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PubMed This is a summary of 17 peer-reviewed journal articles Updated
Pediatric Cardiology · Dextro-Transposition of the Great Arteries

How D-TGA Affects Your Baby's Heart

At a Glance

D-TGA is a congenital heart defect where the two main arteries are swapped, creating separate blood flow loops that prevent oxygen from reaching the body. Babies rely on natural holes in the heart to mix oxygenated blood until they can undergo the corrective Arterial Switch Operation.

To understand D-TGA, it helps to think of the heart as the body’s plumbing system. In a typical heart, the pipes are connected in a specific way to ensure oxygen gets to every part of the body. In your baby’s heart, these pipes are “transposed”—or swapped [1].

Parallel vs. Series Circulation

Normally, the heart works in series circulation, much like a figure-8 [2]. Blood travels from the body to the heart, then to the lungs to get oxygen, back to the heart, and finally out to the rest of the body [3]. This single path ensures that every drop of blood passing through the body has recently been “refilled” with oxygen.

In D-TGA, the heart works in parallel circulation [4]. Imagine two separate circles that never touch:

  • The Body Loop: Oxygen-poor blood comes from the body, enters the heart, and is sent right back out to the body without ever visiting the lungs [4][2].
  • The Lung Loop: Oxygen-rich blood comes from the lungs, enters the heart, and is sent right back to the lungs without ever reaching the rest of the body [4][2].

Without a way for these two loops to mix, the body cannot get the oxygen it needs to survive [4]. This is why babies with D-TGA rely on naturally occurring “holes” in the heart—like a Patent Foramen Ovale (PFO) or a Patent Ductus Arteriosus (PDA)—to allow oxygenated blood to cross over into the body loop [5][3].

D-TGA vs. L-TGA: Why It Matters

As you research, you may see a similar-sounding condition called L-TGA (congenitally corrected transposition). It is important to know the difference so you are looking at the right information for your baby:

Feature D-TGA (Your Baby’s Diagnosis) L-TGA (Congenitally Corrected)
The Issue The main arteries are swapped [1]. Both the arteries and the lower chambers (ventricles) are swapped [6].
Circulation Oxygen-poor blood goes to the body; this requires urgent surgery [7]. Blood flows in the correct direction naturally, though the heart chambers are doing jobs they weren’t designed for [8].
Main Treatment The Arterial Switch Operation (ASO) to move the arteries to their correct spots [9]. Long-term monitoring of the “swapped” heart chambers; surgery may not be needed immediately [10].

How D-TGA is Spotted

Before Birth: The ‘I-Sign’

If your baby was diagnosed during a prenatal ultrasound (fetal echocardiogram), the doctor likely looked at the “three-vessel view” of the heart. In a normal heart, the vessels form a ‘V’ shape as they converge [11]. In a heart with D-TGA, because the aorta has shifted forward and sits directly in front of the pulmonary artery, they appear stacked in a straight line [11]. Doctors call this the ‘I-sign’ [11][12].

After Birth: Cyanosis

If D-TGA is not caught during pregnancy, it usually becomes apparent shortly after birth. As the natural holes in the baby’s heart begin to close, oxygen levels in the body drop [3]. This leads to cyanosis, often called “blue baby syndrome,” where the skin, lips, or fingernails take on a bluish tint [3][13]. This is a signal that the two circulatory loops are no longer mixing enough oxygenated blood [14].

What the Initial Echocardiogram Looks For

Once D-TGA is suspected, an echocardiogram (an ultrasound of the heart) is performed to map out the heart’s specific structure. The medical team is looking for three main things:

  1. Coronary Artery Anatomy: The tiny arteries that feed the heart muscle itself are often in unusual positions in D-TGA [15]. Knowing their exact “map” is critical for the surgeon [5].
  2. Mixing Holes: The team checks if the natural “holes” are large enough to let blood mix [5][16].
  3. Associated Defects: They check for other issues, such as a Ventricular Septal Defect (VSD) (a hole between the lower chambers) or narrowing of the heart valves [15][17].

Common questions in this guide

Why is a hole in the heart actually a good thing for a baby with D-TGA?
Because D-TGA creates two separate blood flow loops that do not mix, natural holes like a Patent Foramen Ovale (PFO) allow oxygen-rich blood to cross over into the body's circulation. Without these holes, the body would not get the oxygen it needs to survive.
What is the difference between D-TGA and L-TGA?
In D-TGA, the main arteries are swapped and oxygen-poor blood is sent to the body, requiring urgent surgery. In L-TGA, both the arteries and the lower heart chambers are swapped, so blood naturally flows in the correct direction, though the heart must be monitored long-term.
What does the 'I-sign' mean on a fetal ultrasound?
The 'I-sign' is a visual marker doctors look for during a prenatal ultrasound. In a typical heart, the blood vessels form a 'V' shape, but in D-TGA, the shifted aorta and pulmonary artery stack in a straight line, resembling the letter 'I'.
What causes a baby with D-TGA to look blue?
Babies with D-TGA may develop a blue tint to their skin, lips, or fingernails, known as cyanosis. This happens shortly after birth when the natural holes in the heart begin to close, causing oxygen levels in the body to drop significantly because the blood is not mixing.
Why do doctors need to map the coronary arteries before surgery?
The tiny arteries that supply blood to the heart muscle itself are often in unusual positions when a baby has D-TGA. Surgeons need an exact map of these arteries to safely move them during the Arterial Switch Operation.

Questions for Your Doctor

4 questions

  • •Is my baby's coronary artery pattern considered 'standard' or 'atypical,' and how does that affect the surgery?
  • •Is the hole in the wall between the top chambers (atrial septum) large enough for blood to mix, or is it 'restrictive'?
  • •Beyond the switched arteries, are there any other defects like a hole between the lower chambers (VSD) or a narrowing of the heart valves?
  • •Could you draw a simple diagram of my baby's specific heart layout so I can visualize it?

