The Labatt Family Heart Center, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada.
Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada.
Eur Heart J Cardiovasc Imaging. 2019 Jan 1;20(1):101-107. doi: 10.1093/ehjci/jey072.
The objective of this study was to quantify imaging markers of myocardial fibrosis and assess myocardial function in long-term transposition of the great arteries survivors after the arterial switch operation (ASO).
Paediatric ASO patients were prospectively studied by cardiac magnetic resonance imaging, including first-pass myocardial perfusion, late gadolinium enhancement, and T1 relaxometry, as well as echocardiography for left ventricular (LV) systolic and diastolic function including strain analysis, with comparison to healthy controls. Thirty ASO patients (mean age 15.4 ± 2.9 years vs. 14.1 ± 2.6 years in 28 controls, P = 0.04) were included. Patients had normal LV ejection fraction (EF) (57 ± 5% vs. 59 ± 5%, P = 0.07), but end-diastolic and end-systolic volumes were increased (104 ± 20 mL/m2 vs. 89 ± 10 mL/m2, P < 0.01 and 46 ± 13 mL/m2 vs. 36 ± 7 mL/m2, P < 0.01, respectively). Longitudinal strain at two-, three-, and four-chamber levels of the LV were lower in ASO patients (-19.0 ± 2.6% vs. -20.9 ± 2.3%, P = 0.006, -17.7 ± 2.0% vs. -19.1 ± 2.4%, P = 0.02, and -18.9 ± 1.9% vs. -20.1 ± 1.7%, P = 0.01, respectively), while circumferential strain was higher at all short-axis levels (-24.6 ± 2.3% vs. -19.3 ± 1.6%, P < 0.001 at the mid-ventricular level). LV native T1 times were higher in ASO patients (1042 ± 27 ms vs. 1011 ± 27 ms, P < 0.01) and correlated with LV mass/volume ratio (R = 0.60, P < 0.001). Myocardial scarring or myocardial perfusion defects were not observed in our cohort.
Children and adolescents after ASO have normal LV systolic function, in line with their overall good clinical health. At a myocardial level however, imaging markers of diffuse myocardial fibrosis are elevated, along with an altered LV contraction pattern. Whether these abnormalities will progress into future clinically significant dysfunction and whether they are harbingers of adverse outcomes remains to be studied.
本研究旨在量化大动脉转位（ASO）术后的长期存活患儿的心肌纤维化影像学标志物，并评估其心肌功能。
前瞻性研究了儿科 ASO 患者的心脏磁共振成像，包括首过心肌灌注、晚期钆增强和 T1 弛豫率，以及左心室（LV）收缩和舒张功能的超声心动图，包括应变分析，并与健康对照组进行比较。共纳入 30 例 ASO 患者（平均年龄 15.4±2.9 岁 vs. 28 例对照组中的 14.1±2.6 岁，P=0.04）。患者的 LV 射血分数（EF）正常（57±5% vs. 59±5%，P=0.07），但舒张末期和收缩末期容积增加（104±20 mL/m2 vs. 89±10 mL/m2，P<0.01 和 46±13 mL/m2 vs. 36±7 mL/m2，P<0.01）。ASO 患者的 LV 两腔、三腔和四腔水平的纵向应变较低（-19.0±2.6% vs. -20.9±2.3%，P=0.006，-17.7±2.0% vs. -19.1±2.4%，P=0.02 和 -18.9±1.9% vs. -20.1±1.7%，P=0.01），而所有短轴水平的圆周应变较高（-24.6±2.3% vs. -19.3±1.6%，在中心室水平 P<0.001）。ASO 患者的 LV 固有 T1 时间较高（1042±27 ms vs. 1011±27 ms，P<0.01），与 LV 质量/体积比相关（R=0.60，P<0.001）。我们的队列中未观察到心肌瘢痕或心肌灌注缺陷。
ASO 后的儿童和青少年左心室收缩功能正常，符合其整体良好的临床健康状况。然而，在心肌水平上，弥漫性心肌纤维化的影像学标志物升高，同时伴有 LV 收缩模式的改变。这些异常是否会进展为未来临床上显著的功能障碍，以及它们是否预示着不良结局，仍有待研究。
