The Thymus: to Remove or Not to Remove? That is the Question.

Why do I ask?

I believe it's very relevant to a parent of a child with Hypoplastic Left Heart Syndrome who has had surgical repair, because in order to access the heart, a surgeon must remove the thymus located above it.

What is the thymus?

The thymus gland is an organ of the immune system. The thymus gland is located in the upper part of the chest cavity, directly behind the sternum. It is largest in size in childhood, about the size of an apple, continues to grow throughout puberty, and slowly shrinks in size into adulthood, to the size of a pea.

                                

What does the thymus do?

The role of the thymus gland is to process lymphocytes, which are white blood cells that travel the body through the bloodstream. These lymphocytes, also called T-lymphocytes or T-cells, protect the immune system by blocking the invasion of viruses and bacteria. They also help to prevent abnormal cell growth that occurs with cancer.

What we don't know.

If the thymus gland is removed in infancy, the immune system may never fully develop. Does this increase the chance of infection in children who have no thymus gland or whose thymus never developed properly, because the majority of t-cell production occurs early in life?

What we do know.

Ancient Greeks believed the thymus to be the seat of the soul, but for centuries its significance remained unremarkable. It wasn't until 1961 when Dr. Jacques Miller, a French-Australian immunologist, solved an ancient medical mystery and proved an unbelievable result…the thymus was of crucial importance to the immune system.

A 1982 article in The New York Times discusses aging and the gradual decline in immune function, demonstrating the importance of the thymus gland in function and protection of the immune system. Many studies since the initial finding of Miller in 1961 have supported the importance of thymus related to asthma, allergy, dermatitis, rheumatoid arthritis, autoimmune disease and cancer.

What does this mean to a child with HLHS?

Are children who have had their thymus removed potentially becoming immunodeficient?  Many doctors do not believe there is an increased risk of infection in children who have had their thymus removed. Does the medical community underestimate the important immunity function of the thymus gland? Research experiments in the 1960's proved it was a necessary organ, and current research studies are being conducted to understand the relationship of thymus gland function and immunity.

Examples of current research.

In 2004, researchers at Children's Hospital Iceland, Reykjavik, published "The influence of partial or total thymectomy during open heart surgery ininfants on the immune function later in life," which describes their findings from a 10-year study conducted on nineteen children who underwent open heart surgery compared to nineteen healthy controls of the same age and gender. Each subject's blood was tested at age ten.  The study group had lower counts for lymphocytes (part of the white blood cell that recognizes a foreign substance) and higher counts for neutrophils (part of the white blood cells that respond to infection) compared to the control group confirming lower t-cell production, but did not demonstrate clinical significance early in life.

Similar studies with similar findings.

Immunodeficiency following neonatal thymectomy in man

Levelsof Recent Thymic Emigrant Cells Decrease in Children Undergoing Partial Thymectomy during Cardiac Surgery

Thymic Function and Impaired Maintenance of Peripheral T Cell Populations in Children with Congenital Heart Disease and Surgical Thymectomy

Complete DiGeorge syndrome: Development of rash, lymphadenopathy, and oligoclonal T cells in 5 cases

Longitudinal analysis of immune function in the first 3 years of life in thymectomizedneonates during cardiac surgery

For neonates undergoing cardiac surgery does thymectomy as opposed to thymic preservation have any adverse immunological consequences?

Where do we go from here?

In 2002, a Monash University researcher presented a very interesting finding in the study, "Regrowing the Thymus Gland," in which he describes the successful regrowth of the thymus back to full size in mice, to begin producing t-cells again to strengthen the immune system. Barring the regrowth of the thymus gland, strengthening the immune system today can be approached in several ways. Proper nutrition in the form of a well balanced diet and antioxidants is one approach. Sweetbreads, made from the thymus glands of young calves, like many organ meats, are a nutritional powerhouse packed with vitamins, minerals, amino acids and other substances vital for nutrition. Although not well studied in humans, supplementing a diet with the thymus gland extract is said to boost the immune system. Thymic hormone replacement therapy, although unapproved and unregulated by the FDA, has demonstrated some potential benefits clinically, with the regular use of thymus therapy.

We simply need more research. Thymus re-implantation in the future? Seems like an inevitable course. 

Author's Note:  My son was diagnosed at 18 months of age with Common Variable Immune Deficiency, a primary immune deficiency.  For more information about primary immune deficiencies, please visit The Immune Deficiency Foundation. 

Gearing Up For Winter - A Heart Kids Challenge

Like most kids, our heart kids face the yearly challenge of winter illness, but sometimes with greater difficulty. What can we do now to prepare them for the cold and flu season?

Prevention

While there is no vaccine against the common cold, there are immunizations to help protect against respiratory infections such as flu and pneumonia.  Flu and pneumonia pose greater danger for children with heart defects. Both the American Heart Association (AHA) and the American College of Cardiology emphasize the importance of getting a flu shot if you have heart disease. According to the AHA, the best time to get a flu shot is between October and November, but you and your child can still benefit by getting the influenza vaccine in January or even later. Flu season can begin as early as October and last through May. Patients with heart disease should not receive the live, attenuated vaccine given as a nasal spray in FluMist. The live vaccine can cause influenza in some high-risk patients. In some cases, a special monthly immunization for a cold virus (RSV) may be recommended during the winter months. Talk to your child's doctor about the influenza, pneumococcal and RSV vaccines.

As much as possible, avoid anyone who has a cold or the flu. Stay out of crowds during the height of flu season (usually October through March). Remind your child to wash his/her hands thoroughly and frequently, especially after using the bathroom and before eating. Keep your child's immune system in good shape by eating healthy and getting the right amount of sleep.  

Over-the-counter Remedies

Most heart parents are instructed to avoid giving their child any cold medicine that contains decongestants. According to the American Heart Association, decongestants should not be used because they can raise blood pressure. While there are some over-the-counter cold medicines that may be safe, always check with your child's doctor first.

Unfortunately there is little we can do to stop the cold virus but we can provide comfort measures to help with the symptoms of the common cold. Visit WebMD and read the article, "10 Natural Ways to Ease the Common Cold."  This article offers great safe tips to help our kids feel better when they do get a cold.

How does cold weather affect the heart?

Children, especially those with heart disease, often have a decreased ability to maintain their normal internal body temperature in very cold, damp, and windy weather. Cold weather has been shown to affect the heart and circulation in many ways. When we breathe cold air into to our lungs, it constricts the blood vessels in our chest area right away. Because those blood vessels are then narrower, the heart must pump harder and beat faster to pump blood in and out. Keep your child warm and dry by dressing him/her in layers of clothing. Layering traps air between the clothing forming a protective insulation. Since heat can be lost through the head, hats and scarves help keep the heat in. Keep hands and feet warm too, as they tend to lose heat quickly. Visit the  American Heart Association website and learn more about the dangers of cold weather for those with heart disease.

Have a happy, healthy fall season!