Fetal Heart Rate and Defects Essay
Electronic fetal heart monitoring is commonly used for tracking how well the baby is doing within the contracting uterus and for detecting signs of fetal distress. External fetal heart monitoring is performed by attaching external transducers to the mothers abdomen with elastic straps. The transducers use Doppler ultrasound to detect fetal heart motion, and the information is sent to the fetal heart monitor which calculates and records the fetal heart rate on a continuous strip of paper. More modern fetal heart monitors have incorporated microprocessors and mathematical procedures to improve the fetal heart rate signal and the accuracy of the recording.
An echocardiography can be used before birth to accurately identify many heart defects. The mother can be treated with medications that may restore normal heart rhythm in the fetus if the test shows that a fetusâ€™s heart is beating too fast or too slow (Emitting Waves, R.C., n.d.).
The fetal heart starts as a tube which folds and fuses in a complex structure that results in a muscular pump with four chambers and four valves. It is not surprising that small errors in development can lead to a wide variety of structural abnormalities in the 4 chambers, the 4 heart valves, the veins and great arteries. During fetal monitoring, a nurse will evaluate the strip for continuity and adequacy for interpretation, identify the baseline fetal heart rate and presence of variability, determine whether there are accelerations or decelerations from the baseline, identify patterns of uterine contraction, and correlate accelerations and decelerations with the uterine contractions. This will allow the nurse to determine whether the fetal heart rate recording is reassuring, non-reassuring, or ominous (Childrens Heart Federation, n.d).
Fetal Heart Rate and Defects
The normal fetal heart rate is between 110 to 180 beats per minutes (BPM), but can vary. Fluctuations of the fetal heart rate (usually associated with fetal movement) during different periods of the day are common and often rise above 160, going as high as 180 to 190 and are considered normal. Listening to a normally beating heart using a fetal ultrasound Doppler as early as 8 weeks can offer reassurance and cut down on a lot of stress and help assure that the developing fetus is healthy. While miscarriage occurs in only about 15 percent of apparently normal pregnancies, it only occurs in about 1 percent of pregnancies where a normal heartbeat has been seen or heard (Medscape, n.d). Recent studies conclude that changes in pregnant womens heart rate and blood pressure due to chronic stress and anxiety can have an effect on the fetal heart rate. The study did not report any negative effects on fetal health but confirmed that emotional based changes in a womans cardiovascular activity can have real-time effectsâ€ on a fetus.
A previous study has shown that stress during pregnancy can cause an increase in the risk of low-birth weight and premature birth. More importantly, increased evidence suggests that pregnancy stress can actually affect the babys behavior and functioning later in life (NT: Detection Rate CHD, n.d.). The ability for expectant mothers to listen to the fetal heart rate with a fetal Doppler offers a safe method of early fetal bonding which was previously only available at prenatal appointments with a medical professional. With its approval for in home by the FDA expecting parents have increasingly been opting to rent or purchase fetal Dopplers to help relieve some of the stress associated with the unknowns of early and late pregnancy. Fetal Doppler rentals are currently available through many online retailers at very affordable rates.
Fetal heart rate monitoring is the process of checking the condition of a baby during labor and delivery by monitoring his or her heart rate with special equipment. Electronic fetal heart rate monitoring (EFM) was first introduced at Yale University in 1958. Since then, continuous EFM has been widely used in the detection of fetal compromise and the assessment of the influence of the intrauterine environment on fetal welfare (Evans and Niswander, 2000).
There are two methods of fetal heart monitoring in labor. External fetal monitoring is done through the skin and is not meant to be invasive. Sensitive electrodes (connected to monitors) are placed on your abdomen over conducting jelly. The electrodes can sense the fetal heart rate (FHR) and the presence and duration of uterine contractions. Usually, the results of this test are continuous and are printed out, or they appear on a computer screen. Internal fetal monitoring involves placing a electrode directly on the fetal scalp through the cervix. The health care provider may use this method of monitoring your baby if external monitoring is not working well, or the information is inconclusive. Both types of tests are performed to evaluate fetal heart rate and variability between beats, especially in relation to uterine contractions. The tests also indicate the frequency and strength of uterine contractions (Belmont, 1998).
