TheFetus.net

Case of the Week #511

Frantisek Grochal (1); Karel Hodík (2); Viktor Tomek (3); Pavel Calda (4)

Affiliations:
(1) Femicare, Center of prenatal ultrasonographic diagnostics, Kollarova 17/A, 036 01 Martin, Slovak Republic;
(2) University Hospital Hradec Králové, Department of Obstetrics and Gynecology, Sokolská 581, 500 05 Hradec Králové — Nový Hradec Králové, Czech Republic;
(3) Department of echocardiography and prenatal cardiology, Children's Heart Centre, University Hospital Motol, V úvalu 84, Prague 150 06, Czech Republic;
(4) Professor, Head of the Fetal Medicine Centre; Charles University in Prague, First Faculty of Medicine, Department of Gynaecology and Obstetrics of the First Faculty of Medicine and General Teaching Hospital, Apolinarska 18, 128 51, Praha 2, Czech Republic.

Posting Dates:  January 02, 2020 - January 16, 2020

Case report:  A 34-year-old woman (G1P0) with non-contributive history was sent to our facility at 19 weeks with a monochorionic, diamniotic twin pregnancy. Our examination revealed twin-to-twin transfusion syndrome (TTTS) with following findings:

Twin A (XY, donor): Twin B (XY, recipient)
• severe oligohydramnios "stuck twin" • polyhydramnios (DVP 85 mm)
• bladder non-visualized • overfilled bladder
• EFW 209 g ± 31 g • EFW 273 g ± 40 g
• tricuspid regurgitation

Scheme
Figure 1: Scheme showing relations of the placenta, insertions of the umbilical cords to the placenta, and position of the fetuses — donor ("stuck twin") and recipient with polyhydramnios during our examination at 19 weeks and 1 day of pregnancy.

The findings were consistent with TTTS stage II (Quintero), or TTTS IIIa (Cincinnati staging system).  The patient was sent to a specialized fetal medicine center in Prague, Czech Republic, and successful fetoscopic laser photocoagulation of placental anastomoses was done at 19 weeks + 6 days of pregnancy. Nineteen days after fetoscopic laser photocoagulation, the following findings were found in fetus A (former donor):

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Image 1
Video 1
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Image 2
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Image 3
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Image 4
Video 2
Video 3: FetalHQ speckle tracking analysis.
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Image 5: FetalHQ speckle tracking analysis.

What is the name of the complication of the twin-to-twin transfusion syndrome described in the images and videos above?

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Answer

We present a case of Intracardiac Twin Circular Shunt

Ultrasound demonstrated the following findings:

  • Image 1, video 1: The image and the video show color Doppler four-chamber view of the of the donor fetal heart after laser treatment of the TTTS. Severe tricuspid regurgitation and cardiomegaly can be seen.
  • Image 2: The images show color Doppler sagittal view of the donor fetal heart after laser treatment of the TTTS. Aortic and ductal arches can be seen with reversed flow within the ductus arteriosus and pulmonary artery.
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Image 2: Ao - aorta (aortic arch); PA - pulmonary artery; DA - ductus arteriosus.
  • Image 3: The images show color Doppler sagittal view of the donor fetal heart after laser treatment of the TTTS. Reversed blood jet from the pulmonary to the right ventricle can be seen.
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Image 3: PA - pulmonary artery; RV - right ventricle.
  • Image 4, video 2: The image and the video show color Doppler transverse scan of the donor fetal heart after laser treatment of the TTTS. The level of the three-vessel view of the heart can be seen. Reversed blood within the pulmonary artery and reversed jet from the pulmonary to the right ventricle can be seen.
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Image 4: RV - right ventricle; PA - pulmonary artery; Ao - aorta; SVC - superior vena cava.
  • Video 3, Image 5: The video and image represent FetalHQ speckle tracking analysis (special software available in GE Voluson machines) of the donor fetal heart after laser treatment of the TTTS - cardiomegaly, ventricular dilatation, impaired contractility and fractional shortening predominantly affecting the right ventricle can be seen.

The above mentioned findings are consistent with Intracardiac Twin Circular Shunt, which is a form of severe right outflow tract obstruction [1]. In this condition, blood originating in one cardiac chamber is shunted through the heart to return to the original chamber without ever crossing a capillary bed. Criteria for diagnosis of twin circular intracardiac shunt are: (1) right ventricular dysfunction, (2) tricuspid pulmonary regurgitation, (3) flow reversal in the ductus arteriosus, and (4) pulmonary regurgitation.

In the intracardiac twin circular shunt, antegrade flow across the tricuspid valve is diminished and the blood from the right ventricle (RV) returns to the right atrium (RA) due to tricuspid regurgitation (red arrow). This blood together with the blood entering the right atrium via inferior and superior vena cava (yellow arrow) enters the left atrium (LA) via the foramen ovale and flows to the aorta. The pulmonary artery (PA) is perfused retrograde via the ductus arteriosus (DA) and pulmonary regurgitation during diastole enables the blood in the pulmonary artery to return to the right ventricle (Figure 2, 3). The circular shunt within the heart thus closes its vicious circle: right ventricle → right atrium →  foramen ovale →  left atrium →  left ventricle A →  aorta  →  ductus arteriosus →  pulmonary artery  →  right ventricle.

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Figure 2: diagram of intracardiac twin circular shunt
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Figure 3: diagram of intracardiac twin circular shunt. Red arrow corresponds to the shunt. Yellow arrow corresponds to normal systemic circulation.

Cardiac anomalies, including right ventricular outflow tract obstruction (RVOTO) or twin circular intracardiac shunt typically affect the recipient twin. Interestingly, in our case the donor was affected.  Laser intervention at an early stage of TTTS is associated with a significant reduction in the incidence of RVOTO. Predictors of RVOTO in TTTS recipients include with abnormal flow in the ductus venosus, pericardial effusion, and early gestational age at onset of TTTS [2].  RVOTO can develop after laser treatment or even in the neonatal period and in all Quintero stages [3]. The donor twin is rarely affected by the RVOTO and the mechanism of this phenomenon in donor twin is still not fully clarified.

References

[1] Pruetz JD, Votava-Smith JK, Chmait HR, et al. Recipient Twin Circular Shunt Physiology Before Fetal Laser Surgery: Survival and Risks for Postnatal Right Ventricular Outflow Tract Obstruction. J Ultrasound Med. 2017 Aug;36(8):1595-1605. 
[2]  Eschbach SJ, Boons LSTM, Van Zwet E, et al. Right ventricular outflow tract obstruction in complicated monochorionic twin pregnancy. Ultrasound Obstet Gynecol. 2017 Jun;49(6):737-743.
[3]  Eschbach SJ, Ten Harkel ADJ, Middeldorp JM, et al. Acquired right ventricular outflow tract obstruction in twin-to-twin transfusion syndrome; a prospective longitudinal study. Prenat Diagn. 2018 Dec;38(13):1013-1019.

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