Build-your-own Heart Valve
This article is published by Children's Hospital in Boston, describing the work that one of their doctors is doing to create a different type of heart valve replacement for children. Read the article, then pursue ONE of the following ideas:
1. Pick a word you aren't familiar with in the article, look it up, and define it for us.
2. Learn about a heart defect that children might be born with, and tell us about it.
3. Give us an example of the business end of heart valves - what companies are in the valve-replacement business? What are some challenges they face?
Be sure to discuss something that wasn't discussed in an earlier comment.
38 comments:
“Congenital” means being born with a condition due to hereditary or environmental reasons. Many heart diseases in children are congenital since they are not acquired over time, but rather naturally part of their essence due to irregularities that occur during their heart’s development period.
Children are sometimes born with a hole in their heart, or an atrial septal (ASD) defect. This defect causes an unnatural hole between the left and right atria where there should be a dividing wall. This opening allows oxygenated blood to flow into the right atrium, which creates a “swishing” sound in the heart. Atrial Septal defects occur weeks after contraception while the heart is still developing. In most cases, the causes of ASDs are genetic. Many children with ASD do not experience obvious symptoms, but those with severe ASDs might suffer from fatigue, lung problems, or growth problems. If not detected on time, an ASD can cause an unmoral heart beat, ultimately leading to an increased risk of a stroke since blood cannot travel to the brain properly. Fortunately, ASDs are usually treated and diagnosed in a timely manner.
http://kidshealth.org/parent/medical/heart/asd.html
Aetna is a company that is in the valve-replacement business. Even though blood clots in valve replacements are low, valve-replacement companies still face the challenge of creating replacement valves that do not create blood clots in their patients. 1.3% to 2.7% patients suffer from severe bleeding each year from blood clots in their valve-replacements. Also, companies face the challenge of creating longer lasting valves that do not require replacement within 10-15 years of time.
http://womenshealth.aetna.com/WH/ihtWH/r.WSIHW000/st.36134/t.36479.html#Risks
From the above article, I think it’s amazing how much science has developed over the years, enabling researchers to even develop “living, growing valves created in [a] lab from a patient’s own cells,” which is done through tissue engineering. They were even able to make pulmonary valve leaflets that “mimic what really happens in the embryo.” In the future, they’re hoping they can fix this condition so that children don’t have to come back repeatedly for multiple surgeries. And although I’m grateful I’ve never had to have a heart surgery, I’m sure there are many people out there that would be relieved to see this article. And now that they’ve already begun to start testing it in animals – sheep first, in this case – I think we’re on our way to another successful breakthrough in the medical science world.
I’ve read about another congenital heart problem that babies are sometimes born with; it’s called a ventricular septal defect, or VSD. It’s a condition in which there is a hole, or an opening, in the septum, which separates the right and left ventricle. So when the heart beats, some of the blood in the left ventricle (which, as we learned in class, already traveled to the lungs and received oxygen) flows through the hole into the right ventricle (which contains oxygen-depleted blood because it’s coming from the body). As a result, the oxygen-rich blood mixes with the oxygen-poor blood and is sent back to the lungs for oxygen, causing the heart to be less efficient. Usually when the opening is small, it may close on its own as the child grows older, or don’t cause problems. But when it’s bigger, the child might need surgery to repair it. A telling symptom to a baby that might have VSD is the bluish tint to the skin because of the oxygen-poor blood, which is most visible in the lips and fingernails. (http://www.americanheart.org/presenter.jhtml?identifier=11066# there’s a picture that shows exactly what it is, so you can see where the hole is)
http://www2.presstelegram.com/ci_8744776
This article is about a 9-year old Cambodian girl who had VSD, and the hole happened to be big – the size of a quarter – so big that her heart was pumping four times more blood than she had to. People thought she would definitely have irreversible lung damage even if the surgery went well. However, they sewed a patch in place (with a smiley face drawn on with Davok’s blood by the surgeon – a bit morbid, no?) and now she’s healthy, and with a “new heart.”
Edwards life sciences, located in orange county, is conducting a lot of research in this field as well as producing many products that encompass new ideas and techneques. They produce partial repairs and full vavle replacements, they are all location specific. For the full valves they use pig/cow heart valves that have been stripped of their dna and other protiens so they are biocompatable with humans, this covers the Aortic replacement and Mitral replacement valves. For the partial valve repair they are able to fix mitral and tricuspid valves that suffer from different desieses. Presently these procedures require open heart surgery, splitting open chest and cutting into the heart, Edwards along with many other companies are working on in between rib approach and other less invasive techniques that can be just as reliable. The other idea that is showing promise is to compress the valve and insert it into the femoral artery located in the leg and push the valve into position and then expand the valve in the desired location by compressing the old valve in its "open position" and mounting the new one to be held in by pressure and tissue encompassment. Some issues that they face are break down of flow, and excess tissue build up on the leaflets. The other problem is making the valves respond to the human bodies pressure differences as opposed to the pig/cow hearts. Red blood cells and somewhat fragile and need to interact with the valve just like the old valve did to prevent RBC breakdown.
http://www.yourheartvalve.com/
Augmentation: “the action or process of making or becoming greater in size or amount.” A child who has congenital heart disease needs their pulmonary artery to be augmented, because as they grow, so does their heart. To solve this problem of valve replacement, children patients will have valves created in the lab from their own cells.
