Approach to congenital heart diseases (cyanotic): Clinical sciences

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Introduction0:00–0:30

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.

Unstable Patient0:30–1:07

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.

H&P1:07–3:29

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.

Increased pulmonary blood flow3:29–3:47

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.

TAPVD3:47–5:31

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.

Truncus arteriosus5:31–6:32

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.

Decreased pulmonary blood flow6:32–7:26

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. First up, it’s pulmonary atresia with intact ventricular septum.

Pulmonary atresia with intact ventricular septum7:26–8:26

On exam, you might find profound cyanosis and respiratory distress in the first days of life, as well as a single loud S2, representing aortic valve closure.
Chest X-ray usually shows decreased pulmonary vascularity and can show severe cardiomegaly which can look like a boot-shaped heart.
The echocardiogram demonstrates right ventricular outflow tract atresia without a VSD, and a hypoplastic right ventricle, which confirms the diagnosis.
Here’s a clinical pearl! Critical pulmonary stenosis also manifests with profound cyanosis and requires PGE1 to promote pulmonary blood flow.
However, affected infants have an enlarged right ventricle and a stenotic pulmonary valve. Next, let’s discuss tetralogy of Fallot, or TOF.

TOF8:26–10:24

These infants might have characteristic features suggesting DiGeorge syndrome. Other findings include a harsh systolic hejection murmur at the left sternal border, indicating pulmonary stenosis; a prominent right ventricular impulse; and a single S2.
Chest X-ray reveals a "boot-shaped" heart, with clear lung fields indicating diminished pulmonary blood flow. Occasionally you may detect a right-sided aortic arch.
Echo findings of an overriding aorta with VSD, pulmonary stenosis, and RVH, confirm the diagnosis of TOF. The degree of pulmonary outflow obstruction in tetralogy determines symptom severity.
While mild-to-moderate obstruction causes minimal cyanosis, which might not be noticeable on the exam; severe obstruction is characterized by significant cyanosis in newborns.
Here’s a high-yield fact! Infants with unrepaired TOF can develop paroxysmal hypercyanotic attacks, also called tet spells.
These spells are often triggered by agitation or illness, which increases pulmonary vascular resistance and right-to-left shunting across the VSD.
Patients with tet spells develop tachypnea, tachycardia, profound cyanosis, and occasionally, syncope. Decreased pulmonary blood flow can cause your patient’s murmur to temporarily diminish or vanish.
You can often resolve a tet spell by calming the infant, administering oxygen, and placing them in the knee-to-chest position, but some may require morphine or medications to control heart rate and increase systemic vascular resistance.

Tricuspid atresia10:24–11:11

Let’s move on to tricuspid atresia. These infants present shortly after birth with severe cyanosis, a single S2, and occasionally, a systolic murmur if there's a coexisting VSD.
Chest X-ray demonstrates decreased pulmonary blood flow and can also show severe cardiomegaly, while the echo reveals an absent tricuspid valve, a hypoplastic right ventricle, and a PFO or VSD, confirming the diagnosis of tricuspid atresia.
In this “single-ventricle” condition, all of the systemic venous return passes to the left atrium through a PFO; or less commonly, a VSD.
Let’s finish with Ebstein anomaly. Affected newborns typically develop significant respiratory distress, as well as hepatomegaly and edema.

Ebstein anomaly11:11–11:51

Chest X-ray reveals massive cardiomegaly which can show a classic ‘box shape’ appearance, while echo demonstrates downward displacement of the tricuspid valve into the right ventricle, right atrial enlargement, and occasionally, right ventricular outflow tract obstruction.
Most infants have a right-to-left shunt through a PFO. With these findings, diagnose Ebstein anomaly.

Decreased systemic blood flow11:51–12:08

Now let’s switch gears to patients with decreased systemic blood flow. In this case, consider hypoplastic left heart syndrome, or HLHS, and start a PGE1 infusion to maintain systemic circulation.
Newborns with HLHS present on the first day of life with cyanosis; and signs of poor perfusion and shock, such as gray, cool, and mottled skin.

HLHS12:08–13:34

Peripheral pulses are typically weak or absent, and there is a right ventricular lift and a single loud S2. Eventually, these infants develop signs of pulmonary overcirculation, such as tachypnea.
You might also notice features suggesting Turner syndrome, including a wide, webbed neck and a shield chest. Chest X-ray typically shows cardiomegaly due to right ventricular hypertrophy, or RVH, as well as pulmonary venous congestion.
Lastly, the echo reveals a hypoplastic left atrium and ventricle; mitral valve or aortic root atresia or hypoplasia; RVH; and an ASD or PFO.
These findings are diagnostic of HLHS. Time for a clinical pearl!
In addition to HLHS, various congenital heart lesions are associated with the absence of 2 normally-sized ventricles. These “single-ventricle” lesions also depend on PGE1 to maintain adequate blood flow to both the systemic and pulmonary circulations.

Inadequate mixing13:34–14:53

Finally, let’s discuss patients with inadequate pulmonary-systemic mixing, which should make you consider transposition of the great vessels, or TGV.
In this condition, the aorta arises from the right ventricle while the pulmonary artery arises from the left ventricle, so the systemic and pulmonary circulations flow in parallel.
As before, start with PGE1 infusion to promote the mixing of oxygenated and deoxygenated blood. History might reveal quiet tachypnea in the first 12 hours of life.
Cardiac exam reveals a loud single S2, but you’ll rarely detect a murmur unless there’s a coexisting VSD. The chest X-ray commonly reveals increased pulmonary vascularity and a narrow mediastinum, giving the cardiac silhouette an "egg on a string" appearance.
On echo, the aorta arises from the right ventricle, and the pulmonary artery arises from the left ventricle. Additionally, you’ll typically see an ASD, a PFO, or less commonly, a VSD.
These findings confirm the diagnosis of TGV. Alright, as a quick recap… Increased pulmonary blood flow suggests mixing lesions like TAPVD with obstruction and truncus arteriosus.

Review14:53–15:26

However, if the pulmonary blood flow is decreased, consider pulmonary atresia with intact ventricular septum, tetralogy of Fallot, tricuspid atresia, or Ebstein anomaly.
With decreased systemic blood flow, think of hypoplastic left heart syndrome, while inadequate pulmonary-systemic mixing should point you to the