1.2 Heart Disease
1.2.1 Definition & Blood Circulation System
Heart Disease is a group of diseases that prevent the heart form working as well as it should.
Only a little larger than a fist, a normal healthy heart is at the center of the body's Cardiovascular system*. Each Day the average heart beats, or expand and contracts about 100 000 times. In a 70-year lifetime, an average human heart beats more than 2.5 billion times.
The Circulatory System* is responsible for providing nourishment to the body cells and removing the heart to the cells; the veins take blood from the cells to the lungs for reoxygenation and recirculation by the heart.
The Coronary Arteries encircle the heart form above and below like strands of ivy. With their strong, flexible walls and smooth linings, healthy coronary arteries supply blood to the heart itself, in much the same way as a hose transports water to a garden.
At birth, these Coronary Arteries are completely open and clear, permitting a maximum flow of blood to the heart, but as people age, these vessels can become clogged with a thick combination of lipids (fats), cholesterol, calcium and other substances. As these layers accumulate inside the Arteries, they can lead to Arteriosclerosis (ar-teer-e-o-skle-ro-sis), a condition also known as "hardening of the Arteries", since the buildup eventually stiffens the inner Artery walls. Atherosclerosis (ath-er-o-skle-ro-sis), a buildup of plaque* on the most common form f Arteriosclerosis. Over time, plaque continues to accumulate in the blood vessels, much like grease that clogs a kitchen drainpipe. The result is a narrowing of the inside diameter of the vessel.
1.2.2 Categories
1.2.3 Causes
Heart Disease is not contagious and, to a large extent, can be prevented, controlled and in some cases, even reversed. When looking at what causes heart disease, researches divide the risk factors into those that people can control and those that they cannot.
Controllable Factors:
- Age - As people age, their cholesterol levels usually increase and hardening of the arteries appears and progresses in most people.
- Gender - Men have higher cholesterol levels than women until around the age of 45. Women catch up after menopause.
- Family Histories - People with a family history of heart disease are at increased risk.
Uncontrollable Factors:
- Smoking - Smokers' risk of heart attack is almost twice that of nonsmokers, and their risk of sudden cardiac death is 2 - 4 times that of nonsmokers. Quitting (or never starting!) is a definite heart-healthy move.
- High Blood Pressure - Hypertension puts extra stress on the heart. Taking medication to lower high blood pressure, maintaining healthy body weight, avoiding salt and increasing exercise can help people reduce blood pressure.
- Blood Lipids - Lowering fats in the blood, such as cholesterol, can reduce that risk of heart disease. Individuals who come from a family with heart disease; who have other risk factors such as smoking, Diabetes, Hypertension, Obesity or physical inactivity; or who have a parent with high cholesterol level should have their lipids levels monitored by a doctor.
- Diabetes - Many people with Diabetes have High Blood Pressure or are Obese. Diabetes can also increase lipid levels and accelerate the development of Atherosclerosis, heart attack and Stroke.
- Obesity - Generally defined as having an adult body mass index greater than 27. Those who maintained their weight form age 25 on had a lower risk of heart disease. Those who lowered their weight over this time reduced their risk even further.
- Physical Activities - Exercisers have lower rate of Cardiovascular disease; those who are inactive have a higher rate. Aerobic exercise lowers heart rate, lipid levels and blood pressure and decreases body fat. Such activities include brisk walking, running, swimming, rowing and jumping rope for at least ten to fifteen minutes.
1.2.4 Symptoms
Heart Disease is the number one killer in developed and developing countries. Heart attacks are recognized as the most obvious sign of heart disease. Heart attack happened to be the first symptoms of 20% - 40% people who have heart disease. By then, plaque may have narrowed one or more arteries, limiting their ability to supply and area of the heart muscle with the oxygen and nutrients it needs.
Because of heart attack can cause severe damage by robbing the heart of oxygen, a quick reaction to the earliest signs of a heart attack is essential. Angina Pectoris, a squeezing, tightness or heaviness in the chest that can extend to the left arm, neck, jaw or shoulder blade is often the first sign that someone with Atherosclerosis is at risk for a heart attack. Physical exercise, a heavy meal, strong emotions or extreme temperatures can bring it on. If Angina occurs when a person is at rest, this means that the heart is starving for oxygen even when it is not working hard. Besides chest pain, weakness, fainting profuse sweating, nausea and vomiting can accompany a heart attack although a heart attack that arrives without Angina - a silent heart attack - may not be revealed until a patient shows up in the physician's office for an unrelated condition.
