In my last post, I wrote about the amazing advances in Congenital Cardiac Surgery and how Heart Defect mortality rates have dropped 38% from 1979 to 1997. But there is still one defect we don’t have a good answer for yet: Hypoplastic Left Heart Syndrome, or HLHS.
Hypoplastic Left Heart Syndrome is not a singular defect, and could have any number of variations. But all of them feature a small (or nonexistent) Left Ventricle and a small Ascending Aorta.
If you look at a cutaway view of a normal heart, you will notice right away that while they are roughly the same size, the Right Ventricle has a larger volume than the Left Ventricle. The Right Ventricle has a smaller pumping muscle: a larger one isn’t necessary because the Right Ventricle only pumps blood to the lungs and back. But the Left Ventricle features a large, thick pumping muscle. When it contracts, the blood is really going places: out into the Aorta, and from there all over the body.
So if the Right Ventricle is content to just drive around the block, the Left Ventricle is at the airport boarding a flight to London. But in a heart with HLHS, the left Ventricle and its pumping muscle are tiny and the Aorta is barely functional. After all, the root word for hypoplastic means “underdeveloped”. Because of this, a right sided heart defect (like Tricuspid Atresia, which is what I have) is more survivable than a left sided heart defect. 95% of children with HLHS who receive no treatment die within one week.
Even with surgery, in the mid 1980’s only 28% of HLHS patients survived. (See the 5th Paragraph of the above link.) Until the late 1980’s an HLHS repair involved only two surgeries – The Children’s Hospital of Philadelphia (CHOP) didn’t begin to use the intermediate operation until 1989. (The entire link is informative, but page down to the section labeled “Discussion” for a look at how the three surgery procedure developed.) Current survival rates for the three stage surgical procedure are roughly 75%, with almost no data for long term survival.
This is completely unacceptable.
So what can we do about it?
1) Pass the Congenital Heart Futures Act. The Congenital Heart Futures Act, currently under review by two Congressional committees, will authorize more National Institutes of Health funding for Congenital Heart Defect (CHD) Research. Research is already going on – this January 2008 report from the National Institutes of Health (NIH) states that families with a Bicuspid Aortic Valve in their medical background are more likely to have an infant born with HLHS – but more funding means more and better tools, and more people trying to find a solution.
The Act will also create a CHD Patient Registry, maintained in one location and accessible to physicians. A properly administered registry will assemble a massive amount of data for study. The Centers for Disease Control will also develop educational programs concerning Congenital Heart Defects and their effects on patients and their families.
2) Identify Major Surgical Hubs. You aren’t going to allow a 200 bed community hospital to attempt the three surgery repair needed for HLHS. And it’s not that they are not careful, caring people… they do not have the experience. Identify the large national centers that perform many difficult medical procedures and create regional pipelines that move patients to these hospitals as quickly as possible.
3) Test new surgical theories. Gone are the days when new surgical procedures were developed through the “try it and see” method. With today’s faster computers, surgery can be simulated. A surgeon can “practice” on a computer before performing the actual operation, which give him the chance to anticipate any problems that may occur. By creating a computer simulation of an HLHS heart (multiple variations of HLHS can be programmed in, as can other defects) and using it to test new surgical theories, surgeons can explore “what if…?” theories without actually harming a patient.
4) Create a HLHS-only Registry. As a subset of the National CHD Registry, create a registry dedicated to gathering data only from patients with Hypoplastic Left Heart Syndrome. Small databases already exist and have been valuable in research: for example, researchers have used a HLHS database to analyze the surgical approaches to HLHS to determine which ones work better. Research and better surgical procedures reduced HLHS deaths in California nearly 50% between 1990 and 2004. But such studies draw on limited databases for their information. Create a national database, and you open even more avenues for study.
5) Determine if HLHS has a genetic or an environmental origin. As noted in the January 2008 NIH report, families with an occurrence of a certain heart defect are more likely to have HLHS occur in the family later. That points to a genetic cause. But there is also evidence of an environmental factor – a “cluster” of twice as many HLHS cases than would be normally expected in a certain section of Baltimore, Maryland. We need to devote the time and resources needed to determine what exactly causes HLHS: Is it a genetic predisposition? Or is the environment the trigger? If it is genetic, can we learn how to prevent it? If it is environmental, what is the cause, and can we eliminate it? Or perhaps certain environmental conditions cause the genetic changes that eventually lead to HLHS.
These are just some of the things that we could do to improve Congenital Heart Defect survivability in general, and HLHS survival in particular. Quite often, we have to “think outside the box” to see the problem from an entirely different angle, and then perhaps we could find the answer.
Because every heart deserves to live a lifetime.