One heart defect some children can be born with is Aortic Stenosis, which is an obstruction of blood flow between the left ventricle and the aorta. The most common abnormality occurs when the aortic valve has only two, rather than three, leaflets: a bicuspid aortic valve. Children with aortic valvar stenosis usually lack symptoms and have normal health. A heart murmur is a common sign indicating that a valve problem may be present. Symptoms occur only with severe aortic stenosis and a newborn usually shows heart failure in the first days of life. Such a situation requires immediate treatment, either “balloon dilation of the valve” or surgery.
http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/avs.htm
Endovalve was founded in 2005 to develop and commercialize the Endovalve percutaneous mitral valve replacement system for treating mitral regurgitation (MR). Some challenges Endovalve faces is the fact that MR sufferers let their disease go untreated. A majority of the estimated four million MR sufferers in the United States fear the risks associated with cardiopulmonary bypass, and avoid the help of companies such as Endovalve.
http://www.endovalve.com/company.html
This article was really informative that showed me just how far technology has come. Heart valve replacements are one thing, but living and growing ones are just amazing. My brother is a biomedical engineer at Abbott Laboratories and he tells me about all the new advances and tools that heart surgeons use. He researches the best tools and creates new devices, such as efficient catheters. When I asked him about how his tools affected children and infants, he said it was hard to create catheters and heart-valve replacements because they need to be so incredibly small, and need to be replaced as the child grows. This new innovation will truly help children with heart defects. The research and technology of today has truly become a great contributor to improving lives.
Pulmonary Atresia is a congenital heart defect in which no pulmonary valve exists. As a result of this defect, blood is unable to flow from the right ventricle into the pulmonary artery, and then flow out to the lungs. With this defect, the left ventricle pumps venous blood, which is bluish in color and lacking in oxygen, into the aorta and out to the body. The infant appears cyanotic (blue) because there is less oxygen-filled blood flowing throughout the body. Treatment for Pulmonary Atresia depends on each case. One option is using a drug that would stop the PDA from closing. The Patent Ductus Arteriosus (PDA) is an open passageway between the pulmonary artery and the aorta. The PDA needs to be kept open and wide because the lung blood flow will be reduced to critically low levels if the PDA becomes to narrow. Open heart surgery is another option that is possible if the right ventricle and pulmonary artery are normal in size. Children born with this defect require life-long appointments with their cardiologists and are at risk for infection in the heart's valves and walls.
http://www.americanheart.org/presenter.jhtml?identifier=1303
Atrioventricular Canal Defect is caused by a poorly formed central area of the heart. It is also known as endocardial cushion defect or atrioventricular septal defect. Usually, there is a large hole between the atria and an additional hold between the ventricles. But with this defect, instead of two separate valves allowing flow into the tricuspid on the right and mitral valve on the left, there is only one large common valve, which is usually malformed. Atrioventricular Canal Defect is usually seen among children with Down syndrome. Sympotoms may occur at any time from birth to several months of age, and infants dont usually grow normally and become undernourished. Also, the large amount of blood flowing to the lungs causes high blood pressure and may cause damage to the blood vessels. In babies with severe symptoms or high blood pressure in the lungs, surgery must be done to close the large hole with one or two patches, and then later the patch will become a permanent part of the heart as the heart's lining grows over the patches. Also, the single valve will be divided between the heart's upper and lower chambers to make two separate valves. The new tissue engineering that uses living and growing valves created in the valves first would help Atrioventricular Canal Defect greatly, especially if the defect is too complex to repair in infancy. Usually, if the defect is too complex, the surgeon would perform pulmonary artery banding, in which a band would be placed around the pulmonary artery to narrow it and thus reduce the blood flow and high pressure in the lungs. Then when the child is older, the band would be removed and the surgeon would perform the surgery. But with the new tissue engineering, only one surgery implant would be required instead of the many heart operations most children would have to go through as they get older.
http://www.americanheart.org/presenter.jhtml?identifier=132
The article discusses how the orignial cells will diffrentiate into 2 cells, endothelial and smooth-muscle-like cells. "Endothelial cells" together form the endothelium which lines the interior surface of blood vessels. The cells serve to help blood move quicker by reducing friction and helps reduce blood pressure by vasoconstriction and vasodilation.
