A 20-day-old baby boy is brought into the emergency department by his parents who noticed that he was “blue.” On examination, he is alert and is cyanotic with an oxygen saturation of 83 percent. His cardiac exam reveals a mild right precordial heave with a harsh, long-grade 3/6 systolic ejection murmur at left upper sternal border. In the ED, he becomes more cyanotic (oxygen saturation of 60%), irritable and his murmur becomes softer. An echocardiogram was performed which identified cyanotic congenital heart disease (Tetralogy of Fallot) (Figure 43-1). He was treated medically and then underwent palliative surgery with a Blalock Taussig shunt. He was discharged in stable condition to be followed up on an outpatient basis until he could have further corrective surgery at a later date.
Tetralogy of Fallot. Note the four components, “anterior-malaligned” VSD, pulmonary stenosis, over-riding aorta and right ventricular hypertrophy. (Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2012. All Rights Reserved.)
Cyanotic congenital heart disease is an anatomic malformation of the heart or great vessels which occurs during intrauterine development (resulting in a right to left shunt) and manifests as cyanosis in the neonatal period.
Congenital heart defects are the most common type of birth defect in the US, affecting nearly 1 percent of newborns, although this number is variable depending on methodology.1
A significant portion of patients with potentially fatal forms of congenital heart disease have cyanotic defects.
The most common forms of cyanotic congenital heart disease are:2
Tetralogy of Fallot (Figure 43-1), transposition of the great arteries (Figure 43-2), truncus arteriosus, tricuspid atresia, total anomalous pulmonary venous return, or pulmonary valve stenosis (severe or critical pulmonary valve stenosis).
Other examples: Ebstein’s anomaly, double outlet right ventricle, pulmonary atresia, or multiple single ventricle variants.
Transposition of the great arteries with the aorta arising from the right ventricle and the pulmonary artery arising from the left ventricle. Mixing (via an atrial septal defect, ventricular septal defect or patent ductus arteriosus) is essential for survival before corrective surgery. (Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2012. All Rights Reserved.)
Etiology and Pathophysiology
Most cases are due to an unknown etiology and are multifactorial.
Systemic venous blood bypasses the pulmonary circulation, resulting in a right to left shunt, systemic arterial desaturation and clinical cyanosis.
Depending on the predominant physiology, cyanosis may be variable and not the primary underlying problem.
Hereditary or genetic risk factors