Right ventricular outflow tract obstruction in complicated monochorionic twin pregnancy

Abstract

Objectives Severe right ventricular outflow tract obstruction (RVOTO) is a potential complication in recipient twins of twin-to-twin transfusion syndrome (TTTS) that requires postnatal follow-up or treatment. We aimed to evaluate pregnancy characteristics of neonates with RVOTO from complicated monochorionic twin pregnancies, determine the incidence of RVOTO in TTTS cases and construct a prediction model for its development.Methods This was an observational cohort study of all complicated monochorionic twin pregnancies with a postnatal diagnosis of RVOTO examined at our center. Cases were referred for evaluation of the need for fetal therapy or intervention because of TTTS, selective intrauterine growth restriction (sIUGR) or multiple congenital malformations in one of the twins. Ultrasound data were retrieved from our monochorionic twin database. Among liveborn TTTS recipients treated prenatally with laser therapy, those with RVOTO were compared with those without RVOTO (controls). We describe four additional cases with RVOTO that were not TTTS recipients.Results A total of 485 twin pregnancies received laser therapy for TTTS during the study period. RVOTO was diagnosed in 3% (11/368) of liveborn TTTS recipients, of whom two showed mild Ebstein's anomaly. Before laser therapy, pericardial effusion was seen in 45% (5/11) of RVOTO cases (P < 0.01) and abnormal A-wave in the ductus venosus (DV) in 73% (8/11) (P = 0.03), significantly higher proportions than in controls. Mean gestational age at laser therapy was (P = 0.03). A prediction model for RVOTO was constructed incorporating these three significant variables. One TTTS donor had RVOTO after the development of transient hydrops following laser therapy. Three larger twins in pregnancies complicated by sIUGR developed RVOTO, the onset of which was detectable early in the second trimester. Conclusions RVOTO occurs in TTTS recipient twins but can also develop in TTTS donors and larger twins of pregnancies complicated by sIUGR. Abnormal flow in the DV, pericardial effusion and early gestational age at onset of TTTS are predictors of RVOTO in TTTS recipients, which suggests increased vulnerability to hemodynamic imbalances in the fetal heart in early pregnancy. These findings could guide diagnostic follow-up protocols after TTTS treatment.

Acquired right ventricular outflow tract obstruction in twin‐to‐twin transfusion syndrome; a prospective longitudinal study

“…Initial mild RVOTO after birth is however important, as it may progress to severe RVOTO with need for intervention in infancy . The total incidence of postnatal RVOTO found in this study is slightly higher than in prior large cohort studies, which found an incidence of 2.1% to 4% . This can be explained by the systematic longitudinal follow‐up of all recipients in pregnancy, which allowed us to detect mild and late‐onset cases.…”

“…In untreated TTTS, approximately 10% to 12% of recipients will develop congenital heart disease, including RVOTO . Fetoscopic laser therapy is known to improve cardiac function, and the reported incidence of postnatal RVOTO in surviving recipients after laser therapy is 2% to 3% in larger series …”

“…The pathophysiology of RVOTO in TTTS is not fully understood, and risk factors for progression to postnatal RVOTO are still difficult to determine. Most studies focus on preintervention assessment of RVOTO, because systematic longitudinal echocardiographic follow‐up of all recipients after laser therapy is difficult to establish in fetal therapy centers . This impedes knowledge on the complete spectrum of RVOTO .…”

Persistent Pulmonary Hypertension of the Newborn in Twin-Twin Transfusion Syndrome: A Case-Control Study

“…Although cardiac function usually improves within a few weeks after FLS, abnormalities of the pulmonary vasculature may persist despite complete laser surgery being performed, and this could lead to PPHN. As an analogy, right-ventricular outflow tract obstruction also occurs in recipients despite complete laser surgery and can result in abnormal development of the pulmonary valve and subsequent pulmonary stenosis or atresia [24]. In cases of incomplete laser surgery and the existence of residual anastomoses, the cardiac burden may be prolonged.…”

Recipient Twin Circular Shunt Physiology Before Fetal Laser Surgery: Survival and Risks for Postnatal Right Ventricular Outflow Tract Obstruction

“…In addition, knowledge of the presence of CSP should motivate the team to attempt to prolong the pregnancy as long as possible, as this baby has a relatively high likelihood of requiring a cardiac intervention shortly after birth. A recent study attempted to construct a predictive model for the development of RVOTO in cases of TTTS, and found that before laser surgery, those at increased risk had a pericardial effusion, an abnormal A wave in the ductus venosus, and earlier GA at surgery . We previously reported that the presence of both pulmonary valve dysplasia and pulmonary regurgitation that is classified as greater than “mild” for the recipient twin on FE before laser surgery indicates a sensitive marker (100%) for postnatal pulmonary valve disease; and if found postoperatively, adds specificity (89%) .…”