A type of birth defect found in children is patent ductus arteriosus (PTD). During the fetus stage of human development the fetus does not use its lungs; therefore, it needs another means of transferring oxygenated blood. This is done by having blood that flows through the pulmonary artery flow directly into the aorta rather than through the lungs by way of the ductus arteriosus, which usually closes during birth do to the pressure of the oxygenated lungs. Children with PDA have ductus arteriosus that don’t close. The result is that the blood flows in the wrong direction, from aorta to pulmonary artery since the aorta becomes very high in pressure. Symptoms are usually chest colds, pulmonary hypertension or thick blood vessels, and even heart failure.
http://www.chdinfo.com/chdarticles/pda1.htm
ATS Medical is a business focused on advancing in heart valve replacement. There first heart valve was the ATS Open Pivot Heart Valve was created to be evolutionary compared to other mechanical heart valves by using a pivot mechanism which consisted of protruding spheres on which the valve’s leaflets pivot to open and close. This was intended to decrease the chance of blood clots. The company suggests that their improvement is fostered by several exclusive partnerships with other companies like Genesee BioMedical, Inc.. This helps with the issue of funding by having multiple supporters of a single cause.
http://www.atsmedical.com/Company.aspx?id=1006
A heart defect that children may be born with is called Ebstein's Anomaly where there is an abnormality in the tricuspid valve. The leaflets of the the tricuspid valve are deformed in some way allowing the blood pumped from the right atrium to the right ventricle to leak back into the right atrium when the right ventricle contracts. This causes the right atrium to become enlarged and may even result in congestive heart failure. In rare cases the tricuspid valve may be so deformed that blood cannot correctly flow in the normal direction. If the pressure persists within the right atrium, the foramen ovale, which is present in the fetus but closes after birth, will remain open allowing unoxygenated blood to bypass the lungs and flow directly to the body, resulting in lower oxygen levels in the blood. For simple defects, no surgery is needed, but in severe situations, surgery may be needed to repair/replace the tricuspid valve or close the foramen ovale. (http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/ebstein.htm)
I'm very amazed by how technology has unfolded and now we are capable of creating "heart structures for children."
One condition a baby may be born with, is the congenital heart defect (CHD). This occurs in the vessels and the structure of the heart of a newborn.
Most of the heart defects that occur obstruct the blood flow to the heart and thus causes the blood to flow in an abnormal pattern. This heart defect is one of the most common birth defects and also one of the main causes for birth related deaths.
Some symptoms for this include no signs while others may exhibit shortness of breath, chest pain, sweating, syncope, heart murmur, respiratory infections, underdevelopment of limbs and muscles, and poor growth. Most of these defects cause whispering sounds, or murmur, as blood moves through the heart causing some of these symptoms. All of these symptoms occur at a young age of a child or infant and during an examination.
http://www.mayoclinic.com/health/congenital-heart-defects/CC00011
Here is a link displaying an article presenting more background information on the Congenital heart defect
In the article, it mentions how researchers "were able to make pulmonary valve leaflets that had the correct mechanical properties" and how the tests showed that the original cells "differentiated" to form other cells.
One of the cells mentioned, endothelial cells, are cells that are involved in many aspects of vascular biology and also control the passage of materials--and the transit of white blood cells--into and out of the bloodstream.
This link discusses more about endothelial cells and their function: http://www.sigmaaldrich.com/Area_of_Interest/Life_Science/Cell_Culture/Product_Lines/Primary_Human_Culture.html
Atherosclerosis, a common disorder of the arteries, comes from the Greek words athero (gruel or paste) and sclerosis (hardness) and is a form of arteriosclerosis. It’s an inflammation in the inner walls of arteries from a constant build-up of deposits of fatty substances, cholesterol, calcium, and other substances which are referred to as plaque. This leads to reduced blood flow through an artery, or a stenosis (narrowing), which may rupture it in the process and result in blood clots that impede blood flow to other parts of the body. It may cause a heart attack or in the case of blocking blood flow to the brain, a stroke. Atherosclerosis is chronic, slowly progressing from childhood to adulthood, and may even lead to Coronary Heart Disease (CHD). Treatments may involve altering your diet or exercising on a regular basis, or drugs that help keep your cholesterol in check. Creating “living stents” would help in physically expanding the narrow passages through which blood travels once implanted into the artery.
With the way technology is involving, there’s no doubt that the tests and trials of today will become the solutions of the future for those that have diseases and disorders pertaining to the heart and other organs vital to life.
http://www.nlm.nih.gov/medlineplus/ency/article/000171.htm
In the article, the author mentions the testing of the valves in a "bioreactor" in this passage "Sales is now refining the lab-grown valves by exposing them to mechanical stress in a bioreactor." I didnt know what a bioreactor was so i looked it up.
