Approach to congenital heart diseases (cyanotic): Clinical sciences

Cyanotic congenital heart disease refers to structural heart lesions that cause significant blood oxygen desaturation and cyanosis. Cyanotic congenital heart lesions can be categorized according to their characteristic circulatory patterns, which include increased or decreased pulmonary blood flow, decreased systemic blood flow, or inadequate pulmonary-systemic mixing.

If a pediatric patient presents with a chief concern suggesting cyanotic congenital heart disease, perform an ABCDE assessment. Cyanosis indicates that your patient is unstable, so first stabilize the airway, breathing, and circulation. You may need to intubate and mechanically ventilate your patient. Next, obtain IV access, consider IV fluids, and begin continuous vital sign monitoring, including blood pressure, heart rate, and oxygen saturation. Finally, provide supplemental oxygen, if needed.

Next, obtain a focused history and physical exam, and measure pulse oximetry in the right hand, which measures pre-ductal saturation; and the feet, which measures post-ductal saturation. Pre- and postductal measurements allow you to compare oxygenation of the systemic circulation before and after the ductus arteriosus inserts into the aorta. If pre-ductal saturations are significantly higher than postductal saturations, it means that deoxygenated blood is being shunted from the pulmonary artery to the aorta, through an open ductus arteriosus. This is called differential cyanosis and suggests the presence of critical congenital heart disease.

Okay, you might find a family history of congenital heart disease, or there may have been a prenatal ultrasound demonstrating a heart defect. Exam findings include central cyanosis in areas like the lips and chest. Some patients may display signs of respiratory distress, like dyspnea or tachypnea, as well as a heart murmur or hepatomegaly.

Lastly, pulse oximetry measurements reveal an oxygen saturation below 90% in the right hand and feet, or a saturation below 95% in the right hand and feet on 3 separate occasions. You might also find a 3% difference in saturation between the right hand and foot on 3 separate occasions if the heart lesion is ductal-dependent.

With these findings, consider cyanotic congenital heart disease, so order a chest X-ray and an echocardiogram or echo, and assess the pulmonary and systemic blood flow.

Here’s a clinical pearl! When evaluating a newborn with cyanosis, consider primary lung disease. If echocardiography isn't available, you can use the hyperoxia test to distinguish congenital heart conditions from pulmonary conditions. To do this, obtain arterial blood gases before and after administering 100% oxygen. The PaO2 will rise by 150 mm mercury or more after hyperoxia if the newborn has pulmonary disease, but there will be little to no improvement in cyanotic heart lesions with a right-to-left intracardiac shunt.

Let’s move on to echocardiogram results, starting with patients with increased pulmonary blood flow. In this case, consider mixing lesions like total anomalous pulmonary venous drainage, or TAPVD, with obstruction, and truncus arteriosus.

Newborns with TAPVD with pulmonary venous obstruction develop profound respiratory distress with rapid deterioration. There is usually no murmur on exam but you may detect hepatomegaly. The chest X-ray typically demonstrates severe pulmonary vascular congestion, and the cardiac silhouette might have a "snowman" appearance. An echocardiogram confirms absent venous connections to the left atrium, with the pulmonary veins draining to the right atrium or to the superior or inferior vena cavae, along with obstruction of pulmonary venous drainage. Findings might also demonstrate an enlarged right atrium with a right-to-left shunt through an atrial septal defect, also called ASD, or through a patent foramen ovale, or PFO. These findings confirm TAPVD with obstruction.

Here’s a clinical pearl! Anomalous pulmonary venous return can be either partial, called PAPVD, where 1 or more pulmonary veins return to the left atrium; or total, called TAPVD, where no pulmonary veins return to the left atrium. While TAPVD with obstruction presents in the immediate newborn period with cyanosis and respiratory distress, TAPVD without obstruction may present later, during infancy or childhood, with gradual signs of heart failure and mild- to moderate oxygen desaturation. In contrast, PAPVD is an acyanotic defect that usually manifests in late childhood with signs suggestive of ASD.

Let’s move on to truncus arteriosus. Physical exam typically reveals a hyperdynamic precordium with a single loud S2, and bounding peripheral pulses. Some infants display distinctive facial and physical features suggesting DiGeorge syndrome, such as cleft lip and palate or hypertelorism. Occasionally, cyanosis and signs of heart failure like tachypnea and poor weight gain begin several months after birth. After the first week of life, chest X-ray typically reveals increased pulmonary vascularity, with a prominent ascending aorta, and sometimes, a right-sided aortic arch. Meanwhile, the echo will reveal a single arterial trunk supplying both the systemic and pulmonary circulations, with the truncal artery overlying a ventricular septal defect, or VSD; and a right-to-left shunt through the VSD. These findings confirm truncus arteriosus.

Let’s now discuss decreased pulmonary blood flow. Here, consider lesions like pulmonary atresia with intact ventricular septum, tetralogy of Fallot or TOF, tricuspid atresia, and Ebstein anomaly. Also, start an infusion of prostaglandin E1, or PGE1, to maintain a patent ductus arteriosus.

Here’s a high-yield fact! PGE1 provides a life-saving bridge to surgery in newborns with ductal-dependent lesions by promoting systemic-to-pulmonary mixing or by restoring systemic or pulmonary circulation. Avoid giving PGE1 to infants with increased pulmonary blood flow, since it can exacerbate pulmonary overcirculation.