Congenital Heart Disease - Essay Example

Human Biology March 14, 2006 Congenital Heart Disease Congenital heart disease refers to any abnormality in the structure of the heart present from birth. Also known as congenital heart defect, cyanotic heart disease, heart defects or congenital cardiovascular malformations, it is the most common type of heart disease among children as it affects six to eight babies out of one thousand full-term live births, with incidence being higher in pre-mature births (Cotran et al 618). What causes this congenital condition is still unknown, but experts at the Texas Heart Institute have identified some factors that may increase the risk of a baby being born with such disease. These are: congenital heart disease in the babys mother or father; congenital heart disease in the babys brother or sister; diabetes in the mother; German measles, toxoplasmosis (an infection that is passed through contact with cat feces), or HIV infection in the mother; the mothers use of alcohol during pregnancy; the mothers use of cocaine or other drugs during pregnancy; and the mothers use of certain over-the-counter and prescription medicines during pregnancy. It should be noted though, that the presence of any one or more of these factors will not absolutely result to the disease. Likewise, the absence of these factors does not assure a pregnant woman that her baby will be safe from any congenital heart disorders, which might be an important point to consider when a woman is pregnant. All safety measures should be observed all throughout the pregnancy as there is no single identifiable factor in contracting life-threatening diseases such as this. This also leads us to the importance of having a thorough knowledge of the subject, for one can never be too sure if one of the members of the family will suffer from such disease. Knowledge on the disease might just be the best way to go about the situation when prevention is not so possible. To better appreciate the mechanisms of congenital heart disease, a thorough understanding of how the human heart works is necessary. Below is an illustration of a healthy human heart. The heart is a muscular organ about the size of the fist. It has two sides, separated by a wall-like structure called a septum. The right side of the heart pumps blood to the lungs where it is oxygenated. The oxygenated blood then goes from the lungs to the left side of the heart, and is pumped out to the rest of the body. The heart is made up of four chambers: the right and left ventricles and the left and right atria. The atria, which are located at the upper portion of the heart, receive the blood coming into the heart, while the ventricles which are located at the lower part of the heart, pump blood out of the heart and into the lungs and the other parts of the body. The flow of blood into and out of the heart is controlled by the valves that open to let blood flow through from one chamber to the next and thereafter efficiently close to prevent blood from flowing backwards. These valves are: 1) the tricuspid valve which is located at the right side of the heart, in between the right atrium and the right ventricle; 2) the pulmonary valve, located at the right side of the heart, in between the right ventricle and the entrance to the pulmonary artery that carries blood to the lungs; 3) the mitral valve, located at the left side of the heart, between the left atrium and the left ventricle; and 4) the aortic valve, located at the left side of the heart, in between the left ventricle and the entrance to the aorta, the artery which carries blood to the body. Arteries and veins are the major blood vessels that carry blood to and from the heart. The major arteries are: 1) the pulmonary artery which carries unoxygenated blood pumped from the right side of the heart to the lungs, 2) the aorta which carries oxygenated blood pumped from the left side of the heart to the rest of the body, and 3) the coronary arteries which carry oxygenated blood from the aorta to the heart. The pulmonary veins carry oxygenated blood from the lungs to the left side of the heart, to be pumped out to the body, while the vena cava carries deoxygenated blood from the body back to the heart (“Congenital Heart Defects”). Any disruption in the smooth flow of blood through the four chambers will lead to anomalies in the structure of the heart as manifested by the signs and symptoms of congenital heart disease. Generally, a baby who has heart murmurs, a bluish tint in the lips, skin and fingernails, has fast breathing patterns or has shortness of breath, has poor feeding habits (in infants as they tire easily), and has poor weight gain and older children who tire easily during exercise or activity may indicate that congenital heart defects might be present (“Congenital Heart Defects”). Congenital heart defects are usually diagnosed within the first few months of life, depending on the severity of the symptoms presented by the patient. Others whose defects are not quite severe are not diagnosed until later in their lives, when their hearts are subjected to more work load. When diagnosed, several tests may be done to know the extent of the defect so that proper medication may be administered. These tests according to the National Heart, Blood and Lung Institute are the echocardiogram, electrocardiogram, chest x-ray, pulse oximetry and cardiac catheterization. The