What is Cyanotic Heart Disease?
Congenital heart disease (CHD) is a condition where the heart or the large blood vessels inside the chest become abnormal during fetal development. It is the most common kind of birth defect and the main reason for death in children with inborn deformities. CHD can be categorized into two types: non-cyanotic CHD and cyanotic CHD, which is also known as critical congenital heart disease (CCHD). CCHD can be further grouped into three types of problems: blockages in the right side of the heart, blockages in the left side of the heart, and mixing problems.
What Causes Cyanotic Heart Disease?
The cause of Congenital Heart Disease (CHD) is largely unexplained. Many instances of CHD are complex and result from a mix of genetic factors and environmental risks. Critical Congenital Heart Disease (CCHD) is typically an isolated condition and happens sporadically, but it can also be connected with genetic syndromes.
It’s estimated that around 15% to 20% of babies with CCHD have identifiable chromosomal abnormalities. The majority of these abnormalities are forms of aneuploidy, which includes conditions like trisomy 21, 13, and 18, as well as Turner syndrome.
Environmental risks that might contribute to CHD include maternal conditions such as diabetes and phenylketonuria. Exposure to toxins or drugs, and getting a viral infection during pregnancy are also potential risk factors.
Risk Factors and Frequency for Cyanotic Heart Disease
Congenital heart disease (CHD) is a heart condition present at birth, affecting around 8 to 9 out of every 1000 live births. Around a quarter of these cases are considered critical CHD (CCHD). If a first child or a parent has CHD, the likelihood increases to 2% to 6% for the second pregnancy. Two common types of CCHD are Tetralogy of Fallot (TOF), which makes up 5% of all CCHD cases, and Transposition of the great arteries (TGA), which makes up about 2% of all CCHD. TGA is particularly noteworthy because it’s the most common type of CCHD found in the first week after birth. Unfortunately, they also contribute significantly to infant deaths due to congenital malformations, with 35% of these deaths linked to cardiovascular anomalies.
- Congenital heart disease affects 8 to 9 per 1000 live births.
- About 25% of these cases are seen as critical.
- The chances increase to 2% to 6% for a second pregnancy if a child or parent has this disease.
- Tetralogy of Fallot is the most common critical congenital heart disease, making up 5% of all cases.
- Transposition of the great arteries is the second most common and makes up approximately 2% of all cases.
- Transposition of the great arteries is the most common type observed in the first week after birth.
- Cardiovascular anomalies like these are linked to 35% of infant deaths from birth defects.
Signs and Symptoms of Cyanotic Heart Disease
Congenital Critical Heart Disease (CCHD) can be overlooked before and during childbirth. Hence, medical professionals should look for early symptoms during an infant’s first weeks. A disease history may not be enough on its own to distinguish CCHD from other issues like lung disease, metabolic defects, or sepsis. In-depth family history should also be gathered because of CCHD’s genetic elements. To confirm CCHD, further physical examinations and diagnostic tests are needed.
Here are signs related to CCHD:
- Fussiness or lack of activity
- Sweating and crying during feedings
- Reduced formula intake per meal
- Taking longer to breastfeed
- Poor weight gain
- Rapid and/or uneven breathing
- Blue or purple tint to the skin or mucous membranes
- In older children, difficulties during exercise, which may show up as breathlessness, sweating, bluish skin or an irregular heartbeat
Physical symptoms related to CCHD include:
- Bluish skin
- Fast breathing
- Extra effort when breathing
- Lung congestion
- Rapid heartbeat
- Abnormal heart noises
- Liver enlargement (liver edge extended more than 2.5 cm past the right rib cage)
- Weak pulses in the thighs
- Signs of low blood flow or shock
- Drowsiness
Testing for Cyanotic Heart Disease
A fetal echocardiogram is recommended to be performed in all unborn babies with a suspected heart abnormality seen in obstetric ultrasound. These ultrasounds can spot heart defects, but their ability to do so varies depending on skills of the operator, the baby’s stage in pregnancy, position, and the type of cardiac defect.
In the US, the pulse oximetry screening for critical congenital heart disease (CCHD) in newborns became a part of the recommended uniform screening panel in 2011. Endorsed by the American Academy of Pediatrics in 2012, this screening is performed in the nursery when the baby is at least 24 hours old, or as late as possible if the baby will be discharged from the hospital before 24 hours. Screening too early may cause false-positive results.