Valve disease can cause related symptoms of dizziness, fatigue, weakness, shortness of breath and chest pain when exercising. These same signs, along with Edema, an accumulation of fluid that occurs when the heart cannot keep the circulation moving properly, can indicate heart failure. Gravity often pulls the fluid downward, causing swelling in the feet, ankles and legs.
1.2.5 Treatments
Although many heart conditions cannot be cured, they can be controlled with lifestyle changes, medication or surgery or a combination of both.
- Medications - Irregular heart beats, heart failure and Angina are often treated with a combination of healthy lifestyle changes and medications. One of the most commons medications used is Nitroglycerine (ny-troglis-er-in), in the form of a tiny pill dissolved under the tongue. which acts to open the heart's blood vessels and permit more oxygen to flow the heart muscle. Beta-blockers decrease the heart's demand or oxygen by slowing down the heart rate. Aspirin, which helps keep the blood from clotting easily, is given to people who have heart disease or high risk of heart disease to decrease the likelihood of blood clots and thereby lowers the risk of heart attack and premature death. At the time of a heart attack, patients may be given special clot-dissolving medications intravenously (injected into a vein) to help unclog the diseased coronary arteries. Medications are also used to control high blood pressure.
- Surgical Procedures - Angioplasty (an-je-o-plas-tee) also called balloon angioplasty, opens up vessels blocked by plaque buildup. A specially designed balloon is threaded through an artery and inflated, pumping up and widening the channel. After the artery is opened, the balloon is withdrawn.
One problem is that Coronary Arteries opened by Angioplasty often close within three to six months. To prevent this, surgeons often place a stent, a 1 inch tube of wire-like stainless steel shaped like a tiny coiled spring, into the vessel, where it is expanded. The stent props the vessel open like scaffolding supports a tunnel. Stents can also be lifesaving for patients whose arteries suddenly collapse or spasm (contract) and close during Angioplasty, setting off a heart attack. - Atherectomy (ath-er-ek-to-mee) - An excision (cutting out) and physical removal of plaque from arteries. It is used in place of or along with balloon angioplasty. Once the balloon is inflated, a miniature cutter whirs forward to scrape deposits from the wall of the vessel like a tiny rotor clearing a clogged drain. Debris is pushed to a special collection chamber and when the device is withdrawn, the debris comes with it.
- Pacemakers - Pacemakers can be inserted to restore a regular heart beat. Advances devices can sense a respond to changes in body movement, temperature and breathing rate.
- Bypass Surgery - A procedure in which a segment of vein taken from the leg or an artery form the chest is gaffed to an opening in the side of the normal coronary artery above the obstructed (blocked) segment and then to the normal portion of the artery below the obstruction. Blood then "bypasses" the obstructed segment, much like taking a road detour around a construction site.
- Mechanical Valves - Damaged valves can be replaced with mechanical calves made of plastic or Dacron or biological valve taken form a pig, cow or human donour.
- Cardiac Transplantation - This is the most dramatic means of treating patients with severe heart failure. Although still filled with challenges, the procedure is well accepted around the world and is being performed more often. However, not enough human hearts are available from organ donours.
1.3 Congenital Heart Disease
1.3.1 Definition & Symptoms
Congenital heart disease (CHD) is defined as a structural, functional, or positional defect of the heart that is present from birth (Joshi, 2006). These abnormalities, or lesions, are often not apparent at birth and may not present until later in infancy or childhood (Abdulla, 2002). The term congenital heart disease encompasses a number of types of heart lesions, with eight common types of lesions making up 85 percent of all cases of CHD (Joshi, 2006). Congenital heart disease in children usually presents itself in a number of ways. Cyanosis, a bluish discoloration of the skin or mucous membranes caused by lack of oxygen in the blood, and heart failure, or a combination of the two, are both symptoms of CHD. Heart murmurs, circulatory shock, stridor, and hypercyanotic spells are all indicative of congenital heart defects, as are recurrent respiratory tract infections, chest pain, and growth failure (Joshi, 2006). Older children with CHD may tire quickly, be short of breath, or faint easily when they exert themselves. Children with congenital heart disease are prone to malnutrition because they may have decreased energy intake, increased energy requirements, or both. The severity of malnutrition can range from mild under-nutrition to failure to thrive (Varan et al., 1998).
