Congenital Heart Disease

According to the American Heart Association, it is one of the most common birth defects affecting around 9 out of every 1,000 infants born in the United States. The congenital heart defects and disease are often used to describe the same thing and is considered an abnormality when the heart or the blood vessels have not developed normally before the birth of the infant. Congenital heart defects usually occur in the initial eight weeks of the child’s development. In most of the cases, the exact cause is not known but in some cases, genetic link could be associated with it or could occur as the result of infection or the use of certain medications during pregnancy.

There are several types of congenital heart disease which range from simple to complex and some could be managed just with medications while others may require surgery soon after the birth of the child. Congenital heart disease can present a range of symptoms as there are different types of heart defect. Some of the common signs of congenital heart disease can include rapid breathing, rapid heartbeat, blue tinge to the skin, fatigue, shortness of breath and swelling of the hands, ankles or feet. The symptoms may in some cases be evident just shortly after the birth of the infant while in other cases, the symptoms may not develop until teenage years or even early adulthood. However, advances in the diagnostic methods and therefore the surgical treatments during the past several decades has transformed it from a hopeless condition among infants and children to a treatable condition with patients living well into their adult years. But, despite the remarkable progress made, the threat posed by the underlying genetic mutation has remained unabated. Also, heart failure has remained one of the leading causes of death among adults with congenital heart disease followed by sudden cardiac death. The genetic mutation involved in the CHD not only impacts the development of the heart but also involves other organs including neurodevelopment abnormalities. However, in the future, it is hoped that the medical research progress will usher in new diagnostic and therapeutic approaches based on the molecular genetics and biology to better care for individuals living with congenital heart disease.

What are the different types of congenital heart defects?

  • Aortic valve stenosis is a serious condition when the aortic value is unable to open completely. It functions as a one-way door that allows the blood to flow forward into the aorta. The severity of the condition is based on how much obstruction to blood flow is present.
  • Coarctation of the aorta is the narrowing of the aorta which requires the heart to pump harder so it can force the blood through it. Although the condition is present at the time of birth, in some cases it might not become evident until adulthood. The treatment for coarctation is usually successful, but it still requires lifelong monitoring.
  • Patent ductus arteriosus is characterized by the unclosed hole in the aorta. As a fetus, the blood skips travelling to the lungs to get oxygenated. Ductus arteriosus is the hole that enables this skipping process but after the birth of the infant, the hole is supposed to close in order to receive oxygenated blood. However, if the hole continues to remain open (patent), it is known as patent ductus arteriosus. When the PDA is small, it will not cause any symptoms and will often close on its own usually within the initial few months. In case the PDA is large, the symptoms could include rapid breathing, trouble feeding and growing at a normal pace or surgery may be required if medications in the first few weeks do not prove to be effective.
  • Pulmonary valve stenosis is the thickening or fusing of the heart valve which does not completely open therefore the pressure is much higher in the right ventricle and the heart must pump harder to enable the flow of blood out into the lung arteries. Therefore, with time this can cause damage to the heart muscle. Pulmonary valve stenosis is one of the common forms of heart defect. The treatment is focused on relieving the obstruction by balloon valvuloplasty to stretch open the valve, however, in some cases, surgery may be required.
  • Total anomalous pulmonary venous connection is the abnormality of the veins from the lungs to the heart meaning the oxygenated blood enters the wrong chamber of the heart. The symptoms could develop soon after the birth of the infant and the severe obstruction could result in the child breathing harder and looking bluer as the result of low levels of oxygen. The treatment is based on surgical intervention in rectifying the abnormality.

Genetic Factors Contributing to Congenital Heart Disease

Certain types of congenital heart defects could be associated with the abnormality in the number of chromosomes, genetic mutation or environmental factors. For instance, in around 30% of the cases, infants with chromosome abnormalities will continue to develop a heart defect. Some of the chromosome abnormalities associated with congenital heart defects includes Down syndrome, Turner’s syndrome, Wolf-Hirschhorn syndrome and DiGeorge syndrome. Also, a single genetic mutation can result in the development of various syndromes which are also a group of health problems. For example, Marfan syndrome, Noonan syndrome and Smith-Lemli-Opitz syndrome are all associated with a higher incidence of heart defects. The inheritance pattern for congenital heart disease appears to have autosomal-dominant inheritance meaning the parent with the genetic mutation has a 50% chance of passing the condition to their child. However, the congenital heart problems can, in most of the cases, develop because of multifactorial inheritance meaning several factors are involved in the development of heart defect. Also, the risk increases when either one of the parents or another sibling also has congenital heart disease. Therefore, fetal echocardiography must be done in the second trimester at around 18 to 22 weeks of pregnancy to detect major heart defects of the fetus. So women with the congenital heart condition are encouraged to consult with a genetic counselor before planning the pregnancy.

References

https://www.ahajournals.org/doi/full/10.1161/CIRCRESAHA.117.310830

https://www.nhs.uk/conditions/congenital-heart-disease/symptoms/

https://www.stanfordchildrens.org/en/topic/default?id=factors-contributing-to-congenital-heart-disease-90-P01788

https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/patent-ductus-arteriosus-pda

https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/patent-ductus-arteriosus-pda

http://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/pulmonary-valve-stenosis