CONGENITAL HEART DEFECTS IN NEWBORNS:
SCREENING & EVALUATION
Congenital Heart Disease as well as Congenital Heart Defect (CHD) is the more familiar category of birth disorder which is a heart complication that affected in the shape of the heart is present at birth. It is a deformity that generates in the womb, before a baby is born. It is also termed as Congenital Heart Anomaly. It is caused by abnormal constitution of the heart during fatal growth.The congenital heart defect in neonates occurs in approximately 8 out of 1000 newborns are diagnosed with a form of CHD in globally per year, is generally accepted as the best approximation. Critical CHD defined as requiring surgery or catheter depended intervention in the first 12 months life of neonates, occurs in approximately 25% of those with congenital heart defect. So that early detection of CHD is necessary because the delayed detection of CCHD can lead too many heart problems such as cardiac failure, cardiovascular collapse and even death. pulse oximetry is a useful screening method for detection of these defects in asymptomatic newborn babies. The initial purpose of newborn screening is the presymtomatic recognition of life-threatening CHD to accomplish a timely diagnosis before cardiovascular collapse or death. This review aims to highlight the importants of early diagnosis of congenital heart defects.
Congenital Heart Disease as well as Congenital Heart Defect (CHD) is the more familiar category of birth disorder which is a heart complication that affected in the shape of the heart that is present at birth. It is the deformity that generates in the womb, before a baby is born. It is also termed as Congenital Heart Anomaly. CHD is the most typical congenital defect in newborns. These disorders are the commonest group of congenital malformations and an important cause of early childhood mortality. It is also responsible for mortality in the first year of life of the newborns. It forms in the new borns when the baby’s heart is developing in the mother’s womb. It is caused by abnormal constitution of the heart during fatal growth. In some cases a baby is born with congenital heart disease, the exact reason is unknown. Few of the familiar cause of CHD such as ; genes-20% of cases has genetic causes and other birth defects include: a baby affected by certain birth defect such as Down syndrome is likely to have malformations of the heart. The heart defects may causes difficulty with blood flow through the heart after a baby is born. This difficulty can affect the baby’s blood and oxygen supply. If these defects reduce the level of oxygen in the body, is referred as cyanotic. Some form of CHD causes no or very less complication in the health, growth and development of the infant. But critical congenital heart defect (CCHD) can show a significant risk of morbidity and mortality, if not diagnosed shortly after birth. Critical congenital heart disease is one of the typical causes of morbidity and mortality in newborns. Critical CHD defined as requiring surgery or catheter depended intervention in the first 12 months life of neonates, occurs in approximately 25% of those with congenital heart defect. CCHD are the deformations consist of some congenital heart problems such as tetra logy of fallout, pulmonary artesian, trunks arteries, transposition of the great vessels, total anomalous pulmonary venous return and tricuspid artesian. The congenital heart defect in neonates occurs in approximately 8 out of 1000 newborns are diagnosed with a form of CHD in globally per year, is generally accepted as the best approximation. CHD affects up to 40% of deaths from congenital abnormalities and 3% to 7.5% of infant deaths. Almost 30% of infant deaths related to birth defects and about 1 in 4 babies (25%) born with a defect will have critical congenital heart disease that means requiring intervention within first year of life. So that early detection of CHD is necessary because the delayed detection of CCHD can lead too many heart problems such as cardiac failure, cardiovascular collapse and even death. CCHD in neonates may have low oxygen saturations unrecognized clinically.
For early diagnosis and screening of congenital heart defect is done by using pulse oximetry in newborn babies. Combining pulse oximetry with clinical examination can augment the clinician’s proficiency to detect life threatening CHD at the right time. Even though CHD can be examined by using Fatal cardiac ultrasonography. The pulse oximetry test was used for the determination of oxygen levels in a baby’s blood. It is a very useful, non-invasive and inexpensive method for routine monitoring of the new borns. Pulse oximetry can also used to detect Hypoxemia. Early detection of CHDs can significantly reduces the risk of sudden cardiovascular collapse and other cardiac defects and can reduces the mortality rate for these heart diseases.
