Heart Defects In Newborns

Heart defects in newborns affect approximately 8 out of every 1000 births.  Causes can include genetic factors, such as those found in Down’s syndrome, or factors due to the developing baby’s environment. Certain medications, such as Paxil (Paroxetine), Zoloft (Sertraline), Wellbutrin (Bupropion), or Prozac (Fluoxetine) may be associated with cardiac birth defects in the babies of mothers who took these medications when pregnant. While some heart defects may only slightly affect a child’s quality of life, others can be very serious and may require surgical correction. Although causes of many heart defects are not known, improvements in prenatal diagnosis has led to better management and outcomes for those babies affected by these conditions.

The most common way to diagnose a cardiac defect prenatally is by sonogram. Many obstetricians order a screening sonogram for their patients during the 16th to 20th week of pregnancy. Part of the standard practice for the sonographer is to identify the four chambers of the baby’s developing heart.

If the four chambers are not seen, or appear abnormal, a more specialized test, called a fetal echocardiogram may be ordered. This test involves a more detailed sonogram examination of the developing baby’s heart. Abnormalities can be further evaluated by this test method.

There are many different cardiac anomalies that affect newborns. Only three (3) will be discussed here:

Ventricular Septal Defect (VSD)- refers to a hole between the ventricles, the two lower chambersof the heart. The mixing of the oxygenated and deoxygenated blood through the defect can cause symptoms. Sometimes, a small VSD may close up on its own; sometimes surgery is required.

Atrial Septal Defect (ASD)- involves a hole in the wall separating the atria, the upper chambers of the heart.

Pulmonary Stenosis- occurs when the pulmonary artery that leads from the right ventricle to the lungs is narrowed. This can obstruct this crucial bloodflow out of the heart and can cause the right ventricle to become over developed and enlarged in trying to overcome the obstructive narrowing.

If proper prenatal testing was not done, or if testing was not read or interpreted properly, medical malpractice may have occurred.  Allegations of medical malpractice may include a negligent delay in diagnosis and/or inadequate surgical treatment and care of the newborn's heart defect.   Lawsuits may also result if a baby was injured by medications used by the mother. Cardiac defects can cause serious health problems in the child and may also involve major surgery for correction. In addition, complications can occur due to the defect, especially if undiagnosed. It is very important that women at risk for having a baby with a heart defect have appropriate screening tests done. Risk factors for congenital heart defects may include prenatal exposure to the medications listed above. Also, factors such as a sibling or family history of congenital heart defects may warrant increased surveillance and testing during the pregnancy.

Increased Fluid Around the Heart May Cause Cardiac Tamponade

Pericardial effusion occurs when there is an abnormal amount of fluid around the heart.  The heart is normally surrounded by a thin membranous sac called the pericardium.  The space between the pericardium and the muscle that is the heart is referred to as the perciardial space.  Normal levels of pericardial fluid within the pericardial space are from 15 to 50 mL, or about 1-3 tablespoons.

iStock_000003834803XSmall.jpgAn effusion, therefore, represents  an abnormal accumulation of fluid in the pericardial space.   Because of the limited amount of space in the pericardial cavity, fluid accumulation will lead to increased intrapericardial pressure and this can negatively affect heart function.  Cardiac tamponade occurrs when there is a  large enough pericardial effusion causing enough pressure to adversely affect heart function.  This is an emergent life threatening condition.

Pericardial effusion symptoms may include difficulty breathing (dyspnea), shortness of breath when lying down (orthopnea), chest pain, cough, dizziness, low grade fever, rapid heart rate (tachycardia), and a feeling of anxiety  

Pericardial effusion may be caused by:

-a disturbed equilibrium between the production and re-absorption of pericardial fluid,

-a structural abnormality that allows fluid to enter the pericardial cavity

-inflammation of the pericardium (pericarditis)

-bacterial or viral infections

-injury to the heart from a medical procedure

-cancer

-heart attack

-autoimmune disorders

Unfortunately, pericardial effusion and cardiac tamponade may result from improper placement of a central venous catheter during a medical procedure involving an infant.  This may arise when there is an inadvertent perforation into the pericardial space by the CVC and fluids are artificially infused into the space thereby causing the tamponade. Upon recognition of this situation, emergent removal of this fluid via a needle inserted through the chest wall and into the pericardial space (pericardiocentesis) can improve the infant's chance of survival. It is suggested that routine radiography be performed to readily identify the CVC tip in all cases when these lines are placed into babies.    Increased awareness of this complication may decrease the mortality associated with CVC related pericardial effusions.   