Questions for You

3 questions

  • •When I look at the diagram of my baby's heart, can I clearly identify the 'two separate loops' of blood flow?
  • •What symptoms was I told to look for if the baby was diagnosed after birth (like blue-tinted skin or fast breathing)?
  • •Do I feel like I have a clear understanding of why a 'hole' in the heart is actually a good thing for my baby right now?

References

References (17)
  1. 1

    Long-term myocardial performance of the systemic right ventricle during exercise in patients with transposition of the great arteries and atrial switch operation.

    Kozicka UA, Kożuch K, Sadowski K, et al.

    Hellenic journal of cardiology : HJC = Hellenike kardiologike epitheorese 2026; (88()):57-62 doi:10.1016/j.hjc.2024.08.004.

    PMID: 39128709
  2. 2

    The hemodynamic impact of congenital heart diseases during fetal-to-neonatal transition: an in-silico investigation.

    van Willigen BG, Krabben BC, van der Hout-van der Jagt MB, et al.

    Pediatric research 2026; doi:10.1038/s41390-025-04565-1.

    PMID: 41617779
  3. 3

    Effects of Prostaglandin E1 and Balloon Atrial Septostomy on Cerebral Blood Flow and Oxygenation in Newborns Diagnosed with Transposition of the Great Arteries.

    Cucerea M, Ognean ML, Pinzariu AC, et al.

    Biomedicines 2024; (12(9)) doi:10.3390/biomedicines12092018.

    PMID: 39335532
  4. 4

    Surgical Treatment of Complete Transposition of the Great Arteries in Newborn.

    Wu QY, Li DH, Xue H, et al.

    Chinese medical journal 2016; (129(19)):2381-3 doi:10.4103/0366-6999.190663.

    PMID: 27647199
  5. 5

    Management of 760-g Extremely Premature Infant With Dextro-Transposition of the Great Arteries.

    Khazaal JR, Sowinski HA, Ratnasamy C, et al.

    World journal for pediatric & congenital heart surgery 2020; (11(4)):518-519 doi:10.1177/2150135120908777.

    PMID: 32645770
  6. 6

    Cardiac Conduction System in Congenitally Corrected Transposition of the Great Arteries and Its Clinical Relevance.

    Baruteau AE, Abrams DJ, Ho SY, et al.

    Journal of the American Heart Association 2017; (6(12)) doi:10.1161/JAHA.117.007759.

    PMID: 29269355
  7. 7

    Pathogenesis and Surgical Treatment of Dextro-Transposition of the Great Arteries (D-TGA): Part II.

    Zubrzycki M, Schramm R, Costard-Jäckle A, et al.

    Journal of clinical medicine 2024; (13(16)) doi:10.3390/jcm13164823.

    PMID: 39200964
  8. 8

    Incidental congenitally corrected transposition of the great arteries (ccTGA) in an adult with suspected coronary artery disease: review on radiological features and pathophysiology.

    Sayuti KA, Azizi MYSB

    BMJ case reports 2020; (13(4)) doi:10.1136/bcr-2019-234225.

    PMID: 32327461
  9. 9

    Long-Term Survival After Arterial Versus Atrial Switch in d-Transposition of the Great Arteries.

    Kiener A, Kelleman M, McCracken C, et al.

    The Annals of thoracic surgery 2018; (106(6)):1827-1833 doi:10.1016/j.athoracsur.2018.06.084.

    PMID: 30172857
  10. 10

    Management Options for Congenitally Corrected Transposition: Which, When, and for Whom?

    Miller JR, Sebastian V, Eghtesady P

    Seminars in thoracic and cardiovascular surgery. Pediatric cardiac surgery annual 2022; (25()):38-47 doi:10.1053/j.pcsu.2022.04.001.

    PMID: 35835515
  11. 11

    Is the "I-Sign" in the 3-Vessel and Trachea View a Valid Tool for Prenatal Diagnosis of D-Transposition of the Great Arteries?

    Palatnik A, Gotteiner NL, Grobman WA, Cohen LS

    Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 2015; (34(7)):1329-35 doi:10.7863/ultra.34.7.1329.

    PMID: 26112638
  12. 12

    A tricky fetal case of isolated transposition of great arteries without the I-shaped sign.

    Kawazu Y, Takahashi K, Tsujie T, Chayama K

    The journal of obstetrics and gynaecology research 2022; (48(12)):3304-3307 doi:10.1111/jog.15410.

    PMID: 36042690
  13. 13

    Hypothermia for cardiogenic encephalopathy in neonates with dextro-transposition of the great arteries.

    Boos V, Bührer C, Photiadis J, Berger F

    Interactive cardiovascular and thoracic surgery 2021; (32(1)):130-136 doi:10.1093/icvts/ivaa235.

    PMID: 33221903
  14. 14

    Anomalous Origin of the Right Subclavian Artery from the Right Pulmonary Artery in a Patient with d-Transposition of the Great Arteries: Diagnosis and Surgical Treatment.

    Sekelyk R, Delikatnyi M, Kozhokar D, et al.

    World journal for pediatric & congenital heart surgery 2025; (16(1)):114-116 doi:10.1177/21501351241286450.

    PMID: 39492117
  15. 15

    A safe and reproducible method to correct a d-transposition of the great arteries with the usual (type A) coronary artery pattern.

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    Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters.

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  17. 17

    Arterial Switch Using an Autologous Aortic Sinus Tube With the Lecompte Maneuver.

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    PMID: 41425407

This page explains the anatomy and diagnosis of D-TGA for educational purposes. Always consult your pediatric cardiologist and surgical team for specific medical advice regarding your baby's heart condition.

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