CLASSIFICATION OF CHD
CHD can be categorized into three main groups according to the clinical basis;
1. LIFE THRETENING CHD
Anatomical heart abnormalities in which cardiovascular destruction is possible and compromised if not treated early. The defects that include Transposition of the great arteries (TGA) ,Coarctation of Aorta(COA) ,Interrupted Aortic Arch(IAA) ,Hypoplastic Left Heart Syndrome (HLHS)/Mitral Atresia, Pulmonary Atresia(PA), and obstructed Total Anomalous Pulmonary Venous Return(TAPVR).
2. CLINICALLY SIGNIFICANT CHD
Anatomical heart abnormalities that are affects the heart function but where the destruction or collapse is improbable to require early intervention. They include defects like Ventricular Septal Defect(VSD), Complete Atrioventricular Septal Defect(AVSD), Atrial Septal Defect(ASD) and tetralogy of Fallot(TOF) with fine pulmonary artery structure.
3. CLINICALLY NON SIGNIFICANT CHD
Structurally established cardiac abnormalities but no functional and clinical significance. They include the defects like small VSD, Atrial Septal Defect(ASD), Mild pulmonary stenosis(PS),only diagnosed by echocardiography and requiring no treatment.
EPIDEMIOLOGY OF CHD
Congenital Heart Defect is affected in infants is about 7-8 per 1000 live-borns, and account for about 3% of all the infant deaths and 46% of deaths because of congenital abnormalities. About 18-25% of defected infants die in the first year, with 4% of infants surviving dying by 16 years.
The possible symptoms of congenital heart defects in infants and children may include;
A bluish tint to the skin, fingernails and lips, this condition is called as Cyanosis ( lack of oxygenated blood ).
Fast breathing and poor nourishment.
Poor weight gain.
Lack of exercise
The causes of congenital heart defects include;
Defects with genes or chromosomes in the child such as Down syndrome.
Taking some certain medications or alcohol during pregnancy period.
The viral infection such as Rubella in the mother in the first trimester of pregnancy.
MATERNAL AGE : Maternal age is one of the important risk factor of congenital heart defects. Progressed maternal age is associated with distinct genetic complications association with Down syndrome that has a high prevalence of CHD.
PATERNAL AGE : Progressed parentage may also be an actuate factor for the formation of defect in the heart.
FEBRILE ILLNESS DURING GESTATION PERIOD
The mother who had history of febrile illness in the gestation period had higher risk of having CHD in their offspring.
BAD OBSTERIC HISTORY: This condition causes greater the possibility of abortions might have been experiencing with serious CHD.
PROGESTATIONAL DIABETES: The progestational diabetes is vigorously associated with the formation of congenital heart abnormalities.
SCREENING AND EVALUATION OF CHD
Heart deformity may produce complications with blood flow through the baby’s heart after the baby is born. These complications can influence the baby’s blood as well as oxygen supply. Many forms of CHD cause no or very little complications in the health, growth and development of the infant. Critical Congenital Heart Disease (CCHD) is one of the acceptable causes of morbidity and mortality in newborns and had need surgery or catheter based intervention, which results in nearly around 25% of those with CHD. If not detected quickly after birth, CCHD can lead to asignificant risk of morbidity and mortality. Initial diagnosis of CHD is very essential because of the delayed diagnosis of CCHD can leads to cardiac failure, cardiovascular collapse and even death.
The initial purpose of newborn screening is the presymtomatic recognition of life-threatening CHD to accomplish a timely diagnosis before cardiovascular collapse or death. Early screening and evaluation for these critically unhealthy patients are the only way to save lives. Now adays the pulse oximetry screening is the frequently used an adequate technique for the early diagnosis of CHD in newborns. This approch is also having high sensitivity and high specificity. The combination of pulse oximetry with clinical examination can intencify the ability to recognise life-threatening CHD in a timely aspect.
DIAGNOSIS OF CHD
Fetal echocardiogram is a diagnostic tool, in which doctor performs an ultrasound. The sound waves from the ultrasound are used to generate an image of baby’s heart, before the baby have been born.
Echocardiogram is done after the baby has been born. It is a non-invasive test, the doctor carried out an ultrasound to generate images of the heart. This test is allows when the baby’s heart in function and to detect the abnormalities in the heart muscle and valves.
