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van Gemert MJC, van der Geld CWM, Ross MG, Nikkels PGJ, van den Wijngaard JPHM. Why does second trimester demise of a monochorionic twin not result in acardiac twinning? Birth Defects Res 2021; 113:1103-1111. [PMID: 33999519 PMCID: PMC8453882 DOI: 10.1002/bdr2.1926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/04/2021] [Indexed: 11/12/2022]
Abstract
Background We previously explained why acardiac twinning occurs in the first trimester. We raised the question why a sudden demised monochorionic twin beyond the first trimester does not lead to acardiac twinning. We argued that exsanguinated blood from the live twin would strongly increase the demised twins' vascular resistance, preventing its perfusion and acardiac onset. However, our current hypothesis is that perfusion of the demised twin does occur but that it is insufficient for onset of acardiac twinning. Methods We analyzed blood pressures and flows in a vascular resistance model of a monochorionic twin pregnancy where one of the fetuses demised. The resistance model consists of a demised twin with a (former) placenta, a live twin and its placenta, and arterioarterial (AA) and venovenous placental anastomoses. We assumed that only twins with a weight of at least 33% of normal survived the first trimester and that exsanguination of more than 50% of its blood volume is fatal for the live twin. Results At 20 weeks, only AA anastomoses with radii ≲1 mm keep the exsanguinated blood volume below 50%. Then, perfusion of the deceased body with arterial blood from the live fetus is about 5–40 times smaller than when that body was alive. Beyond 20 weeks, this factor is even smaller. At 14 weeks, this factor is at most 2. Conclusion We hypothesize that this small perfusion flow of arterial blood prevents further growth of the deceased body and hence precludes onset of acardiac twinning.
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Affiliation(s)
- Martin J C van Gemert
- Department of Biomedical Engineering and Physics, Amsterdam UMC, Location AMC, Amsterdam, The Netherlands
| | - Cees W M van der Geld
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Michael G Ross
- Department of Obstetrics and Gynecology, Harbor UCLA Medical Center, Torrance, California, USA
| | - Peter G J Nikkels
- Department of Pathology, Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands
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van Gemert MJC, Ross MG, van den Wijngaard JPHM, Nikkels PGJ. Acardiac twin pregnancies part VI: Why does acardiac twinning occur only in the first trimester? Birth Defects Res 2021; 113:687-695. [PMID: 33580607 PMCID: PMC8247889 DOI: 10.1002/bdr2.1882] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/20/2020] [Accepted: 01/30/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND Clinical observation suggests that acardiac twinning occurs only in the first trimester. In part, this contradicts our previous analysis (part IV) of Benirschke's concept that unequal embryonic splitting causes unequal embryo/fetal blood volumes and pressures. Our aim is to explain why acardiac onset is restricted to the first trimester. METHODS We applied the vascular resistance scheme of two fetuses connected by arterio-arterial (AA) and veno-venous (VV) anastomoses, the small VV resistance approximated as zero. The smaller twin has volume fraction α < 1 of the assumed normal larger twin, and has only access to fraction X < 1 of its placenta; the larger twin's larger mean arterial pressure accesses the remaining fraction. Before 13 weeks, embryos have a much smaller vascular resistance than placentas. After 13 weeks, when maternal blood provides oxygen, smaller twins can increase their vascular volume by hypoxemia-mediated neovascularization. Estimated AA radii at 40 weeks, rAA (40), are 0.5-1.3 mm. RESULTS Embryos with α < 0.33 unlikely survive 13 weeks and acardiac twinning occurs under appropriate conditions (AA-VV, small placenta). Acardiac body perfusion occurs because of a much smaller vascular resistance than the placenta. When α > 0.33 and rAA (40)=1.3 mm, modeled survival is >32 weeks. CONCLUSION Before 13 weeks, embryos with α < 0.33 cannot survive and may result in the onset of acardia. Beyond 13 weeks, fetuses with α ≥ 0.33 survive because rAA (40) is too small for acardiac onset. Following fetal demise, exsanguination from the live twin increases its blood volume and, we assumed also, its vascular resistance. Perfusion then occurs through the lower resistance placenta.