A bioreactor is "a vessel in which is carried out a chemical process which involves organisms or biochemically active substances derived from such organisms."
Bioreactors are sometimes very complex machinerey that is used in order to grow different types of cells and organic matter. In optimal conditions, cells can reproduce at a very fast rate.
More information about bioreactors can be found here:
http://www.bionewsonline.com/o/what_is_bioreactor.htm
"Matrix proteins" are large molecules that tightly bound to form extensive networks of insoluble fibers which may exceed the size of the cells themselves. The proteins are composed of two general types: structural and adhesive. Their function is to help support and surround cells with their sturdy and pliable fiber networks.
A relatively newer heart defect that was discovered as a separate entity in 1967 is called Kawasaki Disease. Named after a Japanese pediatrician, Kawasaki disease is also known as mucocutaneous lymph node syndrome. It is characterized by fever, rash, swelling of the hands and feet, irritation and redness of the whites of the eyes, swollen lymph glands in the neck, and irritation and inflammation of the mouth, lips and throat. The immediate effects of the disease in children are rarely serious, but long-term heart complications may result. Damage sometimes occurs to the blood vessels that supply the coronary arteries and to the heart muscle itself. A weakening of a coronary artery can result in an aneurysm, an enlargement or swelling of the blood vessel wall. The disease mostly affects children with most patients under 5 years old. Infants under one year old become the most seriously ill and are at the greatest risk for future heart damage. The cause has not been specifically determined, but speculation points to an infectious agent such as a virus because the disease frequently occurs in outbreaks. For more information:
http://www.americanheart.org/presenter.jhtml?identifier=162
CoreValve is a private company in Irvine that was founded in 2001 by Jacques Seguin, a cardiac surgeon. Their mission is to develop technology that allows doctors to replace failing aortic heart valves without surgical access. Their website claims that more than 700 patients have experienced successful aortic valve replacement with their patented Core ReValving Procedure. They are currently focusing on percutaneous aortic valve replacement, but in the future they hope to discover other minimally invasive structural heart disease treatments. They have created two products, Percutaneous Aortic Valve Replacement (PAVR) and the Trans-Apical Aortic Valve Replacement (TAVR), which aren't available over the market yet. The PAVR would be performed entirely in the cardiac catheterization laboratory and the website provides a video of how the procedure would theoretically work. The website doesn't provide any information on the second product yet. The ReValving System procedures are performed on the beating heart without cardiac assistance or rapid pacing, and may result in less trauma to the patient. Simultaneously, this technology may also offer substantial cost-savings to the healthcare system. An interesting piece of news I found was that on February 15, 2008, CoreValve was sued by Edwards LifeSciences (also based in Irvine) alleging infringement of certain Edwards patents. CoreValve states that their claims are "without merit" and intends on defending their products. To find more information:
www.corevalve.com
One more thing to add to the feud between CoreValve and Edwards are some statements made in an article I found that analyzed the results of CoreValve products done in clinical trials. The lead researcher Dr. Grube believes that the self-expanding design of the CoreValve prosthesis offers several advantages over a balloon-expandable device of Edwards. The advantages include minimizing the occurrence of paravalvular leaks in order to treat patients with aortic regurgitation, prolonging valve durability, and providing provides secure fixation in the ascending aorta. The article:
http://www.theheart.org/article/746369.do
ATS Medical is a company involved in manufacturing and developing products for heart surgery. The company provides life sustaining solutions for heart surgeons and patients. The company develops and manufactures different mechanical heart valves, designed with ease and surgeons and patients in mind. ATS open pivot heart valves are the only mechanical valves gaining market share at the moment.
Many of the products are designed with a cardiac surgeon's opinion and input for the result of ease during the procedure. Right now, the company is seeking to develop what they term, "less-invasive" heart valves that are smaller and can take nearly two minutes to insert during surgery.
The ATS heart valve was designed out of a need for an improvement on the current heart valves on the market. It was done by incorporating a pivot mechanism so that the leaflets pivot to open and close.
The rapid growth and development of technology is fostering human's ability to extend further beyond what we once called the "impossible." The newly developed valves, stemming directly from a patient's own living cells is a remarkable discovery that can benefit the patient in numerous ways so that the patient does not have to undergo many surgeries and also huge expenses. I find this to be extraordinary and almost un-real. It excites me for the future of discovery and life improvements.
Here is more information on the successes of ATS medical mechanical heart valves:
http://seekingalpha.com/article/56048-ats-medical-product-shows-early-promise
After reading the article, I was amazed at how people are able to find amazing solutions to serious problems. This article also reminded me of other medical advances a friend of mine had told me about; researchers are coming closer to find genes that cause HIV/AIDS as well as alzheimers, which in turn will allow them to find solutions to those diseases as well.