Electrocardiogram is a non-invasive test. It is perform to record the electrical activity of the baby’s heart and it can be helps to detect the heart the heart defects or to detect the heart rhythmic problems. This test is done by using electrodes which is connected to a computer and printer are placed on baby’s chest and display the waves that illustrates how the baby’s heart is beating.
In the baby’s chest x-ray to identify if the heart is expanded or if the lungs have extra blood or any other fluids. These could be the indication of heart failure.
The pulse oximetry test is helps to measures the amount of oxygen is present in the baby’s blood. This is done by a sensor is placed over the end of the baby’s finger to record the amount of oxygen in the baby’s blood. The amount of oxygen is very less that indicates the child has a heart problem.
This test is done by a thin flexible tube (catheter) is introduced into a blood vessel.
IMPORTANCE OF NEWBORN SCREENING FOR CRITICAL CHDs
Some of the CHDs may be recognised during pregnancy by employing a particular type of ultrasound termed as fetal echocardiogram, which develops the images of heart of the growing baby.
A simple and uncomplicated bedside test for the screening and evaluation of critical CHDs in newborns is termed as pulse oximetry. This technique is measures that the amount of oxygen in the baby’s blood. The low levels of oxygen in the baby’s blood can indicates the presence of critical congenital heart defects. This test is performed by using an equipment called pulse oximeter, along with sensors fixed on the baby’s skin. This test is painless and takes only a few minutes of time.
Pulse oximetry screening is better likely to find seven of the critical CHDs include Hypoplastic Left Heart Syndrome(HLHS), Pulmonory Atresia(PA), Tetralogy of Fallot, Total Anomalous Pulmonary Venous Return(TAPVR), Transposition of the Great Arteries(TGA), Tricuspid Atresia(TA) and Truncus Arteriosus.
Newborns who developed signs and symptoms expressive of a cardiac defect were analyzed incorporating blood pressure, echocardiogram, chest radiograph, pulse oximetry and electrocardiography. CHD are the prominant cause of child deaths in the developed world. Elapsed screening of CHD is correlated with a poor preoperative circumstances. Diagnosing infants with non-invasive assessment of oxygen saturation has been recommended as an aid for early disclosure of CHD. Newborns with severe heart defects may not early have symptoms or the clinical sign may be complicated, severe situation may not be identified on the regular physical examination in majority of cases. Without early intervention, the percentage rate of mortality and endurance with significant infirmity are extreamely high. Early diagnosis can possibly progress healthy strong outcome results in newborns with CCHD. Prenatal diagnosis can turned into a significant contributor even with fetal echocardiograms, which are not available universally, the diagnosis of CCHD during pregnancy is difficult.
Several studies are documented the lack of sensitivity of routine neonatal examination in detecting CHD. Many neonates with CHD have no signs that can be detected by clinical examination. Recent studies have reported a high sensitivity and specificity for pulse oximetry for early detection of CHD in newborn babies.
PULSE OXIMETRY SCREENING FOR CHD IN NEWBORN BABIES
Pulse oximetry screening is a simple, non-invasive, painless technique. It is also safe, feasible, well established exact technique used for to detect the quantification of hypoxemia. Pulse oximetry has excellent detection rate and it is inexpensive and safe method which is used to detect many cases of critical CHD in newborns that may have low levels of oxygen in their blood. Initial diagnosis of critical CHD may point out to earlier interventions and progressed patient outcomes. So the pulse oximetry screening is the commonly use method for the diagnosis of CHD in newborn babies. Clinically this screening technique is used for the detection of undetectable hypoxemia in potentially life-threatening cases. This test should be performed when the baby is older than 24 hours. The pulse oximetry reading is taken up in the 24 hours old babies by using the equipment called pulse oximeter, with sensors placed on the baby’s right hand or right foot. This test is painless and takes only very few minutes of time. Pulse oximetry reading of 95%-100% is the normal value in a healthy baby. If the babies with heart or lung problems the pulse oximeter shows lower readings. This diagnostic test is also used for the measurement of percent oxygen saturation of hemoglobin in the arterial blood and to measure the pulse rate.If the newborns oxygen saturation is less than 95% in either extreamly, with a