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Affiliation(s)
- Martin J C van Gemert
- Department of Biomedical Engineering & Physics, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Michael G Ross
- Department of Obstetrics and Gynecology, Harbor UCLA Medical Center, Torrance, California, USA
| | | | - Peter G J Nikkels
- Department of Pathology, Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands
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van Gemert MJC, Nikkels PGJ, Ross MG, van den Wijngaard JPHM. Acardiac twin pregnancies part V: Why does an acardiac twin with renal tissue produce polyhydramnios? Birth Defects Res 2021; 113:500-510. [PMID: 33529493 PMCID: PMC7986173 DOI: 10.1002/bdr2.1874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 12/17/2020] [Accepted: 01/14/2021] [Indexed: 12/28/2022]
Abstract
Background Acardiac twinning is a complication of monochorionic twin pregnancies. From literature reports, 30 of 41 relatively large acardiac twins with renal tissue produced polyhydramnios within their amniotic compartment. We aim to investigate the underlying mechanisms that cause excess amniotic fluid using an established model of fetal fluid dynamics. Methods We assumed that acardiac onset is before 13 weeks, acardiacs with renal tissue have normal kidney function and produce urine flow from 11 weeks on, and acardiac urine production requires a pressure of half the pump twin's mean arterial pressure. We apply a resistance network with the pump twin's arterio‐venous pressure as source, pump umbilical arteries, placenta, placental arterio‐arterial (AA) anastomoses and acardiac resistances. Acardiac amniotic fluid dynamics excluded acardiac lung fluid secretion, swallowing and the relatively small intramembranous flow. Results In small acardiacs with sufficient urine production, polyhydramnios will occur due to the lack of amniotic fluid resorption. Urine production is dependent upon having sufficient mean arterial pressure, which requires nearly a two‐fold larger resistance within the acardiac as compared to the placental AA resistance. Subphysiologic arterial pressure may result in renal dysgenesis. Conclusion Our findings suggest the potential for prediction of which clinical acardiac cases may or may not develop polyhydramnios based upon noninvasive assessments of renal tissue, blood flow and urine production. This information would be of great value in determining early obstetric interventions as opposed to conservative management. These findings may also contribute to an improved knowledge of the fascinating pathophysiology that surrounds acardiac twinning.
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Affiliation(s)
- Martin J C van Gemert
- Department of Biomedical Engineering & Physics, Amsterdam University Medical Centra, Location AMC, Amsterdam, The Netherlands
| | - Peter G J Nikkels
- Department of Pathology, Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands
| | - Michael G Ross
- Department of Obstetrics and Gynecology, Harbor UCLA Medical Center, Torrance, California, USA
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McPherson E, Korlesky C, Hebbring S. Cardiac Anomalies in Liveborn and Stillborn Monochorionic Twins. Clin Med Res 2020; 18:58-67. [PMID: 31959670 PMCID: PMC7428205 DOI: 10.3121/cmr.2019.1478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 07/25/2019] [Accepted: 10/17/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND Cardiovascular anomalies are more common in monochorionic twins, especially with twin-twin transfusion, compared to other twin types and to singletons. Because previous studies are based on fetal and neonatal echocardiography, more information is needed to study prevalence of cardiac anomalies in twin miscarriages, stillbirths, and children after the immediate neonatal period. METHODS With specific attention to cardiac anomalies, we reviewed the medical records of 335 selected liveborn twin pairs from the Marshfield Clinic Twin Cohort (enriched for twin-twin transfusion) and all twins (175 pairs) identified in the Wisconsin Stillbirth Service Program cohort of late miscarriages and stillbirths. RESULTS Structural cardiac defects occurred in 12% of liveborn monochorionic twin infants and 7.5% of stillborn infants with twin-twin transfusion compared to only 2% of liveborn dizygotic twins and no stillborn dizygotic infants. The most common cardiac lesion in liveborn twins was ventricular septal defect, which was usually isolated and discordant, preferentially affecting the smaller twin in monochorionic pairs. Among stillborn and miscarried monochorionic twins, the most common cardiac lesion was acardia. CONCLUSIONS Monochorionic twins, particularly those with TTT, are at increased risk for a spectrum of structural cardiac malformations which we suggest may be related to asymmetry of the inner cell mass resulting in a smaller poorly perfused twin. In severe cases, limited cardiac and circulatory development in the affected twin leads to acardia. In less severe cases, the smaller infant has deficient septal growth that sometimes results in ventricular septal defect.
