OC07.02: Fetoscopic laser surgery for twin–twin transfusion syndrome after 26 weeks of gestation

Abstract

Objectives: Twin–twin transfusion syndrome (TTTS) results in significantly altered cardiovascular loading conditions, which may affect both donor and recipient myocardial properties. Myocardial deformation analysis using Vector Velocity Imaging (VVI, Siemens) is an angle independent, speckle-tracking technique used to assess regional cardiac mechanics, which may provide insight into our understanding of myocardial dysfunction in TTTS. Methods: Digital dynamic, two-dimensional four chamber views were interrogated off-line using VVI software. Global longitudinal strain (S%) systolic strain rate (SRs) and diastolic strain rate (SRd) were measured in the left (LV) and right (RV) ventricles of 22 fetal pairs with TTTS and compared to 25 gestational age-matched normal controls. Pulsatility indices (PI) for umbilical (UA) and middle cerebral artery (MCA) were calculated. Results: Gestational age at evaluation was 20.5 ± 1.3 weeks. Donor LV-SRs was higher, while donor RV-SRd was significantly lower than controls (Table 1). Recipient S%, SRs and SRd were significantly lower for both LV and RV in comparison to controls. Donor UA PI was higher than controls (1.93 ± 0.48 vs. 1.41 ± 0.25, P < 0.001) while donor MCA PI was lower (1.47 ± 0.29 vs. 1.87 ± 0.21). Recipient UA and MCA PI were no different than controls. Conclusions: In TTTS, donor mechanics reflect loading conditions. Donor LV systolic function is hyperdynamic, due to hypovolemia and ejection into a low resistance cerebrovascular circuit while the RV ejects into a high resistance placental circuit. Recipient RV and LV are both globally depressed with systolic and diastolic dysfunction despite normal vascular resistances and presumed volume overload, suggesting intrinsic acquired cardiomyopathy.