Background

Left ventricular (LV) mechanics in patients with different single morphologic LV subtypes, including tricuspid atresia, double-inlet left ventricle, and pulmonary atresia with intact ventricular septum, remain poorly studied. Given that histologic studies indicate differences in LV myocardial fiber orientation, we hypothesized that this may result in altered LV mechanics. The aim of this study was to evaluate the influence of LV morphology on LV mechanics.

Methods

Fifty-two children with single left ventricles after Fontan operation and age-matched control subjects were prospectively enrolled. Using two-dimensional speckle-tracking echocardiography, longitudinal strain was measured in the four-, three-, and two-chamber long-axis planes, and circumferential strain was measured at the basal, mid, and apical short-axis planes. Apical and basal rotation were measured, and twist and torsion were calculated. We compared strain and rotational mechanics in cases versus control subjects and among LV subtypes.

Results

Compared with control subjects, subjects with single left ventricles had similar LV end-diastolic dimensions but significantly decreased ejection fractions. The single left ventricle cohort had normal global longitudinal strain (P = .20) but lower basal mean circumferential strain (P < .0001). Single left ventricle subjects had higher apical rotation (P = .0001) but decreased basal rotation (P = .0007); there was no difference in twist but increased torsion (P = .001). LV subtypes had different four-chamber (P = .01), two-chamber (P = .006), and global longitudinal strain (P = .01), lowest in the pulmonary atresia with intact ventricular septum subtype.

Conclusions

Longitudinal LV strain was preserved in children with single left ventricles after Fontan. A pattern of reduced basal circumferential strain and rotation with an increase in apical rotation and torsion in the single left ventricle cohort may be related to differences in myofiber orientation, increased fibrosis, and the impact of altered loading conditions throughout palliation. Decreased longitudinal strain in the pulmonary atresia with intact ventricular septum group may also reflect detrimental interventricular interactions.

中文翻译：

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丰坦术后单左心室儿童的应变和旋转力学

背景

左心室（LV）力学具有不同的单一形态学LV亚型的患者，包括三尖瓣闭锁，双入口左心室和具有完整心室间隔的肺动脉闭锁，仍然缺乏研究。鉴于组织学研究表明左心室心肌纤维取向不同，我们假设这可能导致左心室力学改变。这项研究的目的是评估LV形态对LV力学的影响。

方法

前瞻性招募了52名接受Fontan手术后有单个左心室的儿童和年龄匹配的对照组。使用二维斑点跟踪超声心动图，在四腔，三腔和两腔长轴平面中测量纵向应变，并在基部，中部和心尖短轴平面中测量周向应变。测量根尖和基底旋转，并计算扭转和扭转。我们比较了病例和对照对象以及LV亚型之间的应变和旋转力学。

结果

与对照组相比，左心室单个的受试者的左室舒张末期尺寸相似，但射血分数明显降低。单个左心室队列 总体正常纵向应变（P = .20），但基底平均周向应变较低（P  <.0001）。单个左心室受试者的根尖旋转较高（P  = .0001），但基底旋转 较低（P = .0007）；扭转没有区别，但扭转增加（P  = .001）。LV亚型具有不同的四腔室（P  = .01），两腔室（P  = .006）和整体纵向应变（P = 0.01），在具有完整心室间隔亚型的肺动脉闭锁中最低。

结论

丰坦术后左单心室儿童保留了纵向LV应变。单个左心室队列中基底周向应变和旋转减少的模式，其根尖旋转和扭曲增加，可能与肌纤维方向的差异，纤维化增加以及整个减轻病情的负荷条件改变的影响有关。完整室间隔组的肺动脉闭锁患者纵向张力的降低也可能反映了有害的心室间相互作用。