CongenitalHeartDefectsTheproblemPeople with a congenital heart defect (CHD) (also referred to as congenital heart disease, but the term defect poses a more accurate description) are born with a malfunctioning heart(1)due to either decisions made by the mother during pregnancy(e.g. smoking, drinking alcohol, exposure to solvents) or it can be due to an unpreventable disease the foetus develops, for example, the incidence of the general population developing CHD is 0.8 percent whereas a developing foetus with Downs Syndrome has a 40-60 percent chance of being born with a type of congenital heart defect.(17)Some cases of CHD are mild and do not require further treatment as they can easily be treated with medication meaning the patient can live a normal life, the survival rates are also promising as many patients are living with heart defects in adulthood; their heart may just function different to someone without the defect(2). Although, other cases can be life-threatening and require an immediate procedure. Due to CHD being present since birth it affects a lot of children throughout their childhood and later life, 50% of all children born with a type of CHD have to undergo at least one surgical procedure in their life time, in the US twice as many infants die each year from a heart defect they are born with than any other type of cancer making it one of the most common causes of death in the US. CHDs are also the most common birth defect worldwide(3).There are at least 18 distinct recognized types of congenital heart defects, there has been a lot of promising research into many of the different types of CHD therefore the infant mortality rate has dropped considerably(1). CHDs are clearly a biological problem, the fact thatapproximately1 in every 100 births worldwide suffers from a CHD proves it to be a problem impacting much of the population(3).In most cases, there is no obvious cause for a child to be born with a heart defect yet there are some circumstances known to increase the risk of the condition. The most common issues that increase the risk of CHDs include Down's syndrome, the mother having certain infections, such as rubella, during pregnancy and the mother having poorly controlled diabetes.(9)Because heart defects are so common there is notone cause, it can simply be a random occurrence during the development of the foetus.Soon after fertilization, the zygote will travel to the uterus through the fallopian tube. Meanwhile, it begins dividing to form a tiny cluster of cells a morula. At three weeks after conception the heart will begin to develop; this is when problems can occur like CHDs(8).There are many general symptoms that a new-born could express if they have a CHD (if it wasnt already discovered during prenatal scans), they include: excessive sweating, a raised/rapid heartbeat, rapid breathing, shortness of breath, chest pains, and a blue tinge to the skin (known as cyanosis, due to a lack of oxygen in the blood)(9).In milder cases, symptoms may not develop until the child has reached adolescence. Symptoms include:chest pains, cold feet or legs, dizziness or fainting, decreased ability to exercise, poor growth, nose bleeds, and cramps during exercise, pounding headaches, and shortness of breath. There can also be cases expressing no symptoms.(12)The four most common types of congenital heart defects include:Septal defects commonly referred to as a hole in the heart, it is where there is a gap between two of the hearts chambers.Coarctation of the aorta this is where the aorta is narrower than normal.Pulmonary valve stenosis similar to coarctation of the aorta, but it is the pulmonary valve that is narrower than normal.Transposition of the great arteries this defect is recognized when the arteries that the pulmonary valve and the aortic valves are connected to have swapped positions.Figure 1.1 (18)

https://embryology.med.unsw.edu.au/embryology/images/8/8d/Statistics-Utah_heart_defects.jpgTheGraph shows rates over time (1997-2003) of selected heart defects.(18)Seen in figure 1.1,(18)coarctation of the aortais the most common type of CHD. Around 1 in 2,500 babies have coarctation of the aorta and the condition is twice as common in males as it is in females(12). Further analysis of figure 1.1 shows that all types ofdefectfluctuate yet there hasnt been a significant improvement for a number of years. However, this data was retrieved 12 years ago therefore does not show any recent breakthroughs yet it still proves relevance toward the biological issue of congenital heart defects.Coarctation of the aorta is worth much investigation due to its frequent occurrence. Coarctation of the aorta is a narrowing of the main blood vessel carrying oxygen-rich blood from the left ventricle to all the bodys other organs. The most common occurrence of coarctation is in the short segment just beyond where the arteries to the head and arm branch off. This small portion of the aorta is called the juxtaductal.(23)In infants with coarctation,the aortic arch may also be smaller than it is supposed to be, it is also more common in patients with chromosomal abnormalities like Downs syndrome and Turners syndrome. A patients heart, suffering from such condition, has to work harder to pump blood, this generates a high pressure than normal as the blood is forced through a narrowed section.(23)It is important for investigations and studies to be carried out to find appropriate and successful solutions to this particular heart defect. Coarctation of the aorta leads to high blood pressure, this is the main concern with this type of CHD,and highblood pressure can lead to a high number of complications so the defect is best tobe treated as soon as possible. These further health risks of high blood pressure include: Damage to the heart and coronary arteries, including heart attack, heart disease, congestive heart failure, aortic dissection and atherosclerosis (fattybuild-upsin the arteries that cause them to harden)and stroke(25). The heart, along with the brain, is an extremely important organ, so correct function is essential. This highlights the fact that CHDs are a concerning and significant problem worth investigating.

