TY - JOUR
T1 - Alterations in left ventricular torsion and diastolic recoil after myocardial infarction with and without chronic ischemic mitral regurgitation
AU - Tibayan, Frederick A.
AU - Rodriguez, Filiberto
AU - Langer, Frank
AU - Zasio, Mary K.
AU - Bailey, Lynn
AU - Liang, David
AU - Daughters, George T.
AU - Ingels, Neil B.
AU - Miller, D. Craig
PY - 2004/9/14
Y1 - 2004/9/14
N2 - Background-Chronic ischemic mitral regurgitation (CIMR) is associated with heart failure that continues unabated whether the valve is repaired, replaced, or ignored. Altered left ventricular (LV) torsion dynamics, with deleterious effects on transmural gradients of oxygen consumption and diastolic filling, may play a role in the cycle of the failing myocardium. We hypothesized that LV dilatation and perturbations in torsion would be greater in animals in which CIMR developed after inferior myocardial infarction (MI) than in those that it did not. Methods-8±2 days after marker placement in sheep, 3-dimensional fluoroscopic marker data (baseline) were obtained before creating inferior MI by snare occlusion. After 7±1 weeks, the animals were restudied (chronic). Inferior MI resulted in CIMR in 11 animals but not in 9 (non-CIMR). End-diastolic septal-lateral and anterior-posterior LV diameters, maximal torsional deformation (φmax, rotation of the LV apex with respect to the base), and torsional recoil in early diastole (φ5%, first 5% of filling) for each LV free wall region (anterior, lateral, posterior) were measured. Results-Both CIMR and non-CIMR animals demonstrated derangement of LV torsion after inferior MI. In contrast to non-CIMR, CIMR animals exhibited greater LV dilation and significant reductions in posterior maximal torsion (6.1±4.3° to 3.9±1.9°* to versus 4.4±2.5° to 2.8±2.0°; mean±SD, baseline to chronic, *P<0.05) and anterior torsional recoil (-1.4±1.1° to -0.2±1.0° versus -1.2±1.0° to -1.3±1.6°). Conclusion-MI associated with CIMR resulted in greater perturbations in torsion and recoil than inferior MI without CIMR. These perturbations may be linked to more LV dilation in CIMR, which possibly reduced the effectiveness of fiber shortening on torsion generation. Altered torsion and recoil may contribute to the "ventricular disease" component of CIMR, with increased gradients of myocardial oxygen consumption and impaired diastolic filling. These abnormalities in regional torsion and recoil may, in part, underlie the "ventricular disease" of CIMR, which may persist despite restoration of mitral competence.
AB - Background-Chronic ischemic mitral regurgitation (CIMR) is associated with heart failure that continues unabated whether the valve is repaired, replaced, or ignored. Altered left ventricular (LV) torsion dynamics, with deleterious effects on transmural gradients of oxygen consumption and diastolic filling, may play a role in the cycle of the failing myocardium. We hypothesized that LV dilatation and perturbations in torsion would be greater in animals in which CIMR developed after inferior myocardial infarction (MI) than in those that it did not. Methods-8±2 days after marker placement in sheep, 3-dimensional fluoroscopic marker data (baseline) were obtained before creating inferior MI by snare occlusion. After 7±1 weeks, the animals were restudied (chronic). Inferior MI resulted in CIMR in 11 animals but not in 9 (non-CIMR). End-diastolic septal-lateral and anterior-posterior LV diameters, maximal torsional deformation (φmax, rotation of the LV apex with respect to the base), and torsional recoil in early diastole (φ5%, first 5% of filling) for each LV free wall region (anterior, lateral, posterior) were measured. Results-Both CIMR and non-CIMR animals demonstrated derangement of LV torsion after inferior MI. In contrast to non-CIMR, CIMR animals exhibited greater LV dilation and significant reductions in posterior maximal torsion (6.1±4.3° to 3.9±1.9°* to versus 4.4±2.5° to 2.8±2.0°; mean±SD, baseline to chronic, *P<0.05) and anterior torsional recoil (-1.4±1.1° to -0.2±1.0° versus -1.2±1.0° to -1.3±1.6°). Conclusion-MI associated with CIMR resulted in greater perturbations in torsion and recoil than inferior MI without CIMR. These perturbations may be linked to more LV dilation in CIMR, which possibly reduced the effectiveness of fiber shortening on torsion generation. Altered torsion and recoil may contribute to the "ventricular disease" component of CIMR, with increased gradients of myocardial oxygen consumption and impaired diastolic filling. These abnormalities in regional torsion and recoil may, in part, underlie the "ventricular disease" of CIMR, which may persist despite restoration of mitral competence.
KW - Mechanics
KW - Mitral valve
KW - Myocardial infarction
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U2 - 10.1161/01.CIR.0000138385.05471.41
DO - 10.1161/01.CIR.0000138385.05471.41
M3 - Article
C2 - 15364848
AN - SCOPUS:4644271333
SN - 0009-7322
VL - 110
SP - II109-II114
JO - Circulation
JF - Circulation
IS - 11 SUPPL.
ER -