heartAt birth or in infancy, approximately 50% of individuals with TSC have at least one tumour in their heart. These benign (non-cancerous) tumours are called a cardiac rhabdomyoma do not usually cause any symptoms. Most rhabdomyomas decrease in size or disappear within the first 1-2 years of life.

The term used by health professionals for things to do with the heart is cardiac. Doctors who specialise in children’s hearts are called paediatric cardiologists.

Signs and Symptoms

Rhabdomyoma
Cardiac rhabdomyomas may be detected during pregnancy using standard antenatal ultrasound but may not appear until the second half of pregnancy. They may be single or multiple and are usually the first clinical clue that the baby has TSC.
They are non-cancerous tumours, which means they do not metastasize, or spread throughout the body. Although it is not clear why, rhabdomyomas typically regress, or shrink, during childhood. Less commonly they can remain stable, newly appear or even grow.
Symptoms
Most individuals with TSC who have cardiac rhabdomyomas will have no symptoms.
For a smaller number of individuals, symptoms depend on the number of tumours and their size and location within the heart.
Larger tumours can obstruct blood flow through the heart and lead to heart failure or cyanosis (blue discolouration of the skin due to insufficient blood oxygenation).
An abnormal heart rhythm, called an arrhythmia can be caused when a tumour is close to the heart’s electrical conduction system.
Poor heart muscle function, or cardiac myopathy, can be caused by replacement of muscle in the heart ventricles with tumour tissue.
A small minority of TSC patients with rhabdomyomas have a heart murmur.
Other
Some individuals with TSC also have vascular abnormalities, which means abnormal blood vessels. These can lead to high blood pressure and very rarely other complications. High blood pressure can also be caused by kidney symptoms.

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Surveillance

On diagnosis of TSC
An ultrasound of the heart (echocardiography or ECG) is recommended on diagnosis of TSC to look for rhabdomyomas. This is particularly important in infants.
Electrocardiography (ECG) is where electrodes are used to detect the electrical impulses of the heart and is used to understand how well the heart is functioning. A baseline ECG may be done to diagnose any rhythm disturbances.
Although echocardiography is a gold standard in diagnosing rhabdomyomas in the heart, other scans such as Magnetic Resonance Imaging (MRI) and Computerised Topography (CT) may also be used to see other abnormalities in the heart.
Ongoing surveillance
Since heart tumours are not known to arise later in life further imaging tests may not be necessary if initial tests did not show any tumours.
If a person has multiple or large rhabdomyomas, ECGs may be done regularly to monitor these and the person’s heart function.
If there are symptoms such as arrhythmia or unexplained loss of consciousness, then an ECG should be done to investigate the possible causes of these.
Individuals being treated with adrenocorticotropic hormone (ACTH) for infantile spasms, a form of epilepsy, should be monitored closely as there is some evidence of growth of rhabdomyomas in infants being treated with ACTH.
Smoking and a high cholesterol level are also risk factors for heart problems such as aneurysm, patients with TSC so individuals and their family ought to try to maintain a healthy lifestyle and diet. Blood pressure should be monitored at least yearly.

Treatment

Because most rhabdomyomas regress in size, watchful monitoring may be all that is necessary in individuals who have rhabdomyomas that are not interfering with the blood flow or rhythm of the heart.
Individuals with significant arrhythmias may require treatment such as medication. There have been reports of successful use of mTOR inhibitor medicines to treat large rhabdomyomas in infancy.

Read more about mTOR inhibitor medicines

In very rare cases where there are severe symptoms, surgery to remove all or part of the tumour may be required. Because most rhabdomyomas shrink in size or even disappear, surgery is usually only done where there is a severe obstruction or a life-threatening arrhythmia.

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About this article

Last updated: 10 December 2018

Prepared by: Clare Stuart, Tuberous Sclerosis Australia
Reviewed by: Dr David Mowat, Clinical Geneticist, Sydney Children’s Hospital

References:

  1. Kwiatkowski D.J., Whittemore V.H. & Thiele E.A. (2010) Tuberous Sclerosis Complex: Genes, Clinical Features, and Therapeutics. Weinheim: Wiley-Blackwell
  2. Heart Manifestations in TSC, Tuberous Sclerosis Alliance, viewed 30th March 2012, https://tsalliance.org/pages.aspx?content=590.
Parts of this web page have been adapted with permission from copyrighted content developed by the Tuberous Sclerosis Alliance, www.tsalliance.org.