A solutionExitCare Image

Figure 2.1 (13)

Figure 1.2 shows the narrowed section of the aorta- a typical case of coarctation of aorta; in this case, narrowing occurs.(13)Before a solution is found to treat each specific case a diagnosis has to be made to determine the severity of the patient. As coarctation of the aorta is the most common heart defect it is usually checked for during the new-borns first examination (known as the well-baby exam), this is done by checking the infants pulse, and it is an important step as other symptoms may not be expressed until later on in life. After birth the health care provider will perform a physical examination of the baby, taking the blood pressure from the arms and legs along with listening and recording the pulse. There are obvious signs to recognise if the baby does in fact have coarctation of the aorta, including: the pulse being weaker in the groin area than the arms or neck, as the main artery in the groin is the femoral artery and in the neck and arms is the carotid artery. Both blood pressures from both areas of the body (upper extremities and lower extremities) are compared against each other to give a gradient known as the upper to lower extremity systolic blood pressure gradient or ULG. The method to measure this gradient is to first have the patient lying down and then to record the lower extremity systolic blood pressure, by palpation or ausecultation, over the popliteal artery (found in the thigh) or it can also be found within the calf. The blood pressure is then measured in both arms, the difference between the upper extremity systolic pressure and the lower extremity systolic pressure is determined by the structure of the cardiovascular system. In subjects with no structural abnormalities the difference between arm and leg systolic pressure can be up to 10mm Hg higher in the lower than the upper extremity(11), however there are many disputes towards what a normal gradient is, it all depends on the age, sex, weight, height, etc. of the patient, this poses some limitations when drawing conclusions during research and/or clinical trials(7).Due to the nature of the specific defect, the doctor will also listen for a harsh-sounding murmur as the blood is forced through the narrowed section; this can be heard using a stethoscope pressed to the infants back, further tests will be carried out if a heart murmur is heard murmurs, however, are not always due to a congenital heart defect(12).If the aorta is only narrowed very slightly, the patient may not require further medical treatment only medication may be prescribed to manage the condition, however if the coarctation is causing the named symptoms, medical assistance will be required.The main solution toachieve normal function of the cardiovascular system is a stent procedure.It involves the use of a catheter, balloon and stent (small metal structure to act as the walls of the artery, shown in figure 2.2(4)).A coronary stent is a tinymeshtube made of medical-grademetal.It isa tiny, expandablemeshtube made of medical-grade stainlesssteelor cobalt alloymetal. Stents can aid in the reduction of recurrent blockage or narrowing after an angioplasty procedure.(32)The aim is to increase the diameter of theaortato a normal size that will allow maximum blood flow to vital organs.After local anaesthesia in the area, the catheter is inserted through a major artery, usually in the groin, it isthenguided bya doctor usingX-rays towards theaorta and the balloon is inflated with the stent positioned around it. As the balloon is inflated the patient may experience heart pains, this may be upsetting for carers/parents as the procedure us usually performed on young children (but isnt appropriate for very young children),and it can also be distressing for the child as they may not understand that the pains are normal and will stop.When the stent is in the correct place, achieving full diameter, the balloon is deflated and the stent is left in place to hold the aortas new shape. It stops the problem by reducing the narrowing, as this is what is causing the issues. It is a very important procedure because it is successful in treating the defect at hand, it is non-invasive and creates a much better quality of life. The heart is put under much less strain following the positioning of the stent, blood pressure is reduced and the recovery time is short.(30)http://www.cinfinityint.com/images/portfolio/Enterprise/heart_stents_Lg.jpg

Figure 2.2 an image of a heart stent (4).

Effectiveness of the solutionBetween June 1st 2002 and October 31st 2010, a study was performed by the CCISC, it was titled: Comparison of Surgical, Stent, and Balloon Angioplasty Treatment of Native Coarctation of the Aorta. This was a multicentre observational study with follow-ups of patients to take into account the long-term and short-term impacts of each procedure. The trial included 350 participants (all patients weighed more than 10k) from 36 separate institutions. The sample sizes were varied: 217 underwent repair of the narrowed aorta using a stent, 61 underwent a balloon angioplasty procedure and 72 underwent surgical repair. For the study to evaluate the effectiveness of these particular solutions there was two follow-up periods: Short-term at 3-18 months after the procedure and an intermediate follow-up at 18-60 months.(11)There are a number of solutions mentionedin the proposed clinical trial,in this study 3 procedures were performed on 360 patients from 36 institutions, the main solution being focused on in this reportis the stent category, throughout it will be compared to the other two procedures mentioned. All provide a promising prognosis,allprocedures are all considered a viable solution when treating CHD.All three methods proved significant improvements acutely and in follow-up in upper to lower extremity systolic blood pressure gradient (ULG) and in resting systolic blood pressure.

