Sarris G E, Fann J I, Niczyporuk M A, Derby G C, Handen C E, Miller D C
Department of Cardiovascular Surgery, Stanford University School of Medicine, California 94305.
Circulation. 1989 Sep;80(3 Pt 1):I24-42.
The importance of the intact mitral apparatus in left ventricular (LV) systolic performance has been indirectly suggested by clinical studies of chordal-preserving mitral valve replacement (MVR) or reconstruction. The importance of the intact mitral apparatus has been clearly demonstrated in isovolumic experimental preparations but has not been demonstrated unequivocally in ejecting hearts. Therefore, this question was assessed independently of load in an in situ, open-chest ejecting canine heart preparation (n = 9). Three orthogonal LV dimensions were measured by sonomicrometry. During MVR with complete chordal preservation, snares were placed around the anterior and posterior papillary muscles. After the hearts were weaned from cardiopulmonary bypass, LV function was assessed by caval occlusion to alter LV preload abruptly. The slopes of the end-systolic--pressure-volume (end-systolic elastance, Ees) and stroke-work--end-diastolic volume (preload-recruitable stroke work, PRSW) relations were used to measure global LV systolic function; similarly, the slopes of the end-systolic--pressure-dimension (regional end-systolic elastance, rEes) and stroke-work--end-diastolic dimension changes in regional LV systolic performance. All chordae were then divided by pulling the snares. Immediate reassessment revealed deterioration of global LV function: Ees declined by 72% (14.1 +/- 11.2 mm Hg/ml [mean +/- SD] vs. 3.9 +/- 3.5 mm Hg/ml, p less than 0.001), and PRSW declined by 39% (129 +/- 37 vs. 79 +/- 29 mm Hg, p = 0.0001). Regional LV function was also adversely affected but somewhat selectively: rEes decreased significantly in all three LV dimensions (p less than or equal to 0.03), but rPRSW decreased significantly (-21%) only in the anteroposterior minor LV axis (89 +/- 19 vs. 70 +/- 15 mm Hg, p = 0.005) and in the septal-lateral axis (-19%, p = NS). These data demonstrate the importance of the intact mitral apparatus on LV systolic performance in ejecting hearts, particularly in the LV regions subtended by the papillary muscles.
保留腱索的二尖瓣置换术（MVR）或二尖瓣重建术的临床研究间接表明了完整二尖瓣装置在左心室（LV）收缩功能中的重要性。完整二尖瓣装置的重要性在等容实验准备中已得到明确证实，但在射血心脏中尚未得到明确证实。因此，在原位开胸射血犬心脏准备实验（n = 9）中，独立于负荷对这个问题进行了评估。通过超声微测法测量三个相互垂直的左心室维度。在完全保留腱索的二尖瓣置换术中，在前、后乳头肌周围放置圈套器。心脏脱离体外循环后，通过腔静脉闭塞突然改变左心室前负荷来评估左心室功能。使用收缩末期压力-容积关系斜率（收缩末期弹性，Ees）和搏功-舒张末期容积关系斜率（前负荷可募集搏功，PRSW）来测量整体左心室收缩功能；同样，使用收缩末期压力-维度关系斜率（区域收缩末期弹性，rEes）和搏功-舒张末期维度变化来测量局部左心室收缩功能。然后通过拉动圈套器切断所有腱索。立即重新评估显示整体左心室功能恶化：Ees下降了72%（14.1±11.2 mmHg/ml[平均值±标准差]对3.9±3.5 mmHg/ml，p<0.001），PRSW下降了39%（129±37对79±29 mmHg，p = 0.0001）。局部左心室功能也受到不利影响，但有一定的选择性：所有三个左心室维度的rEes均显著降低（p≤0.03），但rPRSW仅在左心室前后短轴（89±19对70±15 mmHg，p = 0.005）和室间隔-侧壁轴显著降低（-21%，p = 无显著性差异）。这些数据证明了完整二尖瓣装置对射血心脏左心室收缩功能的重要性，特别是在乳头肌所对应的左心室区域。
