Effect of selective fetoscopic laser photocoagulation therapy for twin-twin transfusion syndrome on pulmonary valve pathology in recipient twins.

OBJECTIVE: To investigate the impact of selective fetoscopic laser photocoagulation (SFLP) on pre-existing pulmonary valve pathology in the recipient twin in twin-twin transfusion syndrome (TTTS). METHODS: We evaluated preoperative echocardiograms of all pregnancies with TTTS treated with SFLP at our institution from 2001 to 2009 (n = 76). Sixteen (21%) recipients had an abnormal pulmonary valve (stenosis/dysplasia, insufficiency or functional atresia) before SFLP. Postoperative echocardiograms and medical records from these 16 recipients were reviewed. Changes in pulmonary valve structure and function, and overall cardiac function, were noted after SFLP. RESULTS: The mean gestational age at SFLP was 21 (range, 18.7-24.3) weeks. Seven of sixteen (44%) recipients with abnormal pulmonary valve prior to SFLP survived. Six of the 16 (37.5%) recipient twins had documented absence of persistent pulmonary valve abnormalities at birth or at autopsy. Two (12.5%) of the 16 recipients (2.6% of the original cohort) had persistent pulmonary valve abnormalities at birth, requiring intervention. Systolic and diastolic function improved or normalized after SFLP in all patients undergoing longitudinal follow-up. There was a tendency for a better cardiovascular profile score (best = 10 points) at initial evaluation in pregnancies with survivors compared with those with no survivors (mean (SD): 5.6 (2.2) vs. 6.75 (1.28)), but this was not statistically significant. Severity of cardiac involvement did not predict persistence of valve pathology or survival. CONCLUSIONS: SFLP can improve flow through the pulmonary valve of the recipient twin in TTTS, probably as a consequence of improvements in right ventricular systolic and diastolic function. However, pulmonary valve pathology may persist and require postnatal intervention.

Monochorionic twins discordant for congenital heart disease: a referral center's experience and possible pathophysiologic mechanisms.

OBJECTIVE: To describe the spectrum of cardiac defects in monochorionic (MC) twins discordant for congenital heart disease (CHD) in a referral center population. METHOD: Retrospective study of all twin gestations undergoing echocardiography between 2000 and 2009 at our institution. RESULTS: A total of 356 twin pairs were evaluated during the study period, 202 for suspected twin-twin transfusion syndrome (TTTS) and the remainder for other indications. Twenty-nine MC pairs were discordant for CHD: laterality defects, 24% [right (2) or left (3) isomerism (3), primitive heart (2)]; ventricular hypoplasia secondary to semilunar valve obstruction, 14% [hypoplastic left heart syndrome (2), severe pulmonary stenosis (PS) or atresia (2)]; valvar dysplasias in TTTS recipients, 27% [PS (4), mitral/tricuspid dysplasia (4)]; conjoining, 14% (4); and other developmental errors, 21% [conotruncal (1), tricuspid atresia (2), ventricular septal defect (2)]. CONCLUSIONS: The spectrum of lesions in individuals assumed to be genetically identical and the disproportionate incidence of laterality and ventricular hypoplasia in this population leads us to propose potential mechanisms for the development of CHD in this population including local environmental or epigenetic factors influencing gene expression differentially, abnormal reciprocal laterality signaling between twinned embryos, or placental vascular factors affecting hemodynamics, either early in gestation or later in the setting of TTTS, leading to valvar lesions and ventricular hypoplasia.