Without early recognition, diagnosis, and treatment for cardiac lesions, about one in three infants with CHD are expected to die within the first month of life (Thakur et al., 1997). Vaidyanathan and Kumar (2005) cite studies in which children born with severe forms of CHD are 12 times more likely to die within their first year, particularly if the heart defects are missed in the first month after birth.
1.3.2 Categories
Congenital heart defects change the normal flow of blood through the heart. This is because some part of the heart didn't develop properly before birth.
There are many types of congenital heart defects. Some are simple, such as a hole in the septum that allows blood from the left and right sides of the heart to mix, or a narrowed valve that blocks blood flow to the lungs or other parts of the body.
Other defects are more complex. These include combinations of simple defects, problems with where the blood vessels leading to and from the heart are located, and more serious problems with how the heart develops.
Holes in the Heart (Septal Defects)
The septum is the wall that separates the chambers on the left side of the heart from those on the right. The wall prevents mixing of blood between the two sides of the heart. Sometimes, a baby is born with a hole in the septum. The hole allows blood to mix between the two sides of the heart.
Atrial Septal Defect (ASD)
An ASD is a hole in the part of the septum that separates the atria—the upper chambers of the heart. This heart defect allows oxygen-rich blood from the left atrium to flow into the right atrium instead of flowing to the left ventricle as it should. Many children who have ASDs have few, if any, symptoms.
An ASD can be small or large. Small ASDs allow only a little blood to leak from one atrium to the other. Very small ASDs don't affect the way the heart works and don't require any treatment. Many small ASDs close on their own as the heart grows during childhood.
Medium to large ASDs allow more blood to leak from one atrium to the other, and they're less likely to close on their own. Half of all ASDs close on their own or are so small that no treatment is needed. Medium to large ASDs that need treatment can be repaired using a catheter procedure or open-heart surgery.
Ventricular Septal Defect (VSD)
A VSD is a hole in the part of the septum that separates the ventricles—the lower chambers of the heart. The hole allows oxygen-rich blood to flow from the left ventricle into the right ventricle instead of flowing into the aorta and out to the body as it should.
A VSD can be small or large. A small VSD doesn't cause problems and may close on its own. Large VSDs cause the left side of the heart to work too hard. This increases blood pressure in the right side of the heart and the lungs because of the extra blood flow.
The increased work of the heart can cause heart failure and poor growth. If the hole isn't closed, high blood pressure can scar the delicate arteries in the lungs. Open-heart surgery is used to repair VSDs.
Narrowed Valves
Simple congenital heart defects also can involve the heart's valves. These valves control the flow of blood from the atria to the ventricles and from the ventricles into the two large arteries connected to the heart (the aorta and the pulmonary artery). Valves can have the following types of defects:
- Stenosis (ste-no-sis). This defect occurs if the flaps of a valve thicken, stiffen, or fuse together. This prevents the valve from fully opening. The heart has to work harder to pump blood through the valve.
- Atresia (a-tre-ze-AH). This defect occurs if a valve doesn't form correctly and lacks a hole for blood to pass through. Atresia of a valve generally results in more complex congenital heart disease.
- Regurgitation (re-gur-ji-ta-shun). This is when the valve doesn't close completely, so blood leaks back through the valve.
Pulmonary valve stenosis can range from mild to severe. Most children who have this defect have no signs or symptoms other than a heart murmur. (A heart murmur is an extra or unusual sound heard during a heartbeat.) Treatment isn't needed if the stenosis is mild.
In babies who have severe pulmonary valve stenosis, the right ventricle can get very overworked trying to pump blood to the pulmonary artery. These infants may have symptoms such as rapid or heavy breathing, fatigue (tiredness), or poor feeding.
If a baby also has an ASD or patent ductus arteriosus (PDA), oxygen-poor blood can flow from the right side of the heart to the left side. This can cause cyanosis (si-a-no-sis). Cyanosis is a bluish tint to the skin, lips, and fingernails. It occurs because the oxygen level in the blood leaving the heart is below normal.