A heart defect that some children are born with is Tetralogy of Fallout. This defect consists of 4 congenital heart problems: (1)Ventral Septal Defect (VSD; explained in an earlier post), (2)Pulmonary valve stenosis (obstruction of blood flow caused by a narrowed pulmonary valve), (3)a misplaced aorta (lying over the VSD), and (4) a thickened right ventricle wall. This defect allows for deoxygenated blood to be pumped to the body, causing children to have a bluish tint. Other problems include poor eating habits, an inability to exercise, slowed growth, and abnormal heart rhythms. Luckily, it can be treated through surgery (though multiple operations are required).
This website offers a good illustration of the defect:http://www.mayoclinic.com/health/congenital-heart-defects/CC00026/RETURNTOLINK=1&RETURNTOOBJID=F58E80EF-2A5D-9994-E108E105E118A7CA&slide=9
And this one has more detailed information: http://www.americanheart.org/presenter.jhtml?identifier=11071
There are a series of things that can go wrong with an individual's heart before one is born. One such congenital heart defect is called Atrial septal defect or ASD. ASD is basically a hole in the septum separating the left and right atria. When this happens oxygen rich blood from the left side manages to leak to the left side and back into the lungs again, which makes for highly inefficient blood flow.
This defect can be quickly resolved through surgery at birth or later in life, with no complications, if discovered later. A doctor can often diagnose this defect by taking record of blood pressure.
One heart defect that children might be born with is called the Atrial Septal Defect (ASD). The easiest way to explain this is that the Atrial Septal Defect is like a hole in the heart. It is a large defect between the two atria. Blood from the left side flows back to the right side due to the defect in the septum. Blood that already is nourished with oxygen leaks over to the right side and goes through the cycle again.Atrial Septal Defect occurs during birth as the septum that is forming fails to close all the way. This defect is diagnosed while the baby is still in the uterus or during childhood. The methods used in the diagnoses are ultrasounds or irregular heart sounds determined by the physician. The need for surgery is dependent on each person’s case. I thought the most interesting part of this defect was the way it is fixed. Closing this defect actually involves opening one atrium and placing a patch where the septum is still open.
I included this link because it has a visual picture of where the Atrial Septal Defect occurs on a heart diagram.
http://childrensheartinstitute.org/educate/defects/asd-1.htm
One heart defect that children might be born with is called the Atrial Septal Defect (ASD). The easiest way to explain this is that the Atrial Septal Defect is like a hole in the heart. It is a large defect between the two atria. Blood from the left side flows back to the right side due to the defect in the septum. Blood that already is nourished with oxygen leaks over to the right side and goes through the cycle again.Atrial Septal Defect occurs during birth as the septum that is forming fails to close all the way. This defect is diagnosed while the baby is still in the uterus or during childhood. The methods used in the diagnoses are ultrasounds or irregular heart sounds determined by the physician. The need for surgery is dependent on each person’s case. I thought the most interesting part of this defect was the way it is fixed. Closing this defect actually involves opening one atrium and placing a patch where the septum is still open.
I included this link because it has a visual picture of where the Atrial Septal Defect occurs on a heart diagram.
http://childrensheartinstitute.org/educate/defects/asd-1.htm
Congenital Heart Defect (C.H.D.) is a defect in newborns involving the malfunction of vessels in the heart. C.H.D. typically occurs after conception but before the mother is aware that she is pregnant after. The symptoms of C.H.D. are shortness of breath, chest pain, cyanosis--blue skin coloration due to the presence of deoxygenated hemoglobin in blood vessels-- poor growth and sweating. The interesting thing is that some children won't show any symptoms of suffering from C.H.D.. According to www.americanheart.org, at least 8 out of 1000 children will experience some sort of heart defect categorized under C.H.D.. Approximately 35,000 children are born with a heart defect each year. We don't know exactly why these defects occur, however we do know that it is often genetic and can be a result of the mother using drugs. Although numbers still seem high for C.H.D. cases, education on health such as D.A.R.E. help to reduce potential mothers/drug users. Since the 1970's, mortality rates in infants due to heart conditions have reduced from 30% to 5 % presently. And with increasing technological advancements such as artificial heart valves, the number of mortality rates will continue to decrease.
http://www.americanheart.org/presenter.jhtml?identifier=12012
Heart problems are one of the leading causes of death in America and any advance in the technology, knowledge, and medicine to help the human heart is a step to helping those in need. The heart is such a complex organ and with the knowledge gained in class, I learned that it goes through a very precise and complicated process to beat once and it does this very often. When I read the article about the pulmonary semi-lunar valve and how they are developing a way to synthetically create this valve, I wondered of all the other problems that arise in the heart and what has been done about them. There are so many problems with the heart like clogged arteries and such, especially with the unhealthy diet and lifestyle of Americans that I wondered what treatments they have for the heart. I found a website that is there to explain to patients the types of valve repair and replacement surgeries as well as many other facts. It is very informative in the sense that it prepares any normal person for the basics of this open heart surgery as well as giving them the opportunity to find out more about what they might have to go through as they go through this process. Though some of the procedures may be specific to that particular hospital, I assume the surgeries, treatment information, and preparation information are generally similar.
