Adult

Congenitally Corrected Transposition of the Great Arteries

The Normal Heart
In a normal heart (Figure 1) “Blue” blood, low in oxygen, comes back to the right hand side of the heart from the body. The right sided pumping chamber (right ventricle or RV) is designed to pump the blue blood a short distance, under low pressure, to the lungs. After picking up oxygen in the lungs, the now “red” blood returns to the left hand side of the heart. The left sided pumping chamber (left ventricle or LV) is designed to pump the blood at high pressure to the rest of the body.

What is ccTGA?
In a ccTGA heart the two pumping chambers are the wrong way round (see Figure 2). The right ventricle (RV) has developed on the left hand side, and has to pump blood at high pressure to the whole body. The left ventricle (LV) has developed on the right hand side, and only needs to pump blood at low pressure to the lungs.

How is ccTGA detected?

• ccTGA can remain undetected well into adult life unless a “murmur” (noisy heart sound) is detected as a child and a heart scan (echo) is done.
• ccTGA may also be discovered when heart beat problems (arrhythmias or heart block) are investigated since they are common in this condition.
• In a ccTGA heart, the right ventricle can weaken (heart failure) and so the condition can be picked up when investigating for this. 

Complications of ccTGA

• Weakening of the right ventricle (heart failure): This happens because in a ccTGA heart the right ventricle has become the main pump of blood to the rest of the body, instead of just supplying low pressure blood to the lungs as in a normal heart.
• Leaking valve (valve regurgitation): When the right ventricle weakens, it stretches the valve attached to it (Tricuspid valve) causing it to leak.
• Heart rhythm problems – the heart can either beat too fast leading to palpitations, or too slowly leading to dizziness. Some patients with slow heart beats will need a pacemaker.
• Occasionally blood clots can form within the heart..

Treatment for ccTGA
We will monitor how the right ventricle is coping and check for complications with regular out-patient assessment and investigations (such as ECG, Echo, sometimes chest X ray, exercise tests, blood tests).

Medication
We provide medication for symptoms of heart failure, heart beat irregularities, and to reduce the likelihood of blood clots forming.

Pacemakers
May be needed for slow heart rhythms.

Surgery
If the valve attached to the right ventricle leaks severely, then assessment for valve surgery (either repair or replacement) may be recommended. If the right ventricle fails severely in some situations referral for assessment for a heart transplant is made.

Long-term outlook of ccTGA
This depends on how the right ventricle copes with being the left side pumping chamber of the heart. This varies greatly between individual patients.

Pregnancy and ccTGA
If the right sided pumping chamber is working well, pregnancy is generally well tolerated in ccTGA and most women can deliver normally. However, the changes in pregnancy can put stress on the right ventricle and cause it to fail or produce heart beat irregularities. It is important you see your cardiologist to discuss these issues BEFORE you get pregnant. You will need regular reviews during your pregnancy to monitor for complications.
The risk of congenital heart disease in the children of a mother with ccTGA is 6%.

Adult Congenital Heart Team
Leeds General Infirmary