Objective        To evaluate the dynamic evolutions of left ventricular (LV) torsion using velocity vector imaging (VVI) in rabbits after apical myocardial infarction (MI).       Methods        MI model was induced by occlusion of coronary artery in New Zealand white rabbits. Dynamic cardiac images of LV were collected in 1 d before and within 8 weeks after MI. All of these images were analyzed off-line using VVI software and torsion-related parameters were recorded.       Results        Rotate angle

rotate velocity and recoiling velocity of basal LV tended to decrease within 1 week post MI but without obvious difference (P0.05)

and then significantly decreased in 2 to 8 weeks after surgery (P0.05). In 1 d after surgery

rotate angle

rotate velocity and recoiling velocity of apical LV were greatly lower than those before surgery (P0.05)

and then gradually decreased post MI and reached the lowest after 4 weeks (P00.05). Time to peak untwisting velocity of LV gradually prolonged and the percentage of isovolumic untwisting to entire untwisting decreased within 8 weeks post MI (P0.05). Similar to rotational changes of apical LV

twist angle

twist velocity

and untwisting velocity of LV were also decreased after MI (P0.05). The trend of LV rotation parameters was coincidence with that of apical LV.       Conclusion        Apical rotation is gradually decreased post apical MI

with the rotational change of apical LV greater and occuring earlier than that of basal LV. The impairment of systolic twist and diastolic untwisting after MI might be mainly caused by rotational changes of apical LV.