http://www.texasheartinstitute.org/hic/topics/proced/vsurg.cfm
You know, I wasn’t aware that such technologies were so extensively developed until reading that article. I did some more research on who actually manufactured these kinds of equipment (of course, being a business economics major I just had to), and came across Mitroflow (http://www.mitroflow.com/), who designs heart valves for the aortic locations. They are a subdivision of the Sorin Group, which has four business units: cardiac surgery, vacular therapy, cardiac rhythm management, and renal care. According to their vice president of marketing, heart replacement is a lucrative business itself. Apparently they have a market capitalization of $810 million. Of course, it doesn’t take much research to show that many problems can come associated with heart replacement: surgery costs, percentage of people unable to afford this product, and other ties to costs. There are also heavy liabilities tied to these products as an equipment failure usually means… death. Luckily, some more research shows that (in general), the mortality rate is around 6%, so 94% of the patients who undergo these surgeries, both short and long term, live.
http://www.sjm.com/procedures/procedure.aspx?name=Heart+Valve+Replacement
http://www.devicelink.com/mddi/archive/04/07/004.html
The article published by Children’s Hospital in Boston reveal shocking new advancements in tissue engineering for human life—children being able to grow along with heart valves made from their own cells. In fact, it is incredible how patients may only rely minimally on artificial assistance when their own cells can learn to form a heart valve on their own. I noticed that the next step after animals would be to create “living stents” for older patients with atherosclerosis. I learned that Atherosclerosis is the name of a process where deposits of cholesterol and other cellular waste accumulate in the inner lining of a person’s artery. This build-up or “plaque” affects larger arteries by hardening them as the patient grows older. The “plaque” is dangerous because it will grow larger to reduce a patient’s blood flow and may even cause the artery to rupture. If there is a rupture, blood clots will form and travel to other parts of the body, block blood vessels, and cause heart attacks as well as strokes along with difficulty of walking and moving. Males or those with a family history of premature cardiovascular disease have high risk for atherosclerosis and creating “living stents” for older patients is a great next step to possibly using tissue engineering for the younger patients as well.
http://www.americanheart.org/presenter.jhtml?identifier=4440
It is not uncommon for an infant to be born with a congenital heart defect. Some are born with a mixture of abnormalities called Tetralogy of Fallot also known as TOF or TET. TOF occurs because the fetal heart develops oddly, usually during the first eight weeks of pregnancy. this condition is caused by "a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families."
TET problems include pulmonary obstruction and ventricular septal defect (VSD). Pulmonary obstruction occurs when there is a kink in the pulmonary valve which lowers the amount of normal blood flow. VSD occurs when there is a dividing wall between the left and right ventricles.
Infants with these problems can show symptoms that include having blue body parts (blue skin, nail beds, lips) when they feed or cry because large portions of oxygen poor blood (blue blood) flows through their bodies. They can also have damp, clammy skin that is pale in color and can also show signs of constant exhaustion and irritability
Endothelial progenitor cell:
"A primitive cell made in the bone marrow that can enter the bloodstream and go to areas of blood vessel injury to help repair the damage."
-http://www.medterms.com/script/main/art.asp?articlekey=22412
The endothelial cells lining the blood vessels provide essential communication between the vessels themselves and circulating blood cells, allowing the blood to flow smoothly. In diseases such as atherosclerosis, however, the endothelial layer becomes damaged and the vessels do not function efficiently. Until recently, scientists believed that nearby endothelial cells were recruited to help repair damaged blood vessels or form new ones to circumvent blocked vessels or to repair wounds. Evidence now shows, however, that endothelial progenitor cells, probably generated in the bone marrow, circulate in the bloodstream and are recruited to form new blood vessels or repair damaged ones.
-http://www.innovations-report.de/html/berichte/biowissenschaften_chemie/bericht-16446.html
The word (or phrase) I was unfamiliar with was "congenital heart disease." After researching it's meaning, I found that congenital heart disease is:
1. a heart disease found in newborns
2. includes structural defects in different areas of the heart.
3. leads to arrhythmia and then malfunctions of heart muscles
4. This dysfunction occurs when the heart or blood vessels next to the heart are not generated properly before the birth. So, the heart does not function properly because it is not fully developed at birth
5. Is normally present at birth but not always detected
What is important about congenital heart disease that it is acquired due to hereditary or environmental factors. Also, in the past, children who would have died due to this disorder are living full lives because of medical advancements.
