Raboisson M J, Fouron J C, Lamoureux J, Leduc L, Grignon A, Proulx F, Gamache S
Fetal Cardiology Unit, Cardiology Division, Department of Pediatrics, St. Justine Hospital, Université de Montréal, Montreal, Quebec, Canada.
Circulation. 2004 Nov 9;110(19):3043-8. doi: 10.1161/01.CIR.0000146896.20317.59. Epub 2004 Nov 1.
In the twin-to-twin transfusion syndrome (TTTS), pressure rather than volume overload is increasingly considered as a key factor in the pathogenesis of the cardiomyopathy of the recipient twin. If this is the case, cardiac dysfunction should be among the first signs observed with TTTS. The objective of this study was to determine whether intertwin differences in myocardial function are modified early in the course of TTTS and whether they can help to differentiate this condition from intrauterine growth restriction (IUGR).
Eight variables were analyzed on the first fetal echocardiography on 21 pairs of twins with TTTS and 11 with IUGR. No difference was found between the 2 groups for the cardiothoracic ratio, pulsatility indices in the umbilical and middle cerebral arteries, and peak velocity of the middle cerebral artery. Significant difference was found for ventricular septal thickness, but with no association with the conditions under study. With TTTS, left ventricular shortening fraction was consistently greater in the donor twins, and myocardial performance indices (MPIs) were elevated in the recipient twins. This increase in MPI was caused by a lengthening of the isovolumic periods compared with those of the donor twin: left ventricular and right ventricular isovolumic periods 0.105+/-0.047 and 0.097+/-0.026 seconds, respectively, for the recipient twins versus 0.0561+/-0.46 and 0.065+/-0.03 seconds, respectively, for the donor twins (P<0.001). These changes in the isovolumic periods were mainly due to significant prolongation of isovolumic relaxation times. A change in left ventricular MPI > or =0.09 combined with a change in right ventricular MPI > or =0.05 would identify a TTTS with a sensitivity of 75% and a false-positive rate of 9%.
The observed diastolic function impairment goes along with the pressure-overload pathogenic concept proposed in TTTS. Assessment of intertwin difference in MPI is a valuable tool for early differential diagnosis between TTTS and isolated IUGR.
在双胎输血综合征（TTTS）中，压力而非容量超负荷越来越被认为是受血儿双胎心肌病发病机制中的关键因素。如果是这样，心脏功能障碍应该是TTTS最早出现的体征之一。本研究的目的是确定双胎之间心肌功能的差异在TTTS病程早期是否发生改变，以及它们是否有助于将这种情况与宫内生长受限（IUGR）区分开来。
对21对TTTS双胎和11对IUGR双胎进行首次胎儿超声心动图检查时分析了8个变量。两组之间在心胸比率、脐动脉和大脑中动脉搏动指数以及大脑中动脉峰值速度方面未发现差异。发现室间隔厚度存在显著差异，但与所研究的情况无关。对于TTTS，供血儿双胎的左心室缩短分数始终更高，而受血儿双胎的心肌性能指数（MPI）升高。与供血儿双胎相比，MPI的这种升高是由于等容期延长所致：受血儿双胎的左心室和右心室等容期分别为0.105±0.047秒和0.097±0.026秒，而供血儿双胎分别为0.0561±0.46秒和0.065±0.03秒（P<0.001）。等容期的这些变化主要是由于等容舒张时间的显著延长。左心室MPI变化≥0.09且右心室MPI变化≥0.05可识别TTTS，其敏感性为75%，假阳性率为9%。
观察到的舒张功能损害与TTTS中提出的压力超负荷致病概念一致。评估双胎之间MPI的差异是早期鉴别诊断TTTS和孤立性IUGR的有价值工具。
