Atrial contraction and mitral annular dynamics during acute left atrial and ventricular ischemia in sheep.
In six sheep, radiopaque markers were placed on the left ventricle (LV), the mitral annulus, the left atrium (LA), and the central edge of both mitral leaflets to investigate the effects of acute LV ischemia on atrial contraction, mitral annular area (MAA), and mitral regurgitation (MR). Animals were studied with biplane videofluoroscopy and transesophageal echocardiography before and during balloon occlusion of the left anterior descending (LAD), distal circumflex (dLCX), and proximal circumflex (pLCX) coronary arteries. MAA and LA area were calculated from the corresponding markers. LAD occlusion did not alter LA area reduction or presystolic MAA reduction, whereas dLCX occlusion resulted in a mild decrease in the former with no change in the latter. Neither occlusion resulted in MR. pLCX occlusion, however, significantly decreased LA area and presystolic MAA reduction and resulted in increased end-diastolic MAA, delayed valve closure from end diastole, and MR. Decreased atrial contractile function, as observed during acute posterolateral ischemia, is linked to diminished presystolic mitral annular reduction, a larger mitral annular size at end diastole, and MR.
Timek
Tomasz A
TA
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA 94301, USA.
Lai
David T
DT
Tibayan
Frederick
F
Daughters
George T
GT
Liang
David
D
Dagum
Paul
P
Lo
Sidney
S
Miller
D Craig
DC
Ingels
Neil B
NB
D000208:Acute Disease; D000818:Animals; D003331:Coronary Vessels / Q000502:physiology; D006325:Heart Atria; D006352:Heart Ventricles; D008297:Male; D008943:Mitral Valve / Q000503:physiopathology*; D008944:Mitral Valve Insufficiency / Q000503:physiopathology*; D009200:Myocardial Contraction / Q000502:physiology*; D017202:Myocardial Ischemia / Q000503:physiopathology*; D012756:Sheep