Approach to congenital heart diseases (acyanotic): Clinical sciences

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Introduction0:00–0:21

Acyanotic congenital heart disease refers to structural heart lesions that do not cause significant blood oxygen desaturation or cyanosis.
It's crucial to identify acyanotic congenital heart lesions promptly in order to treat any complications, like shock or heart failure.

Unstable Patient0:21–4:27

If a pediatric patient presents with chief concern suggesting acyanotic congenital heart disease, first perform an ABCDE assessment.
If the patient is unstable, stabilize the airway, breathing, and circulation. You may even need to intubate and mechanically ventilate your patient.
Next, obtain IV access, and consider starting IV fluids. Begin continuous vital sign monitoring, including blood pressure, heart rate, and oxygen saturation.
Finally, if needed, provide supplemental oxygen. Once you’ve initiated acute management, perform a focused history and physical examination.
Then obtain pulse oximetry measurements in the right hand, which measures preductal saturation; and the feet, which measures post-ductal saturations.
These measurements allow you to compare oxygenation of the systemic circulation before and after the ductus arteriosus inserts into the aorta.
Unstable infants often present around 2 weeks of age, as the ductus arteriosus begins to close, with symptoms like poor feeding, lethargy, and respiratory distress.
Additionally, there may have been a prenatal ultrasound showing a heart defect. Exam findings include signs of shock, like gray, cool, mottled skin.
You might also find weak pulses in all 4 extremities, or the femoral pulses might be absent. On auscultation, many patients will have an audible S3, and some will have a murmur.
On pulse oximetry, preductal saturations may be higher than postductal saturations. This suggests that deoxygenated blood is being shunted from the pulmonary artery to the aorta, through an open ductus arteriosus, and the lower extremities might appear cyanotic.
This is called differential cyanosis and suggests the presence of critical congenital heart disease. These findings should immediately make you consider lesions associated with critical left ventricular outflow tract obstruction, such as critical aortic stenosis or critical coarctation of the aorta.
Start an infusion of prostaglandin E1, or PGE1, to keep the ductus arteriosus open and restore systemic circulation. Here’s a high-yield fact!
PGE1 provides a life-saving bridge to surgery in newborns with ductal-dependent lesions by promoting systemic and pulmonary mixing or by improving systemic or pulmonary circulation.
Avoid giving PGE1 to infants with increased pulmonary blood flow, since it can exacerbate pulmonary overcirculation. Now that you’ve started PGE1, order an echocardiogram or echo to evaluate the heart and great vessels.
If echo reveals severe aortic valve stenosis, with or without left ventricular hypertrophy, diagnose critical aortic stenosis.
On the other hand, echo may show a hypoplastic aortic arch, possibly with abnormal aortic valve morphology and post-stenotic dilatation.
In some cases, it may demonstrate complete discontinuity of the arch between the ascending and descending aorta, indicating an interrupted aortic arch, which is the most severe form of coarctation.
In either case, diagnose critical coarctation of the aorta. Here’s a clinical pearl!
Critical left ventricular outflow obstruction is commonly mistaken for sepsis, since both conditions can present with shock and similar clinical manifestations.
Remember to check femoral pulses, and consider left ventricular outflow obstruction whenever a newborn presents with shock.
Now that we’ve discussed unstable patients, let’s go back and discuss stable ones. Start by obtaining a focused history and physical exam, and pulse oximetry measurements in the right hand and feet.

Stable Patients4:27–5:29

History usually reveals abnormal prenatal ultrasound findings suggesting a congenital heart lesion. Depending on the lesion, many patients are asymptomatic, but others may experience poor weight gain, difficulty feeding, or fatigue.
As for the physical exam, your patient will not appear cyanotic, but you may detect a heart murmur and notice signs of heart failure, like tachypnea and hepatomegaly.
Finally, pulse oximetry will reveal oxygen saturations above 90% in the right hand and the feet. With these findings, consider acyanotic congenital heart disease.
Next order an echo, and assess the pulmonary blood flow. First let's discuss patients with normal or decreased pulmonary blood flow.

Normal pulmonary blood flow5:29–5:44

If it’s normal or decreased, consider obstructive lesions like non-critical coarctation of the aorta, aortic stenosis, and pulmonary stenosis.
Let’s start with non-critical coarctation of the aorta, which is frequently identified in childhood or adolescence. Symptoms are often absent, but some children experience epistaxis or leg pain with exercise.

Non-critical CoA5:44–6:43

Physical exam commonly reveals upper extremity hypertension, with a blood pressure gradient of more than 20 mm mercury between the upper and lower extremities.
Additionally, you’ll probably find diminished lower extremity pulses with a radial-femoral delay, and there might be a harsh systolic murmur at the left sternal border that radiates to the back.
Echo typically reveals juxtaductal coarctation of the aorta, often with left ventricular hypertrophy, which confirms non-critical coarctation of the aorta.
Next up is aortic stenosis. Patients with mild-to-moderate stenosis are usually asymptomatic, while those with severe stenosis can develop exertional chest pain, dyspnea, or fatigue.

AS6:43–7:54

Physical exam reveals a systolic murmur at the right upper sternal border that is softer with a Valsalva maneuver. There could also be a palpable thrill or a systolic ejection click.
Echo will demonstrate valvular, subvalvular, or supravalvular aortic stenosis and you may notice a bicuspid aortic valve as well as left ventricular hypertrophy.
These findings confirm aortic stenosis. Here’s another clinical pearl!
Supravalvular aortic stenosis is commonly seen in association with Williams syndrome, so be sure to look for phenotypic features of this condition, including a full face, broad forehead, rounded cheeks, and a depressed nasal bridge with anteversion of the nares.
Finally, let’s discuss pulmonary stenosis. If the stenosis is mild or moderate, patients are usually asymptomatic, but if it’s severe, patients may report fatigue, exertional dyspnea, or even syncope.

