Transposition of the great vessels – updated!

Today in ZSFG report the ICU team + Meredith Bock presented a young man with transposition of the great arteries (TGA) and an elevated troponin. I’m pretty rusty on cyanotic congenital heart defects. I hope this review is helpful to others.

Top pearls

  • There are more adults with congenital heart disease in this world than you would expect! Roughly 1 million
  • Transposition of the great vessels is now repaired with an arterial switch. Prior to the late 1980s it was repaired with an atrial switch which had many more complications
  • Call a cardiologist early if you are evaluating an adult with congenital heart disease in the ED. There’s a ton of specialized knowledge here.

As an internist, why should I review this?

  • Disease like TGA used to mean certain death in infancy, but effective surgical interventions have caused mortality to plummet. The mortality rate for TGA with surgical repair is now 5%
  • As a result, ~1 million adults (!) were born with a congenital heart defect of some kind.
    • about half of those are thought to have complex congenital heart disease.
    • 2-3% have transposition
  • So regardless of what you practice you will likely touch them in some way

TGA overview

Anatomy at birth

  • Technically TGA is divided into d-TGA (common) and l-TGA (uncommon)
    • l-TGA does not cause cyanosis, is vanishingly rarely, and will not be reviewed here
  • The name says it all. In d-TGA the aorta is connected to the RV and RA, while the pulmonary artery is connected to the LA and LV (see below)
    • This causes cyanosis because the L sided circulation is basically creates a closed circuit. Deoxygenated blood flows from the SVC/IVC into the right atrium, then the right ventricle, then out the aorta and back into the pulmonary circulation
  • Co-occuring VSDs are common (there’s one in the picture below) and help support oxygenation prior to repair
Anatomy post-repair
  • Since ~1988 uncomplicated d-TGA have been repaired with an Arterial Switch. 
    • How does it work? They cut the pulmonary artery and aorta and put them back where they belong. 
    • Long term complications
      • This repair has relatively good outcomes because it returns basically normal cardiac and great vessel anatomy
      • coronary ischemia – angina is clinically silent after this procedure because the heart is denervated
      • dilation of the aortic root
  • Prior to the late 1980s, most TGAs were repaired with an Atrial switch
    • the words are so similar. The old one switches the atria. The new one switches the arteries =)
  • How does it work?
    • As above, a special channel (called a baffle) diverts de-oxygenated blood from the right atrium to the left atrium. the LV then pumps that blood into the pulmonary circulation. 
    • A second baffle connects the pulmonary vein to the right atrium, so that the right ventricle can pump it to the systemic circulation
  • Complications
    • right heart failure and atrial arrhythmias, because the RV was not designed to act as an LV
    • coronary stenosis in some specific subtypes of procedures
    • problems with the baffle – leaks, occlusions, etc. 

When i see an adult with congenital heart disease, what should I do?

I couldn’t find a review article targeted at generalists that gives a comprehensive approach. So I asked Brad Monash, our (newly appointed !) Moffitt Site director who is med/peds trained. Here’s what he recommends
  • What is the original abnormality?
  • Was it repaired? If so, how and when?
  • What is the current anatomy? (understanding the path of blood flow is crucial.)
  • Is there prosthetic material in place?
  • Are there consequences of the congenital defect or repair? (I.e., pulmonary hypertension, R vs. L-sided heart failure, arrhythmias).
  • Screening for “routine adult heart problems” (eg, atherosclerotic disease, acquired contributors to cardiomyopathy)
  • Miscellaneous considerations: need for infective endocarditis ppx, anticoagulation, exercise restrictions, reproduction issues.

Brad also pointed out that the ACC/AHA has guidelines for managing adults with Congenital heart disease which can serve as a great resource.


Sable CFoster EUzark KBjornsen KCanobbio MMConnolly HMGraham TPGurvitz MZKovacs AMeadows AKReid GJReiss JGRosenbaum KNSagerman PJSaidi ASchonberg RShah STong EWilliams RGAmerican Heart Association Congenital Heart Defects Committee of the Council on Cardiovascular Disease in the Young, Council on Cardiovascular Nursing, Council on Clinical Cardiology, and Council on Peripheral Vascular DiseaseBest practices in managing transition to adulthood for adolescents with congenital heart disease: the transition process and medical and psychosocial issues: a scientific statement from the American Heart Association. Circulation. 2011 Apr 5;123(13):1454-85. 
Skinner J1Hornung TRumball E. Transposition of the great arteries: from fetus to adult. Heart. 2008 Sep;94(9):1227-35.

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