Older children who have severe pulmonary valve stenosis may have symptoms such as fatigue while exercising. Severe pulmonary valve stenosis is treated with a catheter procedure.
Tetralogy of Fallot
Complex congenital heart defects need to be repaired with surgery. Because of advances in diagnosis and treatment, doctors can now successfully repair even very complex congenital heart defects.
The most common complex heart defect is tetralogy of Fallot (teh-tral-o-je of fah-lo), a combination of four defects:
- Pulmonary valve stenosis.
- A large VSD.
- An overriding aorta. In this defect, the aorta sits above both the left and right ventricles over the VSD, rather than just over the left ventricle. As a result, oxygen-poor blood from the right ventricle can flow directly into the aorta instead of into the pulmonary artery to the lungs.
- Right ventricular hypertrophy. In this defect, the muscle of the right ventricle is thicker than usual because of having to work harder than normal.
Babies and children who have tetralogy of Fallot have episodes of cyanosis, which can sometimes be severe. In the past, when this condition wasn't treated in infancy, older children would get very tired during exercise and could have fainting spells. Tetralogy of Fallot is now repaired in infancy to prevent these types of symptoms.
Tetralogy of Fallot must be repaired with open-heart surgery, either soon after birth or later in infancy. The timing of the surgery will depend on how much the pulmonary artery is narrowed.
Children who have had this heart defect repaired need lifelong medical care from a specialist to make sure they stay as healthy as possible.
1.3.3 Causes
Although the exact cause of most cases of congenital heart disease is not known, certain factors often contribute to the creation of heart defects in children. Some heart defects may be genetic, while others are the result of chromosomal abnormalities such as Down’s syndrome or Turner’s syndrome.
Maternal intrauterine viral infection, such as rubella, or taking certain kinds of medications during pregnancy can contribute to congenital heart disease (March of Dimes, 2006). Consanguineous marriages, or marriages between close relatives, which are common in many regions of the world, are also a risk factor that can lead to children with congenital heart defects. Studies have found that the occurrence of congenital abnormalities, as well as other problems such as mental retardation and physical handicap, was significantly higher in the children of consanguineous than in non-consanguineous marriages (Abdulrazzak, Y.M. et al, 1997; Becker and Al Halees, 1999).
1.3.4 Living with CHD
The outlook for a child who has a congenital heart defect is much better today than in the past. Advances in testing and treatment mean that most children who have heart defects survive to adulthood and are able to live active, productive lives.
Many of these children need only occasional checkups with a cardiologist (heart specialist) as they grow up and go through adult life.
Children who have complex heart defects need long-term, special care by trained specialists. This will help them stay as healthy as possible and maintain a good quality of life.
1.3.5 Incidence
The exact number of children born with congenital heart defects is also not known, and estimates of the prevalence of CHD differ. Congenital heart diseases are thought to account for up to 25 percent of all congenital malformations that occur during development (Vaidyanathan and Kumar, 2005). Some studies from developed countries report that the incidence of CHD is about 4 to 5 cases per 1 000 live births (Vaidyanathan and Kumar, 2005); others cite rates of 8 cases per 1 000 (Cohen et al., 2001; Joshi, 2006). Some recent studies have even cited incidence rates of as many as 12 to 14 per 1 000 (Vaidyanathan and Kumar, 2005). However, incidence rates of CHD are generally based only on live-born infants. If the number of children who are stillborn or die prenatally were included, the incidence of CHD would probably be about five times greater (Hoffman, 1995).
Many of the most detailed studies of CHD prevalence have been done in the United States and other developed countries. Fewer examinations of the rates of pediatric heart disease have been conducted in developing countries because of the technical and logistical challenges of conducting systemic population-based surveys in many of these countries. However, some of the studies that have been conducted found rates of about 4 children per 1 000 with CHD (as reported in Vaidyanathan and Kumar, 2005). Most studies report that, with only a few minor exceptions, the incidence of CHD is constant worldwide and across geographic and ethnic backgrounds (Abdulla, 2002; Vaidyanathan and Kumar, 2005). Even so, the absolute number of children with congenital heart diseases may still be greater in developing countries than in more developed countries. Many developing countries have higher birth rates and larger populations, so a greater number of children are born in these countries. The greater number of births then results in an overall higher number of children in the population born with congenital heart disease (Kumar, 2003).