Figure 3.1 Short-term follow-up outcomes by integrated imaging (7).

Figure 3.2 Intermediate follow-up outcomes by integrated imaging (7).In figure 3.1, a table derived from the trial results after short-term follow-up, suggests that the people that underwent stent treatment were subjectupto 23.8% less complications thanpatients that underwent the other two procedures. Stent patients also suffered from less aortic wall injuries and aneurysms(7).Figure 3.2 shows the outcomes between 18-60 months after the procedures. All categories had increased in complication percentage, the stent complications had increased by 4.2%, this number is low suggesting many of the procedures were effective the first time(7).There was also a shorter hospitalisation period for stent patients as the average time was 2.4 days whereas the average time in hospital for the remaining methods was 6.4 days. However, stent patients were more likely to need planned re-intervention (a follow-up procedure). At short-term and intermediate follow-up, stent and surgical patients achieved more promising integrated aortic arch imaging compared to angioplasty patients.236 stent procedures were performed on the 217 patients as 19 patients required a second stent due to 6 patients experiencing stent migration and the remaining patients required a new stent to cover the whole of coarctation segment.Follow-up methods:MRIs, cardiac catheterizations, or multislice CTs were performed at the short-term and intermediate follow-ups, patients upper and lower extremity blood pressures were taken and recorded along with recording antihypertensive medications at the time of imaging.Follow-up outcomes:The calculated mean follow-up time was 1.9 years with a range of 0.1 to 5.8 years, in 68% of stent patients. The follow-up time was 2.1 years with a range of 0.07 to 9.09 years in 77% of balloon angioplasty patients and the follow-up time was 1.9 years with a range of 0.1 to 9.7 years in 81% of surgical patients. All follow-up averages include the most recent data. All of the follow-up patients mentioned underwent imaging with no clinical concerned expressed. No deaths were reported.Re-intervention data:Any re-intervention (planned or un-planned) with patients was recorded as it would affect the efficiency of the performed procedure.Safety endpoint:Safety endpoints included death, aortic wall injury and other serious procedural complications along with unexpected re-intervention acutely and both follow-up intervals.Complications:The group of stent patients was superior to both the balloon angioplasty group and the surgical group in regards to acute complications. For both the balloon angioplasty and stent group the complications were almost exclusive to aortic wall injury. Acute dissections and aortic ruptures were seen in both groups, the majority of these complications were seen in older patients. During the short-term follow-up it was discovered that 2 patients taking part in the trial had aneurysms forming, one patient had surgery and the other was in the stent group. Further imaging was done and at intermediate follow-up the aneurysm hadnt progressed in size for either patient.

Study limitations:The study was not randomised so it cannot be ruled out as being a biased study. Many of the 36 institutes supplied less than 10 candidates, there was a bias toward balloon angioplasty and surgery observed in the trial due to a stent being less suitable for younger patients, a higher number of older patients received treatment via the stent procedure. The number of patients receiving certain treatments for coarctation of the aorta was not equalised, this limits the trial as there were different sample sizes meaning the test was not as fair as it could have been(7). It would have also produced more valid data if this was a dependent variable. The gender of the patients was also not mentioned, gender could also affect this clinical trial as coarctation is twice as common in males as it is in females(12).