The pulse oximetry test measures oxygen levels in the newborn’s body and is designed to identify cardiac lesions that cause a deviation in the normal flow of blood and result in low oxygen levels (cyanosis). The screening will show positive results if the oxygen level is less than 90%, if the oxygen level is less than 95% in both extremities on 3 measures each separated by 1 hour, or if there is more than a 3% absolute difference in oxygen saturation between the right hand and foot over the same period.
If screening results are positive, quick evaluation is needed, which may include measurements of blood pressure, chest radiography, ECG, and echocardiogram. However, bear in mind that CCHD screening can still miss about 15% of all CCHD cases.
Other diagnostic tests include the Hyperoxia Test, which is the initial method used to tell the difference between CCHD and lung disease, an Electrocardiogram (ECG) to discover any rhythm abnormalities, and a Chest X-Ray to check how much blood is flowing into the lungs.
A Two-Dimensional Echocardiography is the definitive noninvasive test to determine the presence of congenital heart disease. In preparation for heart surgery, other imaging techniques such as cardiac catheterization and angiography, magnetic resonance imaging (MRI), and CT scanning may also be used to further understand the structure of the heart.
The final levels of oxygen in a baby’s body can indicate specific diseases. For example, oxygen saturation less than 90% may indicate Right Heart Obstructive Lesions, whereas oxygen saturation less than 95% with a greater than 3% difference between upper and lower extremities may indicate Left Heart Obstructive Lesions. Lastly, a positive CCHD screening with oxygen saturation less than 95% can indicate Mixing Lesions, conditions in which oxygenated and non-oxygenated blood flows mixed together may occur.
Treatment Options for Cyanotic Heart Disease
If a baby is diagnosed with Critical Congenital Heart Disease (CCHD) during a fetal echocardiogram, special planning will be needed for its birth at a specialized medical center. This ensures the baby can be assessed and cared for immediately after birth.
If suspicions of CCHD arise after the baby is born, and a heart specialist is not readily available, urgent care is needed. This includes stabilizing the baby, giving oxygen therapy, administering an infusion of a medication called prostaglandin E1, and quickly transporting the baby to a specialized center. Prostaglandin E1 is useful for specific types of heart defects and can act as a temporary treatment until further interventions or heart surgery can take place. Around 25% of children born with congenital heart disease will need heart surgery or other procedures to survive.
Certain treatments are used to support the baby until surgery can happen. For example, temporarily increasing the size of a natural hole in the heart (balloon atrial septostomy) in some instances, or using a device to improve blood flow (shunt) before surgery. After heart surgery, it’s crucial to identify and treat any issues that may arise, such as breathing difficulties, heart rhythm issues, heart failure or kidney failure, among others.
Regular vaccinations should be given, but the timing of live-virus vaccines should be carefully considered in patients who may need a heart or heart-lung transplant. Preventative treatment against a common respiratory virus is recommended during the virus season in babies with unrepaired congenital heart disease. Also, preventative antibiotics are advised for dental procedures for patients with a high risk of heart infection. Other aspects of care include treatment for low iron levels, close monitoring for abnormal red blood cell levels, and ensuring the baby does not become dehydrated. Parents who have a child with congenital heart disease may benefit from counseling to understand the likelihood of future children also having a heart defect.
What else can Cyanotic Heart Disease be?
When doctors are diagnosing specific health conditions, they may need to contemplate and rule out other potential causes of symptoms. Here are some possible conditions they might consider:
- Diseases affecting the lungs’ tissue
- High blood pressure within the lungs
- A severe illness caused by a body-wide infection known as sepsis
- Inherited metabolic disorders which affect the body’s metabolism
- Conditions related to an abnormal structure or production of the hemoglobin protein, such as methemoglobinemia
By considering these potential conditions, doctors can conduct the necessary tests and provide the most accurate diagnosis.
What to expect with Cyanotic Heart Disease
While the one-year survival rate for infants diagnosed with critical congenital heart defects (CCHDs) has been improving, the mortality rate is still notably high. An estimated 75% of babies with CCHD survive their first year, and around 69% are expected to live up to at least 18 years old.
However, it’s crucial to note that children with CCHD have an increased chance of experiencing developmental delays and disabilities. They are also more likely to encounter heart-related disorders such as heart rhythm problems, heart failure, sudden cardiac arrest, or even stroke.