TY - JOUR
T1 - Ischemia in three left ventricular regions
T2 - Insights into the pathogenesis of acute ischemic mitral regurgitation
AU - Timek, Tomasz A.
AU - Lai, David T.
AU - Tibayan, Frederick
AU - Liang, David
AU - Daughters, George T.
AU - Dagum, Paul
AU - Zasio, Mary K.
AU - Lo, Sidney
AU - Hastie, Trevor
AU - Ingels, Neil B.
AU - Miller, D. Craig
AU - Spotnitz, Henry M.
AU - Adams, David H.
N1 - Funding Information:
Supported by grants HL-29589 and HL-67025 from the National Heart, Lung, and Blood Institute. Drs Timek, Tibayan, Dagum, and Lai are Carl and Leah McConnell Cardiovascular Surgical Research Fellows. Drs Timek, Dagum, and Tibayan were also supported by NHLBI Individual Research Service Awards HL-10452, HL-10000, and HL-67563, respectively. Dr Timek is also a recipient of the Thoracic Surgery Foundation Research Fellowship Award. Dr Lai was supported by a fellowship from the American Heart Association, Western States Affiliate.
PY - 2003/3/1
Y1 - 2003/3/1
N2 - Background: Acute posterolateral left ventricular ischemia in sheep results in ischemic mitral regurgitation, but the effects of ischemia in other left ventricular regions on ischemic mitral regurgitation is unknown. Methods: Six adult sheep had radiopaque markers placed on the left ventricle, mitral annulus, and anterior and posterior mitral leaflets at the valve center and near the anterior and posterior commissures. After 6 to 8 days, animals were studied with biplane videofluoroscopy and transesophageal echocardiography before and during sequential balloon occlusion of the left anterior descending, distal left circumflex, and proximal left circumflex coronary arteries. Time of valve closure was defined as the time when the distance between leaflet edge markers reached its minimum plateau, and systolic leaflet edge separation distance was calculated on the basis of left ventricular ejection. Results: Only proximal left circumflex coronary artery occlusion resulted in ischemic mitral regurgitation, which was central and holosystolic. Delayed valve closure (anterior commissure, 58 ± 29 vs 92 ± 24 ms; valve center, 52 ± 26 vs 92 ± 23 ms; posterior commissure, 60 ± 30 vs 94 ± 14 ms; all P < .05) and increased leaflet edge separation distance during ejection (mean increase, 2.2 ± 1.5 mm, 2.1 ± 1.9 mm, and 2.1 ± 1.5 mm at the anterior commissure, valve center, and posterior commissure, respectively; P < .05 for all) was seen during proximal left circumflex coronary artery occlusion but not during left anterior descending or distal left circumflex coronary artery occlusion. Ischemic mitral regurgitation was associated with a 19% ± 10% increase in mitral annular area, and displacement of both papillary muscle tips away from the septal annulus at end systole. Conclusions: Acute ischemic mitral regurgitation in sheep occurred only after proximal left circumflex coronary artery occlusion along with delayed valve closure in early systole and increased leaflet edge separation throughout ejection in all 3 leaflet coaptation sites. The degree of left ventricular systolic dysfunction induced did not correlate with ischemic mitral regurgitation, but both altered valvular and subvalvular 3-dimensional geometry were necessary to produce ischemic mitral regurgitation during acute left ventricular ischemia.
AB - Background: Acute posterolateral left ventricular ischemia in sheep results in ischemic mitral regurgitation, but the effects of ischemia in other left ventricular regions on ischemic mitral regurgitation is unknown. Methods: Six adult sheep had radiopaque markers placed on the left ventricle, mitral annulus, and anterior and posterior mitral leaflets at the valve center and near the anterior and posterior commissures. After 6 to 8 days, animals were studied with biplane videofluoroscopy and transesophageal echocardiography before and during sequential balloon occlusion of the left anterior descending, distal left circumflex, and proximal left circumflex coronary arteries. Time of valve closure was defined as the time when the distance between leaflet edge markers reached its minimum plateau, and systolic leaflet edge separation distance was calculated on the basis of left ventricular ejection. Results: Only proximal left circumflex coronary artery occlusion resulted in ischemic mitral regurgitation, which was central and holosystolic. Delayed valve closure (anterior commissure, 58 ± 29 vs 92 ± 24 ms; valve center, 52 ± 26 vs 92 ± 23 ms; posterior commissure, 60 ± 30 vs 94 ± 14 ms; all P < .05) and increased leaflet edge separation distance during ejection (mean increase, 2.2 ± 1.5 mm, 2.1 ± 1.9 mm, and 2.1 ± 1.5 mm at the anterior commissure, valve center, and posterior commissure, respectively; P < .05 for all) was seen during proximal left circumflex coronary artery occlusion but not during left anterior descending or distal left circumflex coronary artery occlusion. Ischemic mitral regurgitation was associated with a 19% ± 10% increase in mitral annular area, and displacement of both papillary muscle tips away from the septal annulus at end systole. Conclusions: Acute ischemic mitral regurgitation in sheep occurred only after proximal left circumflex coronary artery occlusion along with delayed valve closure in early systole and increased leaflet edge separation throughout ejection in all 3 leaflet coaptation sites. The degree of left ventricular systolic dysfunction induced did not correlate with ischemic mitral regurgitation, but both altered valvular and subvalvular 3-dimensional geometry were necessary to produce ischemic mitral regurgitation during acute left ventricular ischemia.
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U2 - 10.1067/mtc.2003.43
DO - 10.1067/mtc.2003.43
M3 - Article
C2 - 12658198
AN - SCOPUS:0037348647
SN - 0022-5223
VL - 125
SP - 559
EP - 569
JO - Journal of Thoracic and Cardiovascular Surgery
JF - Journal of Thoracic and Cardiovascular Surgery
IS - 3
ER -