PS7:54–9:20

Physical exam findings include a systolic murmur at the left upper sternal border radiating to the back, and you may detect a palpable thrill.
You might also hear a loud S1, a split S2, and a systolic ejection click that varies with respiration. Echo will demonstrate a stenotic pulmonary valve, often with right ventricular hypertrophy.
With these findings, diagnose pulmonary stenosis. Although this condition is usually acyanotic, newborns with severe pulmonary stenosis can present with profound cyanosis, due to right-to-left shunting at the atrial level.
Time for another clinical pearl! Pulmonary stenosis is commonly associated with Noonan syndrome, so be on the lookout for characteristic features of this condition like hypertelorism, ear abnormalities, downward-slanting palpebral fissures, micrognathia, webbed neck and pectus carinatum or excavatum!

Increased pulmonary blood flow9:20–9:42

Let’s switch gears and discuss patients with increased pulmonary blood flow. In this case, consider lesions associated with a left-to-right shunt, meaning atrial, ventricular, and atrioventricular septal defects as well as patent ductus arteriosus.
First up is atrial septal defect, or ASD for short. These infants and children are often asymptomatic; however, if the defect is large, patients may develop fatigue and exercise intolerance.

ASD9:42–11:01

Physical exam reveals a systolic murmur at the left upper sternal border, with widely fixed and split S2. If a large shunt is present, you might hear a diastolic rumble at the lower left sternal border, which indicates increased flow across the tricuspid valve.
Echo findings of left-to-right flow across a defect in the atrial septum, often with right atrial enlargement, confirm the diagnosis of ASD.
Here’s a clinical pearl to keep in mind! A patent foramen ovale, or PFO, is a common and benign echocardiographic finding during infancy.
Although a PFO is not considered a type of ASD, this connection between the atria plays an important role in structural lesions associated with increased right atrial pressure.
In this setting, venous blood is shunted across the PFO into the left atrium, which results in deoxygenated systemic blood and cyanosis.
Let’s move on to ventricular septal defect, or VSD. Infants with small VSDs are often asymptomatic, but if the defect is large, patients can develop symptoms of heart failure, like dyspnea or difficulty feeding.

VSD11:01–11:55

Physical exam usually reveals a systolic murmur at the lower left sternal border. Small muscular defects classically produce loud, high-pitched, early systolic murmurs; but larger defects produce murmurs that are softer, medium-pitched, and holosystolic.
You might also notice signs of heart failure, like tachypnea and hepatomegaly. Echo will reveal a perimembranous defect or a muscular defect in the ventricular septum, and some patients might have biventricular hypertrophy.
If you see these findings, that’s VSD. Next up is atrioventricular septal defect, or AVSD.

AVSD11:55–13:46

After pulmonary vascular resistance decreases around 1 month of age, these patients commonly develop symptoms of heart failure such as poor weight gain and difficulty feeding.
Physical exam usually reveals a murmur at the left lower sternal border. Either a systolic ejection murmur, or a holosystolic murmur from the VSD.
You might detect a diastolic rumble. There’s usually fixed splitting of S2 and signs of heart failure, like tachypnea and hepatomegaly.
Since AVSD is commonly seen in Down syndrome, you might notice characteristic features like upslanted palpebral fissures, epicanthal folds, flat nasal bridge, protuberant tongue, and a single palmar crease.
Lastly, echo reveals a defect of the AV septum, a contiguous ASD and VSD, a common AV valve, and possibly biventricular hypertrophy.
These findings confirm the diagnosis of AVSD, which was previously called atrioventricular canal or endocardial cushion defect.
Here’s a final clinical pearl! Total anomalous pulmonary venous drainage is a cyanotic congenital heart lesion in which the entire pulmonary venous return drains to the right heart structures.
However, in partial anomalous pulmonary venous drainage, 1 or more pulmonary veins drain to the right atrium or the vena cavae, and 1 or more connect to the left atrium.
This condition isn’t associated with cyanosis and typically presents in late childhood with symptoms similar to those seen in ASD.
Let’s finish with patent ductus arteriosus, or PDA for short. These infants are usually preterm and can be asymptomatic if the PDA is small, but may develop difficulty feeding if the shunt is large.

PDA13:46–14:31

Physical exam reveals a continuous, machinery-like murmur at the left upper sternal border radiating to the back, with bounding peripheral pulses.
Infants with large shunts commonly display signs of heart failure like tachypnea and hepatomegaly. Echo findings including PDA, and possibly pulmonary overcirculation confirm the diagnosis of PDA.

Review14:31–15:22

Alright, as a quick recap… Acyanotic congenital heart disease refers to structural heart lesions that don’t cause significant oxygen desaturation or cyanosis.
If your patient is an infant with signs of shock, consider critical left ventricular outflow obstruction, like critical aortic stenosis or coarctation of the aorta.
For stable patients, order an echocardiogram and assess the pulmonary blood flow. If it’s normal or decreased, consider obstructive lesions, like non-critical coarctation of the aorta, and aortic stenosis or pulmonary stenosis.
However, if pulmonary blood flow is increased, consider lesions associated with a left-to-right shunt, such as ASD, VSD, AVSD, or patent ductus arteriosus.