Effects of mitral valve replacement on regional left ventricular systolic strain.
Effects of mitral valve replacement on regional left ventricular systolic strain.
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二尖瓣置换术对局部左心室收缩应变的影响。
DOI：
10.1016/s0003-4975(99)00619-0
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Miller,DC
中科院分区：
文献类型：
--
作者：
Moon,MR;DeAndaJr,A;Daughters2nd,GT;IngelsJr,NB;Miller,DC
背景二尖瓣置换术（MVR）伴腱索切除会损害左心室（LV）收缩功能，但其机制仍不完全清楚。正常环形乳头连续性的丧失也会对左心室扭转变形产生不利影响，可能是由于心肌纤维收缩模式的变化。方法27只狗接受了左心室心肌标记物的插入和假手术（体外循环，无MVR，n = 6），常规MVR与腱索切除（n = 7），或保留腱索的MVR与前叶腱索重新附着到前部瓣环 (n = 7) 或后瓣环 (n = 7)。在左心室前部、外侧、后部和间隔区域，从每个区域的中央标记到其周围标记构建了线性弦。计算每个弦的收缩期缩短百分比（局部左心室应变），并将弦分配给四个角度组之一：I，左手斜（心外膜下纤维方向）；I，左手斜（心外膜下纤维方向）； II、圆周（中壁）； III、右手斜位（心内膜下）；或 IV，纵向。比较MVR前后的局部左室应变数据。结果假手术和保留前腱索的MVR对局部左室应变影响极小。对于保留后弦的 MVR：前部，左斜 (I) 应变下降 (31%，p < 0.05)，周向 (II) 和右斜 (III) 应变也下降（分别下降 49% 和 51%；p < 0.01）。横向上，左斜 (I) 应变下降了 36% (p < 0.05)，纵向 (IV) 应变也下降了 36%（下降了 54%，p < 0.01）。传统的腱索切除 MVR 会破坏区域纤维的广泛缩短，影响前部和间隔区域的斜纤维（I 和 III），并损害所有区域的纵向（IV）应变（下降 45% 至 68%，p < 0.05）。然而，正常解剖瓣膜-心室完整性（传统 MVR）或后腱索保留 MVR 的丧失导致左心室应变的显着改变，尤其是在纵向和斜纤维方向。这些发现表明，腱索切除的有害影响与扰动的内部心肌收缩变形有关，这表明腱索破坏会扭曲肌纤维结构或局部收缩负荷。
BackgroundMitral valve replacement (MVR) with chordal excision impairs left ventricular (LV) systolic function, but the responsible mechanisms remain incompletely characterized. Loss of normal annular-papillary continuity also adversely affects LV torsional deformation, possibly due to changes in myocardial fiber contraction pattern.MethodsTwenty-seven dogs underwent insertion of LV myocardial markers and a sham procedure (cardiopulmonary bypass, no MVR, n = 6), conventional MVR with chordae tendineae excision (n = 7), or chordal-sparing MVR with reattachment of the anterior leaflet chordae to the anterior annulus (n = 7) or to the posterior annulus (n = 7). In the anterior, lateral, posterior, and septal LV regions, linear chords were constructed from each region’s central marker to its surrounding markers. Percent systolic shortening (regional LV strain) was calculated for each chord, and the chords were assigned to one of four angular groups: I, left-handed oblique (subepicardial fiber direction); II, circumferential (midwall); III, right-handed oblique (subendocardial); or IV, longitudinal. Regional LV strain data were compared before and after MVR.ResultsSham and anterior chordal-sparing MVR had minimal effects on regional LV strain. With posterior chordal-sparing MVR: anteriorly, left-oblique (I) strain fell (31%, p < 0.05), as did circumferential (II) and right-oblique (III) strains (by 49% and 51%, respectively; p < 0.01). Laterally, left-oblique (I) strain fell by 36% (p < 0.05), as did longitudinal (IV) strain (54% decline, p < 0.01). Conventional MVR with chordal excision disrupted regional fiber shortening diffusely, affecting oblique fibers (I and III) in the anterior and septal regions and impairing longitudinal (IV) strain in all regions (45% to 68% fall, p < 0.05).ConclusionsSham and anterior chordal-sparing MVR did not substantially alter regional LV strain; however, loss of normal anatomic valvular-ventricular integrity (conventional MVR) or posterior chordal-sparing MVR resulted in pronounced alterations in LV strain, most notably in the longitudinal and oblique fiber directions. These findings demonstrate that the deleterious effects of chordal excision are associated with perturbed internal myocardial systolic deformation, which suggests that chordal disruption distorts myofiber architecture or regional systolic loading.