Congenital heart defects can involve the interior walls of the heart, valves inside the heart, or the arteries and veins that carry blood to the heart or out to the body. Congenital heart defects also change the normal flow of blood through the heart.
Another interesting fact is that congenital heart defects are the most common heart defect in children (effecting 8 out of 1000) newborns.
source: http://www.nhlbi.nih.gov/health/dci/Diseases/chd/chd_what.html
atherosclerosis
It is a process that deposits fatty substances, cholesterol, cellular waste products, calcium and other substances build up plaque in the inner lining of an artery. The build up can grow so large that it reduces the blood's flow through an artery. The plaques can also rupture blocking blood clots. If the plaque pieces happen to block a vessel that feeds the heart, then that can lead to a heart attack. If a vessel that feeds the brain is blocked, then that can lead to a stroke. Other problems with plaque build up includes gangrene.
The cause of atherosclerosis typically starts in childhood. Scientists think the process begins with damage to the endothelium caused by high blood pressure, smoking, diabetes, high levels of cholesterol.
Arrhythmia is a disorder of the heart's rhythmic beating. Simple, but I wasn't totally sure of the information that surrounded the term. It is acutally quite common as it affects 2.2 million Americans, but it is not that serious. It may, however, indicate serious problems such as heart disease or even death. In general though, arrhytmia in and of itself is not very harmful.
http://www.americanheart.org/presenter.jhtml?identifier=10845
In the late 1980s, when I was an infant, I was diagnosed with Tetralogy of Fallot - a congenital heart disease that affects approximately 3 to 6 of every 10,000 births. My condition was one that, if not repaired, would lead to serious consequences. At the age of two, I had open heart surgery to correct the heart defects I was born with.
Tetrology of fallot is made up of four different defects of the heart, hence the "tetra":
The first is Pulmonary stenosis, and the problem here is that the pulmonary valve narrows significantly, causing a block of the blood flow from the right ventricle of the heart to the pulmonary artery.
The second is Ventricular Septal Defect(or VSD), a hole between the septum that separated the right and left ventricles of my heart. And because of the pulmonary stenosis (its harder for blood to flow through the pulmonary artery), blood shunts from the right ventricle to the left, through the hole and bypasses the lungs!
The third problem is an Overriding Aorta. This is where the aortic valve becomes enlarged and appears to be a part of both ventricles instead of just the left as in normal hearts. Also, the aorta positions itself over the septum and the hole between both of the ventricles (the VSD) "overriding" it, and blood from both ventricles mixes and is pumped through the rest of the body as one.
The last defect is Right Ventricular Hypertrophy and in this defect the muscle wall thickens because of the increased pressure within the right ventricle caused by the pulmonary stenosis.
Eighteen years after my surgery I am healthy and alive! My surgery was a huge success.
http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/tof.htm
http://www.americanheart.org/presenter.jhtml?identifier=11071
http://en.wikipedia.org/wiki/Tetralogy_of_Fallot
This article was amazing - it's hard for me to believe how far technology really has come. Imagine, an artificial heart valve that grows with the patient. That's crazy. But tissue engineering really has come a long way. Tissue engineers have even rebuilt a beating heart with cardiac derived cells. Here's the link: http://www.tissue-engineering.net/index.php?seite=News_detail&action=show&nr=187
One congenital heart defect is Ventricular Septic Defect - also known as VSD. This is a hole in the tissue that separates the ventricles. That means that the blood that has oxygen in it flows from the left ventricle to the right ventricle, instead of to the aorta (which leads to the body) A VSD isn't too bad - just as long as you don't have high blood pressure. The heart has to work harder than usual with a VSD, so if there were both a VSD and high blood pressure, the heart would wear out pretty quickly.
For more information on VSD : http://www.nhlbi.nih.gov/health/dci/Diseases/chd/chd_types.html.
"Augmentation" means the process of becoming greater in size or amount
Atrioventricular Septal Defect is a congenial defect that effects both the left and right atrium. These chambers may have holes or defects and there also may be defects in the bicuspid and tricuspid valves
http://www.driscollchildrens.org/DCHWeb/AboutDriscoll/content/cardio_ASD.asp
ATS medical works with replacement valve. There website does not give much information about the challenges they face but any business has three major challenges. 1. developing their products 2. finding more clients 3. making profit
http://www.atsmedical.com/
While I was reading this article from the Children's Hospital in Boston, I came across a term in the latter part of the article that I have to admit I had no idea what it meant. So my first instinct was to google it. That it where I began researching the word because I needed at least a general understanding of what it meant. The word I did not know was "atherosclerosis". Truthfully, I do not even think I can pronounce that word correctly. So, I first discovered the definition on this link.
http://en.wikipedia.org/wiki/Atherosclerosis
Basically, atherosclerosis is a very harmful disease that affects the arterial blood vessels. It is largely due to the acculmulation of macrophage white blood cells which causes chronic inflammatory in the walls of the arteries. In the simplest terms, it is when the arteries harden. Then I decided to get a little more backround information on the disease so I went to this site....
http://www.americanheart.org/presenter.jhtml?identifier=4440
This site provides a great explanation of the causes of Atherosclerosis.
