Frequently asked questions on HHT
HHT is a congenital disease. Why do babies and little children usually have no symptoms?
The blood vessels can form telangiectases in HHT patients often after some form of trauma (excessive sunlight, dry air, cold or hot air, infections or other kind of damage). These telangiectases are often prone to bleeding as they form weak spots in the vessel wall. A baby or small child often has nog yet had as much exposure to these factors.
What kind of weak spot is present in the bloodvessels of HHT patients?
Telangiectasia often haemorrhage because of weak vessel walls and high perfusion pressures. Further research is performed on the exact anatomy of those weak vessels.
Can something be done about this weak spot?
Thalidomide (Softenon) causes the smooth muscle cells to attach to the vessel wall. However, Softenon has side effects. A search is going on for alternatives of Softenon that have the beneficial effect and not the side effects.
Why do I have a PAVM and both my sisters do not?
This question has not yet been solved. The idea is that the weak spot of the blood-vessel wall becomes a true vascular abnormality, e.g. a PAVM, when the blood-vessel is damaged. The HHT blood-vessel would not be able to recover. Such a damage could be caused for instance by an inflammation.
Another theory is that besides the causative mutation another DNA abnormality is present, which makes the vessel wall extra vulnerable.
Why do all the tests have to be repeated after 5 years?
It is not exactly known why AVMs develop. External factors such as inflammations, injuries are considered to be important. Because of this lack of knowledge it is impossible to predict whether patients without AVMs in 2010 will not have them either in 2015. And, as you know, AVMs may be dangerous.
If I myself have no HHT, how big is the chance that my child will have HHT?
When it is certain that you have no HHT- that is the family mutation is absent- the chance is 0%. It should be realized that HHT starts somewhere in the family in an ancestor, whose parents do not have the disease. In this ancestor a mutation develops for unknown reasons. This is called a spontaneous mutation. Your child could have the bad luck that he/she has a spontaneous mutation but that chance is exceptionally small.
How big is the chance that my child has HHT, when I have it myself?
That chance is 50% and it remains 50% for all the other children that follow.
At what age can my child be examined for HHT?
That is possible at any age. In practice, we start screening from the age of three years, unless there are abnormal symptoms. In the screening of children invasive procedures such as the drawing of blood or intravenous access are avoided.
My mother has HHT. I am 24 years old. Why should I be screened, when there are no symptoms?
Firstly, because you may have HHT nevertheless. Nosebleeds and red dots may appear later in life and the dangerous PAVMs and CAVMs usually do not cause symptoms until a life-threatening complication occurs, such as brain-abscess. These complications can be prevented.
Furthermore, you and/or your partner probably may want to know whether you have HHT or not in case you want or have children.
I have HHT. Can I give birth at home?
We prefer delivery in the clinic or outpatient department. After all , severe nosebleeds or other complications may occur. Also, the oxygen levels of the baby should be checked with oximetry, a cap placed over the fingertip.
Why do nosebleeds occur so frequently in HHT?
The blood vessels in the nose are vulnerable, because the nose is in direct contact with the outer world. Polluted air, dry or cold air, colds, allergies, turbulence of the inhaled air may all cause damage. Furthermore, the blood vessels of the nose are extra vulnerable, because they are only protected by a thin mucous membrane and lay on a hard layer of cartilage. This explains why children and adults without HHT also often have nosebleeds.
When do I have to go to the hospital because of a nosebleed?
It is difficult to give firm rules for this problem.
Previous severe nosebleeds, a long distance to the hospital, other diseases such as heart-failure or the use of anticoagulants are reasons not to wait too long.
A rule of thumb is that you should not wait until you have lost more than one litre (=1000milliliter) of blood; the adult body contains only five litres of blood. However, the blood-loss is difficult to estimate, unless you collect the blood in a bowl. You can also calculate the blood-loss: twenty drops constitute one millilitre. That is 180 millilitre per hour, when you lose sixty drops per minute. And it will be 300-600 millilitre, when there is a gush.
My ENT doctor wants to cauterise the bloodvessels in my nose. Should I give permission?
No, that is not advised unless your ENT doctor has great experience in HHT. The old fashioned cauterisation gives only temporary results and can lead to further damage and more nosebleeds in the future. Argon-plasma laser-beams are at present the best to cauterise.
Are there professions that should be avoided, when one has HHT?
Large differences in temperature may provoke nosebleeds. Therefore, working in for instance refrigerated chambers is not recommended. Strenuous effort may also provoke the bleeding. Thus, heavy professions may not be ideal. Frequent nosebleeds may have social implications. This may interfere with representative jobs. On the other hand several top sportsmen with HHT are known. In general, it is true that nobody knows in advance how serious his/her HHT will be.
Can I do every kind of sport with HHT?
Yes. You can do every sport, except scuba diving when you have a PAVM or when a PAVM has not been ruled out. Tiny nitrogen bubbles often are formed in the blood, when you dive. These may pass to the brains, when there is a PAVM. If you have been diagnosed with a brain AVM, combat sports are ill advised but talk to your HHT doctor about it. Some patients experience that heavy effort provokes nosebleeds. If that is the case you should refrain from that sport.
Should I avoid certain foods or beverages with HHT?
In general not. But some patients feel that spices and alcohol provoke nosebleeds. Some foods or drinks may aggravate nosebleeds in certain individuals, for example alcohol, spices, foods high in salicylates (including red wine, spices, chocolate, coffee, and certain fruits), natural antiplatelet activity (garlic, ginger, ginseng, ginkgo biloba, and vitamin E15), or omega-3 acids (oily fish, salmon). Follow your own experiences.
Can I fly with HHT?
Yes, in general there are no objections to flying. However, sometimes precautions are necessary. The air in the plane is dry. That may lead to nosebleeds. You can moisten the inspiratory air by holding a wet cloth in front of your nose.
The oxygen pressure in the plane is lower than on earth, comparable with a mountain of 2000 meters. This may be dangerous, when your oxygen saturation on the ground is already low due to PAVMs. Consult your HHT doctor, when that is the case. Severe anaemia is also dangerous at low oxygen tensions. Consult your HHT doctor.