In a follow up to PCHA’s series on complications resulting from CHD, Dr. Nidhy Varghese, of Texas Children’s, adds insight to the pulmonary implications in patients affected by Congenital Heart Disease.
Pediatric Pulmonary Complications of Congenital Heart Disease
Dr. Nidhy Varghese, pediatric pulmonologist at Texas Children’s
Congenital heart disease is the most common birth defect in the world, affecting the hearts of thousands of children each year. However, congenital heart disease (CHD) affects more than just the heart. Abnormal cardiac development can have significant effects on other organ systems such as the lungs. The lungs are directly connected to the heart and they share a unique relationship of development and physiology. Effects of CHD can be seen in lung growth, in anatomy and in lung function. Although these can be considered as prenatal and postnatal consequences, the pulmonary complications of congenital heart disease represent a spectrum of consequences.
What is the function of the lungs?
The lungs are the gas exchanger for the body. A multilevel organization of airways present oxygen and remove carbon dioxide through contact with a rich network of blood vessels in the lungs. The lungs are connected to the heart through the pulmonary artery and the pulmonary veins. They’re located in the chest, on the sides of heart.
The lungs are made up of conducting airways, air sacs (known as alveoli) and blood vessels. These structures begin to form by the end of the first month of embryonic development. The development of the vascular system within the lungs and the branching of alveoli are directly related to circulation. Abnormalities in blood flow due to CHD can cause alterations in development of the lungs’ vascular system (arteries, capillaries and veins) and the division of the airspaces into the millions of alveoli needed for adequate gas exchange. This results in simplification of the alveolar and vascular networks, which can produce symptoms of chronic lung disease and pulmonary hypertension.
In the setting of CHD, the flow of blood within the heart and through the blood vessels is abnormal. Different parts of the heart or the blood vessels themselves may become enlarged or may be atypically located within the chest, causing compression on the nearby lungs and airways. CHD examples in which this can be seen are anomalous innominate artery and conditions causing cardiomegaly (an enlarged heart). Compression can cause respiratory distress, stridor, wheezing and recurrent areas of lung collapse.
In certain types of CHD, there may be increased blood flow to/through the lungs (for example, patent ductus arteriosus, ventricular septal defect). The arterial system in the lungs is not used to receiving such large amounts of blood flow. Subsequently, the pulmonary blood vessels can become scarred and narrowed. While this effectively reduces the flow through the lungs, the pressure in the lungs can increase: a condition known as pulmonary hypertension.
Pulmonary edema is another complication of CHD. This is a condition in which high blood pressure occurs in the vessels close to the alveoli. As the pressure rises, water diffuses from the blood into the airspaces. The effect on gas exchange can be variable. Pulmonary edema is more likely in conditions such as pulmonary vein stenosis and mitral valve abnormalities.
In summary, CHD can cause many abnormalities in the lungs. The respiratory system in children with CHD is more likely to be simplified which may affect gas exchange. Certain types of CHD can cause further symptoms such as airway compression, pulmonary hypertension and pulmonary edema. Pulmonary complications in children with CHD are part of a spectrum and can vary significantly in each child. It is therefore important that children with CHD undergo respiratory assessment for early detection of these consequences.
As a pediatric pulmonologist, Dr. Nidhy P. Varghese’s specific area of interest is pulmonary hypertension and pulmonary complications of sickle cell disease. She enjoys working closely with families and colleagues to deliver the best care possible to care for children, so that they may thrive. She earned her medical degree from Albany Medical College, completed her pediatrics residency at New York University School of Medicine and her pediatric pulmonary fellowship at Baylor College of Medicine.