increased. If the reduction in cardiac output is to be less than 10%, passive constraint should not exceed 2.3 mm Hg. On the other hand, this amount of constraint may be sufficient to reverse eccentric hypertrophy after myocardial infarction.
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U2 - 10.1016/j.athoracsur.2009.08.075
DO - 10.1016/j.athoracsur.2009.08.075
M3 - Article
C2 - 20103222
AN - SCOPUS:76449120049
SN - 0003-4975
VL - 89
SP - 132
EP - 137
JO - Annals of Thoracic Surgery
JF - Annals of Thoracic Surgery
IS - 1
ER -