- ChildrenHeartlink Report, 2007, p. 8 - 9
1.3.6 Mortality Rates
Not only is the incidence of congenital heart disease poorly known, but the number of children who die each year from complications related to congenital heart lesions is also uncertain. At best, childhood mortality as a result of CHD and its complications can only be estimated. In 2001, the Disease Control Priorities Project (DCPP), a joint partnership of the Fogarty International Center (FIC) of the US National Institutes of Health, the World Bank, World Health Organization, and the Bill & Melinda Gates Foundation completed a comprehensive assessment of the global burdens of disease and mortality in developing countries as a way to guide the development of health care priorities in international assistance. In this report, the Project ranked the leading causes of death in children aged 0 to 14 years by country type and age group. In high-income countries, the second greatest cause of all childhood mortality is congenital anomalies, which include congenital heart lesions. These anomalies account for 20 percent of all childhood deaths in high-income countries. In low and middle-income countries, congenital anomalies are the eighth leading cause of childhood deaths, or 3.7 percent of childhood mortality (Jamison et al., 2006). In these countries, the leading causes of childhood deaths each year are perinatal conditions (20.7 percent of total child mortality), lower respiratory infections (17 percent), diarrheal diseases (13.4 percent), malaria (9.2 percent), measles (6.2 percent), and HIV/AIDS (3.7 percent).
The lower percentage of deaths from congenital anomalies in low and middle-income countries merely reflects the fact that childhood mortality in less developed countries is much greater overall than in those with higher-incomes. Fewer children die each year in high-income, developed countries because there is better sanitation, water quality, prenatal care, and health care systems in these countries. Because total child mortality is lower in industrialized countries, the absolute number of children who die from all congenital abnormalities in the developed world is much smaller than the number of childhood deaths in low-income countries. As seen in Table 1, overall child mortality rates for neonates, infants, and children under five years of age are much higher in poor and less-developed countries than in industrialized nations. Mortality rates also differ by region, with Sub-Saharan, West, and Central Africa having the greatest mortality rates in all categories.
In 2001, childhood deaths from congenital abnormalities in developed countries, while still 20 percent of total childhood mortality, totaled approximately 20 000 children. However, congenital abnormalities in low-income countries, while only 3.7 percent of total mortality, took the lives of over 440 000 children. Even though congenital heart diseases account for only some of the congenital anomalies in these estimates, the overall pattern of childhood mortality undoubtedly holds when considering only congenital heart lesions in high-income versus low-income countries: more children die of congenital heart disease in low-income countries than in more developed countries.
- ChildrenHeartlink Report, 2007, p. 11
1.3.7
While congenital heart diseases, if untreated, will often lead to early death in infants and children, the advancement of pediatric cardiology has significantly improved the outcomes for children born with heart lesions. Treatment or surgery can have dramatic results in children’s lives, and most forms of CHD can now be corrected or improved. Improved diagnostic abilities, such as chest radiography, electrocardiograms, echocardiography, and cardiac catheterization, allow for better and earlier diagnosis of cardiac lesions (Joshi, 2006). Non-surgical interventions have reduced the number of children who require surgical treatment for CHD. Improved surgical techniques also decrease the risk of death or serious complications for children who must undergo heart surgery. Advancements in pediatric medicine have ensured that children born with CHD have a greater chance to lead healthy, normal lives than ever before.
Although many children who have congenital heart defects don't need treatment, some do. Doctors repair congenital heart defects with catheter procedures or surgery.
The treatment your child receives depends on the type and severity of his or her heart defect. Other factors include your child's age, size, and general health. Some children who have complex congenital heart defects may need several catheter or surgical procedures over a period of years, or they may need to take medicines for years.
Catheter
Catheter procedures are much easier on patients than surgery because they involve only a needle puncture in the skin where the catheter (thin, flexible tube) is inserted into a vein or an artery.
Doctors don't have to surgically open the chest or operate directly on the heart to repair the defect(s). This means that recovery may be easier and quicker.
The use of catheter procedures has grown a lot in the past 20 years. They have become the preferred way to repair many simple heart defects, such as atrial septal defect (ASD) and pulmonary valve stenosis.
