As the mother of a child with HLHS, I have wondered what causes this rare heart defect. I have done a lot of research, attended conferences and spoken to doctors about HLHS. We have mused together about potential causes and in the past most of the doctors I spoke with seemed to feel that it was not something simple. They seemed to feel that it was probably caused by a combination of genetic and environmental factors. For a while, there were some research projects about HLHS being caused by a virus. I never saw a finished report on those studies and a cursory search on Google did not reveal any such study.
What do we know for certain? Are parents to “blame” for their children’s heart defects? Could they have been avoided? What guarantee do we have that our children’s children will not have the same heart defect?
We know that the heart develops in the fetus very early --within the first eight weeks of life a child with HLHS will already exhibit some abnormalities. We also know that the sooner a diagnosis of HLHS is made, the sooner parents can start researching this heart defect and prepare themselves for the challenging road ahead.
Some research suggests that a prenatal diagnosis results in improved surgical outcome (see: http://circ.ahajournals.org/cgi/content/full/103/9/1269 ) while others warn about the additional risk factors possibly associated with HLHS (see: http://www.med.umich.edu/opm/newspage/2003/uterodiagnosis.htm ). I think one of the greatest benefits of prenatal diagnosis, especially EARLY prenatal diagnosis is the potential opportunity for in utero surgery to stave off the complete development of hypoplastic left heart syndrome or at least give the baby a fighting chance for the 3-staged procedure which allows some children with HLHS to have a chance for a quality life. http://circ.ahajournals.org/cgi/content/abstract/103/9/1269 and http://web1.tch.harvard.edu/views/feb03/fetal_cardiac.html
What is now being suggested by new research, however, might rock the HLHS world. Until this time, parents have been told that the cause of HLHS is unknown. Mothers and fathers were told that the often-fatal heart defect was not their fault. They were told that there was nothing that could have been done to prevent it. Those words may not be uttered by all doctors from this point on.
According to a study done at Cincinnati Children's Hospital, doctors now believe that HLHS is caused by genetic factors. Personally, I was stunned to read this. I have read before that it is not uncommon for first degree relatives of children with HLHS to have congenital heart defects themselves, most commonly bicuspid aortic valve (BAV) and coarctation of the aorta (CoA). Now there are even guidelines for clinicians dealing with families who have HLHS in their families in order to properly screen for congenital heart defects in first degree relatives ( http://www.adhb.govt.nz/newborn/Guidelines/Cardiac/ScreeningRelativesForCHD.htm ). But never before have I read that HLHS is caused by genetics alone.
The article is short ( http://www.news-medical.net/?id=31066 ) but the implications are overwhelming and will affect people all over the world. Could it be that there are no environmental factors that help to produce HLHS? Is it possible that viruses play no role in the development of HLHS? Is the sole cause of HLHS genetic?
I caution anyone reading this research to keep the following facts in mind:
1) This study was conducted with a very small group of people (only 38 families were studied). This may not be representative of the population at large.
2) This study was conducted at only one institution --for this study to be validated, other institutions around the world would have to conduct similar studies and come to the same conclusions. Otherwise, if all families were from the same general area, there may indeed be some environmental factors that the researchers did not take into account.
3) This study, as well as some others, may make it possible for people who have a child with HLHS to take their other children in for an echocardiogram. Not long after I read about the higher-than-average incidence of BAV or CoA occurring in first degree relatives --a number of which had gone undiagnosed until the study was done --I took my older son in for his annual exam and I spoke to his doctor about what I had read and my concern that Joey might have an undiagnosed CHD. Because he had never heard anything unusual with Joey's heart and Joey was a competitive athlete, he said he couldn't recommend an echo. I didn't realize how much I worried about Joey until a friend told me a couple of years later that her hospital was offering free echo screenings of athletes. I took Joey in and watched the echo. I was amazed at how much I was able to identify. Joey's heart was so easy to "read" compared to Alex's heart! After 12 years of watching Alex's echos, I guess I had learned quite a bit. I made it to the car before I cried tears of relief. Joey's heart is fine. I have never had an echo; maybe I should. Perhaps this bit of research will help doctors in recommending echocardiograms for all first-degree relatives of children with HLHS.
This research means that it might become possible for us to finally know what really causes HLHS, but more importantly, for us to cure this dreaded heart defect. Once we know what causes the heart defect, we might be able to take more aggressive actions to stop it from occurring all together. This is very important research --research that could save countless lives. Research that could spare parents from living with a child who has to undergo three surgeries to have a heart that functions --but still is not a "normal" heart. Research that could spare children from living a life where they cannot do everything their heart-healthy siblings can do. This research, and more research like it, just might prevent me from becoming the grandmother of a child with a congenital heart defect.
Copyright © October 2007 Anna Jaworski
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