echocardiogram is the most commonly used tool to diagnose the disease. It uses sound waves to create a picture of the heart. A special type of echocardiogram may be done on pregnant women if the doctor suspects a defect in the heart of the fetus. This is called a fetal cardiogram and is done usually during the fifth month of pregnancy. This step is of great help to the doctor as well as to the patient, as it enables him to prepare the treatment plan even before the baby arrives. The electrocardiogram (ECG or EKG) measures the rate and regularity of the child’s heartbeat. The chest x-ray makes a picture of the patient’s heart and lungs showing the heart’s relative size and the probable presence of fluid in the lungs. The pulse oximetry makes use of a sensor attached to the patient’s fingertip or toe which shows how well a child’s lungs are passing oxygen in the blood and if there is a mixing of oxygen-rich and oxygen-poor blood. In cardiac catheterization, a thin flexible tube that is passed through an artery or vein in the groin or arm to the heart enables the doctor to see the patient’s blood flow through the blood vessels and the heart. It also measures the pressure inside the heart and blood vessels and can determine if there is mixing of blood between the two sides of the heart (”Congenital Heart Defects”). According to Cotran et al, the varied anomalies in heart with defects generally fall into two major categories namely shunts and obstructions (619). A shunt means that there is an abnormal communication between the heart’s chambers or blood vessels or between the chambers and the blood vessels. The abnormal channels permit the flow of blood form left to right or the reverse depending on the pressure relationships. When blood from the right side of the heart enters the left side, the flow of poorly oxygenated blood to the body results to cyanosis, a condition characterized by a bluish color resulting from a lack of oxygen in the blood. Congenital heart defects that produce right-to-left shunts are called cyanotic congenital heart diseases. Examples of these are the Tetralogy of Fallot, transposition of the great arteries, persistent truncus arteriosus and tricuspid atresia. Obstruction, on the other hand, is the result of the abnormal narrowing of the blood vessels. Certain anomalies in the structure of the heart lead to obstruction in the flow of blood. They do not cause cyanosis and are therefore referred to a noncyanotic or obstructive congenital heart diseases. Examples of these are coarctation of the aorta, aortic valvular stenosis and pulmonary valvular stenosis. The following are the descriptions of each type of congenital heart defect and their corresponding treatment according to the Texas Heart Institute. Tetralogy of Fallot is made up of 4 heart defects: 1) a hole in the wall between the ventricles (septum), which lets oxygen-poor blood mix with oxygen-rich blood; also called a ventricular septal defect; 2) a narrowed outlet to the pulmonary artery, usually along with an abnormal pulmonary valve. This can block blood flow from the right ventricle into the lungs; 3) an aorta that straddles the wall between the ventricles. This lets oxygen-poor blood flow into the aorta; and 4) thickened and enlarged heart muscle tissue in the right ventricle. The narrowed pulmonary valve and the hole in between the ventricles make oxygen levels in the blood that circulates in the body too low, resulting to cyanosis. Treatment for this type of defect usually involves surgery. A shunt procedure may be done to temporarily allow more blood to reach the lungs and reduce cyanosis, until the child is old enough to undergo an open-heart surgery, which is usually between ages 8 months and 5 years old. The ventricular septal defect is usually covered with a patch and the pulmonary valve is widened to increase blood flow to the lungs. Studies have shown that the earlier surgery is done, the better the heart works later in life. The transposition of the great arteries involves the pulmonary artery and the aorta. The pulmonary artery is normally connected to the right ventricle and carries oxygen-poor blood to the lungs where it is oxygenated. The left ventricle pumps oxygen-rich blood into the aorta which then carries blood to the rest of the body. In the transposition of the great arteries, the positions are reversed, thus delivering the oxygen-rich blood back to the lungs and the poorly-oxygenated blood to the rest of the body. The only way for oxygen-rich blood to reach the body is through another defect that connects the two routes. An atrial septal defect allows the exchange of blood between the two atria, a ventricular septal defect allows the exchange of blood between the two ventricles, and a patent ductus arteriosus connects the pulmonary artery and the aorta. To treat this anomaly, a newborn baby may be given medicine to keep the ductus arteriosus open which usually closes soon after birth, thereby allowing some oxygen-rich blood to reach the body. Another way to treat it would be to create a defect called an atrial septal defect, if the baby is not born with, it to temporarily allow oxygen-rich blood to flow through the body. A surgery called arterial switch is then done on the baby during the first month of life. This procedure reverses the position of the aorta and the pulmonary veins to their normal positions and sets them back to normal functions. In