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Affiliation(s)
- Elizabeth McPherson
- Center for Human Genetics, Marshfield Clinic Research Institute, Marshfield, Wisconsin USA
| | - Colin Korlesky
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Scott Hebbring
- Center for Human Genetics, Marshfield Clinic Research Institute, Marshfield, Wisconsin USA
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Vitucci A, Fichera A, Fratelli N, Sartori E, Prefumo F. Twin Reversed Arterial Perfusion Sequence: Current Treatment Options. Int J Womens Health 2020; 12:435-443. [PMID: 32547251 PMCID: PMC7266514 DOI: 10.2147/ijwh.s214254] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Twin reversed arterial perfusion (TRAP) sequence is a specific and severe complication of monochorionic multiple pregnancy, characterized by vascular anastomosis and partial or complete lack of cardiac development in one twin. Despite its rarity, interest in the international literature is rising, and we aimed to review its pathogenesis, prenatal diagnostic features and treatment options. Due to the parasitic hemodynamic dependence of the acardiac twin on the pump twin, the management of these pregnancies aims to maximize the pump twin's chances of survival. If treatment is needed, the best timing of intervention is still debated, although the latest studies encourage intervention in the first trimester of pregnancy. As for the technique of choice to interrupt the vascular supply to the acardiac twin, ultrasound-guided laser coagulation and radiofrequency ablation of the intrafetal vessels are usually the preferred approaches.
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Affiliation(s)
- Annachiara Vitucci
- Division of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Anna Fichera
- Division of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Nicola Fratelli
- Division of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Enrico Sartori
- Division of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Federico Prefumo
- Division of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
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Korlesky C, McPherson E. Early demise of twins in a cohort of stillbirths and second trimester miscarriages. Am J Med Genet A 2019; 179:350-355. [PMID: 30663217 DOI: 10.1002/ajmg.a.61014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/08/2018] [Accepted: 11/16/2018] [Indexed: 11/11/2022]
Abstract
Twins, particularly monochorionic (MC) pairs, are at increased risk for fetal death. Whereas previous work has sought to understand the mechanisms for this increased mortality, most studies analyze viable twin pregnancies or liveborn twin cohorts. In the Wisconsin Stillbirth Service Program cohort of 3,137 stillbirths and second trimester miscarriages, we identified 175 twin pregnancies for a twinning rate of 56/1,000, which is approximately double the general population. The excess of twins among miscarriages and stillbirths was attributable to MC pairs as the incidence of dizygotic (DZ) twinning was not increased compared to livebirth data. The leading causes of fetal demise among twins were twin-twin transfusion, acardia, and twin-twin disruption. Maternal causes of death, primarily premature rupture of membranes, were moderately increased in both MC and DZ twins relative to singletons. Although deceased twins were smaller than expected for viable twins at comparable gestational ages, placenta weights of deceased MC pairs were large compared to combined fetal weight, which indicates placental inefficiency likely due to vascular shunting. Co-twin survival was much lower for MC than for DZ pairs. Therefore, earlier diagnosis and treatment of MC twinning complications may decrease prenatal mortality.
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Affiliation(s)
- Colin Korlesky
- Center for Human Genetics, Marshfield Clinic Research Institute, Marshfield, Wisconsin
| | - Elizabeth McPherson
- Center for Human Genetics, Marshfield Clinic Research Institute, Marshfield, Wisconsin
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Sherer DM, Dalloul M, Garza M, Benton L, Abulafia O. Prenatal sonographic diagnosis of acardiac twin embedded within placenta. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2018; 52:120-121. [PMID: 29155482 DOI: 10.1002/uog.18964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/01/2017] [Accepted: 11/10/2017] [Indexed: 06/07/2023]
Affiliation(s)
- D M Sherer
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, State University of New York (SUNY), Downstate Medical Center, 450 Clarkson Avenue, Box 24, Brooklyn, New York, NY, USA
| | - M Dalloul
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, State University of New York (SUNY), Downstate Medical Center, 450 Clarkson Avenue, Box 24, Brooklyn, New York, NY, USA
| | - M Garza
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, State University of New York (SUNY), Downstate Medical Center, 450 Clarkson Avenue, Box 24, Brooklyn, New York, NY, USA
| | - L Benton
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, State University of New York (SUNY), Downstate Medical Center, 450 Clarkson Avenue, Box 24, Brooklyn, New York, NY, USA
| | - O Abulafia
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, State University of New York (SUNY), Downstate Medical Center, 450 Clarkson Avenue, Box 24, Brooklyn, New York, NY, USA
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