Fortunately, fetal heart monitoring tests can detect numerous abnormal situations or conditions during pregnancy, such as reduced blood flow to the developing baby (cord compression), block of electrical signals within the heart muscle, causing an altered heart beat (fetal heart block), incorrect positioning of the baby (fetal malposition), too little oxygen supply to the developing baby, suggest the presence of infection, too little oxygen exchange between the uterus and the placenta, fetal distress, placenta abruption, and severe anemia in the developing baby. Most common heart defects, such as holes between the chambers (atrial septal defect, ventricular septal defect) and even more complex conditions such as transposition of the great arteries and tetralogy of Fallot, can be successfully managed after birth (Belmont, 1998).
Many of the aforementioned situations detected during a fetal heart monitoring could mean that the baby has a congenital heart defect. There are many types of congenital heart defects which is why it is so important that the fetal heart monitoring be done before and during labor. A fetal heart defect means that the baby will be born with a problem in the hearts structure. Learning of the childs congenital heart defect can help to understand his or her condition and what you can expect in the coming months and years. Some congenital heart defects are simple and dont need treatment. Other congenital heart defects in children are more complex and may require several surgeries performed over a period of several years. Heart-related complications can be temporary or may affect the child long-term (Emitting Waves, R.C, n.d.).
One examples of a congenital heart defect is pulmonary atresia, which is when no pulmonary valve exists, so blood cant flow from the right ventricle into the pulmonary artery and on to the lungs. The right ventricle acts as a blind pouch that may stay small and not well developed. The tricuspid valve is often poorly developed, too. An opening in the atrial septum lets blood exit the right atrium, so venous (bluish) blood mixes with the oxygen-rich (red) blood in the left atrium. The left ventricle pumps this mixture of blood into the aorta and out to the body. Pulmonary atresia occurs in about one out of every 10,000 live births (Pulmonary Atresia, n.d.).
Another type of congenital heart defect is congenital heart block, when detected at or before birth in a structurally normal heart, is strongly associated with autoantibodies reactive with certain proteins. In this defect, the hearts electrical signal doesnt pass from the hearts own natural pacemaker in the atrium to the lower chambers. When this occurs, an independent pacemaker in the lower chambers takes over. The ventricles can contract and pump blood, but at a slower rate than the atrial pacemaker. Complete heart block is most often caused in adults by heart disease or as a side effect of drug toxicity. Heart blocks can be present at birth (Belmont, 1998).
Continuous lumbar epidural anesthesia is commonly used for analgesic treatment during labor and delivery; It is still a matter of controversy whether epidural anesthesia has direct or indirect side effects on the fetus. It has been reported that local anesthetics can cause changes in the fetal heart rate patterns in the sense of direct myocardial side effects (Evans and Niswander, 2000).
It is apparent that there are marked cardiovascular changes that occur in the fetus with a congenital heart defect compared with the normal healthy fetus. Without the use of fetal heart monitoring tests, we would be unable to determine if the fetus has a congenital heart defect which could drastically delay treatment of the condition. Treatment varies widely with the type of disease, the effect that pregnancy has on the disease, and the effect that the disease has on pregnancy. If it is the fetus that has a problem, serial ultrasounds may be performed. Fetal heart rate monitoring may be necessary, or amniocentesis may be required. In addition, it may be essential to give the mother medications to act on the baby (Belmont, 1998).
A fetal heart defect is an abnormality in any part of the heart that is present in an unborn child. Approximately 35,000 infants are born with heart defects each year in the United States. An echocardiography can be used before birth to accurately identify many heart defects. The mother can be treated with medications that may restore normal heart rhythm in the fetus if the test shows that a fetusâ€™s heart is beating too fast or too slow. In most cases, scientists do not know what makes a babyâ€™s heart develop abnormally, but genetic and environmental factors appear to play roles.