persistent truncus arteriosus, there is a large hole in the septum that separates the two ventricles (called a ventricular septal defect) which causes the oxygen-poor blood to mix with the oxygen-rich blood resulting to cyanosis. It also causes the arteries to form abnormally such that instead of the pulmonary artery connecting to the right ventricle and the aorta connecting to the left ventricle, the heart has just one big artery that connects to both ventricles. These cause too much blood flow to the lungs and force the heart to work too hard, which results to difficulty in breathing, feeding and growing normally in babies. To correct this defect, a surgery is done during infancy where the pulmonary arteries are separated from the common artery and attached to the right ventricle with a tube. The hole in the septum is then covered with a patch. In tricuspid atresia, the valve which allows blood to pass from the right atrium to the right ventricle for oxygenation in the lungs is missing. Blood is thus unable to reach the lungs or the left side of the heart unless other defects such as atrial septal defect, ventricular septal defect or patent ductus arteriosus are present. These defects would allow some blood to flow through the lungs, although oxygen–poor blood is still allowed to flow through the body along with the oxygen-rich blood thereby causing cyanosis. Different surgical procedures may be done to correct this defect depending on the case, but the goal of the treatment would be to improve blood flow in the lungs by making the blood route as normal as possible. Coarctation of the aorta means that one area of the aorta is abnormally narrow. This makes the arteries that branch off before the narrow point of the aorta receive more blood than the arteries that branch off after it. This results to an increased blood pressure in the arteries that supply blood to the head and arms and a decreased blood flow to the legs. The heart is tehn forced to work harder, causing it to get larger. In time, this extra work leads to heart failure. Some of the symptoms associated with it are a blood pressure that is higher in the arms than in the legs, a weak or no pulse in the groin area, cold legs and feet, nose bleeding, dizziness, fainting, and leg cramps with exercise. In most cases, surgery is recommended to remove the narrowed part of the aorta. A non-invasive catheterization procedure called balloon angioplasty may also be done to widen the narrowed segment. In this procedure, a long, thin tube called a catheter is inserted into the body, usually in the groin area.  From there, it is guided through an artery up to the narrow part of the aorta. Once inside the narrowed part of the aorta, a tiny balloon on the tip of the catheter is inflated, causing the opening to widen. Then, the deflated balloon and catheter are removed. More recently, doctors are using wire-mesh devices called stents which are implanted during an angioplasty procedure to support the aorta and keep it open. Aortic valvular stenosis is the narrowing of the aortic valve making the left ventricle pump harder to force blood through the valve, which results to a larger left ventricle and eventually leads to heart failure. Symptoms may include chest pain, unusual tiredness from activity, dizziness, and fainting. Children with mild stenosis usually do not require surgery, but they should be watched carefully and see their doctor on a regular basis. Other cases may require balloon valvuloplasty or open heart surgery. Surgery for aortic stenosis may include the Ross procedure. This procedure involves replacing the childs diseased or abnormal aortic valve with his or her own pulmonary valve (called a pulmonary autograft). A valve from a human donor is then placed where the pulmonary valve was. After balloon valvuloplasty or valve surgery, the valve sometimes narrows again. In these cases, the valve may need to be replaced with an artificial one. Similarly, pulmonary valvular stenosis is the narrowing of the valve that lets blood flow from the right ventricle into the lungs making the right ventricle work harder and become enlarged. Children with mild pulmonary stenosis usually have no symptoms and do not require surgery while infants with severe stenosis usually exhibit cyanosis which calls for an immediate open-heart surgery or balloon valvuloplasty. Clearly we could see how latest trends in biotechnology have improved the lives of patients suffering from a disease which used to be thought of as incurable five decades ago. With the advent of newer procedures and interventions, children now have better chances of not just surviving, but living longer lives not quite different from the rest. Continuing studies and innovation in the field of cardiology have continued to improve the quality of lives of people and give us new hope that the life of a child need not end in a condition known as congenital heart disease. Works Cited “Congenital Heart Defects.” Diseases and Conditions Index. January 2006. National Heart, Lung and Blood Institute. March12,2006 “Congenital Heart Disease.” Heart Information Center. July 2005. Texas Heart Institute at St. Luke’s Episcopal Hospital. March 12, 2006 < http://www.texasheartinstitute.org/HIC/Topics/Cond/CongenitalHeartDisease.cfm> Cotran, Ramzi, Vinay Kumar and Stanley Robbins. Robbins Pathologic Basis of Disease, 4th ed. Philadelphia: W.B. Saunders , 1989. Read More