Treatment depends on the underlying cause and the severity of the heart impairment. Pericardial effusion due to a viral infection sometimes goes away within a few weeks without treatment.  Some pericardial effusions remain small and never need treatment.  If the pericardial effusion is due to an autoimmune condition treatment with anti-inflammatory medications may help. If the effusion is compromising heart function and causing cardiac tamponade, it will need to be drained, most commonlyby a pericardiocentesis.  In some cases, surgical drainage may be required by cutting through the pericardium creating what is referred to as a pericardial window

Ventricular Septal Defect in the Newborn

A ventricular septal defect (VSD) refers to a hole in the ventricular septum, the wall dividing the left and right ventricles of the heart. VSDs are the most common congenital cardiac anomalies. They are found in30-60% of all newborns with a congenital heart defect, or about 2-6 per 1000 births. During heart formation, when the heart begins life as a hollow tube, it begins to partition, forming a septa. If this does not occur properly it can lead to an opening being left within the ventricular septum.

As noted above, during ventricular contraction some of the blood from the left ventricle is forced into the right ventricle from where it enters the lungs through the pulmonary arteries and then reenters the left ventricle via the pulmonary veins and left atrium.  This refluxing of blood causes volume overload on the left ventricle.  This increased blood volume also increases pressure in the right venticle eventually causing pulmonary hypertension with its associated symptoms. This effect is more noticeable in those with larger defects, who may present with shortness of breath, poor feeding and failure to thrive in infancy.   

Because structural cardiac anomalies are estimated to occur in 8 of every 1,000 live births, it is imperative they be discovered before birth. Cardiovascular anomalies, such as VSD, are frequently associated with other congenital anomalies because the heart is among the last organs to develop completely in the embryo. The guidelines for routine prenatal evaluation of both the American College of Radiology and the American Institute of Ultrasound in Medicine require evaluation of the fetal heart.  To not do so, may be consistent with medical negligence or medical malpractice.

The ultrasound view that is most commonly used is the four-chamber view of the heart.  This allows for the assessment of abnormalities involving both right and left ventricles.  Normally, both ventricles are approximately the same size. The left ventricle is posterior and to the left of the right ventricle.  The wall between them, known as the interventricular septum separates the right ventricle from the left ventricle.  A normal septum goes from the cardiac apex to the atrial septum. Formation of the interventricular septum begins at approximately 28 days gestation.  A VSD results from maldevelopment of the embryonic  septum.

A large VSD is easily diagnosed on the four-chamber view alone. However, color Doppler ultrasonography may be needed to demonstrate smaller defects, and some really small defects may not be detected until after birth.  However, most of these close spontaneously.  Fetal position is a major factor in the detection of VSD.  For accurate diagnosis, it is critical that the ultrasound technician positions the transducer so the ultrasound beam is correctly directed relative to the septum.  Not only can a VSD be missed, but a pseudo-VSD may result if performed incorrectly.  

A small ventricular septal defect may never cause any problems. Larger defects can cause a wide range of disabilities, from mild to life-threatening.  If pulmonary hypertension develops due to a large ventricular septal defect that goes untreated, over time, permanent damage to the lung arteries develops and the pulmonary hypertension becomes irreversible.  This complication is known as Eisenmenger's syndrome, and may occur in early childhood, or it can develop slowly over many years.  Other complications that occur are heart failure, endocarditis, stroke, and heart arrhythmias which can lead to fatal complications. Becoming pregnant is also of concern due to the additional risks of pregnancy to women with VSDs undetected before birth and throughout childhood.   

Though no treatment is necessary for small VSDs, larger VSDs demand certain precautions be taken, often with the baby being born in a tertiary care center and directly placed into the care of a pediatric cardiologist to determine if medical or surgical therapy is necessary to prevent the complications that will occur.  That is why it is imperative that the diagnosis of VSD be made prior to birth.