For an ASD, the doctor inserts a catheter through a vein and threads it into the heart to the septum. The catheter has a tiny, umbrella-like device folded up inside it.
When the catheter reaches the septum, the device is pushed out of the catheter. It's positioned so that it plugs the hole between the atria. The device is secured in place and the catheter is then withdrawn from the body.
For pulmonary valve stenosis, the doctor inserts a catheter through a vein and threads it into the heart to the pulmonary valve. A tiny balloon at the end of the catheter is quickly inflated to push apart the leaflets, or "doors," of the valve. The balloon is then deflated and the catheter and ballon are withdrawn. This procedure can be used to repair any narrowed valve in the heart.
To help guide the catheter, doctors often use echocardiography (echo) or transesophageal (tranz-ih-sof-uh-jee-ul) echocardiography (TEE) and angiography (an-jee-og-ra-fee).
TEE is a special type of echo that takes pictures of the back of the heart through the esophagus (the passage leading from the mouth to the stomach). TEE also is often used to examine complex heart defects.
Doctors also sometimes combine catheter and surgical procedures to repair complex heart defects, which may involve several kinds of defects.
Surgical Procedures
A child may need open-heart surgery if his or her heart defect can't be fixed using a catheter procedure. Sometimes, one surgery can repair the defect completely. If that's not possible, the child may need more surgeries over months or years to fix the problem. Open-heart surgery may be done to:
- Close holes in the heart with stitches or with a patch.
- Repair or replace heart valves.
- Widen arteries or openings to heart valves.
- Repair complex defects, such as problems with where the blood vessels near the heart are located or how they developed.
- http://www.nhlbi.nih.gov/health/dci/Diseases/chd/chd_treatments.html
1.3.8 Factors that Prevent Diagnosis & Treatment of CHD
- Lack of Access to Cardiac Care
- Few Facilities to Treat Pediatric Heart Disease
- Shortage of Trained Pediatric Cardiac Specialists
- Prohibitive Expense of Pediatric Cardiac Treatment
- Lack of Basic Health Care
- Shortage of Health Care Workers
- Migration of Health Care Workers to Developed Countries
- Lack of Investment in Public Health Sectors
- Competing Priorities in Health Care
1.3.9 International Strategies to Treat CHD
Given the competing priorities in health care for many poor and underdeveloped countries, congenital heart disease is often not considered as much of a priority as many other health issues. In the developing world, the burden of poverty, lack of economic growth and stability, and poor governance combine to prevent the necessary investment in health care, infrastructure, and staff training that many countries need to build sustainable health care systems. When countries are unable to supply even a minimal amount of health care to their people, there may be little incentive for them to dedicate resources to train and retain pediatric cardiac personnel or to build facilities and institutions that can handle the advanced technological requirements of pediatric cardiac surgery.
Because so many countries’ medical systems are unable to afford treatment for children with congenital heart diseases, the international community often steps in to offer treatment for these children and infants. Numerous nonprofit and nongovernmental organizations, as wells as hospitals and institutions, work with facilities in developing countries to provide interventional techniques and cardiac operations available to children. Many of these organizations have been working in other countries for years, while others have begun their partnerships with overseas hospitals more recently. The ways in which these organizations offer treatment has also changed over the years and modes of delivery for treatment have evolved as costs of health care and transportation change. In addition, many organizations constantly try to improve the types of treatment they offer while also increasing the number of children with CHD they can treat. Some are moving beyond simply treating a few children and are looking for more sustainable ways to treat as many children as possible. While some international organizations fund a single type of project to treat congenital heart diseases in the developing world, others fund multiple types of projects. Transporting sick children to developed countries, sending surgical teams to developing countries, training doctors and nurses in other countries, or establishing regional centers are the major means by which international organizations treat children with pediatric heart diseases in developing countries. These strategies, in addition to some of the difficulties each face, are discussed below:
- Transporting Children with Heart Disease to Other Countries for Treatment
- Sending Surgical Teams to Developing Countries
- Training Local Doctors and Staff in Developed Countries
- Creating Regional Centers for Treatment of Pediatric Heart Disease
- Other NGOs are encouraged to be an Affiliate to The World Heart Foundation
