Green G R, Dagum P, Glasson J R, Daughters G T, Bolger A F, Foppiano L E, Ingels N B, Miller D C
Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, CA 94305-5247, USA.
Circulation. 1998 Nov 10;98(19 Suppl):II128-35; discussion II135-6.
Previous studies have revealed that rigid mitral annuloplasty rings may be associated with left ventricular (LV) systolic dysfunction, but whether ring type affects regional systolic function at the base of the LV, in the region near the mitral annulus, is unclear. We tested the hypothesis that rigid fixation of the mitral annulus results in significant regional systolic dysfunction at the base of the LV.
Twenty-six adult male sheep underwent placement of 13 miniature tantalum markers into the LV epicardium and around the mitral annulus to allow calculation of LV volume and regional epicardial area. Group I (n = 7) sheep served as controls; animals randomized to groups II (n = 11) and III (n = 8) underwent mitral annuloplasty with either a semirigid or flexible ring, respectively. After a 7- to 10-day recovery period, animals were studied in a closed-chest, sedated, autonomically blocked state. Global LV systolic function (end-systolic elastance and preload recruitable stroke work) were not significantly different among the 3 groups (P = 1.0, ANOVA). Regional systolic function at the base of the LV (fractional area shrinkage [FAS] of 4 epicardial areas) at comparable LV preload and afterload was similar in the 4 basal areas (P = 0.223, MANOVA). With the use of load-insensitive indexes (slope and area intercept of the end-systolic pressure-regional area relationship and regional stroke work-end-diastolic area relationship), regional systolic function also was not different between groups at baseline or with inotropic stimulation in any basal region (P > 0.05, MANOVA). Furthermore, neither annuloplasty ring perturbed the regional pattern of basal LV systolic function.
Postoperative LV systolic function, both globally and in the region of the base of the LV (near the mitral annulus), was not altered with either semirigid or flexible ring fixation of the mitral annulus.
既往研究显示，刚性二尖瓣环成形环可能与左心室（LV）收缩功能障碍有关，但环的类型是否会影响LV底部（二尖瓣环附近区域）的局部收缩功能尚不清楚。我们检验了以下假设：二尖瓣环的刚性固定会导致LV底部出现明显的局部收缩功能障碍。
26只成年雄性绵羊在LV心外膜和二尖瓣环周围植入13个微型钽标记物，以便计算LV容积和局部心外膜面积。I组（n = 7）绵羊作为对照；随机分为II组（n = 11）和III组（n = 8）的动物分别接受了半刚性或柔性环的二尖瓣环成形术。经过7至10天的恢复期后，在闭胸、镇静、自主神经阻滞状态下对动物进行研究。三组之间的整体LV收缩功能（收缩末期弹性和可募集前负荷的每搏功）无显著差异（P = 1.0，方差分析）。在可比的LV前负荷和后负荷下，LV底部的局部收缩功能（4个心外膜区域的面积缩小分数[FAS]）在4个底部区域相似（P = 0.223，多变量方差分析）。使用负荷不敏感指标（收缩末期压力-局部面积关系的斜率和面积截距以及局部每搏功-舒张末期面积关系），在任何底部区域，基线时或使用正性肌力刺激时，组间局部收缩功能也无差异（P > 0.05，多变量方差分析）。此外，两种环成形环均未扰乱LV底部收缩功能的局部模式。
二尖瓣环的半刚性或柔性环固定术后，整体LV收缩功能以及LV底部（二尖瓣环附近）区域的收缩功能均未改变。
