Abstract

Optimal management of twin-twin transfusion syndrome (TTTS) in monochorionic diamniotic (MCDA) twins remains challenging. Our aim was to investigate whether Vector Velocity Imaging (VVI), a non-Doppler speckle tracking ultrasound technology, was feasible in twin pregnancies and could aid management of TTTS.

VVI was performed during routine fetal echocardiograms in 55 women pregnant with monochorionic diamniotic (MCDA) twins (27 affected by TTTS and 28 non TTTS controls). Right (RVs) and left (LVs) free wall ventricular Lagrangian strain was measured off-line using Syngo VVI tracking of four-chamber clips recorded with dummy ECG to retain high frame rates for analysis. Within-twin pair differences in strain and relationship to Quintero staging at presentation were analysed.

Gestational age was similar between non TTTS controls and TTTS cases (22+4 vs 21+2; p=0.26). VVI strain measurements could be analysed in 182/200 (91%) TTTS and 94/112 (84%) non TTTS control ventricles. Within-pair strain was concordant in non TTTS controls. Recipient LVs was reduced at all Quintero stages compared to Donors (Stage ≤2: 20.0±2.5% vs 22.3±2.1%, p<0.001; stages 3 and 4: 16.9 ± 3.9% vs 21.6 ± 2.8%, p<0.001). Recipient RVs was reduced only in stages 3 and 4 (18.2 ± 3.5% vs 22.0 ± 3.6%, p<0.01). Strain improved at a median of 2 weeks following successful laser treatment. Intertwin differences in strain were independent of weight discordance.

Recipient LVs is reduced in stage 1 and 2 TTTS and its within-pair discordance may distinguish early disease from selective growth restriction and guide timing of and management following laser.