Left ventricular echocardiographic and histologic changes: Impact of chronic unloading by an implantable ventricular assist device
Left ventricular echocardiographic and histologic changes: Impact of chronic unloading by an implantable ventricular assist device
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DOI：
10.1016/0735-1097(95)00555-2
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发表时间：
1996-03-15
影响因子：
24
通讯作者：
Thomas, JD
中科院分区：
文献类型：
--
作者：
Nakatani, S;McCarthy, PM;Thomas, JD
目标.我们研究了心室辅助装置对慢性左心室去负荷的影响，并评估了左心室形态学和组织学的变化。植入式左心室辅助装置已成为心脏移植的有效“桥梁”。虽然有报道证明其循环支持，但对慢性左心室负荷对心脏本身的影响知之甚少。我们在19例终末期心力衰竭患者中进行了HeartMate左心室辅助装置插入和取出时的术中经食管超声心动图。他们通过辅助装置支持3至153天（平均值[+/-SD] 68+/-33）。回顾性测量左心房和左心室直径以及室间隔和后壁厚度。本文对15例心脏移植患者的左室心肌标本进行了组织学检查。定性（0 ~ 3级）比较插入和取出标本的波形纤维、收缩带坏死和纤维化，并定量测量穿过细胞核的最小肌细胞直径。左心房和左心室舒张期和收缩期直径在插入左心室辅助装置后立即减小（分别从46至35，63至41和59至36 mm，所有p < 0.001）。左室室间隔壁厚度从10 mm增加到14 mm（p < 0.001），后壁从10 mm增加到13 mm（p < 0.001）。超声心动图测量结果显示，在慢性阶段没有显着的后续变化。心肌组织学检查结果表明，心肌细胞损伤减少（波形纤维从1.9到0.5，p < 0.001，收缩带坏死从1.3到0.2，p < 0.01）和纤维化增加（从1.3到1.9，p < 0.05），但肌细胞直径没有显著变化（从15.6到16.8 μ m，p = 0.065）。使用植入式辅助器械的左心室卸载导致壁厚立即增加，与腔室尺寸减小一致，从而降低壁应力。慢性卸载允许心肌愈合和纤维化，而没有持续的肌细胞损伤或萎缩的证据。左心室辅助装置的插入可能在选定的心力衰竭患者的心室“休息”中发挥作用。
Objectives. We studied the effects of chronic left ventricular unloading by a ventricular assist device and assessed left ventricular morphologic and histologic changes.Background. The implantable left ventricular assist device has been effective as a ''bridge'' to cardiac transplantation. Although there are reports documenting its circulatory support, little is known about the effects of chronic left ventricular unloading on the heart itself.Methods. We performed intraoperative transesophageal echocardiography at the insertion and explantation of a HeartMate left ventricular assist device in 19 patients with end-stage heart failure. They were supported by the assist device for 3 to 153 days (mean [+/-SD] 68+/-33). Measurements were taken retrospectively to obtain left atrial and ventricular diameters and interventricular septal and posterior wall thickness. Histologic examinations were made from the left ventricular myocardial specimens of 15 patients at the times of insertion and explantation for heart transplantation. Insertion and explantation specimens were compared qualitatively (0 to 3 scale) for wavy fibers, contraction band necrosis and fibrosis, with quantitative measurement of minimal myocyte diameter across the nucleus.Results. Left atrial and left ventricular diastolic and systolic diameters decreased immediately after insertion of the left ventricular assist device (from 46 to 35, 63 to 41 and 59 to 36 mm, respectively, all p < 0.001). Left ventricular wall thickness increased from 10 to 14 mm (p < 0.001) for the interventricular septum and from 10 to 13 mm for the posterior wall (p < 0.001). No echocardiographic measurements showed significant subsequent changes at the chronic stage. Myocardial histologic findings demonstrated a reduction in myocyte damage (from 1.9 to 0.5, p < 0.001, for wavy fiber and from 1.3 to 0.2, p < 0.01, for contraction band necrosis) and an increase in fibrosis (from 1.3 to 1.9, p < 0.05), but without significant change in myocyte diameter (from 15.6 to 16.8 mu m, p = 0.065).Conclusions. Left ventricular unloading with the implantable assist device induces an immediate increase in wall thickness, consistent with the reduction in chamber size, thereby decreasing wall stress. Chronic unloading allows myocardial healing and fibrosis without evidence for ongoing myocyte damage or atrophy. Left ventricular assist device insertion may have a role in ''resting'' the ventricle for selected patients with heart failure.