The second trial explores the effects of using only a stent to treat coarctation of the aorta, the trial was accepted in 2000, and the research was carried out at the Department of Cardiology at Sophia Childrens Hospital, Athens.(15)The method was as follows: the clinical study took 17 patients with coarctation of the aorta with an age range of 0.4 to 15 years of age. 6 of those were treated for isolated coarctation, 9 were treated for recurrent coarctation (3 had undergone a single surgical repair, 1 had undergone two previous surgical repairs and a balloon dilatation, and 4 had undergone balloon dilatation only). 8 subjects had the stent procedure as a first choice (not previously having any surgery or otherwise for their coarctation defect) 2 of which patients had complex long segment coarctation therefore the surgical risk was considered high, due to this consent was not given by the parents of the children for a surgical procedure. The trail also had an initial and intermediate follow-up after the stent implication. Although the study was accepted and published to this source in 2000, the study was carried out between November 1992 and January 1999, of the 17 patients 11 were girls and 6 were boys, the median body weight was 36kg with a range from 6-55kg, suggesting no children in the trial were overweight (weight can increase the risks associated with coarctation as extra body mass may increase blood pressure, altering the systole gradient). 10 of the procedures were done with local anaesthesia and sedation, whereas the remaining 7 were performed under general anaesthesia(15)as a stent procedure does not require any surgical techniques due to the fact that a catheter is used to position the small metal structure(12).The results from the study were promising: Immediately after the stent procedure was performed on the patients there was a decrease in the systolic blood pressure gradient (a decrease in gradient means the difference between the upper extremity pressure and the lower extremity pressure has decreased, it is a sign that the patients cardio system structure has improved). Mean results were calculated, an average was taken across all patients, and the gradient had decreased from 24.5mm Hg to 2.4 mm Hg, the diameter of the stenotic lesion also increased from 1.5mm to 2.4mm. Increasing the diameter results in a wider aorta, therefore less pressure in the lower extremities. No deaths were recorded across the study and there were also no recorded complications during the procedures.At a median of up to 33 months (10-82 months) a follow-up showed that no patients experienced re-coarctation, the follow-up also included the distribution of 3-5 mg/kg given to each patient for 6 months along with recording the arm and leg blood pressure measurements and chest radiography. This was performed 1 and 3 months after the procedures, also every 6 months after that. An angiographic study was also performed on 13 of the 17 patients, the follow-up time for this study was 30 months with a range of 18 to 72 months. The results from this proved the technique requiring the use of a stent as treatment for coarctation of the aorta to be successful as the pressure gradient dropped to less than 20mm Hg (this reading can be considered as within the normal range)(15).

Figure 6.1 Patient 7s angiogram results (A) immediately after and (B) following multiple stent implantations.(15)Figure 6.2 a table showing the results of the stent procedures across all 17 patients (15)

It is clear in figure 6.1 that this patients aortic arch has been significantly increased in diameter, there was also a decrease in the systolic pressure gradient post procedure, proving the solutions success.(15)

Figure 6.2 is clearly showing a very significant decrease in SPG, is it emphasised in patient 8, 9 and 14 more so, but every patient has substantial improvement. The results continue to prove positive across the table for all patients, the follow up only highlights one concern for patient 7 but with that exception the results are extremely optimistic. In patient 7, however, the follow-up times are a lot higher than all other patients, this factor could explain the emphasised increase in SPG therefore would patient 7 would not express abnormal results. This conclusion cannot be certified unless similar follow-up periods are repeated on other subjects. The CoA sizes also look promising for all 17 patients, there has been an increase in the size of the coarctation after the stent procedure for every patient. Patient 1 could pose a concern as their increase is noticeably smaller than the other 16 patients, due to patient 1 being absent in the follow-up catheterisation study, it cannot be assumed that the size improved or worsened. Yet, due to 1s huge decrease in SPG (dropping from 45mm Hg to 5mm Hg) it is possible that patient 1 experienced no further complications. The conclusions drawn from this trial are that stent procedures to treat this particular congenital heart defect have very low mortality and morbidity rates, however the long-term freedom from coarctation are yet to be compared with other techniques, such as balloon angioplasty(15).Bothclinical trials performed were legal, accepted by various domains, and published.The first and second trial prove to produce valid data in the study of solutionsforcongenital heart defects, trial 1 may produce more valid results due to treating 200 more patients with a stent procedure. The follow-up for both trials was similar yet trial 1 had an intermediate follow-up and a further SBPG follow-up to record any other improvements. Trial 2 appears to have recorded each individual patients results in a table, whereas trial 1 took averages for each groups and showed percentages, the problem with this technique is that anomalies (if any) arent highlightedor any specific procedures that didnt work as there was an overall implication percentage of 12.5%. We do not know what circumstances caused these implications or what the implications were. Some aspects,such as these,arent cleartoothersusing the data.Both trials highlight the fact that using a stent to treat coarctation of the aorta is a solution to the problem as in the first trial the stent procedure was the most effectiveout of the other solutionsas it had the lowest percentage of further implicationsand increased the aorta width to a normal size, the particular solution is proved effective again in the results for the second trial as for all patients the CoA sizes have increased significantly.The improvements continue to match as for both trials the solution is working at the follow-up recordings. This suggests the solution to treatcongenital heart diseaseis effective and successful.ImplicationsThe clinical trials mentioned were performed on young children (with exceptions), this could pose an ethical implication due to the fact that they have no choice and no understanding of the situation. The procedures carried out may also highlight social issues within families that have children participating in the studies, especially the open heart surgery patients. To have this kind of procedure carried out on your child would be extremely traumatic. In some cases it was mentioned that certain children had to undergo the surgery twice. This factor makes it ever more difficult for parents/relatives. During a stent procedure the patient must also have an X-ray whilst the catheter is guided towards the heart (named an angiogram)(21), this can cause further health implications for patients as X-rays and gamma rays are known human carcinogens (cancer-causing agents)(22)which can cause distress for many people and increase risk. These particular implications are examples of social implications for the solution. The production cost of the stents may cause economic problems to arise for the NHS as the organisation offers free treatment across the UK. The long-term implications for surgery are the risks that follow after the procedure; continued or repeated narrowing of the aorta, endocarditis and high blood pressure.(12)These are continuous risks patients could face after their surgical repair which leaves the sufferer with worry that the procedure may have to be repeated.The stress of the procedure could cause some social issues, the recovery time could also have an effect on young patients as time off education will be necessary, therefore children are likely to miss out on vital education at an important stage of their lives. Thus, this could lead to the career/parent being stressed and worried about their child, leading to further issues. There are also following check-ups for patients that undergo a stent procedure meaning more time spent traveling and missing out on primary or maybe secondary education. These visits may cause economic issues within families as the time off work and traveling costs money, however the NHS supplies free healthcare meaning these costs are reduced dramatically in the UK this is not the case for people that have private healthcare. After a stent procedure the patient is not allowed to engage in any physical activity for at least a week.(31)