The dictionary definition of atherosclerosis is: a disease of the arteries characterized by the deposition of plaques of fatty material on their inner walls.
The plaque build up can grow to create a significant reduction of the blood flow through the artery. However, the most dangerous characteristic of atherosclerosis is that the plaque can harden and rupture creating blood clots. These blood clots can either prevent blood flow, or they can break off and travel to other parts of the body. If a blood clot prevents blood going to the heart, and heart attack and occur, and if a blood clot forms in the brain, a stroke may result.
For more information about atherosclerosis and the factors that may cause this disease you can go to this website:http://www.americanheart.org/presenter.jhtml?identifier=4440
Tricuspid atresia is a type of congenital heart defect present in children. It involves the absence or poorly developed tricuspid heart valve which blocks the flow of blood from the right atrium to the right ventricle. Usually, blood flows into the right atrium, then to the tricuspid valve which leads into the right ventricle and ultimately to the lungs. However, if the tricuspid valve is damaged or absent, the blood will not make it from the right atrium to the left ventricle and eventually to the lungs where it will become oxygenated. This condition is also known as tri atresia and is very rare with a ratio of 5 to every 100,000 live births. Also, about one-fifth of children with this condition will also suffer from other heart problems.
There are many symptoms for tricuspid atresia but two of the most common and pressing symptoms are a bluish discoloration of the skin, also known as being cyanotic, and a shortness of breath, dyspnea. Other symptoms include fatigue, clubbing of fingers or toes, quickened breathing, and slow or poor growth. Usually, this condition is discovered through routine prenatal ultrasounds or through post natal examinations. However, other tests to detect tricuspid atresia include electrocardiogram, echocardiogram, chest x-ray, cardiac catheterization, and MRI of the heart.
Even though tricuspid atresia cannot be prevented there are treatment possibilities. Treatment for tricuspid atresia involves three stages beginning with initial surgery that inserts an artificial shunt to help blood flow to the heart. Stage two is called the Glenn shunt or Hemifontan procedure which connects half of the deoxygenated veins to the vessels that leads to the lungs. Lastly, the final stage involves connecting the rest of the deoxygenated veins to the blood vessels that lead to the lungs. After these three stages, improvement is likely to occur. However, sudden death can occur with arrhythmia which involves the heart beating too fast or too slow.
http://adam.about.com/encyclopedia/infectiousdiseases/Tricuspid-atresia.htm
"Atherosclerosis" occurs in the arteries when fatty substances form plaque on the inner linings of arterial walls.
A congenitial defect that children might be born with is Tetralogy of Fallot (FOT) in which the body is not recieving enough oxygen through the blood because there is not enough blood flow through the lungs. This abnormality causes numerous problems such as a hole in the ventricular septum, a muscular obstruction in the right ventricle, and aorta that is shifted towards the right side of the heart in which it is over the ventricular defect. This disease ultimately leads to poor oxygen to the body.
A Company that provides heart valve replacements is ATS Medical. In fact, it uses sutureless technology. The new company has had 47 patients that have used the new technology for their valve replacement. They face many risks because since this is new technology and patient's bodies can react different ways to the new valve. However, this is the only way to test if it will make valve replacements easier and less invasive. In this link there is a picture of the new technology. http://www.heart-valve-surgery.com/
heart-surgery-blog/2007/12/06/
sutureless-heart-valve-replacement-
by-ats-medical/
A heart defect that children are sometimes born with is coarctation of the aorta which is when the aorta narrows itself. The narrowing (coarctation) of the aorta causes a decrease in the blood flow from the heart to the lower portion of the body because the heart has to pump harder to get blood to the rest of the body.
There are three types:
1.Preductal coarctation: the narrowing is proximal to the ductus arteriosus.
2.Ductal coarctation:The narrowing occurs at the insertion of the ductus arteriosus this usually occurs when the ductus arteriosus closes.
3.Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. Even with an open ductus arteriosus blood flow can still be impaired. Newborns with this type of coarctation can be sick from birth.
http://www.mayoclinic.com/health/congenital-heart-defects/CC00026/RETURNTOLINK=1&RETURNTOOBJID=D81D5EF7-2A5D-9994-EC167F31EFB2A181&slide=7
The above website provides people with a descriptive and informative view of coarctation of the aorta.
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