Benefits and risks of the solution

An obvious benefit stent proceduresisthat it corrects the defect or at least improves the patients survival chance and quality of life dramatically. This is highlighted thoroughly in the results of the first and second trial. The procedures would not be worth preforming if they left patients with a poor qualityof life, without the techniquementioned the patients life expectancy is dropped to approximately 40 years, this is why children are encouraged to have a procedure best suited to them before 10 years of age.(12)Most patients report that they are able to do many things they could not previously do before the stent, this improves quality of life and makes the solution worth-while.(30)Children being treated for CHDs used to be discouraged from doing extensive or straining exercise, however it is now believed to improve health, boost self-esteem and help to prevent further problems from developing later in life. Says the author of the NHS online information in 2013.(24)The issue of reoccurring problems is reduced when using the stent procedure rather than BA or surgery. The stent, acting as the main structure of a section of the aorta, rarely allows the narrowing to reoccur which results in the patient being more optimistic about the procedure, this claim is evidenced in the Journal of the American College of Cardiology as it states: Stent patients hadsignificantly lower acute complications compared with surgery patients or BA patients.(7) A further obvious risk with the solutions is death else it would not be mentioned in the endpoint. This risk is small as 0 out of 360 patients were recorded to have died at follow-up or duringthenumerous procedures, suggesting thebenefits of the solution outweigh this risk.Theres also a risk of tearing the arterys wall after the procedure is performed, this is shown in figure 3.2 as the percentage of the people suffering from a tear increased by 1.8% whereas it does not increase for the other methods mentioned in the first trial. This could be due to its metal structure.

Alternative solutionsThere are other alternative solutions to the problem than just using a stent,this is obvious due to the other procedures used in the first trial. The first alternative solution is a methos called balloon angioplasty, the official Google definition defines balloon angioplasty as: surgical widening of a blocked or narrowed blood vessel, especially a coronary artery, by means of a balloon catheter.(26)It isamore recent technique of treating this particular defect.Its more commonly used in children or adults that have been able to live with their condition as an infant, whereas at an older age receiving the surgery is important to maintain a normal, healthy life. The technique is performed using a balloon catheter (a thin tube with a deflated balloon attached to the tip), it is inserted into a major blood vessel, usually the groin, the doctor will then use X-rays to guide the catheter to the aorta to reach the narrowed section, the balloon is then inflated to expand the aortas internal width.(12)Figure 7 - http://www.revespcardiol.org/en/balloon-angioplasty-for-native-coarctation/articulo/13078854/(27)

A clinical trial was carried out to assess the success of balloon angioplasty when treating nativeaortic coarctation:Theiraims were to reporttheir medicalexperienceswiththetechnique and to compareit tothe immediate and medium-term results obtained during 2 different time periods.The method included53 patients who underwent balloon angioplasty for native coarctation, theywere divided into 2 groups: (A) those treated between 1985 and1988which was a group of 26; and(B) those treated between 1993 and2003being the remaining 27. The immediate result was good (i.e., pressure gradient,